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Philco 50-T702
#31

Thanks guys. Maybe a few more days till I try it again!

Crist
#32

Hey Crist, excellent workmanship!! Seems to be rare now a days, keep up the good work.

Gregb
#33

Thank you for the kind words.

Crist
#34

I like your meticulous attention to labeling all the old components, it will minimize errors and make future reference to your pictures a lot easier if you need to do that. 

For future reference where did you find your H.V. capacitors?  When I rebuilt my little Pilot tv many moons ago I scoured hamfests to find my H.V. caps.  I bought enough to do a second Pilot tv I have, but if I ever get around to that I'd rather use new caps.

I'm also looking forward to seeing a picture on that old Philco again.  During a radio club open house I once had, I hooked the little Pilot to a VCR so I could use channel 3 or 4 and played old Laurel and Hardy movies.  There's some old tv gear around you can use to make a low-power tv transmitter, but I haven't fooled around with any of it yet.

John KK4ZLF
Lexington, KY
"illegitimis non carborundum"
#35

(04-11-2016, 11:04 AM)Eliot Ness Wrote:  I like your meticulous attention to labeling all the old components, it will minimize errors and make future reference to your pictures a lot easier if you need to do that. 

For future reference where did you find your H.V. capacitors?  When I rebuilt my little Pilot tv many moons ago I scoured hamfests to find my H.V. caps.  I bought enough to do a second Pilot tv I have, but if I ever get around to that I'd rather use new caps.

I'm also looking forward to seeing a picture on that old Philco again.  During a radio club open house I once had, I hooked the little Pilot to a VCR so I could use channel 3 or 4 and played old Laurel and Hardy movies.  There's some old tv gear around you can use to make a low-power tv transmitter, but I haven't fooled around with any of it yet.

John,

I got my 6Kv caps from a surplus electronics dealer.  The same caps that JustRadios sells.  If I couldn't get elsewhere I was just going to order them from JustRadios along with some caps and resistors I needed.

See the next post!

Crist
#36

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

[Image: http://i1060.photobucket.com/albums/t458...ipukxe.jpg]

[Image: http://i1060.photobucket.com/albums/t458...lhhvc0.jpg]

[Image: http://i1060.photobucket.com/albums/t458...ynmtdd.jpg]

Crist
#37

Regarding the low B+ voltage, have you checked the selenium rectifiers? I believe they are located in a cage on top of the chassis near the back. They deteriorate with age and may be causing the low supply voltage.

You can replace them with silicon rectifiers, but you may have to add some series resistance to compensate for their lower voltage drop.
#38

(04-12-2016, 07:02 AM)Mondial Wrote:  Regarding the low B+ voltage, have you checked the selenium rectifiers? I believe they are located in a cage on top of the chassis near the back. They deteriorate with age and may be causing the low supply voltage.

You can replace them with silicon rectifiers, but you may have to add some series resistance to compensate for their lower voltage drop.

Not yet.  I'll replace the paper caps first.  The B+ does go to about 298V then drops back to 228V within about 30 seconf
seconds.  I think that might be an indication of bad caps.  I have all the replacements so it's just a matter of time till they get replaced.

Then I plan on replacing the selenium rectifiers.

Crist
#39

  if the raster,,,not opening up,,then High voltage section,,,BUT,,could be the (YOKE) on back of picture tube,,not strong enough  to open raster,,,just sum thing I seen ,,when my father worked on this stuff,,,maybe some HELP,,,Cheers
#40

(04-12-2016, 05:32 PM)Kenneth F. Besso Jr. Wrote:    if the raster,,,not opening up,,then High voltage section,,,BUT,,could be the (YOKE) on back of picture tube,,not strong enough  to open raster,,,just sum thing I seen ,,when my father worked on this stuff,,,maybe some HELP,,,Cheers

Thanks for the suggestions.  This TV doesn't have a yoke.

Crist
#41

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

Crist
#42

Congratulations, Crist ! Great works so far ! If you are getting that good a picture it means you have sufficient voltages to give full deflection in both vertical and horizontal directions, as well as to produce a decent picture, which is a great sign. Looks like you still have some oscillator instability, but I'm sure you'll get that fixed. If it has a horizontal linearity control, you might see what that does to the picture, same with the vertical linearity control if it is there. Keep on plugging. You're making great progress.
#43

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

[Image: http://i1060.photobucket.com/albums/t458...fol0kl.jpg]

[Image: http://i1060.photobucket.com/albums/t458...ojhtgt.jpg]

[Image: http://i1060.photobucket.com/albums/t458...y8diai.jpg]

Crist
#44

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
Edit/Delete Message

Crist
#45

Hate to say it but it looks like the pix tube to me too. A brightener might help. It will raise the heater voltage slightly causing the gun to give more emissions. Low high voltage will cause blooming when the brightness is increased and loss of focus. May be a combination of both. A picture tube tester should verify, unless the tube is gassy.

If I could find the place called "Somewhere", I could find "Anything" Icon_confused

Tim

Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44




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