Service Manuals and Schematics!

[Rasputin]

The rare and elusive Akai Z4 and Z8 service manual and schematics:
http://www.mediafire.com/file/lduhp0tbm ... l.pdf/file

Sorkin Multivox MX3000 Owners Manual (with schematics):
https://mega.nz/file/sZlzFLRI#VktgG5ot1 ... a8eaHfRKbQ

Kawai R50/R50e Service Manual (with schematics):
https://mega.nz/file/wA0h3SaR#dYLOJD_1P ... Gf0SghJL6w

[blueknob]

Anyone know if there is a schematic for the Emu E4K. Mine has a warm up issue with the keyboard part, 8 keys don't work but come into life about 20 mins later and then work perfectly. My guess is a bit/line on the keybed contact scanner chip is failing. It would help to know if it's a replaceable chip or some custom device. The former I can replace. A schematic would help me locate the culprit much faster.

[Yekuku]

Hi blueknob, I have uploaded it here :
https://www.sendspace.com/file/8648nc
You can use a hairdryer and a freeze spray to find the culprit.

[blueknob]

Thanks Mr Y - that's very good of you and sooo fast!

Had a quick look.. hmm.. once big chip does it all, more.. hmm.. at least I now know where to look.

thanks again

[Yekuku]

You are welcome blueknob!
A few ideas :
1) check/clean/reattach the fatar keyboard connectors. Replace cable if possible.
2) 8 keys mean that 1 bus has the problem. Could it be due to a leaky diode ? Replace diode on the specific bus.
3) The scanner ic looks like a custom EMU ic, thats bad news.

[blueknob]

I studied the circuit, got to the K-Chip emu use for keyboard scanning, worked out exactly which bus line (pair - make and break) - took close look for that specific connector and noticed it was slightly skewed (not in 100% on one end) - pushed it in 1mm. So far all working now result.

[Yekuku]

Like a pro ! Good work Blueknob!

[Gerrymc2010]

I'm looking for the Schematic s for the Jen SM2007.

If anyone still has them could I obtain a copy please.

Many Thankx in advance.

G.M

[Gerrymc2010]

I found my docs about that JEN SM2007.
If you still need it, please tell me, I can send them to you through email.

Anybody about the KORG 900PS service manual?

Hi Orjen.
Do you still have details of the Jen SM2007.
If so could I obtain a copy.

Thanks

G

[blueknob]

Alesis Microverb schematic needed - (first generation from 1986 and not the Mk II version).

I got this little beauty new in 1986, (£200) but now on a hot day it decides not to play anymore

The analogue parts work (opamps) it's the digital stuff that ain't. For example when the MIX knob is set to DRY the audio gets through fine. When I rotate MIX to "wet" as in all digital reverb... silence, not even noise.

A clue is, from power up it mostly works fine for about 1 second then the digital section goes silent. I'm thinking there might be a wonky reset or mute signal. From what I can tell the PCM54 DAC is doing something sensible (probe with 'scope).
It would help a lot if I had the schematic. This unit has the DASP-16C DSP/CPU. I've found the circuits for similar products but they are using slightly different DSP/CPU chips. eg DASP-8 or DASP-32.

Thanks

[Yekuku]

Hi Blueknob,
unfortunately I dont have the schematics, I was in the same position trying to repair a midiverb II only to realise that there not any schematics available out in the wild.
In my case the problem was a failed DASP CPU, hopefully yours should be ok since the cpu works for a sec, could it be the ram triggering the crash?
Do you have a clean 5V line ? The electrolytics after the rectifier are known to fail.

[blueknob]

Thanks Yekuku, you saved me some time. After some study I narrowed the fault down to 3 candidates in the sample and hold cct. So I swapped the source, a 4053 whose output would fall to zero, much to my surprise that didn't fix it. Next is a simple 470pF cap, I swapped that as it was easy, no difference, the only thing left is a TL084. These things never fail... until now It was such a strange way to fail, it seemed like a dry joint malfunction.

So far the Microverb is working well one again I am impressed its reverb quality.

[Yekuku]

Good work blueknob!

[Tekhed66]

Thanks Yekuku, you saved me some time.

Yekuku never fails... always helpful and always has a valuable bit of advice. +1

[Rasputin]

Here are some upgraded versions of material which was otherwise available but needed improvement:

Akai AX60 Service Manual and Schematics
https://www.dropbox.com/s/jexqfq04tft6r ... s.pdf?dl=0

Akai S1100 Service Manual and Schematics
https://mega.nz/file/zsFGkawL#VZ6D8WJlU ... 8URjxjYQFI

Again, these are much better versions compared to the commonly found scans.