On Thu, 8 Sep 2022, Sven Schnelle wrote:
"Sven Schnelle" <svens@...> writes:
The HP4145A + B are likely easy repairs, on one the 1345 XY display
sometimes only shows a vertical line, pointing to a problem in the X
deflection. The X/Y outputs at the back of the unit are showing the
proper signal. The tube isn't getting any signal, so it must be the
output amplifier.
Might be just the gain pot - it says 1k, but i measure 1.6k. I put a
fixed 270Ohm resistor now because i don't have the right pot, lets see
whether that helps. Crossing fingers...
Most common failure in 1345 is one (or more) of the trimpots lost connection
in one of terminals. Those small Bourns round trimpots are a real disaster.
I had at least a couple of dozens of those replaced in all kinds of HP and
Tektronix gear and that was the only parts failed. That included 3 or so
1345 displays.
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Sergey Kubushyn