Dynaco PAS restoration issues.

Freddie_Freekowtski wrote:

peterh wrote:I contacted the seller "re-engineer" and asked if the potentiometers in the
pas potentiometer kit. Did they have correct values .
The answer was not to my satisfaction :

The question you're really asking is:
Are they the same resistance as the
originals.
The answer is:
If they were, there would be no need for the
kit.
Thanks for stopping by...C


In other words he refuses to tell what he sells.
Maybe better to skip this seller.

He was quite problematic during communication. His instructions for troubleshooting werent exactly clear, and they did did change...I had reported a value across pins 5 that was in the 30's and he freaked. sent back explicit step by step instructions which differed from the first set which stated to take out the tubes  and power unit off....which then changed to remove rectifier and 12ax7's in the phono board, power on and measure. We then got an acceptable value, at least to him, of 28.66 VDC. He has not replied since we got the phono stage working by bypassing his buffer. We followed his supplied instructions to the letter and still had a wire that originally ran from point 1 on the line board to RCA ground. His instructions never mentioned what to do with it.

The brightness issue still exists. When I was listening, it seemed to become more of an issue as the thing was running. The line stage never experienced that issue. Another poster in a different forum said the selector switch could be at fault. I wouldnt be surprised if it was. It was literally frozen in place when I got the unit. My guy had to soak it in something to dissolve the gunk that crippled it. I am not a fan of its feel, it doesnt seem to sit properly in the phono spot. slight turns to either the left or right can cause a channel to drop out completely. The line stage, on spare, seems to feel like it rides its groove better, but you can still cause noise and dropouts by the slightest turn. Edited to add that all resistors were within 10% tolerance of their original values. Bass pots read 71.2k for left and 71.5 k for right..now treble is 368.6k for left and and 345.2k for right.

peterh wrote:

Freddie_Freekowtski wrote:

peterh wrote:I contacted the seller "re-engineer" and asked if the potentiometers in the
pas potentiometer kit. Did they have correct values .
The answer was not to my satisfaction :

The question you're really asking is:
Are they the same resistance as the
originals.
The answer is:
If they were, there would be no need for the
kit.
Thanks for stopping by...C


In other words he refuses to tell what he sells.
Maybe better to skip this seller.

He was quite problematic during communication. His instructions for troubleshooting werent exactly clear, and they did did change...I had reported a value across pins 5 that was in the 30's and he freaked. sent back explicit step by step instructions which differed from the first set which stated to take out the tubes  and power unit off....which then changed to remove rectifier and 12ax7's in the phono board, power on and measure. We then got an acceptable value, at least to him, of 28.66 VDC. He has not replied since we got the phono stage working by bypassing his buffer. We followed his supplied instructions to the letter and still had a wire that originally ran from point 1 on the line board to RCA ground. His instructions never mentioned what to do with it.

The brightness issue still exists. When I was listening, it seemed to become more of an issue as the thing was running. The line stage never experienced that issue. Another poster in a different forum said the selector switch could be at fault. I wouldnt be surprised if it was. It was literally frozen in place when I got the unit. My guy had to soak it in something to dissolve the gunk that crippled it. I am not a fan of its feel, it doesnt seem to sit properly in the phono spot. slight turns to either the left or right can cause a channel to drop out completely. The line stage, on spare, seems to feel like it rides its groove better, but you can still cause noise and dropouts by the slightest turn. Edited to add that all resistors were within 10% tolerance of their original values. Bass pots read 71.2k for left and 71.5 k for right..now treble is 368.6k for left and and 345.2k for right.

I assume the bass pot is 710k
But, as you suspect, if the selector has been troubling, yes that may very well happen, and
the riaa equalisation is done via a few of it's connectors.
Cleaning the selector is possible, with care and some mild cleaing oil. 5-56 comes to my mind,
i'm sure better advices may com ( peter ?).
The selector is delicate but not impossible to get working again. The good thing
with the selector ( that none of thereplacement parts offer) is that it shorts unused
inputs to proevent them from "bleeding throu". This bleeding can be quite annoying
in an amp that lacks this shorting feature.

peterh wrote:I contacted the seller "re-engineer" and asked if the potentiometers in the
pas potentiometer kit. Did they have correct values .
The answer was not to my satisfaction :

The question you're really asking is:
Are they the same resistance as the
originals.
The answer is:
If they were, there would be no need for the
kit.
Thanks for stopping by...C


In other words he refuses to tell what he sells.
Maybe better to skip this seller.

