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Hi, Has anyone managed to get a copy of the HP70875A on a card? Hope to hear, thanks, Bas.

OK, then this gives me an idea of what you might be familiar with. I'd suggest looking for some 6800 or 6502 data sheets that include read and write timing diagrams.? Any tutorials that include basic

Hi Harvey: Thanks this is helpful information! There is, what I am pretty sure is RAM located on the same board. Based on my brief reading of the service manual while attempting to source schematics,

This is shocking. I have had other HP tests equipment of the 8753E era and they were pretty well documented to include schematics. Diagnosis of the 8753E as described in the service manual very

FW versions: That is only true for 8753D with the CPU upgrade option. The CLIP unfortunately only describes the original 8753D CPU board.

Chad-? Check the switch with a meter when it won't power up to see if the contacts are okay.? I'd do that before going after the caps since it was working for a while. The contact lube in the some

The 8753D CLIP is available at ko4bb.? The 8753D takes the same latest firmware version 7.74? as the E and ES.? The processor schematic might be close enough to help you.

Ok, the actual kind of processor is a little less important than you think.? You can pretty much interface an 8080 style (intel) chip to a motorola (68xxx) style processor with a little logic. What

Hi Harvey: I do not know what kind of processor just yet. I thought I got an abbreviated copy of the service manual without schematics. I am now looking at another service manual that also has no

I guess none of the service manuals have a schematic for the 8753E. Anyone know of a source for these schematics? If not all them, I could use the A9 CPU board Schematic.

OE is generally derived from the processor's read/write outputs (what kind of processor is it? 68xxxx series).? IIRC, it's likely a read/write level combined with a "valid memory address (i.e now do

Spec for the old 8656A is 0.5% THD, but is normally much better for the internal oscillator.? You can use a low distortion external oscillator of course, and even an MPX generator.? I don't know

This I do not know yet. I was able to trace OE to another chip (U402). CE and WE go off to another section of the PCB. Need pull down a schematic and have a closer look. The service manual I

Looks like the idea of trying to read it, then putting a new one in is a good thought, however, what's driving the WE?? Is there a lockout we don't know of? You may have a fragile EEPROM, but the

Hi Harvey: Well the results are not good: STANDBY: CE = 4V - Should be between 4.5 - 5.5V OE= Cycles between 0 - 4.5V (Like there is data on this pin) WE= 5V WRITE: Tested when attempting to write

Hello, I’m looking for the bracket that holds the N type connector on the front panel, the short piece of hairline coax would also be a bonus. If anyone has a parts unit laying around I would sure

Hi Joe: Thanks for offering to help. I am in the Washington DC metro area (Virginia). I have found some original AM290F010’s, so I ordered those. Ideally, I would like the existing one read saved,

Rich, Where are you located? I can read, archive and program the AM29F010 in PLCC if needed. I’m in NW FL. Happy to help if I can. Joe Sent: Saturday, February 12, 2022 12:08 PM To:

Ok, you could perhaps use some #30 wire wrap wire as a probe on the socket itself The 0.025 square ww style/breadboard pins are way too big. Harvey

Yes, I have the tools, but need to dig in and see if there is an alternate point to attach to those lines. I have some pins that I use with my Logic Analyzer, but they are too thick to insert into the