Zenith space command 600

[John Marinello]

$35

http://minneapolis.craigslist.org/clt/491111543.html

[drh4683]

Very nice! Has the newer generation 600 remote which is for the '73 models only, original probably defective.
That set is a '68 with a 20Y1C50 chassis. Can't beat the price either!

[jpdylon]

They 20y1c50 produces an awesome picture too when working right. I've worked on three that all have a problem with the HV regulation that had the HV go really high at random times. Watch for open caps and drifted cathode resistor in the regulator circuit.

[kx250rider]

Originally Posted by jpdylon

They 20y1c50 produces an awesome picture too when working right. I've worked on three that all have a problem with the HV regulation that had the HV go really high at random times. Watch for open caps and drifted cathode resistor in the regulator circuit.

I had that too on one of those... I never was able to get it down quite at specs though. I changed everything, even the varistor. Before I worked on it, the HV was skyrocketing to who knows what, and I got it to regulate, but still about 26KV peak at 0 brightness. Should be 21.5, if I recall. It was about 22KV at normal brightness though.

Charles

[3Guncolor]

If I remeber correctly the 23" Zeniths should be at 25KV so 26 is close but if it drops to 22KV with video the regulator is not really working as it should.

[jpdylon]

I have an article from a 1971 issue electronics magazine describing these troubles specific to the 20y1c50 and how to go about troubleshooting them if someone wants scans, let me know.

[drh4683]

This is very true regarding the HV regulation. The 20Y1C48 is basically the exact same chassis. Lots of times, the flyback runs very hot on these sets. The problem off HV regulation loss is an open .22uF@600v molded cap and a low resistance 220 ohm 1/2 watt carbon resistor paralleled to ground in the cathode of the 6HS5 regulator. Change those, and the set works fine with good HV range of the HV control. Ive probably had 10+ sets that used the 20Y1C type chassis and about 3 or 4 had HV issues caused by this bad cap + resistor. After being replaced, the set works fine and you can put it to daily use without worry that it will fail again.