Philco rescued in Minnesota

[DaveWM]

for comparison, 25kv 200ma brighness turned down all the way. Horz bias set too near min. FYI, could not get the KV lower than 25kv with min brightness.

Normal viewing has it bouncing around 220-240, kv jumps around a little in scene changes, but not too bad. No blooming or other issues.

I still have a soft focus. coil is turned all the way in, but that maybe due to some early work I was doing to it when I played with different focus coils, I plan to reinstall the old one. Right now in never goes thru a focus point just gets close until it bottoms out. All the way out is not better.

[miniman82]

Sounds like the VDR in yours has drifted or something, it's part of the feedback mechanism which regulates high voltage. Same principle as the circuit used in the Portapotty.

[dieseljeep]

Originally Posted by miniman82

Sounds like the VDR in yours has drifted or something, it's part of the feedback mechanism which regulates high voltage. Same principle as the circuit used in the Portapotty.

Also Motorola's and some Admiral's. Did Philco use second anode voltage for the focus? If not, it might have a focus rectifier. No schematic handy!

[miniman82]

Originally Posted by DaveWM

for comparison, 25kv 200ma brighness turned down all the way. Horz bias set too near min. FYI, could not get the KV lower than 25kv with min brightness. Normal viewing has it bouncing around 220-240, kv jumps around a little in scene changes, but not too bad. No blooming or other issues.

I'm not currently able to read HV because I gave the meter back to Mark, but I just checked HOT current and grid voltage. I have spot on -60 VDC on the HOT grid just like Sams says, and I get anything from 210-240ma depending on picture content. Seems pretty normal to me.

[DaveWM]

thats about the same current I I am getting.

one thing odd about mine, if I set the setup switch to serv, and adj the screen G2 for just being able to see the lines, I end up with a pretty dim pic(not bad just not as bright as some of my other roundies). I have a feeling the bias is off, I need to check the voltages at the cathodes.

I can of course increase the cathode bias to get a decently bright pic, but I have always read that is not the correct way to set it up, and that the bias pot should be fully CCW unless a gun can not produce a line, in which case you max that drive and then turn up the bias until it can produce a line.

IIRC my CRT tested fine, so I am back to thinking I must have something off in the overall bias of the CRT, esp considering I am at 25kv (even when fully loaded, it only drops a bit).