philco on the bench - Videokarma.org TV - Video

radotvguy · #1 12-08-2008, 11:27 AM

heres my newest project

radotvguy · #2 12-08-2008, 11:28 AM

another front photo

radotvguy · #3 12-08-2008, 12:25 PM

I am helping out a friend trying to get this up and running . Its a model 22BU4302. Have not found a chassis number yet . It has a 21zp4a picture tube . Here is the tube layout in this set .

12b4a (vertical output)
12au7 (vertical osc)
6al5 (phase comp)
12au7 (horz osc)
6bq6gt (horz output)
1b3gt (hv rectifier)
6ax4 (damper)
6cb6 (if amp)
6x8 (osc mix )
6bz7 ((rf amp)
6au6 (video amp)
6v6gt (aud)
6t8 (agc/fm det)
6cs6 (sync sep)
6aq5

I am trying to obtain a schematic however have not found one yet . Found the horizontal output tube bad , replaced that as well as the damper and rectifier . Powered it up breifly on my variac and had high voltage and sound , however i had just a white horizontal line across the screen . Then replaced the electrolytics ,wax caps and bumble bee caps . I used orange drops there . I only worked on the chassis on right side which is the vertical, horizontal and high voltage . Put the chassis back in and got the same issue . Checked the pots(vertical height and lin, which were definitly dirty, sprayed them with some de-oxit and then they seemed to read ok in circuit . Still have same issue except the horizontal line opens up a but more when height is set to max . Seems to be a straight forward set, however my next step is obtaining a shematic and i guess check all resisters , then go from there . Can anyone chime in and give me any advice .

thanks
Mike

Reece · #4 12-08-2008, 01:21 PM

Sorry I can't help but just wanted to say that's a very nice-looking Philco.

Reece

mattdavala · #5 12-08-2008, 06:41 PM

I've got a 22BU4001, a cheaper tabletop version that was my dads in college. It was my first attempt at a electronic restoration. This was around 96-97 when I was in 8th grade. I recapped the set, but after it had a sync problem. Wouldn't lock vertical or horizontal. I was told to check the sync resistors. That was too hard then, having to disconnect one side just to test it accuratly. I moved and the TV has been in storage for 10 years. It is 3000 miles away and still awaiting those resistors.

I'm sorry my schematic for the TV is with the set. Why don't you order one from Justradios.com? Its always great to have a schematic on hand.

My dad hated the TV. It was great when it worked, but it uses a hot chassis design, and there are two metal CRT support brackets that extend to the top corners. The focus adjustment too is connected to ground and is "hot" too. He got shocked by it in the 60's and put it into storage in our basement.

So be careful after you have the TV back together and have to adjust something. be sure your not grounded!

Best regards,
Matt Davala

radotvguy · #6 12-09-2008, 06:15 AM

i dont think mine is a hot chassis . I am obtaining a schematic shortly so i can see what i am up against here . The high voltage chassis is almost completly recapped. I didnt check the red mica caps yet becuase i was under the assumption they usually hold up till i talked with a friend who advised me to check them becuase of their age . I am assuming i can check them with my sencore LC103 i hope or a meter . I guess if there are bad ones in there then i will order new ones from antique electronic supply. I dont know who else might have them , maybe Moyers . I was wondering am maybe someone can chime in if the red mica caps could be changed with regular mylar caps . I seriously dont think so but i wanted someone elses opinion . I also found two bakalite caps or at least thats what they look to be stamped [email protected] , i am assuming regular orange drop replacements should be ok . Next week the schematic should be here .

bgadow · #7 12-09-2008, 11:36 AM

I have a good shot at having the Sams. I've been organizing them over the last week; I'll try to check tonight.

Don Lindsly · #8 12-09-2008, 05:18 PM

That is a "hot" chassis. One side is connected to the AC. For shock protection and safety, use an isolation transformer. If you don't have one, make sure the set is connected with the chassis on AC neutral. Measure from chassis to power line ground and look for zero AC voltage. If you measure 120 VAC, reverse the plug.

wa2ise · #9 12-10-2008, 12:45 AM

Quote:

Originally Posted by Don Lindsly

That is a "hot" chassis. One side is connected to the AC.

A brief look at the tube line up made it look like a transformer powered set, and I thought I saw a power transformer in there. But I don't see a rectifier tube in the list. Must be only a "filament" (heater) transformer and otherwise a hot chassis. Probably a selenium rectifier (maybe a doubler circuit) in there. I've seen sets that have the chassis at voltage either way the plug is plugged in, chassis tied to a negative rectifier output, and B+ tied to a positive output of a 2nd rectifier. Similar to how a modern PC power supply, set to 120V mode, does it on its input (line) side. And modern SS sets usually have a bridge rectifier, so the chassis ground looks to always have about 80VAC on it. Isolation transformers would be a must. One that can do around 250W should be what you'd need.

bgadow · #10 12-10-2008, 07:42 AM

Mike, I do have the Sams. Send me a PM with your address if you want it, $3 be alright?

radotvguy · #11 12-12-2008, 06:13 AM

i did obtain a sams from Moyers , i did arrive yesterday . Yes you guys are right it is a HOT chassis , i havent done one of these yet so i didnt reconize it right away

radotvguy · #12 12-12-2008, 06:32 AM

HHm , well i will take Don Lindslys advice and check the ground at the plug before operating . It does have two selenium rectifiers and from what i seen last night they are a doubler circuit . It would explain the way i saw the one electrolytic ground wiried and the wiring of the rectifier . I did power up before with a cheater cord before i actually read this thread and realized what i was dealing with . It powered up fine , i think it works either way however i hope i didnt damage anything . I pretty much has high voltage and sound however it has a vertical issue . I have a horizontal line across the screen . I have yet to recap the IF/TUNER/VIDEO chassis yet , maybe the problem lies there . I do not have a isolation transformer and would like to obtain one soon but i have not come across one and i am afraid of buying one on ebay and it wind up being someones broken junk . I have had bad luck with buying test equipment from Ebay . It usually does not work and gets damaged in shipping . Usually my best bet is a radio swap meet or a yard sale .

Don Lindsly · #13 12-12-2008, 11:02 AM

The problem described is in the vertical sweep circuit, not video, IF or tuner. I would suggest changing only the molded caps on the RF chassis, not the ceramics now. The RF plate limiting resistor is the most frequent tuner trouble. It will not cause your symptoms.

Make sure all the voltages are correct in the vertical circuit. Height, hold and lin controls are a place to start and, of course, the two tubes. Check coupling cap from vertical oscillator to output and discharge cap from vertical oscillator plate.

radotvguy · #14 12-12-2008, 12:00 PM

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 .

grimer · #15 12-13-2008, 12:08 AM

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