RL02 Question

[Aaron Jackson]

>>> It is also possible that a capacitor has deteriorated in the
>>> timeout one-shot
>> 
>> I was beginning to wonder if it was a capacitor
>
> FWIW, while restoring my 11/45 and its RK11-C, I found several failed 74LS123 dual one-shots in various places.
>
> Haven’t looked at the RL02 drawings yet, but it seems it was a popular part in DEC designs; if you have one there it might be a more likely fail than the associated small-value timing caps which tend to be fairly robust ceramics?
>
> They are pretty easy to diagnose with a chipclip and a logic analyzer.
>
>   —FritzM.

Hmm, thinking about this a bit more though...

I have tried three controllers, two r/w modules and two servo
controllers. I'm beginning to think the drive is fine and there is a
problem with the RLV21 controller. I measured the frequency of its
pulses and they seemed to be within spec.