1961 Grundig Majestic.jpg 52.13 KiB Viewed 5327 times Last September I paid $900 for this beautiful looking and sounding 1961 stereo. Everything on it worked and it came with all the original documentation. It even had the original microphone for recording on the reel to reel. I was aware a mechanical antique such as this would require upkeep, but like anything made prior to the advent of planned obsolescence I expected it to be somewhat reliable. Within one month the volume output was halved, and by the start of November it didn't produce any sound at all.
Model: Majestic Musical Instrument 7028/USA - Grundig Radio-Vertrieb, RVF, Material: Wooden case: Shape: Console, Lowboy (legs: 50%). Dimensions (WHD) 800 x 820 x 410 mm / 31.5 x 32.3 x 16.1 inch: Notes: The Grundig Majestic Musical Instrument Model 7028/USA is an AC operated FM-BC-SW 9 Tube Receiver with 4 Speed Automatic Record Changer.
I made a call to the repairman who had previously worked on it (one of only two service providers within a two hour drive,) and set a time for him to come out. He arrived and quickly determined the speakers were blown, which struck me as odd as I don't listen to loud music. He also said the tuner should be rebuilt as well stating he'd recently rebuilt the amplifier in the unit, and though somewhat expensive if I chose to have him do so it would sound 'better than new.' He gave me an estimate of $550, and because I love my Grundig I told him to go ahead. He gave me a time estimate of one month.
One month comes and goes and I don't hear from him. Five weeks and silence. Finally at the end of the sixth week I call the number on his business card and his wife answers, and after explaining the situation to her she assures me he'll call. I wait another week and call the number again and l reach his voicemail where I leave a message, Nothing. Another week and I leave another message, he's now taken twice as long as his estimate. He calls back within an hour, and tells me he sent the speakers out but they 'did a bad job' and he had to resend them, furthermore says his parts distributor is foot dragging.
He never apologizes for taking twice as long as his estimate nor failing to return my calls. He blames everyone else for what's going wrong, then tells me he estimates another month to complete the job. I call him next weekend for a progress report and get his voicemail where I leave a message. There's no reply. The following weekend I call again, and again get his voicemail.
Amazingly he call two hours later and tells me the job is done and he'll be by next weekend. Saturday rolls around and he shows up, then explains his estimate was a little low and the total is now $655. Awesome, he's charging me a late fee I think to myself as he commences reassembling the unit. After 45 minutes I hear my stereo. 'It's alive!' I say, to which he replies 'Kind of.'
Another 45 minutes goes by and now he's having a full conversation with himself. I'm unhappy with this guy so I stay in my bedroom, from where I start hearing POP! Coming through the speakers at full volume as he punches the push button selector on the tuner. 'Isn't that bad for the speakers?' I inquire, to which he merrily responds 'Yup!!'
I close my bedroom door wondering if this is really happening. Twenty minutes later there's a knock, so I open the door and am informed he can't 'figure out what's making that noise,' so he'll have to take all the components back to his house for what he calls 'round two.' I tell him I'm about out of money, and that I've almost paid twice what the unit is worth for a broken stereo, and that I'd appreciate it if he can finish the job inexpensively.
I'm appalled, and when all is said and done if the stereo breaks down again within 4 to 5 months I'm going to take it out to the Black Rock Desert and blow it up-only kidding (sort of.) For the price I'm paying the guy I would expect him: 1. To answer or return my calls in a timely manner. Return with a working stereo. I don't understand why he didn't thoroughly test the stereo at home to make certain it would work before transporting it all the way to my house. If he had 'restored' the unit shouldn't it have worked immediately? Can someone tell me if I've been taken for a ride, or is $655+ a reasonable price to restore a tuner and a couple of speakers? Is there's any way I can look and see if he's rebuilt the tuner and speakers?
I've got a feeling the guy can't be entirely trusted. Obviously I'm going to require a detailed, itemized invoice from him with replacement parts and associated labor.
Any feedback or comments gratefully appreciated, Greg Allen Last edited by on Feb Sun 22, 2015 10:17 pm, edited 3 times in total. You already know the answer to this.
The best thing to do is to remove the chassis and speaker drivers with associated components, and ship them to someone who knows what they are doing. Whether they can undo the damage already done, remains to be seen, but obviously this guy doesn't have a clue. You might be lucky to find another repair guy nearby that knows what they are doing. This one doesn't.
As far as getting your money back, good luck. German sets take a special tech as they are not the easiest things to work on. What a story. If 'round two' doesn't pan out, I would definitely try to find a more competent repair person. You've already paid an extremely top dollar amount for this radio (although I must admit it looks gorgeous), and the repair bill is absolutely outrageous! (Especially for it not to have been thoroughly bench tested for functionality before being returned to your house!) I hope you made an agreement with the repair person that he is not to charge you any more for the second round of repairs. I'm not sure if you agreed on any guarantee of his repair work, but if his work is shoddy, that shouldn't be coming out of your wallet.
