[vcf-midatlantic] Repairs to a Heath WH19 Terminal
perkins.jason at gmail.com
Sun Mar 12 12:37:53 EDT 2017
Looking for some advice on getting a Heath WH19 terminal going again.
First, some schematics:
My annotations on the x-ray view: https://goo.gl/photos/PF8N7wRDPLc1czUU7
What I observed:
When first powering the terminal it did nothing. The fast blow 1A fuse was
open, the wire was broken. As it was handled it broke more, suggesting it
could have simply failed from vibration? The manual said that a 2A slow
blow fuse is appropriate for 120v operation.
I replaced the fuse with the smallest one I had on hand, a 4A slow blow,
connected the terminal to a current meter, and powered it up. It beeped :)
But was drawing 5A :( and then there was a little smoke :( :( I quickly
powered it off.
R263, a 1.2 ohm 2W resistor had cracked. R263 supplies the +53v rail to the
C228 seems to be good (open resistance, correct mfd), D208 and D211 seem to
be good (.5v one way, open the other), C229 isn't shorted but my meter
can't measure its capacitance.
I replaced R263 with a 4w 1.2 ohm resistor I had on hand, and powered up
again. Still too much current draw, and more smoke in the area of Q217.
Does this suggest Q217, the HOT, is bad? I pulled it out and did the diode
test on it, it seemed to test OK? It's a BU500, and I see some NOS ones on
I'm unsure what my next step should be.
Thanks for your input!
313 355 0085
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