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Voice of Music Tri-o-matic Model 560A Issues
Hello Everyone, today a buddy of mine over at one of the local flea markets had purchased at auction a Voice Of Music Tri-O-Matic Consolette Model 560A and he let me work on it for him so he could eventually sell it in his shop, anyways when I took the unit apart I noticed it was full of Helicopters (maple tree seeds) and other kinds of yard debris which I'm not sure how they got in there except maybe a mouse tried nesting in the unit at some point and used the helicopters and other yard debris as nesting materials (I'm suspecting this record player may have been stored in a back yard shed or a barn.) anyways when I got the unit cleaned out with the vacuum and replaced a gassed 12AX7 and a shorted 5Y3GT tube I fired up the unit to see if it worked or not and sure enough every tube in the record player glowed except the 12AX7 tube so I'm guessing it has a loose wire or two on the 12AX7 socket that needs to be reattached for the heater or something (this unit has a power transformer so it was apparently a higher end unit and it has push-pull 6V6s in the amplifier stage which also tells me this must of been a higher end unit.) The unit is a Hi-Fi record player (mono but hi-fi mono as its got 3 speakers in the cabinet which would explain the push-pull 6V6s) anyways I was wondering what wires could of possibly came loose on the 12AX7 socket to cause it not to work anymore (the non-functioning 12AX7 explains why I had no audio through the record player when I tried to play a record on it.)
Any help would be appreciated. -Levi EDIT: I just noticed that there's a 220k Ohm Resistor and part of the tuner input wiring that seems to be disconnected from somewhere in the circuit but not sure where and the schematic in the bottom of the cabinet isn't of much help (it seems that its supposed to connect to pin 2 of the 12AX7 socket according to the schematic, but when I look at pin two of the 12AX7 socket it doesn't look like anything broke off of it) some help is needed here concerning the no audio output issue when trying to play a record and a non-glowing 12AX7 tube issue. Thanks. Last edited by Captainclock; 08-16-2015 at 08:15 PM. |
#2
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Is that the only 1st amp tube before the output tubes. One section would be the 1st amp and the other, the phase inverter. As of now, don't worry about the 220K resistor, until you resolve the 12AX7 heater problem. |
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anyways like I said I'm really not sure as to what could be causing the 12AX7 to get no power because its got all of the connections to the socket intact from what I can see... EDIT: Just noticed that the 12AX7 tube socket is suffering from Cadmium corrosion (where the Cadmium Plating they used to plate the contacts on the tube socket turns into a fine yellowish colored powder on the socket) I wonder if that Cadmium corrosion is what's causing the 12AX7 tube to not work right. Last edited by Captainclock; 08-16-2015 at 10:36 PM. |
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Clean the socket and tube pins, and if that don't work check the voltage at the heater terminals of the socket (wires can go open and cold solder joints can stop the flow of current so just because it is connected don't assume the connection is infallible).
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
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Also hw should I go about cleaning the socket? I don't really have anything small enough to get down into those socket holes, and I don't have any de-oxit on me right now. |
Audiokarma |
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Checking voltages, you have to have the amplifier powered on. If you want to be sure that there wont be further damage to other components, remove the rectifier tube, probably a 5Y3. |
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If you are seeing 104 volts on the fimamant pins...it is some sort of bias applied to the line. That is NOT the filamant voltage...it should be either 6.3 or 12.6 volts AC_-NOT DC..ACROSS the filamant....NOT to ground.
I had to help someone working on a commercial clothes drier today...the heater would not come on. he had measured 120 volts AC--to GROUND on EACH heater pin...but he did NOT realize...you have to measure ACROSS BOTH PINS..to get the right reading of the supply to the element !! He had chenged nearly EVERYTHING...the element..thermostats, limits, even motor and centrifiigual switch....STILL no heat. It took me maybe SEVEN minutes...to find an open switch on the timer. Measuring ACROSS the element reveeled NO voltage... and when the timer switch was bypssed FULL heat began to work fine !! he just said "I have trouble reading diagrams" and i let him know...I have known how to read diagrams since about TEN years old !! This guy has worke don this stuff since I was a CHILD...not really SURE HOW one can effectively repair things like this... WITHOUT knowing how to read a SIMPLE diagram...for a MECHANICALLY controlled clothes drier? SO..my point is measure ACROSS BOTH pins --to see if you are getting filament voltage...and likely it will be AC. It iS possible that it is a seperate DC supply....but nOT likely on that cute little amp. I have a couple of those nicely-built players myself. One was a goodwill purchase for a long time ago...the other I think I got at an auction for nearly nothing some years back... |
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