Do you have any evidence that the speakers were actually replaced with new ones? When I replace large components, I like to show them to the person as evidence of work done. I've had issues with two things on these German made sets that tend to effect the audio output: dirty contacts on the pushbutton controls, and bad or intermittent wirewound resistors in the audio output stage. To me it sounds like you have a case of dirty controls, dirty tube sockets, or something of the like. I'm not sure which model of radio you have, but I couldn't see charging more than $400 for a complete electrical restoration on something like this.
I'm sure other board members will chime in shortly. After round 1 I would cut my losses and not use this guy for round 2.
I seriously doubt both speakers were 'blown' and from your experience there is no reason to expect the outcome is going to be better. Yes, sometimes things go wrong with a repair outside of the restorers control. Several years ago I went through a pair of Drake C line twins for a friend and a week after he got them a 6HS6 developed a short, fortunately no collateral damage. But delays, excess charges without informing customer in advance, and the behavior you saw at delivery are all big red flags. Get it back while it is still all there and use somebody else. I wish I felt differently but I have found the 1960s vintage German radios a nightmare.
Their switching assemblies are complicated, prone to collecting debris and by now are becoming problematic. Their hybrid tube/transistor designs use printed circuit boards that attract residues, easily carbon track, yield flaky tube socket pin connections and when applying the least amount of low wattage heat to unsolder, tend to lift far easier than even the junk cranked out of Asia. I no longer work on Grundigs, Nordmendes or Telefunkens. Documenttion is awful for these Europeans and simple troubleshooting isn't as simple as those who've never worked on these things think ('H-m-m-m, is this the 'rot' wire or the 'gelb' wire?' Very often just identifying what the parts ARE (because they sometimes use different body styles on their components) require laborious line-by-line tracing out of all-too-often crappy documentation. I don't condone your repair guy's unresponsiveness but he probably should be cut a little break. Until you dig into one of these beasts and start pealing back the layers of problems, you have no idea how the problems set up a tag team of frustration.
What appears as a simple repair job becomes a protracted parade of unanticipated problem. Tell him you want him to communicate with you but cut him a little break.
By the way, depending on the version of your Majestic.the stereo portion may only apply to the phonograph. The 'stereo' on many of those models have nothing to do with their FM circuits.
Greg, The repair charges are beyond ridiculous! Stop dealing with the jerk!
There is no real mystique in restoring German radios of which I have a couple of dozen, including some really esoteric sets, such as the top of the line 14 tube Saba Freiburg models, which are considered rather difficult. Nevertheless, they are all doable and if you were located anywhere near my place, I would fix it for you for nothing except for the cost of a couple of parts that may need to be replaced. George G. Within one month the volume output was halved, and by the start of November it didn't produce any sound at all.
I Here is where the trouble started. A 54 year old radio like this one should never be returned to a consumer (you) without a full restoration. You never plug in an old radio. Scenario: You buy it, then seek a restoration shop, who will return it to you with a performance warranty. During your month of deteriorating usage, possible expensive damage was occurring. If you wanted to ship the record player, tape deck, radio chassis, and raw speakers to a company for service, first you would have to find a competent technician to disassemble it and mount the parts into a shipping case.
Those sets are best shipped by a furniture mover in the cabinet, after securing it for shipment as described in your owners manual. I worked on those sets in the 60'. They always were brought to the shop in the cabinet. Covered by a shipping rug, like piano. We did jut fine with sets that arrived all the way from Germany to Vancouver BC.
I suspect your radio first came to Grundig Majestic in the USA first, then onto retailers. At that time there was a network of service shops. I knew how much it cost to run a service shop in the 60's. Back then all the parts were available.
The imported radios were needful of specialists back then all up the line, buyers, shippers, sales staff, and to a certain extent customers de VE7ASO VE7ZSO Amateur Radio Literacy Club. May we help you read better. Greg, post a picture of your Grundig. I have one and it sounds like yours is a dual chassis model. My speakers also blew. They have the flimsiest foam surround that just crumbles and it is not like modern surrounds but rather a VERY open cell foam.
It is indeed a mechanical and electrical nightmare. I've been playing with mine since the mid 60s. I was fortunate enough to pick up a second unit for parts at an auction a few years back. Yes, the buttons are a huge source of trouble. Cleaning and 'exercise' keep them in good shape. The FM is up there with the better units and the low end sounds just seem to 'fall' right out of the bottom of the set.
