Vintage Simmons Drums (UK) Users Group

Just this past year, I have been working on refurbishing my Simmons SDS1000 brain that I got with my kit in 2006. I know the CPU is an Intel 8051 but I am not sure if any 8051 will work, or if it has to be the one marked SDS1000 for it to work with the rest of the unit. Does anyone know where I can get the service manual with schematics? I looked all over the net for them but couldn't find any.

The 8051 has the SDS1000 software programmed into it, so you need a specific SDS1000 8051. 

Are you sure the 8051 is faulty?  I fixed up my SDS1000 and the 8051 looked dead, but something else (actually a load of stuff) had failed and an 8051 interrupt pin was being held low.  When I disconnected the device(s) holding it low, the 8051 started working normally.

I have a circuit somewhere - I'll look for it but don't hold your breath...


Steve

SDS1000 service manual scanned and in files/manuals/SDS1000.

It's a heap of jpegs - it'd be good if someone could turn em into a pdf.

steve

PDF of service manual added to SDS1000 files folder. Hope this helps.

I have wondered if the Intel 8051's ROM is an MROM or if it is a form of PROM. If it is a form of PROM, there should be a way to copy the SDS1000 source code onto an unblown, new-old-stock 8051 if I can get a hold of a PROM/ERPROM blower that I wouldn't need an old computer for. As for an MROM, there would be nothing I could do about replacing the SDS1000's 8051 if it gets damaged because MROMs are physically assembled by the factory.

Thanks! I didn't mind if it were either a group of images or a pdf but a pdf is just one file and would be less hassle. After looking at the computer section schematic, I could upgrade my SDS1000 to be MIDI compatible.

I believe the 8051 is MROM.  There is (was) a programmable version - the 8751 - so you could program the code into one of those.  Your problem will be extracting the Simmons code from an 8051 - possible but difficult.

Are you 100% sure the 8051 is dead.  It needs pulses from IC2 to work correctly.  Check pin 12 with a scope and make sure it's getting pulses from IC2 pin 3 - otherwise it will play dead.  Also worth checking pins 18 & 19 to see if the clock is running - crystals and ceramic caps can go bad.

Before you go much further, check the supply - there should be 5v and +/-6v.  I've seen the regulators fail, giving out raw +/-12v.  This will cause a lot of damage - probably toasting the CEM3394s and other stuff - and cause enough damage to upset IC2 and freeze the 8051.  The cost of replacing three blown 3394s would be similar to the cost of a working SDS1000.

 

Steve

I need to find where I put the IC's that were pulled and hope the pins are not broken, since I have been working on the project since late last year. If bent, I should be able to order a tool from an electronics catalog that will allow me to straighten the pins. I just checked eBay to see how much a CEM3394 synth-in-a-chip costs and those things are very pricey.

Den 2016-10-03 kl. 16:50, skrev hamsterdrum85@... [Simmons_Drums]:

> I need to find where I put the IC's that were pulled and hope the pins
> are not broken, since I have been working on the project since late last
> year. If bent, I should be able to order a tool from an electronics
> catalog that will allow me to straighten the pins. I just checked eBay
> to see how much a CEM3394 synth-in-a-chip costs and those things are
> very pricey.

The 3394's tipped the scale towards "buy" when I was offered a broken
one cheap. To my joy it was a dead prom that time and it's up and
running. But I bought it to scrap it if it should prove non-fixable...

:)

--
electronically yours, jesper

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www.electronic-obsession.se

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