After 37 years my 4.6 phono stage needs help

Audio Components Preamplifiers
1

Hi all,

This is my first post. I’ve owned my PS Audio 4.6 pre amp since the late 80s. Aside from some scratchy pots over the years it’s been trouble-free (no cap job or any other interventions) and of course the phono stage sounds great. Til now, that is.

Today I noticed some hash/distortion on the left channel. The ol’ scientific revealed that the left phono input is compromised. This is true for Straightwire, High Gain, or Mono modes. Short of full cap job, any suggestions on where to start just to get it up and running? Other inputs are fine. Thanks! Happy Thanksgiving! - Winslow

2

That’s an oldie buit goodie and I would guess caps are not happy. Start with replacing all the power supply caps and see if it doesn’t help. All in you’re probably looking at less than $20.

3

Thanks Paul. The other inputs work fine. Can bad caps in the power supply only affect the phono stage but not the others? - Blake

4

No. So that’s out. Maybe look at the coupling caps on that (both actually) input. Those are cheap and easy to replace.

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Considering its age a complete electrolytic recap seems to be worthwhile. A schematic from PS Audio may be helpful in identifying the actual caps.

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