A very satisfying sound. I hope you find someone more competent AND reasonably priced. Jim seems to Never met a Philco I didn't like!
The set should have been entirely rebuilt if it had not before. The Achilles heel of any old radio are the capacitors which dry out and can cause all kinds of problems.
As far as 'The speakers blew', well you said that the sound gradually faded and then no sound? Even if the speakers blew you should have heard. Maybe not a good sound but sound nevertheless. The piano keys in these have to be very clean. I have probably 10 total of these German sets and they work great only if those switches are nice and clean. This is just my opinion.
But if you were charged $900 for the set then first of all, that is a HUGE premium over what such sets generally go for. At the very least the first repair should have been free. A set that was 'supposedly' refurbished SHOULD work.
1 month is a short time for a restored set to have major issues. Is there's any way I can look and see if he's rebuilt the tuner and speakers? I've got a feeling the guy can't be entirely trusted. Obviously I'm going to require a detailed, itemized invoice from him with replacement parts and associated labor. You would have to open it up to see which new components he installed. Depending on where you live, you might be able to track down a generous hobbyists (perhaps at a radio club) who can at least advise you on how to find a competent repair person locally to get this beautiful set working again. I'd also be interested in knowing the 'who' and 'where' about this situation.
Although in my opinion, $655 ish isn't an unreasonable price - if that's a complete re-cap, mechanical fix, and alignment. If he just did 1 or 2 things and is charging you at an hourly rate, you're being sorely ripped off.
I agree it looks like an SO 191, I have one that's been in my shop for a little while and it's going home on Sunday. Easier to work on than most German stuff I've touched, actually - the dual chassis design meant all 14 tubes weren't crammed into one place, so it was decently accessible though.
From what i can see, even if the set was troublesome with some surprise issues, he has poor working practices and business practices. To stay with him in hopes of getting your moneys worth out of him is fantasy to say the least. Honestly, if it was my radio that i loved to listened to all the time, and he was punching the buttons at full volume like that, i would've shown him the door and given him a swift kick in the derriere on the way out! It's a costly lesson but what if it gets to a point and he says'sorry, i can't fix it' because of something he did? Dwayne.
Superhet with RF-stage; ZF/IF 460/10700 kHz Wave bands Broadcast, 2 Short Wave plus FM or UHF. Details Changer (Record changer) Power type and voltage Alternating Current supply (AC) / 110 / 220 Volt Loudspeaker 5 Loudspeakers Power out from Radiomuseum.org Model: Majestic Musical Instrument 7028/USA - Grundig Radio-Vertrieb, RVF, Material Wooden case Shape Console, Lowboy (legs. Hi Glenn, It looks like this must be the unit that has your Perpetuum-Ebner turntable in it. Just a quick pointer on how to start a new thread like this: Always go to the model page for the specific radio you have a question about. In this case, that is, but you can also find it by a search from the home page. To answer your question, looking at the schematic, it appears that the power to the turntable goes from the power cord through the main power switch for the radio chassis (but not through the fuse for the radio) and then to the turntable via two pins of the speaker connector. Check the main power switch with an ohmmeter to make sure it closes properly.
If that switch is OK, then check the power wiring for the turntable going through the speaker socket and a special 0.5 amp fuse for the turntable. Since you mention that the whole unit is dead, also check the fuse for the radio chassis. Have you done any work on the radio chassis yet, such as replacement of electrolytic capacitors? The have a high failure rate at this age, and if one of them shorts, it could blow the radio chassis fuse. Tom Glenn Pride 03.Mar.14 3. Tom: I have replaced the tuner fuse.
That is the first thing i checked. It had no effect. I will check the switch and look for the special fuse for the turntable. That should tell me if the power supply is bad or not. I have not did any work on the caps.
I was able to get it to fire up, knowing I was probably on borrowed time. I suspect that I did blow a cap during my turntable witch hunt. Before I get too deep, I am new to AC circuits.
So, do you have an recommendations for tools, and books that i can get up to speed. I know I need to get a 1000Ohm resistor to drain capacitors for safety. I understand what the components do like resistor vs. Capacitor etc., but typically not in a AC setting. I have a Heathkit TC-2.
I tested 3 tubes 2 EL95s and one other. When i put the tubes(Two EL95 6DL5s (I do have a valid chart) ) the needle does not deflect to either good nor bad. I am new to this technology, so for this type of tube I don't know if that is normal. However, One of them shows a glow briefly where the heater pins are connected, the other nothing. I am trying to figure out if that (the tubes) are inline to prevent power to go to the turntable. In reading the schematic, (which is more like guessing) it looks like at some point power is diverted to the turntable and tuner, but i am not clear if the EL95s are prior or post that split.
