GE TC-34P1-R (Hitachi NP6C chassis) bad screen supply oil capacitor

[japlytic]

Someone gave me a GE TC-34P1-R TV set with the symptom "no picture". When I turned it on, I got a station with a bit of "blue static" and then the set shut down, with a "ticking" sound from the power supply, which suggested there was an overload.

Opening the set revealed that the +800V screen supply, derived from a diode connected to the collector of the horizontal output transistor, had a faulty 0.068uF 1000V oil capacitor which has overheated and bulged.

Replacing this capacitor with a polyester unit (two 0.22uF 630V units in series), along with two other oil capacitors (one after an inductor after the mains rectifier, and one used as an AC filter (yellow ring), even though they were still good.
There were two 4.7uF 315V electrolytics on the +200V CRT bias supply; they were slightly leaking. They were also replaced with one 22uF 350V unit.

When the set was turned on with a series lamp limiter, there was a picture (slightly shrunken because of the lower input voltage) with no other serious problems. The set was then plugged straight into the wall and there was a fairly good picture, which needed focusing.

Because this set was a live chassis , I plugged it into an isolating transformer and adjusted the focus with a mirror in front of the set.

[kc8adu]

Re: GE TC-34P1-R (Hitachi NP6C chassis) bad screen supply oil capacitor

looks like a late 70's hitachi to me.
if its like the ones i remember it will play forever.
had 30 of those that were trashed by lightning given to me.
i still have a few of the crt's left.
most went into arcade games which are still looking good 15 years later of 24/7/365 use.
a funny note is that some hitachi sets here were ge chassis.
they even had the schematic in a box on the back .good thing too as you needed it!