Marantz 10b repair

Ive worked on a few 10B's and I would send it back to AC. BTW that tuner was designed by Dick Sequerra. Every tuner that came off the assembly line had to be trouble shot. No 2 are alike. I received this info. from a 2 hr. conversation with the late Sid Smith. Sid worked for Marantz for many years and was responsible for the output transformer designs on the 8B. He told me he went through almost 50 incarnations of transformer before he arrived at the one they used in the amp.
G.Garfield

Hello to all,

Well, here we are, a new year 2011.

I have a beautiful Marantz 10b that needs the magic touch of someone who is good with them.

I have replaced all electrolytics and the 3 optocouplers.

All tubes tested on a good mutual conductance tester, and subbed with new tubes to rule out.

It just has a fairly high distortion level, especially in the bass.

No alignment adjustments have been made as I am smart enough to know my limits!!

Help someone. Most appreciated to know who to sent this to.

Thanks, Bruce in South Carolina

Bruce,
Can you tell us where you found the optocouplers and how much you paid for them? These would be easy to repair or replace with CDS light-dependent resistors (LDRs) and NE2 neon bulbs. The trick is knowing the specs of the specific CDS resistors used (dark resistance and illuminated resistance). I haven't come across this info for the 10B on the web yet. Surely someone knows or could measure a known-good original 10B optocoupler. Once that is known, CDS resistors are relatively cheap and easy to find.

Yeah, I'd be curious about opto-coupler spec as well.

I always made up the opto couplers under the assumption I would never find the originals. Seems to me most of the time the neon bulb has failed and you can re-use the LDR. I wonder if that HiFiBruce ever got his sorted tuner out? Sounds like the discriminator was out of alignment.