First thing first, I am going to have to get the chassis out into the open so that I can access the components. Thomas Albrecht 03.Mar.14 4. Glenn, On tester, the tube filaments sould light, and except in fairly rare circumstances, the meter needle should deflect. Do you have confidence that the tube tester is working properly? In any case, the tubes should not play any role in whether power reaches the turntable. Check the main power switch next. This is a fairly complex radio for a beginner.
To get some knowledge of radio circuitry and radio servicing, I'd recommend the following books, which do a good job of making the technology accessible without too much abstract theory or math: Elements of Radio by Marcus and Marcus (best place to start) Elements of Radio Servicing by Marcus and Levy You can find these as used books online, and you might even find a downloadable copy online. Tom Glenn Pride 03.Mar.14 5. Tom: Yes I realize that I picked a fairly complex radio.
The encouraging part was that it was working. So, for me getting to a root cause will be great and an excellent learning experience. I also, have options if things get too complex for my skills. I have inquired to a local shop to check to see if my tube checker is accurate and working properly. So, if you are willing to point me to some common component problems, I can figure it out. Just want to avoid getting hurt in the process.
Thanks for the problem solving so far. I really appreciate it. Thomas Albrecht 03.Mar.14 6. A good first exercise would be to use an ohmmeter to check wiring and switch continuity from the power cord to both the turntable motor and the primary of the power transformer on the radio chassis. You can do this without powering up the radio. In general, once the radio has sat without power for several hours, it is safe to work on, even if you have not taken any explicit step to discharge the electrolytic capacitors in the power supply. If you want to be very certain, however, just use a simple wire to momentarily short between the two terminals of any large cylindrical electrolytic capacitors (do you know how to identify them?).
Then they will definitely be discharged. Basically what you're looking for is to show that the circuit is complete, starting from one prong of the power cord, through the switch, through the turntable motor fuse, through the turntable motor, and back to the other prong of the power cord. Likewise, you should see a similarly complete circuit through the switch, the radio chassis fuse, the voltage selector switch, and through the primary winding of the main power transformer back to the other prong of the power cord.
Are you familiar with how to do continuity checking with an ohmmeter? Try and see if you can understand how the wiring you're observing on the radio chassis and turntable relate to what you see on the schematic. Do you have the U.S. Grundig-Majestic version of this radio, or do you have the German version?
The language of the labeling on the front panel should make clear which you have. The Sams schematic available here at RMorg for the U.S. Version is a little easier to read than the schematic available for the German version. The Sams schematic also appears to include more explicit information about how the turntable power is wired.
Glenn Pride 04.Mar.14 7. Typically it's necessary to remove the knobs from the front, and then there are four or more screws holding the chassis from the bottom. Speaker wires may need to be temporarily removed (desoldered or unplugged), the antenna unplugged, and the tuning eye (if present) may need to detached from the front panel if it is not mounted directly to the chassis. These are just general guidelines for typical German radios. Yours may be a little different.
Someone with specific experience on this model may be able to provide more tips. Glenn Pride 09.Mar.14 9.
Tom: I have successfully removed the chassis from the cabinet. However, I had to disconnect the turntable and will not be able to reconnect unless I put it in close proximity to the cabinet. So, at this point I can only diagnose the tuner, until I can wire up the turntable. Ok so here is what I have done. I put the ohmmeter on the connector to the main power.
I perceive this as testing the tuner circuit. I originally got a a resistance reading, then I didn't. I powered it up, and actually for a few moments it was working then not. I did then a stupid thing. With the power on I reconnected the multimeter and got a spark. I blew my variac fuse, and a spark took a bit of metal out. I went on continue to receive open circuits.
G G Thomas Albrecht 09.Mar.14 10. You were on the right track using your multimeter to take a resistance reading across the power cord. When everything is proper, you should get a resistance of somewhere in the range of 1 to 20 ohms with the power switch turned on, and infinite resistance with it off. Check to see if your multimeter still works properly. If you leave it on the resitance setting when votlage is applied, the meter might be damaged, but most likely not.
When voltage is applied, the meter needs to be set to read AC volts. The power cord, power switch, radio chassis fuse, and the primary winding of the power transformer form a simple loop circuit. Use your ohmmeter to check this element by element and you will find which one is intermittent or open circuit. Once you get to the point that the radio powers up properly, you'll want to replace the electrolytic capacitors and many of the paper capacitors. Since you're a beginner at this, be very careful. Keep your hands out of the circuitry when power is applied. If you want to probe live circuitry, a good approach for a beginner is to use alligator clips to connect your meter probes to the points you want to measure with the power off, and the apply power without having to hold any probes in the live circuitry with your hands.
