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Model 19 Cap List

wow that would be great the original caps are odd values going by the servise manuel and i just wanted to know if they are able to be raised up a little cuz i have most common values
 
Mark.Cass said:
wow that would be great the original caps are odd values going by the servise manuel and i just wanted to know if they are able to be raised up a little cuz i have most common values
Click to expand...
I don’t know enough about circuits to feel confident about changing the values most of the time. If there is a consensus on AK, then I do it. Also, if it is a very minor change, I will do it. For example, I recall the service manual stated one of the caps was 8uf value on the model 19. I replaced it with a 10uf. But that’s about as crazy as I get. Good luck.
 
Thank you soooo much dr*audio for the tip about the PSU can grounds. I had the hum problem everywhere on this Model 19, and I don't know if I'd ever find it without your tip!

The positive common to can really screwed me up. I used to use can caps back in the '70s in ham radios and colour TV receivers. I don't think I've ever seen anything other than negative common to can, so that's the way I hooked them up. The positive ones all bulged up right away and I had to order more from Digikey, lol.

After full recap, and still with hum, I replaced the rectifiers with modern fast-recovery diodes for good measure.

Sounds just wonderful now. This restoration was quite a journey. (I won't get into the tuning scope and dial cord stringing issues, but then nobody actually enjoys dial cord stringing.)

All the best. I invite you all to have a look at the restoration on my blog.

Another small issue, quite common to these old receivers actually: One side is slightly louder than the other.

If I feed the same sine wave through both channels, I can see it clearly on the scope. Sometimes it's just the balance control, where the two strips get out of spec with each other. (If it's just a bit, I'll tighten up the balance control to compensate one way or the other, but that's cheating.)

But in this case, I think it's the right side driver/amp boards. I'm hoping a final setup of bias, etc. might fix this, but failing that, I'd welcome any suggestions.

All the best.
 
nebulix said:
Thank you soooo much dr*audio for the tip about the PSU can grounds. I had the hum problem everywhere on this Model 19, and I don't know if I'd ever find it without your tip!

The positive common to can really screwed me up. I used to use can caps back in the '70s in ham radios and colour TV receivers. I don't think I've ever seen anything other than negative common to can, so that's the way I hooked them up. The positive ones all bulged up right away and I had to order more from Digikey, lol.

After full recap, and still with hum, I replaced the rectifiers with modern fast-recovery diodes for good measure.

Sounds just wonderful now. This restoration was quite a journey. (I won't get into the tuning scope and dial cord stringing issues, but then nobody actually enjoys dial cord stringing.)

All the best. I invite you all to have a look at the restoration on my blog.

Another small issue, quite common to these old receivers actually: One side is slightly louder than the other.

If I feed the same sine wave through both channels, I can see it clearly on the scope. Sometimes it's just the balance control, where the two strips get out of spec with each other. (If it's just a bit, I'll tighten up the balance control to compensate one way or the other, but that's cheating.)

But in this case, I think it's the right side driver/amp boards. I'm hoping a final setup of bias, etc. might fix this, but failing that, I'd welcome any suggestions.

All the best.
Click to expand...
My suggestion is to look at the different sections with a scope and see where the gain is different between channels. I don't have the problem on mine. There is a procedure in the service manual on how to find the center on the controls and then attach the knobs with the set screw. I know it applies to the tone controls but I think it also applies to the balance. Check the manual.
 
nebulix said:
Thank you soooo much dr*audio for the tip about the PSU can grounds. I had the hum problem everywhere on this Model 19, and I don't know if I'd ever find it without your tip!

The positive common to can really screwed me up. I used to use can caps back in the '70s in ham radios and colour TV receivers. I don't think I've ever seen anything other than negative common to can, so that's the way I hooked them up. The positive ones all bulged up right away and I had to order more from Digikey, lol.

After full recap, and still with hum, I replaced the rectifiers with modern fast-recovery diodes for good measure.

Sounds just wonderful now. This restoration was quite a journey. (I won't get into the tuning scope and dial cord stringing issues, but then nobody actually enjoys dial cord stringing.)

All the best. I invite you all to have a look at the restoration on my blog.

Another small issue, quite common to these old receivers actually: One side is slightly louder than the other.

If I feed the same sine wave through both channels, I can see it clearly on the scope. Sometimes it's just the balance control, where the two strips get out of spec with each other. (If it's just a bit, I'll tighten up the balance control to compensate one way or the other, but that's cheating.)

But in this case, I think it's the right side driver/amp boards. I'm hoping a final setup of bias, etc. might fix this, but failing that, I'd welcome any suggestions.

All the best.
Click to expand...
Check out this thread. Reply #13. That information helped me bring both channels on my model 19 to matching output levels (reply #17). Good luck.

Model 19 - I think I took a wrong turn....

Hi guys. I picked up a Model 19 some time ago and decided to replace caps in selected locations, i.e. power supply, tone board, and driver board. Took my time and did board by board checking after each installation. The unit would work after each board installation, and I would move on...
audiokarma.org
 
Last edited:
Jamie Starr said:
Check out this thread. Reply #13. That information helped me bring both channels on my model 19 to matching output levels (reply #17). Good luck.

Model 19 - I think I took a wrong turn....

Hi guys. I picked up a Model 19 some time ago and decided to replace caps in selected locations, i.e. power supply, tone board, and driver board. Took my time and did board by board checking after each installation. The unit would work after each board installation, and I would move on...
audiokarma.org
Click to expand...
Bingo.
 
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