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I'm going to get the CRT tested tomorrow with a working set. A full report when I get back!
If all goes well, then I'll order the parts that I need. |
The CRT 7JP4 tested good to very good! We could easily see the picture with the lights on.
I still have to figure out a way to get the metal sleeve off the neck so I can re-glue the base. It has just a little movement to it. I'll order up the resistors and capacitors and will press on with the restoration. Anybody go knobs for this TV? http://i1060.photobucket.com/albums/...psjtscifa5.jpg |
I see JustRadios has the .0047uf 6Kv caps. Are there any other suppliers?
Thanks. |
Allied has a selection of 6000 & 8000 volt ASC capacitors.
http://www.alliedelec.com/passive-co...281-4294965387 |
I found a source for the HV capacitors.
I have most of the resistors and some of the film caps so I decided to replace what I could till the rest of my orders come in. One of the first things I did was to clean up the mess that had happened from Philco's famous black tar/wax that had melted down to underneath the chassis. While I was at it I removed the phenolic pot board to aid cleaning up the mess and to clean up the pots. After several hours the mess was cleaned up and the pots were cleaned and fully checked for smooth operation with no bad spots. I then installed everything like before. I then replaced some caps and resistors along the terminal strip behind the rear pots. I'll replace what I can with what I have for the time being. http://i1060.photobucket.com/albums/...psrcohehy4.jpg http://i1060.photobucket.com/albums/...psf2plyyyl.jpg http://i1060.photobucket.com/albums/...psepietk03.jpg |
I just got a used interlock power cord. It is serviceable, but a little stiff. Is there any way to "rejuvenate" the vinyl or plastic coating to make it a bit more pliable?
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I started pulling the cans from the chassis to prep them for re-stuffing. My E-Caps will be in on Thursday. It'll take me a few days to re-stuff them and get them back into the chassis. By then the HV caps will be in and I'll turn my attention to the HV section.
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The rest of my orders came in so I'm tackling the filter E-Caps and the high voltage sections which consist of the HV cage and the HV board underneath the chassis.
I first did the HV Cage then followed by the HV board. I still have to install the HV board. I'll install the HV cage just before I power it up. With it off it makes working on the chassis a lot easier. http://i1060.photobucket.com/albums/...psq0ufrydq.jpg http://i1060.photobucket.com/albums/...psguj5xjlw.jpg http://i1060.photobucket.com/albums/...ps5zipjx1h.jpg http://i1060.photobucket.com/albums/...psa7dcvvy1.jpg |
I replaced the the 6 HV caps and resistors in the HV cage and the HV board. I also replaced the filter E-Caps in the power supply.
I have a raster! All of the picture controls does affect the picture to a degree. My HV is about 3500v but my B+ is only about 228V when it should be 310V. I'm guessing that as I replace more of the E-Caps and paper caps the B+ voltage should come up and with that my HV should be up too. I was playing a VHS tape through my tape player. I also noticed I didn't get any sound. Anyway we have a good start! I also shot a very short video of the picture. https://youtu.be/6LiHqtkO7PM http://i1060.photobucket.com/albums/...psduipukxe.jpg http://i1060.photobucket.com/albums/...psgnlhhvc0.jpg http://i1060.photobucket.com/albums/...pslfynmtdd.jpg |
Looking good! Constant progress and that is a good thing. Congratulations.
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Does this set have seleniums, if so there could be one going bad as I had low b++ in one of my 7 inch sets because of a bad selenium rectifier. I replaced the 2 with 1n4007 diodes and cured the voltage problem. I had noticed one selenium was much hotter then the other so befor it shorted and and smelled up my house I changed them. Could be power supply caps too but I see your going over the whole chassis so I'm sure you will find the culprit. Does that set have an adjustable ring on the hv rectifier tube, if it has one that will affect the hv output.
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This won't be difficult to scope out. Only real potential problem would be if a deflection plate in the CRT was bent or damaged and I think that's highly unlikely. Gotta be a vintage or capacitance issue, both easily remedied. I'm happy he's got HV. This'll come together nicely with relatively short effort. George |
I run seleniums in my restored sets (radios more so than TVs). If B+ is good after a FULL recap, the seleniums run cool, the set has not been exposed to a corrosive/outdoor environment, and it is not a set I plan to use heavily then I just leave the seleniums in. Not all of them are ticking time bombs...
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I replaced a bunch of caps and resistors today. I have an image now but it is very wavy. More caps tomorrow and I'll look at the selenium's too. BTW the B+ voltage rose from 228V to 251V. At least it's in the right direction.
https://youtu.be/kSXk_JTiJQQ http://i1060.photobucket.com/albums/...pscx3crkkk.jpg |
This reminds me that I need a TV pattern genterator or one of those DVD's/videos. I have a vhs and a DVD player. Do I DL a test pattern the make a DVD, then have hte DVD palyer paly into the VHS player which "talks" to the tv?
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Thats improvement Crist, when you complete the caps definitely do the two selenium rectifiers. At the absolute least you'll know that you will have full voltage coming forward from the rectifiers and they are going to be stable and safe. Then address video & sweep issues as they may appear!
-George- |
George,
Right! |
I finished replacing the paper caps. All the E-Caps have been replaced. When a resistor and capacitor share the same point, the resistor got changed too.
B+ is still too low. Selenium's are next to get replaced. Getting closer. https://youtu.be/CzThLSIsM9Q http://i1060.photobucket.com/albums/...psh9fol0kl.jpg http://i1060.photobucket.com/albums/...psdbojhtgt.jpg http://i1060.photobucket.com/albums/...ps9ay8diai.jpg |
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- |
BTW: I betcha you'll be amazed when you get full B+ on a nice new set of diodes!!!!!
-George- |
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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. |
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 |
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 |
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. |
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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.
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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
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Are you saying that the Philco HV transformer is my problem?
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-- Dave Sica |
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. http://i1060.photobucket.com/albums/...psl5scnq5t.jpg |
Mine is more pale than that... but could have faded over time. It is greener than the 7JP4.
jr |
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. |
Sorry, mine is a 701, may or may not be different.:scratch2:
jr |
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George |
We had the chance to check the CRT in another chassis today. Looks like mine isn't so good. My friend's tube worked and looked really great! At least I know my chassis is good. I'm pressing on now with the cosmetic part of the restoration. I'll keep an eye out for another better CRT.
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Just an update on cleaning up the chassis. Still more to do.
http://i1060.photobucket.com/albums/...pstrey10oo.jpg http://i1060.photobucket.com/albums/...ps91zs8ylu.jpg |
Here is a short video of the restored chassis.
I just taped the mask into place on the CRT. I'm playing it now for an hour or so. I want to see if I get the HV fade. BTW, the video is "White Christmas". https://youtu.be/TwwV8PGGjtc |
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