1958 RCA VCR-244 Superheterodyne Console
- Thread starter Quick Cal
- Start date
Quick Cal
Active Member
As I said before, my repair guy hasn't touched something like this in many years. His line of thought is "If it aint broke, don't fix it",,,lol.
He checked everything with an oscilloscope and said everything was good. Except for the one bad cap that he changed. He checked the power supply caps and said they were fine.
I know this is just more of a job than he wants to tackle. And he's doing it for free. So I can't force him,,,lol.
I'm sure you guys might suggest another tech, or do it myself. But I can't afford to pay someone. And I don't have the skill.
But could you please explain to me just why you should change all the caps, or what ever other parts. My excuse is I'm new and ignorant. Is it more for a preventive measure. Or would there be any improvements that will be seen. Maybe I can convince him to do a little more,,,lol.
knockbill
Lunatic Member
Electrolytic, paper and wax caps have a useful life, they are well past that after 50+ years... Resistors also go out of value,,, both caps and resistors are very cheap, and modern replacements are much closer tolerance now than when the amp was built... Basically, its just cheap insurance, if you want to use it...
Quick Cal
Active Member
Do I have a tube problem? Tom thinks I do. If you look at the pic below this is the bad 6bq5 that was replaced. It was glowing really red between the lines. Tested bad on a tester.
So I put in one different used tube. Things are much better.
Now I'm occasionally get some slightly red glowing in that center section of some of the 3 6bq5's. Is this normal. Tom says they are biasing correctly. That the right and left channel's are equal, but the bass channel is by itself. All have proper measurements.
If we move them around to different positions different things happen. Sometimes they glow brighter than others.
Toms thinking I should get some matched tubes.
Is there any reason to buy a more expensive tube over a cheaper one. Does one sound better. Would you guys recommend something like these?
https://www.amazon.com/Sovtek-EL84-...1489422489&sr=8-3-fkmr0&keywords=slovtec+6bq5
![20170313_112330[1].jpg](/forums/data/attachments/761/761303-20996f1d4369e3d6cd5a726f7375ecc1.jpg?hash=IJlvHUNp49 "20170313_112330[1].jpg")
https://www.amazon.com/Sovtek-EL84-...1489422489&sr=8-3-fkmr0&keywords=slovtec+6bq5
So I put in one different used tube. Things are much better.
Now I'm occasionally get some slightly red glowing in that center section of some of the 3 6bq5's. Is this normal. Tom says they are biasing correctly. That the right and left channel's are equal, but the bass channel is by itself. All have proper measurements.
If we move them around to different positions different things happen. Sometimes they glow brighter than others.
Toms thinking I should get some matched tubes.
Is there any reason to buy a more expensive tube over a cheaper one. Does one sound better. Would you guys recommend something like these?
https://www.amazon.com/Sovtek-EL84-...1489422489&sr=8-3-fkmr0&keywords=slovtec+6bq5
https://www.amazon.com/Sovtek-EL84-...1489422489&sr=8-3-fkmr0&keywords=slovtec+6bq5
Often the tubes start to glow red on the plates because the capacitors have gone leaky.
The way this is supposed to work, the one side of the cap has a couple hundred volts DC on it, the other should have zero. The capacitor passes only the AC audio signal. When they start to fail, instead of passing just the AC audio, you get some DC as well. That causes the tube to draw way too much current, which makes the plate structure start to glow red. It won't survive that for long before it fails.
The construction on those isn't all that amazing. Its two strips of aluminum foil with a piece of paper between them, all rolled up and stuffed into a paper tube, then sealed with wax. Over time, moisture gets into that and it fails.
The Sovteks are fine. The JJ EL84's are also supposed to be pretty decent.
The way this is supposed to work, the one side of the cap has a couple hundred volts DC on it, the other should have zero. The capacitor passes only the AC audio signal. When they start to fail, instead of passing just the AC audio, you get some DC as well. That causes the tube to draw way too much current, which makes the plate structure start to glow red. It won't survive that for long before it fails.
The construction on those isn't all that amazing. Its two strips of aluminum foil with a piece of paper between them, all rolled up and stuffed into a paper tube, then sealed with wax. Over time, moisture gets into that and it fails.
The Sovteks are fine. The JJ EL84's are also supposed to be pretty decent.
knockbill
Lunatic Member
Did you see the answers to your previous question? You can use any new tubes you want, but if the caps and resistors are out of value, the new tubes will still red plate....
Shadowdog
Super Member
Besides the output tubes you risk any or all the Transformers due to the possibility of a cap shorting!
It will likely sound much better with the tubes being run right also!
Soldering new caps isn't hard, as it just takes a little practice. Just like painting or using a calking gun etc.
Just buy decent solder and a station (they are more $ , but make it easier). All you have to do do is heat the solder
till it melts. As long as it looks shiny after you've replace a part it will be fine. The only other thing is it's best to make a
mechanical connection with the wire leads (loop around a tie point or twist leads together.
You can leave the old leads to twist around the leads on the new part to make it easier. You can also make small wire coils with 3 or 4 wraps of lead wire (make like a half size spring from a pen by wrapping around the ink refill) in which you insert your leads and then solder.
Best to take plenty of detailed pics first and only replace part at a time & then test.
Never run a tube amp without a load of speakers or big 25W 16 ohm resistors & they don't like to be short cycled (let the tubes cool well
when swapping etc) as you risk the tubes.
It will likely sound much better with the tubes being run right also!
Soldering new caps isn't hard, as it just takes a little practice. Just like painting or using a calking gun etc.
Just buy decent solder and a station (they are more $ , but make it easier). All you have to do do is heat the solder
till it melts. As long as it looks shiny after you've replace a part it will be fine. The only other thing is it's best to make a
mechanical connection with the wire leads (loop around a tie point or twist leads together.
You can leave the old leads to twist around the leads on the new part to make it easier. You can also make small wire coils with 3 or 4 wraps of lead wire (make like a half size spring from a pen by wrapping around the ink refill) in which you insert your leads and then solder.
Best to take plenty of detailed pics first and only replace part at a time & then test.
Never run a tube amp without a load of speakers or big 25W 16 ohm resistors & they don't like to be short cycled (let the tubes cool well
when swapping etc) as you risk the tubes.
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