New Vintage Audio Restoration HQ

[Michaels HiFi]

This is the unit I paid $100 to an EE to get running and he failed to get it running.

After I spent some time with it, poking around, and changing some things, this happened.....

 

[atmasphere]

This is the unit I paid $100 to an EE to get running and he failed to get it running.

After I spent some time with it, poking around, and changing some things, this happened.....

Most of the tube testers I've seen have had really minor problems, mostly due to age. Some of them are difficult just because of figuring out how to use them (especially older ones like this)!

 

[Michaels HiFi]

Most of the tube testers I've seen have had really minor problems, mostly due to age. Some of them are difficult just because of figuring out how to use them (especially older ones like this)!

It's interesting, starting to deal with these things I feel like I learned there are different ways of looking at this gear.

I think there is traditional electronics fixing and then what I'm calling "vintage" electronics fixing. It's almost two different ways of looking at the electronics and fixing potential problems.

For instance one of my testers I received would not read 45 tubes. I think many would open up the unit and start trouble shooting (I would have). My old tube buddy friend (he used to work on tube testers in the Navy) instead had me simply stick a pipe cleaner sprayed with QD cleaner in the 4 pin socket on the tester without opening anything.

Bingo, it worked wonders.

I bet with everything you've worked on you approach it a similar way.

 

[atmasphere]

It's interesting, starting to deal with these things I feel like I learned there are different ways of looking at this gear.

I think there is traditional electronics fixing and then what I'm calling "vintage" electronics fixing. It's almost two different ways of looking at the electronics and fixing potential problems.

For instance one of my testers I received would not read 45 tubes. I think many would open up the unit and start trouble shooting (I would have). My old tube buddy friend (he used to work on tube testers in the Navy) instead had me simply stick a pipe cleaner sprayed with QD cleaner in the 4 pin socket on the tester without opening anything.

Bingo, it worked wonders.

I bet with everything you've worked on you approach it a similar way.

Its been different over the years. It used to be that when restoring an old radio or tube amplifier all you had to do was replace filter capacitors. These days you have to go over the whole thing because so may coupling caps have rotted and resistors are miles off value.
In this amplifier

oddly, all the coupling caps were good, but nearly all the resistors had drifted off value. Its worth noting that this amplifier had sat for decades in a warehouse in Canada, unused. Allegedly was NOS and came with the paper covers for the transformers a bit rotted but still intact. So my surmise is the resistors drifted off value without any use. But the amp is 68 years old. A lot of corrosion can occur in that time...

 

[Michaels HiFi]

Making progress.

I've not got it powering up so I'm working more on the super stiff pot.

You can see it in this pic with a temp knob on it.

I decided to turn the multi-layer switch upside down and that helped me see part of the problem - the wiper on the underside of the top most layer was corroded and such.

So I hit that with some DeOxit and a pipe cleaner to scrub it clean a bit and have been turning it till my fingers are sore.

I also hit each layer where the shaft goes all the way though with a drop of Kroil and will let that sit over night.

Then I'm going to check the resistors to see if they have drifted over time.

 

[atmasphere]

Making progress.

I've not got it powering up so I'm working more on the super stiff pot.

You can see it in this pic with a temp knob on it.

I decided to turn the multi-layer switch upside down and that helped me see part of the problem - the wiper on the underside of the top most layer was corroded and such.

So I hit that with some DeOxit and a pipe cleaner to scrub it clean a bit and have been turning it till my fingers are sore.

I also hit each layer where the shaft goes all the way though with a drop of Kroil and will let that sit over night.

Then I'm going to check the resistors to see if they have drifted over time.

View attachment 35370
View attachment 35371
View attachment 35372

The switch doesn't look bad at all!

 

[Michaels HiFi]

The switch doesn't look bad at all!

It's slowly getting better thankfully.

The main wiper arm is a double wiper arm and sits about a 1/4 inch right under the black faceplate (you can see it partially in the first pic).

Hopefully after tonight's cleaning it will be good to go.