Need help diagnosing a preamp problem


I have a Shindo  Monbrison preamp with a MM/MC phono section.  It is about 12 years old, maybe more. The phono section contains a 12AU7 and 12AT7 in both right and left channels.  No other tubes in the phono section.

Two days ago  the right channel stopped producing output when playing a record.  Other source inputs are working fine.

I replaced all 4 tubes with known working tubes of the same type and vintage.

Problem remains.

I have a standalone phono preamp available if that would help.

clio

I've heard the Switchcraft jacks Shindo uses can be a bit flimsy it very likely is a bad RCA jack as suggested by @mulveling above.

Currently I am experiencing intermittent right channel in/out when cables are correctly connected.  I have reversed connections several times.

@clio When the channel is out, try wiggling the interconnect cables, on the offending channel, to see if the sound comes and goes. So far this sounds like an intermittent cable.

@atmasphere   I did this today.  When I started a record playing the right channel was completely out, then became intermittent.  I then 'wiggled' the right cable connector and the channel came back for the entire record.  I will turn everything off and come back later to see if all is still ok.

I recommend Chopin Etudes as an aid to diagnosing this kind of problem.

As well as a strong suggestion from Ralph.