1956 VM sound fading out??

[rob Cashin]

I have a 1956 Voice of Music 1285 Tri-O-Matic. It plays beautiful, i bought a new needle and cartridge for it, greased it up and it works great. It has been recapped recently so the old owner told me. Only problem is after about 15 min of being on, the sound starts to fade out and sounds like its being turned on and off. Ive been told its a tube going bad. I dont have a tube tester and ive found new replacements for it. a couple concerns, for the price of the 3 new tubes for it seems cheap, is that anything to worry about? And does it make a difference if i use GE or RCA tubes instead of genuine VM tubes? No idea if those exist either way. Any input helps, thanks a lot.

[Eric H]

It's unlikely to be a tube and certainly not all three of them, either way it doesn't matter what brand they are, VM never made tubes as far as I know, they probably just had them branded with their logo.

I would be more suspect of a bad connection somewhere between the cartridge and the Amplifier, it could even be a bad cartridge, it's fairly common for 50+ year old Ceramic cartridges (even new old stock ones) to start getting flaky.
Next time it fades out try tapping the tone arm around the cartridge with a Pencil and see if it cuts back in.

It's also possible that whoever recapped it forgot to solder a connection.

[Eric H]

One oter thought, if it fades in and out slowly it could be a tube losing it's heater, possibly due to a bad connection with the socket or a bad tube.

Look at the tubes when it fades out and see if one of them is not lit, if you see one that's out wiggle it gently and see if it comes back.

[rob Cashin]

the cartridge and needle is brand new. ive taken it apart checked for loose connections. everything looks ok. i talked with a friend of mine father, he used to work on tvs radios and phonos back in the 50's and 60s, he speculated a tube. i guess worse case ill be out 25 bucks if it isnt that. ill keep diggin. thank you.

[rob Cashin]

is it safe to grab it when its hot? i wouldnt think so? one of the tubes looks dimmer than the others, but i was told its nothing to accurately go by. it doesnt get dimmer, its just dim to begin with

[rob Cashin]

i tried jiggling them while it was playing and it plays but still fades in and out. boy is it hot in there too

[Eric H]

Is the Cartridge current manufacture or new old stock that may have been sitting around? Any original style cartridge for that player probably hasn't been made since the 1970's at best so they can still be bad just from sitting around.

Try this, when it fades out, touch the wire connectors at the cartridge with a finger, one at a time and not touching anything else that's metal (to avoid getting shocked) you should get a loud hum if the amp is working.

the dimmer tube is probably not a concern, all tubes do not glow the same.

[Username1]

I would go with a bad audio output tube, or rectifier tube....

Set comes on runs fine, then gets warm 10 - 20 minutes then is seems like the volume goes down, but you can turn down the volume and it plays a little clearer, turn it up, or turn up the bass and it seems to be cutting out on a thump... I had this on an old Emerson record player I had as a kid.

One of the tubes that provides power, or uses power (not the pre-amp stages usually) is using up the reservoir of electrons available. Either the output tube's cathode can't produce enough free electrons for the tube to conduct as much current as needed to provide clear sound. Or the rectifier tube is not passing enough current to provide the set with sufficient B+ at current drain requirements.... So B+ will be dragged down as the set heats up... So when the set begins to degrade in sound quality... What happens to B+ ? You can find it at the rectifier tube, 5U4 or at one of the posts on the multi-section cap.

[rob Cashin]

well, i took matching tubes out of a working zenith radio, let it play and it still did the same thing. so, im just going to get it re-caped, again.

[bob91343]

I am guessing the grid coupling capacitor to the output tube is faulty.

[radiotvnut]

From experience, I've found that just because something has been recapped does not mean that it was done with new production parts. I recently re-recapped a Hammond Leslie amp where someone had recapped it with a mix of orange drops and those horrible red '50's-ear plastic cased paper capacitors. I left the orange drops; but, those red things had to go.

I had a friend who was so tight that he wouldn't invest in new production capacitors. Instead, he'd use slightly less leaky paper capacitor chassis pulls to replace capacitors that were too leaky to function properly.

Oh, and one other thing to look for is bad soldering. I've seen plenty of recapped pieces of equipment where good capacitors were used; but, the soldering was horrible.

[holmesuser01]

I've seen amplifiers that had their capacitors replaced, and the repair guy managed to miss some. You need to pull the amplifier and have a look.

[Celt]

Old resistors can be intermittent too. Look for any that appear blackened or charred and replace.