spx90 PSU schematic needed

Anyone can float me a copy? pro favor :guinness:

Schematic, no...

However...

Replace the main primary abd all the secondary electrolytics. Check the big diodes for continuity.

That'll get 90% of them.

Keef

thats the plan.... However Got a couple of caps that have been leaked on so Can't read the values to clearly. Just needed to double check. However the values I have made out seem pretty usual values so they must be that. Same with the diods but starting with da caps :thumb:

I don't have a schematic but I've got an SPX90 with the top off. Which caps?...

would be the electrolytics in the power section....

I got 200uF/10, 1000uF/10V, 2 470uF/25V and 2 330uF/25V

IS that correct?

Yeah, that appears to be correct. It's a 2200 not 200 but I got a feeling that you just had a typo. There's something in mine that looks like leakage as well. Dried, orange-brownish... It looks like old hot glue?... Let me know if there's anything else that I can take a look at that might be helpful...

IIRC I've also change two resistors in the PSU, grey 1/2 or 1W resistors, can't remember the values but they where "opened" without burnmarks.

The Orange-Brown stuff is normal - some sort of adhesive, not capacitor spew. The caps definately go bad though. They use miniatures - sometimes it's a little tricky to find replacements that will "fit under the hood", especially the 1000 and 2200 uFs.

Hello Pucho.
I can scan the SPX90 PSU for you. Do you have an email address I can send it to ? (Not sure how to send it otherwise).
The power supply was always a weak point on these units as there was never sufficient ventilation for it. All Yamaha FX units of that era got incredibly hot if they were tight up against anything else in a rack.
From memory, its the big 68uF capacitor that dries out and gets a big blister on top. The last two units I had I managed to get replacement PSU boards for.
Fault finding on switched-mode PSU's is a pain !

Actually I've just had a look at the schematic and the boards for the US model and the European model are a slightly different design.
The big cap is 150uF rather than 68uF for instance.
I take it that the US version is the one you want ?

Found your email address.
Just sent sent you the schematic.

Martyn

I had a prob with my REV 5 earlier this year and tracked it down to the pwr sup caps so I did my SPX at the same time.......some caps were common to both.

Yamaha SPX and REV 5 Caps


# Value Volts Temp
C11 68uf 400V 105 deg
C19 470uf 25V
C20 330uf 25V
C21 470uf 25V
C22 330uf 25V
C23 1000uf 16V ESR (REV 5)
C23 1000uf 10V (SPX)
C24 2200uf 16V (REV 5)
C24 2200uf 10V (SPX)

I've got two of these things on my bench right now.

Did the cap thing, measured the battery, all good there.

The PS outputs +5, -17.9 and +30-45V.

The trimmer next to the digital out seems to adjust voltage on the +-18V side as well.

Another note, when powered off it takes forever for the +V to drain off whereas the -V drops off within a few seconds.

Any ideas??

Thanks,

James

[quote author="pucho812"]Anyone can float me a copy? pro favor :guinness:[/quote]

If you need a copy of the service manual, let me know... I can send the pdf to you.

marc

Hello, since all this time the schematic became available on the net .
Could anyone a bit aware of switching psus tell me what does VR1?

Indeed it's to calibrate the +5v , after a clean with isopropyl alcool it does what's it's supposed to do.