Philco 50-T702

[reichsrundfu]

Well Damn! Thats looking pretty nice! Your vertical height is excessive but the nice part is that can be corrected by adjusting the vertical height pot on the back!!!!!!! :-)

Damn good work Crist! And that picture is looking pretty nice and sharp, and with good greyscale too!

-George-

[reichsrundfu]

BTW: I betcha you'll be amazed when you get full B+ on a nice new set of diodes!!!!!

-George-

[Crist Rigott]

Originally Posted by reichsrundfu

BTW: I betcha you'll be amazed when you get full B+ on a nice new set of diodes!!!!!

-George-

I replaced the selenium's tonight per your instructions. Work great except I need to go down to 20 Ohms to get 308 volts. Sams list the B+ at 310 volts. Still more issues and I'll keep replacing more resistors tomorrow.

I am keep a tally on each resistor as to what it checked when removed. There were quite a few that were out of tolerance, some were almost spot on, and several were low.

The picture tube isn't as bright as I though it should be. Can't see it with the lights on.

[reichsrundfu]

As for the B+ if 20 ohms does the trick then just go with it. As for brightness, have you replaced all the caps associated with the HV? Don't miss anything. And also make sure the tubes in there are up to snuff!

George

[Crist Rigott]

All paper caps both LV and HV have been replaced along with all the resistors, and all the e-caps too. The only thing done to the tuner was to clean the wafer switches.

Here is a very short video of my biggest problem right now. The picture goes negative when I turn up the brightness. I substituted the miniature tubes along with the 6V6 HV Osc. tube. I don't have 1B3GT tube or any of the Loctals. A club member thinks its the CRT and to prevent it it needs a brightener. BTW my HV is still low at about 4Kv instead of 5Kv.

Any ideas of what to do?

https://youtu.be/pz6hSvGtM10

[Eric H]

Going negative at a higher brightness setting is a classic symptom of a bad 7JP4, I've seen a lot of them like this.

If the HV was affecting it the picture would bloom and go out of focus, it looks fine other than being dim.

You said you plugged this tube into another set and it was bright? Did you actually display a picture on it or just plug it in and light it up?
I've noticed that simply lighting one up can be deceptive, it may appear okay but won't work well when an image is displayed.

[Crist Rigott]

Originally Posted by Eric H

Going negative at a higher brightness setting is a classic symptom of a bad 7JP4, I've seen a lot of them like this.

If the HV was affecting it the picture would bloom and go out of focus, it looks fine other than being dim.

Well, that's not good news! I'll try the tube in my friends set again and see what happens.

[Crist Rigott]

I hooked up the heater wires to my BK 467 CRT tester so I could vary the heater voltage. I varied the voltage from 6.3 to 7.5vac and saw very little changed to the "negative" effect. The CRT did get just barely a very little bit brighter. I did not want to go any higher on the heater voltage seeing it seemed to make little difference.

[broadcaster]

Listen to TV Dude with his HV fix. I have repaired several of the 7 inch Philcos using a Motorola 7 inch HV transformer. Works great. I also have a SS tiny module that will make 7KV, allowing you to eliminate that troublesome Philco HV transformer

[Crist Rigott]

Are you saying that the Philco HV transformer is my problem?

[Dave S]

Originally Posted by reichsrundfu

Greetings: I just am completing restoration of this model set and its a fun one! Its a little cramped underneath but if you take your time you'll get it restored. I really suggest that you do your filter capacitors one section at a time (resist the temptation to just cut the leads and do all the sections at one fell-swoop). Its easy to omit something or make a mistake. Thats what happened to my set when a friend of the previous owner I acquired it from went through the capacitors. He made a couple mistakes which prevented the set from working, but correcting those errors resulted in a nice picture. Also you probably should not overlook the mica capacitors especially in the vertical and horizontal sections; I am seeing more and more of them getting bad and you'll see it in poor linearity. Pay special attention to the mica 100pF / 500 volt cap in the vertical amplifier!

Good luck and have fun! This is a cool set!

-George-

Hi George, hey it's been a long time since I've seen you. Good to 'see' you here!

-- Dave Sica

[Crist Rigott]

I'm getting started on the cabinet and I have a question. I pulled the safety glass and the mask and the mask color looks like a very pale avocado green. If anybody else has a 50-T702 can you confirm what color your mask is?

Thanks.

[jr_tech]

Mine is more pale than that... but could have faded over time. It is greener than the 7JP4.

jr

[Crist Rigott]

jr-tech,
Is your TV a 50-T702? It doesn't look like it though. I thought the mask was going to be more of an antique white color. I was surprised to see it have a green tint to it.

[jr_tech]

Sorry, mine is a 701, may or may not be different.

jr