Discussion about the Korg PolySix synthesizer

Robert,

 

I had similar problems in the past, however, in my case replacing the SRAM
cured the fault. This was a new component and not old stock or something
pulled from a 'working' chassis. Not quite sure about the reliability of
some things bought from eBay I am afraid to say..

 

So you have done all the tests and it would appear to be working correctly
although it isn't. One of those types, eh? I know it is old ground but I
would go over the board once again with copy of schematic in one hand and
squeaky marker in the other and do a full continuity test on the data bus
(d00 - d07), etc. I have a gut feeling that this one is not going to be a
component fault.

 

Cheers,

Andy

 

From: PolySix@yahoogroups.com [mailto:PolySix@yahoogroups.com] On Behalf Of
Robert Weigel
Sent: 08 December 2008 08:31
To: PolySix@yahoogroups.com
Subject: [PolySix] STrangggeeee. Can't write to memory or..it's not reading!

 

All the patches are the same on boot up. I haven't bothered sticking
a battery in this one because the problem exists where it simply won't
save patches when it's powered up even. hmmm.... now I know on other
units I've done it without the battery. I don't think a local
capacitance is required from the battery... but anyway basically it
will edit everything fine. I've calibrated reset and dac. All good
there.

But once you hit write with memory protect off, the light flashes and
you select a location and the light stops blinking. Great. All
normal. But as soon as you select another patch and come back it's GONE!

Now..I assume that the patch buffer on these things is the 64 byte of
RAM in the CPU? Does anyone know for sure?

The data lines are hooked straight to the cpu of course. There are
4042 f/f latches separating most of the address lines from the buss
and two of them go direct to the cpu. Clock gets about a 167hz 30%
duty cycle waveform or so on the 4042 and all of the lines show data
moving on them just fine..... and the WE and CE move when you
initiate a write!

I haven't checked the sync on those signals yet but I thought I'd stop
for the night and just see if anyone has seen this peculiar problem. 
OH and I did install new memory chips...went through all three I got
off ebay and none worked any better. Also replaced one of the 4042's
to no avail. Not a single parameter changes anything when its' saved!

 



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