volume pot install


i have a dynaco pat3 and i had to change the volume pot.
i installed a 100k alps and everything seams fine but when i turn the volume close to full the volume goes to zero. the previous pot did not cause this to happen.
yes i know why would i ever want to turn the volume up full?
i don't but, this must be a sign that i have done something wrong or the pot is faulty. or should i be using a dif. value?
it is feeding a bryston amp. any suggestions would be appreciated. thanks rick
uncleryk
when you turn the volume up full probably the rotor goes outside of the contact of variable resistor making it an open circuit.
it may be due to the manufacturer's defect.
you can still us it if you don't plan to turn the volume all the way up.
thanks for the reply ... one thing i was wondering as well, i have read in a few posts that the original pas3 requires a 250k volume pot to preserve the original phono riaa. i have also read that using a 250k can produce a lighter tone with possibly a bit more air compared to using a 100k, which can tend to sound a little darker. is any of this true?
thanks again
rick
I don't think 100K is the original value pot. for a PAT 3. Still though, shutting off at full volume looks like a defect and not caused by the wrong value pot. You really should stick with the orig. value to retain the Dynaco's sonic signature. Go to DIY audio's site, or Audiokarma. The people there can probably tell you more than you ever cared to know about this.
It's quite tough to find ones that will go for original fittings, but usually collect some junk to find good one and install.
One could be found among vintage Kenwoods, Technics receivers.
There is no such thing as a Dynaco PAT 3. There is a PAT 4, PAT 5, PAT 5 bifet, PAS 2, PAS 3, PAS 3X and PAM 1 for the Vincent Van Gogh crowd, but no PAT 3. Panor made PAS 4 or some such hokum as well.

The answer to your question is dependent on the output impedance of your sources, and most sources in common use today will not have any issue working into 100K or 250K loads. So it really doesn't matter.

All of the PAS preamps came with 250K standard and working into the lower load would not change the RIAA, but might roll off the bass a hair.

For what it's worth, I use a 100K Alps pot on my PAS3 and it works fine, my PAT 4 still has the original pot and it works nicely as well.

If you would like to hear a large improvement in the PAS, bypass the tone controls and filters, particularly that horrible blend thing. Beefing up the power supply helps a lot as well. And the mod that subs the LED for the light bulb made my trannie run cooler. YMMV and good luck.