Glenn Pride 18.Mar.14 11. Hi Glenn, That particular capacitor is part of the speaker system crossover network.
If that capacitor is open, the midrange speakers won't have any sound. If that capacitor is shorted, the midrange speakers will carry bass content along with the woofer. You can replace it with two 10 uF 50 V non-polarized capacitors in parallel from your local Radio Shack. You can likely also find a 20 uF 50 V non-polarized electrolytic from one of the many electronics mail order places like Digi-Key or Newark. Note, however, that that particular capacitor failing wouldn't be responsible for blown fuses or other power supply problems, so you may have some additional problems to troubleshoot. Glenn Pride 18.Mar.14 13. Glenn, Although the speaker wires and the turntable power happen to go through a common connector, their circuits are independent, so the speaker crossover capacitor will play no role in whether power is applied to the turntable.
To get started with your troubleshooting in a concrete fashion, let's take a look at some specific parts of the power supply circuitry. From what you've said above, it sounds like the complete unit is totally dead right now - there is no evidence of anything really being powered up when you plug it in and turn it on.
Please get the first schematic page from the model page (which is the left hand side of the Sams schematic, and says page '5' at the bottom). The first thing we want to check is the circuitry carrying power from the power cord through the power switch and fuse to the primary winding of the main power transformer.
If you look at the middle of this schematic page, you see the following: - the power cord has an interlock connector - there are two RF chokes L34 and L35 (basically for noise suppression) - there is a fuse M2 - there is the main power switch M18 - there is the voltage selection switch (marked with two positions '220 VAC' and '110 VAC') - there is the primary winding of the main power transformer T1, with three connections labeled 'BLK,' 'GRN,' and 'WHT.' - there are wires U and V going to the speaker socket (carrying the power to the turntable motor) By tracing the route of the wires yourself, and by looking at the pictures in some of the other Photofact pages you can download from the model page, try to find every one of the components mentioned above, and then start by testing them individually: - The interlock should show a low resistance from the plug prongs of the power cord through the contacts of the interlock. Resistance should be less than 1 ohm. Both chokes should have very low resistance, probably less than 1 ohm - The fuse, in its holder, should have very low resistance, less than 1 ohm. This is a high failure rate area; the contacts on the prongs of the fuse holder are often oxidized and the fuse makes poor contact. If you see high resistance, first check that the fuse is good, and then try scraping the fuse holder contacts until you see a reliable reading of less than 1 ohm between the connections of the fuse holder. The main power switch should show less than 1 ohm across it when it is turned on, and infinite resistance when it is turned off.
This is another high failure rate component, and may be failing to turn on. If the switch doesn't work, you can bridge a wire across it for now, so the radio is always turned on (temporary fix). Check that the voltage selector switch is set to the 110 VAC position, and that there is less than 1 ohm of resistance across that pair of contacts. Check the resistance of the primary winding of the main power transformer. When the voltage selector switch is set to 110 VAC, you are using the part of the winding that is between the black and green wires. The Sams schematic tells you the resistance between these two wires should be 9 ohms. Confirm that this is correct (it doesn't have to be exact; it might read somewhere in the 8 - 12 ohm range).
This can also be a point of failure. If the primary winding of the main power transformer is open (infinite resistance), you will have to replace the transformer. If each of the above tests good, then try testing the entire circuit loop, starting from one prong of the power cord plug and measuring its resistance to the other prong. If the power switch is on, this should show basically the resistance of the primary winding of the power transformer, or around 9 ohms.
When the power switch is off, it should show infinite resistance. If the individual component checks seem OK, but the total circuit check is open, something's wrong in the wiring. You should be able to figure it out by observation, or by measuring resistance step-by-step through the circuit. For example, measure from one prong of the power cord through the following in sequence, and see where the circuit goes open: interlock connector, L34, fuse, voltage selector switch, transformer winding, power switch, and back to the other prong of the power cord.
If there's a problem, you will find it. Using the principles explained above, you can then follow the power from wires U and V through the speaker connector to the turntable. There will be more to address after these first test are done, but this is a good place to start. Glenn Pride 18.Mar.14 15. BTW, I really appreciate the effort you are taking with me to uncover this mystery.
I hope this is appropriate for the musesum. I find it really interesting. My goal is restore power and then replace the caps (i hope). I hope this is helpful for other members of radiomuseum, I am by no means a technologist, but am having fun. (I have marked my responses with gp Glenn, Although the speaker wires and the turntable power happen to go through a common connector, their circuits are independent, so the speaker crossover capacitor will play no role in whether power is applied to the turntable.
