RCA KCS 94 Aquisition and Questions

[mr_rye89]

Did a recap yesterday, powered up tonight. so far we have sound, vertical sounds like its running, horizontal is running (doesn't sound right), no smoke! no raster or picture though. B+ voltages are a tad high (I might increase the value of the fuse resistor) most tubes test ok, the HV rectifier seems flaky, I'll likely get a replacement before the weekend is out. When I first got my Motorola set it's HV rectifier was flaky and it wouldn't make a picture either.......

EDIT: The thermistor in the link worked well

[mr_rye89]

Kinda quiet in here.......

I changed some resistors, put a new HV Rectifier and damper in and farted around for an hour to get it to make a picture..........Turns out the ion trap was mis-adjusted. This set won't make a picture without it lined up right..D'oh!

It makes a good picture now, but I'm not watching it due to the burning resistor smell coming from it, I think it's the 150 ohm 1 watt resistor that goes between the vertical output transformer secondary center tap (or yoke) and the control grid on the vertical output tube. Vertical seems fine.

And yes the centering magnet needs adjustment

[JohnCT]

Originally Posted by mr_rye89

I changed some resistors, put a new HV Rectifier and damper in and farted around for an hour to get it to make a picture..........Turns out the ion trap was mis-adjusted. This set won't make a picture without it lined up right..D'oh!

Heheh... ion traps..

I had exactly one experience with an ion trap (although I'll be seeing more after joining this group and getting into old TV).

Back before I was even a young shaver, my dad would throw me $5 to change picture tubes in TVs for him. He had me change a B&W tube in an old RCA, and I put everything back in it *exactly* as it came out. I turned the TV on and the picture didn't look any better than the worn out tube that I changed.

When dad came back, I told him the new tube was no good. He looked at it a second and rotated the ion trap around the tube and the damned thing sprung to life.

I never forgot that, but I haven't seen one since.

Picture looks strong and linear on your project.



John

[compucat]

I have always like that particular model. I am rather fond of those metal cabinet RCAs. I have one of the eight inch portables I restored ages ago which still works great. Too bad RCA was so sold on using printed circuit boards. The heat from the tubes just does them in.

[JohnCT]

Originally Posted by compucat

Too bad RCA was so sold on using printed circuit boards. The heat from the tubes just does them in.

I can't recall any issues with RCA printed circuits, at least those in the color chassis.

I recall bad connections on tube sockets that were tough to make right because of the oxidation, but I found that replacing the socket fixed it permanently. The copper itself was never a problem.

I do recall Philco circuits having the copper roll up like carpet as soon as a soldering iron touched it.

John

[mr_rye89]

Yeah im not a big fan of old phenolic PC boards in tube gear. The ones in this TV aren't too horrible, I didn't disturb any traces either, I just cut the old capacitors out while leaving some of the old leads, I twisted and soldered the new leads to the old ones. Not pretty but better than lifted traces. That 150 ohm resistor is still running too hot, probably because the b+ is 20 volts too high, and I increased the fuse resistor from 5.6 to 8.2 ohms with little difference.

this is a cool set an it has a 4 legged base with a lazy Susan so you can swivel the whole set.

[JohnCT]

Originally Posted by mr_rye89

That 150 ohm resistor is still running too hot, probably because the b+ is 20 volts too high, and I increased the fuse resistor from 5.6 to 8.2 ohms with little difference.

Sometimes a resistor will run hot if the filter in front of it is weak.

John