HP 9825 16K 09825-66523 memoryboard failure

[Rik Bos]

It's not really a array.
The banks are build op from 16 times 1*8k RAM's there are two banks one low
one high.
Octal 60 and 70 and I replaced on both banks the bit 9 chips, because the
program marked the bit 9 as faulty.
The problem is it's always bit 9 but not always the same address and not
always the same output sometimes sense is 0 sometimes sense is 1.
So the suggestion from Tony to check the vias, is the next step I'll take.

-Rik


> -----Oorspronkelijk bericht-----
> Van: cctalk-bounces at classiccmp.org 
> [mailto:cctalk-bounces at classiccmp.org] Namens dwight elvey
> Verzonden: zaterdag 4 april 2009 23:41
> Aan: General Discussion: On-Topic and Off-Topic Posts
> Onderwerp: RE: HP 9825 16K 09825-66523 memoryboard failure
> 
> 
> 
> 
> ----------------------------------------
> > From: hp-fix at xs4all.nl
> > That wasn't the problem, the errors are a bit erratic 
> always the same 
> > bit 9 but not always the same address.
> > Today I replaced the address buffer ('LS368) but that wasn't the 
> > solution too.
> >
> Hi
>  Do realize that with a RAM array, the failing location of a 
> RAM test is not always the bad RAM. It could be most any of 
> the other RAMs on that same wire.
> Dwight
>  
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