19" K7000 dead after cap kit, 135vdc on both sides of R301 but VR is good

Xyla

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19" K7000 dead after cap kit, 135vdc on both sides of R301 but VR is good

I'm about to throw this chassis in the trash.

New flyback
New VR
New caps

VR is not functioning, even though it is good. Both sides of R301 read 135vdc, so it's not doing a damn thing. I have swapped the VR, and then replaced with a brand new one. I also replaced C57 again as suggested by the Randy Fromm flowchart.

What the hell is going on??? Is it trash can time?
 
Definitely not trash can time, take the voltage regulator back out and then measure the resistor and see if you get your 220 ohms across it like you should. You may want to do that before you remove the regulator too, just to see if it changes.

if it's shorted (0 ohms resistance) while it's in the board, you've got something back there in that back corner shorted together, looking at the schematics it's got to be pretty much that resistor or the VR, Make sure you didn't put the WRONG Voltage Regulator in, too, there were two types used and they have jumpers installed back there to set it up... install the wrong one, and it jumpers the wrong things to the wrong places and can short something out like yours is doing.
 
STR3123

I just swapped the entire R301 assembly from another chassis.

Dead dead dead.

It's actually 130v on the tube side and 132v on the other side.

Trash can.
 
that sounds like a good puzzle to have on my bench.

before you trash it, send it my way, i would like a crack at it.

of if you don't want it, sell it to me as is and don't take any parts off it so i can have the complete problem.

sounds like you have an open resister or trace somewhere.

Peace
Buffett
 
I've pretty much given up... but I'm wondering if I should replace the flyback one more time. It's a Bob Roberts flyback, one of the last ones I had. I don't use his flybacks anymore but I was hoping this one was ok.

Could a dead flyback cause this? It reads the same as working flyback I have, although I know you can't actually test a flyback with a regular meter.
 
well, if you do give up.
i still want the chassis and all of those "bad" flybacks, i would like to try them in a working chassis to see what results i get.

you can try another branded flyback to see what you get.

i have never seen a flyback do what yous seem to be doing.

i wounder if there is another resister that is having problems in the VR circuit.

i have also seen bad traces cause low B+
they were hard to find because of the solder mask and that they had continuity with a meter.

Peace
Buffett
 
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