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Thanks for the info Scott. I would suggest that when you screwed the case together again, the CPU or memory PCB has "warped" a bit. I have found that if either of these cards is not 90 degrees to the back plain pcb, expect problems. The contacts in the card slots don't make good contact with the CPU and memory card fingers.
The components and design of the cpu card in the SDS7 is really old school. It has "somewhat" less processing power than a Sinclair spectrum, probably similar to a Commodore Vic20. Once booted up, all the processor is doing is monitoring the panel buttons, displaying it's current function and sending the control voltages and setting signals to the voice cards. That's it!! nothing really more. If you look at the CPU and memory design in the schematics of the SDS7, 90% of what you see is now contained in a single chip with modern micro controller designs. Some of you may have heard of PIC's, AVR's, Arduino's etc. ALL of these could be used to do what the SDS7 cpu is doing plus way more.
The vast majority of non booting, memory loss etc problems people have with the SDS7 is because of the original hardware design. By today's standards it is seriously lacking. I have said it many times that most of the issues are due to poor connections somewhere in the system. Oxide on contacts, weak connection pressure in PCB sockets (due to miss alignment or general age and wear and tear), poorly routed ribbon cables picking up electrical noise. I have never liked the fact that the cartridge socket pins are so exposed at the rear of the SDS6,7 The pins should be protected from both physical AND electrical damage. One dirty, broken, bent or poorly aligned pin in the socket will cause cartridge save failure.
Richard
---In simmons_drums@yahoogroups.com, <scott@...> wrote:Hard to say exactly what the problem / solution was with mine, but here's
what I did:
First, the "Display & Switch Board" (programming panel) on mine was
incredibly flakey, so I replaced it with a working one.
While the unit was open, I checked all of the cabling and PCB connections.
Nothing was loose, but I did wiggle them all to make sure they were all
seated properly.
Finally (and this may have been what did the trick) I sprayed some Deoxit
onto the DIN pins where you plug in the Memory Cartridge, and then wiped
each pin with a cotton swab.
Then I plugged it in, powered it up, and everything was working perfectly!
Unfortunately, then I decided to reassemble the case and put it back into
the rack. After doing that, it wouldn't work. I get power (voice card
lights are on) but the display is blank and the lights are wonky. So I
opened it up and re-checked everything, and even tried it with my old
Display & Switch Board, but no dice. So I handed it off to a local tech
who's brilliant with vintage gear... ∗SIGH∗
Anyway, I noticed I was getting some crud off the pins when I was cleaning
them off; I would suggest to anyone having problems to make sure the pins
are all straight and clean. Many years ago I had a Kawai voice ROM that
was missing one of it's pins, and I had to solder some wire in place to
get it to work in my R-100. It may seem obvious, but do a visual
inspection to verify that all the pins are there - they can snap off or
get bent...
all my best,
- Scott