Found these inside a non-working 71B

[Paul Berger (Canada)]

(03-11-2018 03:17 PM)MikeSD Wrote:  I found a schematic. It shows 5 mem chips. Mine has 6. Based on differences, I assume the 2 I have on right in my pic are ROMs. I'll do a little more checking around. I know I have the IDS on my computer. I'll take another. Maybe the schematic there is different.

NOTE: Wonder if anyone has an original service manual to sell. I have a copy but...

Mine is metal back. I have half dozen non-working ones I need to get around to one of these days.

My IDS only has block diagrams and nonpin-outs. Only names. Guess I have a brief version. Still I think I have enough information to tackle this.

Thanks

Yes I think the two on the right in your picture are ROMs too. See my previous post the document I mentioned is the hardware IDS and it is in the MoHPC collection.

I only have a PDF of the service guide apparently sourced from hpmuseum.net unfortunately the schematics in that PDF where cut up, but they are complete in the IDS found on the MoHPC collection.

Yes only pin names numbering was arbitrary based on +5 (Vdd) being pin 1.

Paul.