ADM 3a with no horizontal scan

Mark J. Blair nf6x at
Fri Apr 8 22:47:40 CDT 2016

> On Apr 8, 2016, at 11:59, Seth Morabito <lists at> wrote:
> One more observation: Two of the three +5V regulators cut out
> when their input voltage exceeds about 11.5V. The input voltage
> comes from a 9.4VAC winding on the primary transformer. Input ripple
> is VERY low, maybe 200mV. So, I suspect those regulators need to be
> replaced.

Could they be going into thermal shutdown? I don't recall whether linear regulators from that era commonly had thermal shutdown features yet.

Mark J. Blair, NF6X <nf6x at>

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