To get started with your troubleshooting in a concrete fashion, let's take a look at some specific parts of the power supply circuitry. From what you've said above, it sounds like the complete unit is totally dead right now - there is no evidence of anything really being powered up when you plug it in and turn it on.
Please get the first schematic page from the model page (which is the left hand side of the Sams schematic, and says page '5' at the bottom). The first thing we want to check is the circuitry carrying power from the power cord through the power switch and fuse to the primary winding of the main power transformer. If you look at the middle of this schematic page, you see the following: - the power cord has an interlock connector gp I have identified it. Black Left top, Red right bottom - there are two RF chokes L34 and L35 (basically for noise suppression) gp need to identify it - there is a fuse M2 gp Getting flow from interlock to behind fuse bracket. there is the main power switch M18 small black device and shows resistance - there is the voltage selection switch (marked with two positions '220 VAC' and '110 VAC') gp triple confirmed it is on 110 V. there is the primary winding of the main power transformer T1, with three connections labeled 'BLK,' 'GRN,' and 'WHT.' Hi Glenn, A few clarifications: When you press the 'off' button, the power switch is off.
When any other button is pressed, the power switch is on. To check the transformer primary winding, locate the green and black wires coming out of it. Then follow these wires to where they are soldered to something. That's where you can probe them and measure the resistance of the winding.
You should also be able to see that they are connected as shown on the schematic diagram. For all of the tests discussed in the last few posts, the unit should be unplugged. No power applied.
Glenn Pride 19.Mar.14 17. If you're mechanically inclined, try disassembling the switch and see if you can fix it. Sometimes you can; sometimes you can't.
If that route isn't going to be successful, I suggest simply bridging the switch by soldering a wire across it for now. That will mean the radio is always on when it is plugged in, and you can troubleshoot the rest of the radio. If you get the rest of the radio working, and you would like a working power switch, you'll have to get creative.
It might not be possible to find a modern switch that is a direct replacement (unlike most other components that have modern replacements that are easy to substitute). You can advertise to see if someone has a good one from a junker they can sell you. There might possibly be someone making a replica or substitute switch that you can buy. You can install a modern switch somewhere on the cabinet wall or back, bypassing the original switch. Or you can leave the internal switch bridged and use a power strip with a switch to turn the radio on and off. I wouldn't worry about implementing a final fix for the power switch until you get the rest of the radio (and phonograph) working. Glenn Pride 19.Mar.14 19.
Hi: Thanks Michael, I will take a closer look. I did some more checking last night on the transformer. I put my red on the black wires just behind the fuse, leading into the T1 transformer.
I then looked at the output of wires from the T1. I traced the blue to ground, and checked resistance. I got nothing. I traced the brown output towards the face of the stereo. I got nothing as well. The yellow I traced to the coupling and got 0 ohms as well. I also tested the leads across the 'microswitch' and it tested 0 ohms.
So, my next step is to bridge across the microswitch by removinng it out of the circuit, and see if the chassis powers up. I am guessing that i can just connect the two to cut the microswitch out of the picture. That will at least remove the question of the switch being defective or not. If it is the transformer, which seems a likely culprit.
What are my options for repairing it? Buying a new one? Getting the transformer rebuilt? Michael Watterson 20.Mar.14 23.
'nothing' is ambigious. An OFF switch should read infinity (open circuit), a kind of 'nothing'. An ON switch should read 0 Ohms (or very close), a different kind of 'nothing'. A transformer winding can be a fraction of an Ohm (winding for powering valve/tube heaters, or winding for a 3 Ohm to 16 Ohm loud speaker) or 50 Ohms (high power primary) to 1000 Ohms (very miniature transformer). The Primary to anode/plate of output transformer normally 100 to 500 Ohms (the 2000 Ohms or 4000 Ohms is AC load transformed from the 3Ohm to 16 Ohm speaker, never the DC resistance).
The HT Secondary might be 100 (large) to 500 Ohms (small) depending on power rating. Check any fuses and voltage selector switches. From the main switch mains wiring. 0 ohms means a connection 1 at left and blank not 000000 on rest of DMM usually means infinity or open circuit or more than 1M ohm on really cheap meter or more tnan 20 M ohm on more expensive.
If your fingers are sweaty and pressing on probes you can measure as low as 100K Ohm. Very dry skin and loose touch can be over 2M Ohm. Some models only switch one of the mains wires and others have switches in both wires. A DMM / DVM can get confused by inductance of Transformers and take a while to stabalise reading. Very high inductance chokes may need a PSU and ammeter or an analogue meter! Switching the DMM/DVM from Auto to manual and selecting the correct resistance range is a big help.
