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The 5000 grit was not used on the rubber pads (I do use paper for that). That was on the circuit board itself. The issue here is that the keys that are unreliable do not change when plungers are swapped. The conductive rubber all read well within spec with a meter, but the keys in the lower left...

I burnished it well and then cleaned with alcohol. Obviously 5000 grit doesn't take much material off. I swapped posts with keys that were working well and put it back together. It's a bit better but not much. The problem keys are still c a s d & f so it's not the posts or the issue would have...

This contact point on the board has the same issue with all my plungers. On most key contact I can press a plunger sloppily and quickly and get fast characters while on these, and especially the one, any plunger is hard to get a press out of. After messing with it I think that the left contact...

I took the closest pictures I could then tried wearing 3x reading glasses along with a magnifier "Helmet of Goober" with both lenses in place and I still cannot see anything off. Out of desperation I burnished the contacts with 5000 grit sand paper (For polishing car paint) and, indeed, the...

I am certain its not the pads. They read ok and work perfectly on all the other positions on the board. Any pad has issues on these few contact points on the board. Flexing the board a little in either direction doesn't help. THe only thing that has been helping is pressing the pad down so that...

On my pet 4032 there are 3 or 4 keys, all in the lower left corner that are very unreliable. This is a Graphics Keyboard The stems are good and work perfectly in other positions (They read about 200 ohms) The board has continuity (I had to repair 3 of the overlay traces) Here's the rub, the...

They go with the RAM Links. I thought they used a Wall wart but that goes with an fd-4000. I've been trying to recreate the setup all these came off of originally. It looks like the cmd hdds have smaller black supplies with the same outputs

That was it I think. It matches the pin out for the CMD hard drive. I have a smaller, CMD branded, PSU but this looks to have the same specifications. I will also pull down my 1581 this weekend and see if it is missing the PSU in the box. Mike

I checked and the A570 takes a square connector I don't have a CD-32 or A590. Here are some images.

Good thought. I do have a cd-rom for the 500. I'll check this evening and get pictures

Nope they are labeled as DSP A-500 but that same label has the pinout for the 4-pin round din thats on the cord. The 4 pins dont match the offset type 4-pin din as a C64 either. I compared it to a real A-500 psu and they look to have the same specs, just different connectors on the label.

I got 2 of these power supplies in a collection last summer and had originally put them aside thinking they were replacement PSUs to go with REUs on the C64. Today I found the correct REU PSUs and noticed that these ones only puts out +5V, 4.5A and +12V, 1 Amp so they can't be for C64s with no...

I am off on a little bit of a tangent looking at the keyboard because its going to a meeting Friday of the group that gave me this machine (It was in such bad condition several members had already rejected it). They are going to "Bestow" a reproduction label upon it and all that is preventing it...

I had to do a refresher on open collector. You are right, it is fine. In fact it seems my issue is that I burned the wrong Edit ROM. I have found multiple things online on the keyboards and some call mine a graphics keyboard and others a business keyboard. I used the edit ROM that was for the...

Disregard this. I finally found the matrix for the graphics keyboard. It looks to me like the 74ls145 binary to bcd decoder is bad. The variances on the matrix make no sense. The keys all produce consistent results but they don't follow any logic for a bit or two being stuck or a key code...

One more quick question. My keyboard has a 5x4 key numeric keypad and the matrix in the manual is 3x4 with a double wide 0 key. Is the matrix the same electrically on the different layout? Mike

OK all the ROMS are in and I finally have good checksums on everything. I am starting in on the RAM issue and so far have found that /CAS_1 is always high. Checking the 74LS00 at UD5 I found that the inputs to the NAND gate that puts out /CAS_1 are both active but are never both high at the...

OOPS, I forgot that the Promenade C1 Requires that 24 pin chips go in to the right side of the socket even though the Pin one side goes to the left. These ICs are all erased and appear fine. Mike

The EPROMS came in, I accidentally ordered 2716s so they had to be reordered. The NoS 2532s are not erased and i just discovered that the old EPROM eraser I was given recently had the leakiest batteries I have ever seen in it. The Circuit board and tube were absolutely destroyed. Now I am trying...

I adjusted the monitor and it was only detecting 16k of RAM. I got in my replacements today and swapped out the bad IC but it is still only showing 16k. I inadvertantly did a 36 hour test on the machine where it was running on my bench doing the PETTESTER RAM test the entire time so perhaps...