PeterCapo wrote:It's a sensible approach.  But there are a couple of problems.  First, you'd have to get a hold of Joe.  He hasn't posted in his forum for some time - is he still in business?  Second, when I ordered this replacement selector switch from him some years ago, he sent a very cheap switch that I ended-up having contact problems with.  I replaced it with an Electroswitch rotary switch - a high quality product.  Grayhill is also quite good (Cary Audio used them as upgrades).  The trick is figuring out how rotary switches can be configured and then map the original PAS wiring to it.  No easy task.

Midwestside wrote:I had wondered which area on the selector switch shorts the unused inputs.  I have a tiny bit of bleed through, only say when move to an album and the cd player is on. Sometimes while testing i have forgotten to stop the cd playing, but switched the knob to phono, this is how i know there is bleed through. Its not the worst thing and perhaps this is normal and that shorting other inputs only helps with low level noises (cd still playing music). I realize its common sense to stop the CD source, but was curious if the shorting feature was designed to actually quiet another source's full signal strength.

peterh wrote:

Midwestside wrote:I had wondered which area on the selector switch shorts the unused inputs.  I have a tiny bit of bleed through, only say when move to an album and the cd player is on. Sometimes while testing i have forgotten to stop the cd playing, but switched the knob to phono, this is how i know there is bleed through. Its not the worst thing and perhaps this is normal and that shorting other inputs only helps with low level noises (cd still playing music). I realize its common sense to stop the CD source, but was curious if the shorting feature was designed to actually quiet another source's full signal strength.

Yes, i think it should totally silence unused inputs.
AT the time this was designed tuners were tubes. They had no crystals and
drifted somewhat during warm up. Thus one wanted the tuner to be
warm and active all the time, but when listening to records the tuner
should not be heard.

If it bleeds through i think some cleaning of the selector is needed. Look at
the schematics to identify which contacts to clean. And be careful !
i know only of one spare selector in existence !

Midwestside wrote:

peterh wrote:

Midwestside wrote:I had wondered which area on the selector switch shorts the unused inputs.  I have a tiny bit of bleed through, only say when move to an album and the cd player is on. Sometimes while testing i have forgotten to stop the cd playing, but switched the knob to phono, this is how i know there is bleed through. Its not the worst thing and perhaps this is normal and that shorting other inputs only helps with low level noises (cd still playing music). I realize its common sense to stop the CD source, but was curious if the shorting feature was designed to actually quiet another source's full signal strength.

Yes, i think it should totally silence unused inputs.
AT the time this was designed tuners were tubes. They had no crystals and
drifted somewhat during warm up. Thus one wanted the tuner to be
warm and active all the time, but when listening to records the tuner
should not be heard.

If it bleeds through i think some cleaning of the selector is needed. Look at
the schematics to identify which contacts to clean. And be careful !
i know only of one spare selector in existence !

Thanks, just out of curiosity , are you saying modern replacement selector switches just dont seem to take shorting the other inputs into consideration?

PeterCapo wrote:If the original selector switch is failing to function and is beyond repair, there's no choice than to get a new one.  It may be possible to get a new, multi-deck switch and wire it up the same way as the original with the shorting.  But determining whether this would be possible, and, if so, how to do it, would take detailed analysis.

KeyserSozo wrote:I'm in the process of restoring an old PAS myself right now.  I reached out to a few vendors to assemble some parts, and my dealings with 'C' from DynacoDesigns.com was about the same as mentioned above.  I inquired to find out a few particular details about pots/switches/PCB's and after a few back and forths it ended with him telling me he 'was not interested in selling to someone like me' lol

Luckily enough for the Dyna community there seems to be a bunch of other great sellers (DynakitParts/Erhardt/etc...) that carry enough parts to assemble a PAS from scratch.