hv issue

[bgadow]

I think so; I wouldn't go that far off spec.

[dieseljeep]

Originally Posted by timmy

well im going to, i do think it may be a source but the way this set is made up i have to find either a tap or another way to test the b+. the chassis has all plugs and everything else is left in the cabinet. ill have to find a way to power up the main transformer to check these voltages, or course not under load but it should show something.

That set should have a metal cover on the bottom of the cabinet like a Zenith. Tip the cabinet on its side and remove the cover to trouble-shoot the B+ circuits. Set uses a voltage doubler, like the earlier RCA's and clones. B+ should be around 380-400 volts.

[miniman82]

For sure replace those doubler caps and the first filter, that alone should fix a lot of the issues with this set.

[timmy]

i posted in the vintage tv part of this forum about the red button breaker if anyone ever had low b+ due to black dirty contacts inside the breaker. odd as it may seem i got very little across the 2 terminals, continuity, and unless i played with the button pushing in and out and snapping it i then got good continuity.i took it out and cleaned the contacts as they were black and had no shine to them at all and its fine now. i know these breakers are problems but could there be high enough resistance between the contacts to give low b+ voltage. has this ever been heard of.

[zenith2134]

Sure it's very possible. I've seen many, many protection relays in stereo amplifiers which get tarnished contacts and lose either 1 or both channels.

Also, I had to jumper across the push-in circuit breaker while troubleshooting the 19" XAM color set...it would lose width and have sound crackle due to bad contacts in the breaker. Simply omitted it from circuit(abandoned in place) and added a line fuse.

[timmy]

well just waiting for 3 more caps and with the breaker now cleaned maybe this will do it.hopefully it will also take care of the hv issue being very low.

[dieseljeep]

Originally Posted by timmy

well just waiting for 3 more caps and with the breaker now cleaned maybe this will do it.hopefully it will also take care of the hv issue being very low.

If you had that much of a voltage drop in that circuit breaker, you'd know it. It's probably a 2 amp breaker. The breaker would get hot and arc. If the doubler caps are bad, it isn't even carrying the full current. First, you have to determine, that you have enough B+.

[timmy]

well the main source coming directly off the b+ diodes are supposed to be 390v so when im done with the caps ill see if that voltage is present. and yes your right the breaker if it did get hot its bimetal tab inside would have tripped it off and that has not happened.