philco on the bench

[Don Lindsly]

Make sure you only change split chassis halves with one of the same number. They are marked with numbers like RF91, RF44, etc. The other side will be marked with D191 type numbers. Don't mix and match. Each RF chassis is intended to go with a specific deflection chassis. Plugs may fit, but the wiring varies.

Good move on the isolation transformer. That is the safest solution.

[Eric H]

I have a 53 Philco with the same type chassis.

If you see any flat square capacitors that look like Mica or say Micamold on them you should change them.

This little cap here shorted solid enough to blow the fuse.


Don is right about the chassis numbers also, make sure your schematic is for the numbers you have.
I struggled with one set for years after recapping because I had the wrong schematic!

[jeyurkon]

I understand that Micamold made paper capacitors that looked like mica and that they caused many problems.

When you say "any flat square capacitors that look like mica..." do you mean to replace them also because they might not be mica?

John

[radotvguy]

I found three caps that looked like mica or bakalite. Two were [email protected] and one at [email protected] . They were original and stamped . Replaced all three . Now i have 3/4 of a screen , which is a improvement however not there yet . I can fill 3/4 of three screen with height control at its max .I checked all resisters in this set and they seem ok or within range of what they are suppose to be . Only found one way off which i replaced. There are a couple of mica caps which have not been replaced yet , however they dont appear to be in the directly in the vertical circuit . I sprayed the controls with de-oxit and also gave the tube sockets a quick spray . Even wiggling the tubes in the socket makes no difference, so i guess i can rule out bad connections . Guess i will continue my trouble shooting tonight . Got my isolation transformer in yesterday . Got a question . Can i pull the high voltage sweep chasiss and being the a/c plug does plug into it , can i take voltages on the bench with just that chassis or do i have to pull the other chassis and have the yoke connected . The schematic i have seems to be correct so far .

[Don Lindsly]

You need both chassis and the yoke for all the voltages to make sense. It's not much trouble and you can be fooled by the missing half. I would not recommend running the sweep chassis without the yoke. That will throw the boost voltage off as well.

Check the resistance of the height and lin controls and the resistors in series. Check for a high resistance from the height control tabs to ground. That should read open. Sometimes grit will get in the front of the control and load down the voltages slightly.

The discharge cap off the oscillator plate is another suspect.

What is the chassis number?

[bgadow]

A bad pot can play tricks on you. I've pulled my hair out only to discover the trace inside one was cracked.

Make sure you got rid of every black beauty since they all will be bad.

[radotvguy]

Thanks guys for all your help . I am going to recheck the vertical height and lin controls again . I believe two mica caps are bad in this set . It has a total of four in this chassis . Will be removing them tonight going to check them . I never had to replace a mica cap yet on anything i worked on . I usually thought they were pretty reliable however i guess after 50 yrs anything is prone to fail . My next step i guess after that is the voltage readings .

[gadget73]

I have a '53 model thats nearly identical to that. Mine has a different grille cloth and some brass stuff in the grille, but thats about the only obvious difference. Also mine doesn't have the paper tube up to the deflection coils.

Mine had 2 bad silver mica caps in the horizontal stage, causing the oscillator to be extremely unstable. SM caps are generally reliable but after 55 years anything is possible. It was also packed with black beauties, most of which were split open. I still need to do some more tweaking, the picture is a bit cone-head looking but I think thats just adjustment at this point. I haven't had time to mess with it though. If you play with the adjustments, you'll find the vertical linearity and the height control interact, so if you can verify all the parts are good, it might be a case of adjusting both controls to get a full size picture.

Also, the model number you should be able to find on a paper stuck behind the speaker somewhere. Mine was on the left side as viewed from the back. It should be two numbers, a dash, a T, then a model number. The first two digits are the model year.

[jeyurkon]

Hmm, maybe you can replace the "black beauties" and come out ahead financially. I guess audiophiles don't mind the risk.

http://www.tmworld.com/article/CA439412.html

John Y.

[radotvguy]

The black beauties in the high voltage sweep chassis were all replaced already with orange drops . I am doing this set for a friend . He replaced a few caps before bringing to my house . I did find last night that there are suppose to be 2 120mf electrlytic caps in the power supply / rectifiere stage . One was replaced with a 100mf, so i am going to correct it and add another cap(22mf) to make it the correct capacitence . Also found a off value resister in the supply circuit as well . I aint sure if this is my problem however it needs to be addresssed i gues before i start taking voltage readings . One of the mica caps in the horizontal circuit tested shorted when i checked it with my DMM , however i tested it in circuit . Does anyone know if i can plug in this chassis alone on the bench to check if my supply voltages are correct ????

[radotvguy]

Well i finally fixed the vertical issue, it was a wrong value cap that i installed . I read the bumble bee cap however the schematic listed a different value . After reinstalling the cap according to the schematic the vertical height came back . My friend who owns this philco came over and recapped the if/rf chassis and now we lost sound . Back to trouble shooting . Does anyone have the philco logo which goes inbetween the front controls .

[Old1625]

Originally Posted by radotvguy

Thanks Don , i will check that tonight . I also found today a new isolation transformer from a parts place i been using and got a great deal on it . So i took the plunge and bought one . A little more then i want to pay for it however its definitly something important to have on the bench when working on old tvs and radios . It is suppose to be able to handle up to 450W , WHICH IS A BIT OF A OVERKILL !!!! But better then not being up to what i need . The two tubes vertical ossc and output are new . There is a bakalite .047 @ 400 cap which is in the vertical circuit that i have not replaced yet .

Good for you! That isoformer is worth every penny you spent! It's too easy to "forget" and plug the set in the wrong way. And some old radios back in the day had the on-off switch on the chassis side of the line, meaning with the plug inserted one way you get a 60~ handshake when the radio is off, the other way and it'll give you a zingie when it is on. It's not only your own life at stake but remember that your generators, bridges and other 110V operated test gear can get caught in the loop as well, and suffer damage.

[radotvguy]

Well with the help of a few AK members this set is up and running . It went home to its owner a friend of mine this past weekend . IT performs excellent and was running in my basement for hours. After fixing the vertical issue , then my sound was lost when i recapped the IF/RF chassis . It wound up being a loose connection . Then i had a no video problem, justy a grey screen . With the help of a fellow ak member it turned out to be a bad contrast control .

thanks guys

[Ampico-kid]

Originally Posted by radotvguy

Well with the help of a few AK members this set is up and running . It went home to its owner a friend of mine this past weekend . IT performs excellent and was running in my basement for hours. After fixing the vertical issue , then my sound was lost when i recapped the IF/RF chassis . It wound up being a loose connection . Then i had a no video problem, justy a grey screen . With the help of a fellow ak member it turned out to be a bad contrast control .

thanks guys

Hi Mike;
Glad to hear you finally conquered the beast.

Seems like it was a long hard fought battle, but once again persistance and patience have paid off.

Each set we work on is a new learning experience, and it's great to have a place like AK where knowledge is plentiful and people are always willing to share it.

Congratulations and keep up the good work!

Bob