Snagged a TU-9500 to go w/ my AU-9500!!! (help w/ FM output?)

Found this one locally. Shop had an AU-9500/TU-9500 combo w/ all original sales literature, taken in trade from the original owner when he updated his system. I didn't have the $$$ to snag the tuner when I found it, but wanted to BADLY as I recently picked up a gorgeous AU-9500 (see thread HERE).

AU-9500 sold before I could come up w/ the $$$, but the owner had set the TU-9500 aside for me: how cool is that!? Pays to support local shops.

Cosmetically its in fantastic shape & the equal of my AU-9500. Going to need some TLC though, functionally. No output at all on the FM side, "okay" output on the AM side using the in-built antenna. The FM tuner appears to be working as I can watch the signal come up on strong stations & it illuminates the "stereo" indicator. Read in an old thread there is a possible fault in the FM muting circuit (though no change when I switch out the FM mute). Also, the tuning action is a bit jumpy & rough, will sort that as well. . . overall VERY excited to have the pair, though I would've loved to snag the paperwork as well.



Sorry for the crap picture - didn't want to turn off my Son's cartoons, so there is quite a bit of flare from the television (just above the Sansuis, out of frame). . .

Go through the power supply.

Congrats

Thanks bktheking - any thing specific I'm looking for?

That is just a beautiful pair. Don't know anything about the tuner, but I just did a 9500 and think it's one of the best amps that's ever crossed my bench. If you get a chance, there are two small blue caps at the end of the tone board in your photos that would benefit from a change. They're the input caps to the FETs from the volume control. Change them to physically small films like 0.47 uF (P4671-ND, Digikey), not giant polypropylenes with a lot of stray capacitance. It's a bit of a PITA because the supply board and bracket have to be lifted. If everything else is in order, the 9500 will be the equal of even a healthy 919.

It it were a fault in the muting circuit FM stereo wouldn't illuminate. Stupid question- you have this amp connected to OUTPUT and not MULTIPATH OUTPUT?

Correct, have tried both the normal & tape outputs, same result. Multiparth is output for a scope, correct? It gives a low, fixed volume, but not usable for listening. . .

Very nice pair - congratulations.

drasp said:

Correct, have tried both the normal & tape outputs, same result. Multiparth is output for a scope, correct? It gives a low, fixed volume, but not usable for listening. . .

Click to expand...

The output jacks put out volume but it is low?

bktheking said:

The output jacks put out volume but it is low?

Click to expand...

Nope. Both sets of output jacks (normal & tape) have the expected variable output on AM & no output of any kind on FM. The Multipath outputs, which are for viewing the signal on an scope (labeled H & V) do output a small amount of audio, which is normal, but its not a usable signal & the output is fixed (not affected by the volume knob).

Voltmeter set to dc, black to ground- F1455 board test for DC volts at OF OG and OH to start. Post results for each point.

Beautiful! Haven't had a chance to tear into it, but will post results this weekend. THANKS!!!

Whew! Took WAY longer than I meant to finally get the lid popped & check voltages, but here ya go!

OF to ground: 21.4VDC
OG to ground: 12.4VDC
OH to ground: .70VDC

I popped the lower cover as well & found a board with three fuses soldered on, all test good.

Further help troubleshooting would be GREATLY appreciated!!!

Since there are no voltages in the SM I'd hazard a guess that there should be more than .7v coming from OH. Can you measure ECB of tr006/007/008 and post?

Since nobody's mentioned it so far, I'd be inclined to go through all the switches and RCA jacks with contact cleaner.

Since it works on AM, I'd assume the power supply was ok.

There is one section of the PS that supplies FM, happens to be the one with low V.

Here we go!

TR006, C: 0 B: .7 E: 0

TR007, C: 12.37 B: 0 E: 0

TR008, C: .7 B: 12.37 E: 12.37

TR006 & TR007 are marked C945 TP244
TR008 is marked 4735 426H

^ Let me know if that helps!!!

*bump*

What's the base of 006? I will look at it later today, bday party day for a family member.

Info on 6, 7 & 8 is two posts above. Base of 6 = .7V. THANKS!!!

Pull tr006 and diode test it, numbers are strange, base should be in the VOLTS for measurement. If it's good, test tr007 and those two diodes. Something is dead.