[vcf-midatlantic] Repairs to a Heath WH19 Terminal

Jason Perkins perkins.jason at gmail.com
Sun Mar 26 23:57:46 EDT 2017

With some extra off-list help from Dave I found that the main power
transistor Q213 is leaky.

Now the challenge will be to find one of those, or something that can sub,
without having to pay $50 in shipping!


On Sun, Mar 26, 2017 at 4:58 PM, David Gesswein via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

> On Sun, Mar 26, 2017 at 04:51:30PM -0400, Jason Perkins via
> vcf-midatlantic wrote:
> >
> > After the regulator I measure 61.5 volts DC w/ .35v to .41v of ripple at
> > 60hz. - sounds like it's not regulating much
> >
> > Reading the manual more, it doesn't use an integrated voltage regulator
> > "The unregulated 65-volts DC from the power supply circuit board enters
> the
> > video circuit board at plug P202, pins 2 and 3.
> > Assume that the Terminal has just been turned on and the output of the
> > +53-volt regulator is at zero volts.
> >
> Didn't have time to look at the schematic but if you are reading 61.5V on
> the 53V output the regulator probably isn't regulating so its not filtering
> the ripple. Are you able to understand the circuit to see how it should be
> regulating and that the correct output should be close to 53 volts?

Jason Perkins
313 355 0085

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