[vcf-midatlantic] Repairs to a Heath WH19 Terminal
mspproductions at gmail.com
Mon Mar 27 11:49:03 EDT 2017
Jason, what is the transistor model? on the schematic that just looks like
a house part number?
On Sun, Mar 26, 2017 at 11:57 PM, Jason Perkins via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> 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
> > > 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
> > the ripple. Are you able to understand the circuit to see how it should
> > regulating and that the correct output should be close to 53 volts?
> Jason Perkins
> 313 355 0085
Owner, MSP Productions
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