Does anyone have a Heath Zenith 151 (8088 XT)??

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Joined: Feb 18 2015
Posts: 22

I recently acquired a Heath Zenith 151 XT. It has onboard diags and upon booting I get (error at addr 0000 bit 3 on chip #308). According to what info I can find this means chip at location #308 on the video board has an error. These are 4464 (4x64k) chips and since I do not have spares, I swapped this chip with another memory chip in a different location expecting the chip # to change but I am getting the same error at #308. The CPU board are #200 chips, Video board are #300 and the memory board are #400 locations. I removed the memory board to have better access and now gotting a (error at addr 0000 bit 3 on chip #406). This is puzzling since the 400 chips are on the Memory board which is laying on the bench. The #308 error is gone. When I put the memory board back in the error returns to #308. I have reseated all chips on all boards and checked P/S voltages which are in spec.
Does anyone have any experience with these old Heath Zeniths? This is one that has a back plane and not a motherboard (cpu on plugin board).