Thomas Albrecht 20.Mar.14 24. Glenn, Your switch may be OK. As both Michael and I have pointed out above, it should read close to zero ohms (less than 1 ohm) when it is turned on, and infinite resistance when OFF. Since you measured zero ohms across your switch, it was probably turned on, and that means it is fine.
On the transformer, as mentioned above, you want to measure the resistance between the black and green wires, and that resistance should be around 9 ohms, as indicated on the Sams schematic. Measuring resistance between the black wire and other wires will in most cases give an infinite resistance reading, and that is fine. Glenn Pride 20.Mar.14 25. All: I realize that 'nothing' is ambiguous. I was originally going to provide some photos to validate my transformer testing.
But they are quite dark, so you can't see what I wanted to share. What I did, was find at the back of the fuse a collections of wires both black and brown bundled to go into the T1 transformer. I placed my multimeter's live (red) to that connection.
There is another bundle of wires which travel to the T2 power supply, or somewhere else. I made sure there wasn't heavy oxidation that would block readings when I checked the connections. From the output of wires from the T1 transformer I traced Brown which goes toward the Ferrite antenna and Volume pot. I have switched to a new analog multimeter, as I became suspicious of my original multimeter, especially when measuring AC Volts. When I touched the black(MM) to the brown wire, i received no needle movement, no response, no ohms. Secondly, i traced the ground (blue wire), and received no response, no needle twitch, no ohms detected.
Thirdly, I traced the yellow wire, to the power coupling (suspecting it goes to the power the turntable) and also received no response, needle twitch, no ohms. What I cannot recall, is whether i had the M18 microswitch in off or on. I will have to make a matrix to check my combinations. There is still a chance for me to mess up as some of the wire colors have become oxidized and the area is quite small.
What I am going to do next is to take the red lead and place it on the interconnect. That way i know it will ultimately be in the 'correct' position to power a check. Then return to my matrix with the FM switch pushed to On, and then Off. At that point, I understand that I would not be able to eliminate the switch, but my method should I be able to determine if those two items in conjunction pull any ohms. (Perhaps this is your point, that 0 might be a valid answer) After that, I think I should bridge (by eliminating the microswitch and connecting the two wires together to see if the unit then powers up).
If so, it eliminates the T1 being the open circuit. If nothing happens, I can then contemplate replacing/repairing the T1. If i have missed anything or there is another option in this test to consider I am all ears. Thanks for all the help. Glenn Pride 23.Mar.14 26.The cap you referenced should be fine. You may need to get the clamp to go with it because the original is probably mounted to the chassis with metal tabs and the new one won't fit (unless that's the reason you're asking about the silicone adhesive).
Also, that cap has a separate negative terminal (not connected to the can) that will need to be connected to the chassis (where one of the original mounting tabs is probably soldered).,What do you have for a soldering iron that has such a 'chunky' tip? That might actually be OK for the soldering work you will probably have to do directly on the chassis, such as removing that old electrolytic can. For the smaller work, especially where you're in a tube chassis without a printed circuit board, I'd suggest a Weller SP-23 'Marksman' (they still make some version of it). It's a 25W 'pencil' iron with replacable tips (there are a few different types; I'd suggest a tip with at least one flat side) and it's fine for normal under-the-chassis work (it's also OK for the older PC boards with larger traces and pads if used carefully, but on anything newer I'd look for something smaller). Glenn Pride 27.Mar.14 33. Omer: Not sure what you mean by bypassing the capacitor. I was able to figure out that the switch on the chassis was broken.
I have bypassed that switch and the unit came back to life. I am now in the process of replacing my power capacitors. I have removed the first can, which was highly relunctant to leave. I am now in the process of figuring out which way to go on replacing the can. I have inquired at hayseedham to see if they could build me a cap with the same specs and connector.
I have also looked into to cutting the can and replacing the innards with a modern cap. But during the removal process the three tabs that mounted the cap got mangled.
I have tried to find replacement ones, but there aren't any out there. My best point of view is to see what the heyseedham folks come back with. I am open to suggestions. Would love to save the can, but I am not so married with looking the same. I just don't want to have to modify the chassis.
Newer cap mounts require screw holes to be drilled. Glenn Pride 02.Apr.14 39.are you talking about the voltage ratings? Most of the paper capacitors you can replace with 630V film caps (but note that C86 is rated at 1000V; you should stick with 1000V or higher for that one and I'd advise the same for C85). Also note that this is a fairly early Sams and it is somewhat inconsistent with the cap values; note, for example, that you have C81 shown as '220mmf' (220pF), but C85 is shown as '.00047' (that's 470pF) and C86 is shown as '.00082' (that's 820pF).You also have three smaller electrolytics in there (C2, C3 and C4).
