This Philco is driving me nuts... - Videokarma.org TV - Video

Big Dave · #1 07-02-2004, 10:22 PM

Model 50-T-1403 (SAMS 114)

I replaced all of those evil black beauties and electrolytics. The horizontal is way off frequency. I can draw a small arc off the 1B3, but I can tell the HV at the anode is very low. I can barely see light on a good tested 12LP4 when I kill the lights (image is barely noticeable). voltages on the hor out are within specs, but the control grid measures -25 volts where the SAMS calls for -11.

Dumb question number 1... (not necessarily in any order here)...

Can an off freq hor oscillator cause low HV at the anode?

On pin 5 (6SN7 (v17 on the print) I should get 45 volts, but am getting twice that.

I'll post the readings vs. what the SAMS says tomorrow (I had a few lites, so it's not a good idea to play with electricity).

Are there any parts on these Philcos that are notorious (besides caps)?

I am getting very healthy readings from the power supply. The vertical section appears to be working properly (hard to tell without a picture) and the sound is good. Side note, one of the lugs on the volume control broke during the recap and I used a rat shack pot (please help me before shooting) and the sound is great.

Back to the subject at hand. The horizontal section is driving me koo-koo. If you look at my website, this is the one that had the broken CRT. It's come a long way (transformer and high voltage cage repainted).

Again, any help is greatly appreciated.

***Eric H*** · #2 07-02-2004, 10:56 PM

Most sets will have an adjustable coil in the horiz oscillator circuit to adjust the horiz within the range that the hold control will flop it both ways.
Look for a tunable coil hooked to the horiz osc tube.
Eric

ChuckA · #3 07-03-2004, 07:30 AM

Dave,

Yes if the frequency is way off the HV will be low. The flyback circuit is tuned to about 4 times the horizontal rate. A counter or scope is the best way to troubleshoot this kind of problem.

I had one of these 50T Philcos drive me nuts with low HV, turned out I put the wrong value cap (missed the decimal point) in the flyback circuit. The HV is developed during the retrace time (about 10us) my replacement cap changed the timing to less than 4us.

The coarse frequency adjust is the coil along the left edge, front (nearest to volume control). If adjusting this doesn't bring frquency within lock range, I would replace the 270pf and 1500pf caps connected to the coil, and of course check the coil for continuity. It's center tapped, 40 ohms and 100 ohms either side of CT.

Your dc grid bias on the hor output will depend on the hor drive setting, wouldn't worry about that until the frequency is correct.

Chuck

Big Dave · #4 07-04-2004, 07:07 PM

I think I may be on to something.

I will replace the two caps Chuck mentioned. I did find the 47K resistor in the screen grid of the hor out had doubled in value (out of circuit). I am just going to replace everything in the horizontal AFC, oscillator and be done with it. Considering the conditions this set was kept in at one time, I wouldn't be surprized if more resistors had drifted. Some of them look like they had toasted sometime in their life.

I'll keep you posted here and on my website.

This Philco will not beat me. It will give my years of enjoyment after being dead for so long.

Big Dave · #5 07-05-2004, 05:54 PM

I changed the two micas and a few off value resistors. Still no change. This now a junk set. Screw it.

Big Dave · #6 07-05-2004, 08:31 PM

So, I lied about lying. Now that I have had some time to cool off, I will once again retrace my steps. I think the side effects of new blood presure medicine is taking its toll. More later, hopefully, an image.

bgadow · #7 07-05-2004, 10:12 PM

I have a similiar set and had a hard time getting the horiz/hv to run. I had to go through my whole pile of used 6SN7's to find a good enough horiz. osc. It had other problems but that was the only one keeping the screen dark.

Big Dave · #8 07-05-2004, 11:51 PM

After playing with it more and replacing a few more resistors, I figured out not having the yoke/focus magnet assembly effectively shut down the HV. To avoid boring you, I think my spare yoke or focus magnet crapped on me. Next thing I knew, the 5U4 was red. I powered down the variac and swapped it for the original. I got a good healthy arc and some light. After swapping out ion traps and playing with them, I got a decent picture.

