[time-nuts] Re: HP 3561a Service Manual

[Jim Harman]

If you are getting RAM refresh errors with a device of that vintage, check
the power supplies that feed the RAM chips. In those days, there was a
second supply voltage (-12V?) that was used only for refreshing the data.

On Sat, Nov 13, 2021 at 12:27 AM Dan Rae via time-nuts <
time-nuts at lists.febo.com> wrote:

> Norman,
>
>  From the code 0 7 26, if there is just one faulty RAM IC you will see
> down the bottom of the screen a RAM hex number from 0 to F. On page 6-59
> in Volume 1 you will find a list of the IC numbers that correspond to
> those RAM numbers.   However since you seem to have an additional Error
> Code 31 and the full list of RAM numbers displayed it is likely to be
> more than a simple one IC failure. 31 indicates RAM refresh test error,
> if that means anything to you, I'm a bit lost frankly.  It might be
> worth checking the board connections...
>
> Good luck!
>
> Dan
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-- 

--Jim Harman