Yamaha D85 Organ

Uncle Krunkus

I need some help to track down a problem with a 70s/80s Yamaha Organ - Model No. D85
All the keyboards work fine, as do most of the instrument switches, but the rhythm section has no tempo LED, and won't start.
The old guy who owns it is going nuts about whether it will ever beat again.
Any help or advice would be greatly appreciated.

Uncle Krunkus · Posted: Sun Nov 20, 2011 5:00 pm Post subject:

Surely someone here has worked on these old organs?
Maybe just a hand to guide me through the process?
If I can't fix it, this guy is gonna have a meltdown! Shocked

Cynosure · Posted: Sun Nov 20, 2011 7:01 pm Post subject:

Yamaha has a page where you can download schematics for anything they ever made. That would be a good place to start.

Sounds like it might be a power issue for the rythm section. Start there - make sure the board with the rythm stuff is getting power.

From what i have read about other old organs, the most common problem is old capacitors that have gone bad. Look for any that have the top popped or are oozing goo.

v-un-v · Posted: Mon Nov 21, 2011 1:24 am Post subject:

Uncle Krunkus · Posted: Mon Nov 21, 2011 1:25 am Post subject:

Thanks for your help Cynosure,
I'll check the Yamaha site,
and the power situation. Very Happy

Uncle Krunkus · Posted: Mon Nov 21, 2011 2:09 am Post subject:

I can't find any info for the D-85 on the Yamaha site.
There are other sites which have some connections to the D-85, but no schematics.

v-un-v · Posted: Mon Nov 21, 2011 2:14 am Post subject:

Cynosure · Posted: Mon Nov 21, 2011 6:58 am Post subject:

Ok sorry - no schematic. just the manual.

http://www.usersmanualguide.com/yamaha_audio/electronic_organs/d-85

But try checking the other things I mentioned.

EdisonRex · Posted: Mon Nov 21, 2011 2:07 pm Post subject:

It may also be that the rhythm section has its own part/model number as those were frequently bolted onto console organs. Get the thing out of the console if you can. I suspect power and whatever else got in there.

Uncle Krunkus · Posted: Mon Nov 21, 2011 4:47 pm Post subject:

The top half, (where all the keyboards, and most of the main PCBs are) is quite clean. apart from some solder splashes, so I'd say it's been worked on quite a bit.
I'm also starting to wonder about the PSU, which would be in the base, and so far, unsighted. Actually, loss of the +5V rail would create the symptoms,....... All sounds normal, but no rhythm section or CPU.

EdisonRex · Posted: Mon Nov 21, 2011 5:27 pm Post subject:

That's a fairly sensible deduction. PSU in the base eh, any fuses down there?

Uncle Krunkus · Posted: Mon Nov 21, 2011 8:30 pm Post subject:

I hope so.
I actually had to give a once over and leave it there, it's just impossible to move without a truck.
So I want to have a few options to check when I get back there.