Kurzweil SP2X piano problem

[Pilsener]

I'm working on a Kurzweil SP2X electric piano with a strange problem.
When powered on, all LEDs in the knobs and segments in the display lights up twice, then nothing more happens.

I have checked the internal voltages according to the schematics and they are all present and OK on all boards.
No excessive current drain either.
I'm not able to get into any service modes, so I cannot perform a hard reset as described in the service manual.

Any ideas I can try?

[Jazz P Bass]

Here is a link to the SM.
Link: KURZWEIL SP2X Service Manual free download, schematics, eeprom, repair info for electronics
I would start by looking to see that you have clock pulses.

[philbo]

I worked on a Kurzweil PC88 that was about 6 years old with similar problems. Most issues were solved by using contact cleaner on all the internal connectors, and the rest were solved by reflowing pretty much every solder joint.

While I love the sound of them, their soldering quality could be greatly improved.

[Enzo]

My first thought is the thing is not able to complete its power up reset routine. Which of course does not narrow it down all that much.

How healthy is the memory battery?

Try configuring it as minimally as possible. I have not worked on one of these in some years, my memory is not good. But is it possible a ribbon cable is plugged on backwards or off one pin or off one row? I seem to recall marking ribbons because they could be reversed in some cases. I could be confused.

I think the thing will fire up with the keybed disconnected. Try doing that. A short on the keybed could conceivably halt the procesor.

Assuming nothing:

You checked voltages, so the main P/S has +/-12 and +5 on page 60, then on page 57, looks like 3.5v, 2.5v and 1.8v, yes? And a second +5 for analog. Looks like there are test points for those.

Page 60. I invent some shorthand. LL is lower left, UR is upper right, etc. Page 60LL - /reset signal, across C44. Is that logic HI? Not stuck at ground? And nearby BUVdd, it goes to page 60UR J11-7. Is there voltage there? That feeds over to page 52LL, thence to page 52UR over U3, whwich it powers. Also, U3LL pin 6 is pulled up to that BUVdd. Make sure.

Page 52LL, J6-8 /pwruprst. Is it stuck low? To the right of that, it splits into three reset signals. Are they all at appropriate logic levels?

[mfuller526]

Battery

The repair shop replaced my "lifetime" backup battery solving the problem.

[impacter]

where can i get the lifetime backup battery pls

[Jazz P Bass]

Ensoniq Battery Memory Backup TS 10 TS 12 KT 76 KT 88 Sq 1 Sq 2 Sqr Mrrack | eBay