Silvertone roundie focus issue

[timmy]

well here goes yet another thing going on here with this set, im sure this 21fb is tired but what its doing is after turning it on the picture appears focused for about 5 seconds then the picture is totally out of focus for about 3 minutes then it clears up nice. its got the clone ctc15 chassis so im thinking the crt, focus rectifier, otherwise i dont know. the flyback is new so it wont be that. any ideas would help, thanks

[dieseljeep]

Originally Posted by timmy

well here goes yet another thing going on here with this set, im sure this 21fb is tired but what its doing is after turning it on the picture appears focused for about 5 seconds then the picture is totally out of focus for about 3 minutes then it clears up nice. its got the clone ctc15 chassis so im thinking the crt, focus rectifier, otherwise i dont know. the flyback is new so it wont be that. any ideas would help, thanks

Try a new HV rectifier and regulator tube.
Remove the CRT socket and check the focus pin for corrosion. It also might be a bad 66 meg focus resister.
I also wouldn't doubt, the CRT is acting funky.
When I replaced the flyback in the clones, I always replaced the focus rectifier stick.

[timmy]

Originally Posted by dieseljeep

Try a new HV rectifier and regulator tube.
Remove the CRT socket and check the focus pin for corrosion. It also might be a bad 66 meg focus resister.
I also wouldn't doubt, the CRT is acting funky.
When I replaced the flyback in the clones, I always replaced the focus rectifier stick.

i dont have a schematic but i think the focus rectifier is a 66 meg 6000 volt and i know the hv rec is good but i will try another and the reg tube does do alot of hissing or crackling but no arcing or corona smell.

[dieseljeep]

Originally Posted by timmy

i dont have a schematic but i think the focus rectifier is a 66 meg 6000 volt and i know the hv rec is good but i will try another and the reg tube does do alot of hissing or crackling but no arcing or corona smell.

You should be able to use any of the clone's schematics for the focus circuit.
That circuit was about the same, in most of the chassis. The 66meg is a focus bleeder resister. The focus rectifier is a selenium stack. When they were bad, I used to snap them in half, just for S&G's.

[reeferman]

If you PM me with model/ or chassis number I might be able to provide a Sams.
Tap the CRT base and socket with a nut driver when both in and out of focus and pull on the focus lead to see if there is any change. Over the years I changed many sockets to correct bad focus.
When out of focus listen for any arching sound.
I would re solder the focus pin on the CRT, and be sure to check the focus tube socket.