slyvania roundie

[miniman82]

Sounds like your Automatic gain isn't being very automatic.

[DaveWM]

well I did a few more tube swaps, figured it could not hurt (famous last words). this time IF tubes, I had some NOS the last one was brand new and shorted, oh well I got it out before it did any damage. At least the AGC issue seems working somewhat again (do not need to flip the channel selector).

I realize IF tube swaps "could" mess up the alignment due to gain differences but then again I figure if things got bad I would just put the old ones back in.

Also the line pairing seems less. hard to say as it largely depends on the screen content as to how well I can pick it up.

Anyway time for a break again, will let everything cool done and will check again.

Oh and checking the video feed to the AGC, it was much lower than what sams said, so more cheking and I find the outpuf from the video detector to be about 5v PP sams says it should be 15 (this is at the grid of the 1st video).

So before I go nutz I check it to my CTC-16 hmm say PP, so not sure if the IF tubes were all just weak (this was done before the swap) on both the sylvania and the RCA or if the Sams is just wrong, 15v seems like a lot at the video detector output.

Anyhow I am chipping away at it. I sure am glad I dont get paid to do this, considering how many hours I fiddle away, I would never have a customer willing to pay. I really just dont know how TV guys back in the day made money. Of course with time I guess I would get better at diagnostics and not spend so much time second guessing and wonder what looks 'right".

[old_coot88]

Originally Posted by DaveWM

...Anyhow I am chipping away at it. I sure am glad I dont get paid to do this, considering how many hours I fiddle away, I would never have a customer willing to pay. I really just dont know how TV guys back in the day made money. Of course with time I guess I would get better at diagnostics and not spend so much time second guessing and wonder what looks 'right".

Heh.. back in the day, there seemed to be three fairly defined classes of TV guys. There were the tube jockeys who did the house calls and pulled the sets in when tubes or fuses wouldn't fix the problem. And there were the shop techies who dug in and did the actual troubleshooting and circuit diagnostics. Of course those two classes did tend to overlap somewhat. Then there were the 'dog shooters', the supergeeks who took on the real brain-buster repairs, who usually worked by piece work (as opposed to by the hour).
oc

[DaveWM]

while comtemplating my next move on this set, I will go ahead and replace a funky Left blue horz pot, its very touchy.

I am short on 6KT8's and 6AW8's (sync/AGC and 1st/2nd video driver, will pick up a handfull of those from my tube guy. Have some pulls but they all tested kinda weak. I am hoping those may shead some light on the odd AGC, esp the tendancy for it to overload when 1st turned on.

[DaveWM]

it was not a 6KT8 but a 6KA8, an replaced it with an older used one and it seems to work better. I have a thread on this over at ARF as well for those who dont frequent both sites. I think I am getting close.