You should also change those out. C2 is shown as 4µF but it's on a B+ line for the audio and eye tubes that carries about 200V, so I'd use a 4.7µF 450V for that one. C3 is a filter for the FM detector and shown as 10µF. Even though the schematic does not show a lot of voltage on that capacitor, the original is probably going to have a '70/80V' rating on it, so use a 10µF 100V for that one. C4 is the cathode bypass capacitor for the output tubes and is shown as 50µF, You can put a 47µF 25V there. (A bad C3 is going to cause audio problems on FM, and a bad C4 will cause low volume overall.) Glenn Pride 02.Apr.14 41.
The Mica are flat rectangular and paper tubular, though there are paper caps in similar rectangular cases, but they are not common and may not be faulty. There are also paper caps in large rectangular cans (0.1uF to 10uF depending on voltage), but mica caps are never physically much larger than 1cm x 2cm x 0.5cm. They can be 'naked', wax coated or encapsulated in a moulded case. Paper caps are not always faulty. Also Electrolytic capacitors can be reformed. I don't replace capacitors with out testing and considering circuit voltage as leaky paper caps may be fine at low voltage and low impedance.
It's rare that I haven't reformed Electrolytics. Of course I have to replace most paper types. Often I leave the chassis / earth end connected on decoupling parts and tuck the small modern part behind it. ONLY replace one at a time to avoid wiring errors! See The article by Ciardiello also shows photos of Mica and Paper types. Also on the schematic usually paper types are 1nf (= 0.001uF or 1000pF or 1000uuF) to 2uF.
Mica types are typically 5pF to 1000pF (large). I recently found a 1950s technical book which discussed paper capacitors. They were rated according to encapsulation with life estimates.
The best hermetic metal cap types had a 20 year rating and the cheapest waxed card case only 2 to 3 year rating. The manufacturers knew when they were fitting rubbish.
Non-metal (often military) cased tropicalised perhaps 10 years. My own experience is that the crumbly Hunts brand, soft waxed card and black 'tar like' case are usually useless. EMI (Marconi / HMV) at certain periods must have been using tropicalised parts as though card they often are not sticky wax but a hard sheen and often low enough leakage to be left in place except on Anode to Grid coupling. I've found that either all the metal can tubular paper caps are OK or all bad in a particular radio.
The paper (in early 1950s UK anyway) was not Wax or Oil impregnated but actually Petroleum jelly, i.e. The plates of course Aluminium foil. There are two leakage modes: 1) The paper is a poor choice and becomes leaky, perhaps due to contamination reacting.
2) The sealing isn't good enough and the paper absorbs water. Water does gradually penetrate wax and Petroleum jelly. Though of course modern candle (paraffin wax) is related to Vaseline as Vaseline is to paraffin (Kerosene). You can make the softer wax used to 'lock' cores or coat card capacitors (for replica cases on plastic film types) by blending Petroleum Jelly BP with cheap candles. Vaseline is just a more expensive branded product often with added colour and scent. Glenn Pride 03.Apr.14 45.
So, what i heard is that I need to inspect each capacitor and determine its type. There isn't a tell in the schematic numbers or the way that farads are represented that indicate whether it is electolyic,mica etc. I am trying to gather a list of problematic capacitors and replace them while I have the chassis out. If there is a good starting list of capacitors that immediately need replacing I would appreciate it and that would be my starting position for replacement. Since, I am new to classic radios and I picked a complicated one, I am trying to skim the surface and only deep dive when necessary or required.
After getting this up and running, I intend to get a simpler one to cut my teeth deep. Michael Watterson 03.Apr.14 46.
(note: Glenn and I have been discussing this via e-mail).I can now see why you are unable to reuse the original housing. I don't know if you would have been any better off using 450V caps instead of those 600V caps in terms of size and getting them to fit inside the can. But you definitely have the right idea. The one thing I would add is putting some shrink tubing on that solder joint where you connected the black wire to the two negative wires. Try to get the caps down as close to that base as you can and then use some RTV silicone to fill and secure the base. That will seal everything up, keep the wires from moving, and be flexible for vibration.
Once that is set, strip one of your green wires, fold it down against the base, wrap it around the base of the lug a few times and solder it. Do the same with the other green lead and the other lug. Now, you should be able to fold those negative leads down close to the caps and bring them together, then tuck them into that area between the caps.
Wait until you actually remount this assembly before you connect the black wire; then you'll do the same thing you did with the two positive leads: strip it, fold it down close and connect it to one of the mounting lugs. Once you have everything in place and hooked up, you might be able to find some large heat-shrink sleeving that you can slide over the caps and shrink down to cover them. (This is only a suggestion for a little extra neatness and not really necessary for function.).