Strange SP 1200 issues

[Elmbeatz]

After firing up my black boy (or: re-issue) in a pretty long time, I found it to behave very odd:

I used a disk that works perfectly with my grey boy next to it.

The black boy seems to 1) change channels of certain sounds, and 2) it pitches some sounds super-weird while playing segments: pitch changes continously, it sounds like a non working tape machine... pitch goes up and down (while the sample is shot!), really bad... I also have pitch issues when manually playing these sounds on the pads..

Again, everything works fine on my original grey when using the exact same disk.

Anyone experienced this behaviour, too? Any solution?
Thanks for replying in advance.

[Elmbeatz]

Update:

It's gotten worse:

So, now, tuning via slider doesn't work anymore at all. Trying so results in turning the level (!!!?) of the sample to zero, if slider is moved just below the middle position. I mean - OFF. Pushing the slider to the middle (or further up) again turn's the samples level back on (all without transitions... like a switch).

WEIRD.

Also: In special mode 23/20 (initial tune), tuning can neither be adjusted. Only if the slider is pushed up completely, the sample is transposed up one octave (again - like a switch).

Cut short: tuning a sound doesn't work anymore. Note that in "mix" mode, the sliders work and adjusting levels works, too - as usual.

What I tried:

- run diagnostic mode; result: no faults (except some during the floppy test, I think these are not worth considering in this case)
- calibrated Trimmer RT-1
- reseat ALL reseatable ICs
- exchange Z80 CPU (with the grey boys' one)
- exchange various other IC's (as above)

no luck.
Grey boy runs like a charm.


HELP!

[lunatic]

My first try would be to exchange the upper logic board to determine which of the two has the issue. Then take it from there with further diagnostics.

[Elmbeatz]

Thanks for getting at me, lunatic!

What do you mean with "upper logic board"?

If you mean the User panel board - I swapped that out already, both User panel boards work fine with the grey mainboard. Or do you mean something different?

I strongly suspect the fault on the mainboard - Does anyone know which IC controls the pitch of the samples?

[lunatic]

That is exactly what I meant Elm. It must be the logic board then. However I have no clue which IC controls the pitch.

[Elmbeatz]

Another chip-swapping party last night....  I think I swapped ALL reseatable ICs by now... no success. 

I think the SP must see a doctor...

Does anybody know a capable Tech in Germany?

PLEASE!

[inthedisco]

Hi, maybe reseating power connectors, checking for dry/brittle cables, bent or corroded pins on the IC's, the processor, memory, sockets ?

Wrong power voltages could be it.

A dirty / corroded slider or bad button sensor sending continuous data to the cpu could explain the behaviour you described.

[Elmbeatz]

Hi, maybe reseating power connectors, checking for dry/brittle cables, bent or corroded pins on the IC's, the processor, memory, sockets ?

Wrong power voltages could be it.

A dirty / corroded slider or bad button sensor sending continuous data to the cpu could explain the behaviour you described.

Hi!

At this point, I can exclude anything on the Panel side of things (buttons / sliders, etc...), as the complete panel works absolutely fine with my grey SPs mainboard.
Also, I reseated all connectors and ICs - I even exchanged most of the ICs with those of my grey SP. No luck, as I stated above.

What I didn't check, but have to I guess, are the voltages, indeed. I tried to connect the grey SPs power supply to the black's mainboard, but unfortunately, its cable is too short. I will have to find another way to check the voltages. I have no electrician experience though, so...

[Elmbeatz]

Just checked voltages.

5V Testpoint -> in spec.
15V Testpoint -> in spec.
-15V Testpoint -> in spec.
12V Testpoint -> ZERO, nothing, dead.  WTF?

I also opened up the grey SP and checked: 12V Testpoint -> in spec.

What should I do now?
Does anyone know any other Testpoints to measure the 12V rail (to check if wether the power supply is faulty, or the rail has been interrupted somewhere?)

Can I check the PSU outputs directly? How would I do this correctly?

[inthedisco]

The best thing to do imho is to take your sp/psu to a an electronic music instrument repair shop and ask for a diagnostic to follow up on the 12v.

You might want to look at the service manual/schematics and follow the 12v distribution for knowledge.

Also important to demagnetize yourself by touching a heavy metal piece before touching any electronic part.

[Elmbeatz]

The best thing to do imho is to take your sp/psu to a an electronic music instrument repair shop and ask for a diagnostic to follow up on the 12v.

You might want to look at the service manual/schematics and follow the 12v distribution for knowledge.

Also important to demagnetize yourself by touching a heavy metal piece before touching any electronic part.

Thanks for replying.
Yeah, I always touch a radiator from time to time when doing such things..
Well, I really suck in reading schematics, so I guess I have to take it to the doctor.

Again, does anyone know a good tech in Germany?

[lunatic]

Elm, there is Nikolaus Riehm (www.studiorepair.de) who does a good job but is totally covered on work normally. In hannover i got Wolfgang (http://www.musikstudio-garbsen.de/) who repaired my SP twice. He got the service manual from me & repairs synths and other stuff since more than 30 years.

[Elmbeatz]

Wow - thanks so much Lunatic!

I stumbled across studiorepair.de already while googling for techs.

What kind of SP repairs were done by Wolfgang?