I will need to make a rig to hold the CRT while I make adjustments. It's not a good idea to support your 12LP4 on a phone book (flame later, please).

After replacing the caps Chuck suggested and figuring out my spare yoke/focus was bad, I got the horizontal to lock.

The tuner needs some attention and the vertical may. I think the vert lin control may have a bad spot. This set uses a 6AQ5 for vert out, not a good choice.

Thanks for the help and pics will follow here and on my site.

The cabinet has a couple of gouges, which I think stain will hide. Laquor will come later. I really think cleanup and touchup will make this a very presentable set.

Big Dave · #9 07-06-2004, 10:48 PM

SUCCESS!!

I now have a very viewable picture. The vertical was fine, needing only height and lin adjustments. This time, I was able to set the tube on the chassis. Though the picture is lopsided, I played it for over an hour and a half with no problems. The tuner's channel slugs did need readjustment, since I only had sound on channel 10 (WBNS). 4 and 6 were picture only, fixed after adjustment.

The cabinet was not near as bad as I first thought. I cleaned it with a citrus based cleaner called DE-SOLV-IT. It removed tons of crud and the cabinet now has a nice satin sheen to it. The few gouges seem to have hidden well. I'll still need to touch those up.

I'll post updated chassis pics and pics of the set running out of the cabinet on my website in the next few days.

BTW: The doc took me off those rotten BP pills and gave me others.

Next up...either the Hallicrafters or one of the basket case RCA's.

Big Dave · #10 07-11-2004, 09:45 AM

The Philco is now back in the cabinet and looks great. I still need to get a switch for the replacement volume control (I know there is one in a junk box in my mother's basement. I'm getting the missing knob from Tony.

I have decided to get one of those disposable film/digital cameras, the ones where you can get a photo CD in addition to the prints. I will be replacing some of the pics on my site across the board, except for those I made before getting the camera. Hopefully, these pics will look better than the vidcaps (it wouldn't be hard).

I have decided to do the Hallicrafters next, since I know I have a SAMS for it.

Note of interest (or lack of)... I will be replacing all pictures of the sets running.

Thanks to all who helped me solve the ailment which drove me nuts, and to the doc who prescribed a different BP medicine.

#11 07-11-2004, 01:11 PM

Hi Dave, sorry that I couldn't contribute any help but sure would love to see screen pix once you get a chance.

As far as BP medicine goes, that stuff can be nothing nice as I had a boss who had been prescribed the wrong flavor initially. I knew when he had taken a pill as the back of his neck would turn red and he'd become real surly.....he wouldn't listen to me so I spoke to his wife who in turn spoke to his Doc and he finally changed it......boss man eventually thanked me for meddling!

Anthony

Big Dave · #12 07-18-2004, 06:48 PM

Just about done.

***Eric H*** · #13 07-18-2004, 07:26 PM

Dave, good job on the Philco!

Don't you just love Philco, their extensive use of Black Beauties, the mix of Octal, Loctal, and Miniature tubes, the cramped chassis's...

Whats the difference between the 50T-1403 and the 50T-1400?

The only obvious difference I can see is your has the painted screen bezel with brass trim and mine is just a clear piece of plastic.

I took the channel selector bezel off of a 1404, not sure if it's correct for the 1400 or not as this set has a dot for a channel indicator underneath that brass plate.

The CRT I put in this set is an inch shorter than the 12LP4 I took out but it's unmarked so I don't know what it is? 12WP4 maybe?
Don't know if it will work either

Eric

Big Dave · #14 07-18-2004, 10:17 PM

According to the SAMS, there are some minor electrical differences (some caps aren't used in certain models). I think the main difference is the cabinets. I know there is a square box version of this one. The safety glass and possibly the finish might be the differences.

I'll throw in a shot of the set working out of the cabinet.

Charlie · #15 07-19-2004, 04:42 PM

I also have the 1403. I think one of the differences is that the 1403 has the signal attenuator control on the top of the cabinet just above the crt. I don't believe that the 1400 has that feature.

I've never tried mine out. I've had it nearly a year, but haven't had the chance to get to it. I've got too many pulled apart as it is... don't need to start another right now!