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OK.. so I'm a glutton for punishment - Printable Version

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OK.. so I'm a glutton for punishment - BrendaAnnD - 02-23-2014

You've possibly seen these lovely pics of the E-818 I got in the other day:

   

   

Well.. tonight I started to try to revive it. I super glued the pieces of the board back together (not an easy task on its own, since I had to patiently hold the pieces together till the glue set). Then I began to reinforce the cracks by bridging solder across the crack on each trace. Once that was done, I further reinforced the connections by running small gauge stranded wire all along the traces, attaching them to hard solder points at each end.

I've got filaments now, and 157 VDC at every B+ point, so obviously I've missed a break somewhere (not really surprising, there were a LOT of them!) Once I have found and repaired all broken traces, I plan to coat the entire bottom of the PC board with epoxy to prevent it breaking too easily again.

I've also patched the speakers, and mended the broken terminal strip on the loop antenna.

So far, this is what it looks like, at least from the front of the chassis.

   

So, now, supposing I get this all working properly, I'm not at all sure what I'm going to do with it, since the front panel is pretty well hosed, and I doubt there are enough pieces left to mend it properly. I have, however, repaired the wooden cabinet, and it looks quite presentable.

RE: OK.. so I'm a glutton for punishment - jerryhawthorne - 02-23-2014

Nice work Brenda, you truly are a glutton for punishment. I enjoy watching your work.
By the way, what is that "clip" in the last picture for? Looks like something to hold an eye tube.
Jerry

RE: OK.. so I'm a glutton for punishment - BrendaAnnD - 02-23-2014

Holds the socket for the C-7 dial lamp.

RE: OK.. so I'm a glutton for punishment - BrendaAnnD - 02-24-2014

It sings. Took locating 5 more broken traces, two in the screen supply to the outputs and the screen/plate supplies to the front end tubes. One to the detector. One to one of the plates of the 25F5's (which, I find, are just half voltage versions of 50C5's.) Also had to repair the LO coil, which had been bent out of its plane and the center tap needed to be reconnected to the lug. Now to see what I can do with that poor cabinet front...

RE: OK.. so I'm a glutton for punishment - Mondial - 02-24-2014

Whats going on with the two output tubes? Does each speaker have its own tube and output transformer, or are they in parallel?

RE: OK.. so I'm a glutton for punishment - morzh - 02-24-2014

It is an FR2 PCB right?
Yeah....you are a glutton for punishment borderline masochistic. Icon_mrgreen

My old experience with Russian TVs - those were the only devices I saw using FR2 PCBs and tubes:
lots of times due to the tubes panels getting hot (yes, with the miniature tubes) the pins of the panels develo cold solder spot around them. When looking at it it might even look normal but touch it with soldering iron and the solder becomes powdery and the pin inside is not wetted and oxidized. And even the solder pad could be grey and not wetted with solder.
Also sometimes due to the weight of the tubes and the temperature the solder pad start separating and eventually tearing off the traces.

Check for that just in case. At least in the TPA-1 all transistor player it did not take any temperature rise, about 1/3 of the solder pads we separated and tore off.

RE: OK.. so I'm a glutton for punishment - TV MAN - 02-24-2014

Brenda, that is amazing! Did someone drop that thing off a cliff or went through a nuclear powered blender? I have repaired several busted up pc boards over the years, including an entire corner broken off a tv around the flyback. One thing I learned, and might mention is future repairs. If that board is completely covered in epoxy underneath, imagine the fun next time you need to repair something, like a hairline crack that got missed. Just ... been there - done that.

RE: OK.. so I'm a glutton for punishment - BrendaAnnD - 02-24-2014

Madmurdock,

Understood. I feel it needs SOME sort of reinforcement. Perhaps a couple layers of duct tape applied to the bottom of the board. It seems stable now, and plays pretty well.

Morzh,

First thing I do on PC boards with tubes is to go around every socket and reflow the solder. Learned that one a LONG time ago.

Mondial,

Tubes are in push-pull. another of Philco's oddball drive arrangements. This one's not even the one with the screen feeding the alternate tube, it seems to make use of a negative feedback loop off the transformer secondary.

RE: OK.. so I'm a glutton for punishment - morzh - 02-24-2014

Was probably a longer time for me - learned that some time end of 70s.....

RE: OK.. so I'm a glutton for punishment - BrendaAnnD - 02-24-2014

For me it was sometime in the 70's as well. I'm no spring chicken, you know. Icon_smile Just a baker's dozen months till I turn 60.

RE: OK.. so I'm a glutton for punishment - jerryhawthorne - 02-24-2014

Aw BAD, I figured in your 40s! Enjoy your help and your a smart spring chicken.
Jerry

RE: OK.. so I'm a glutton for punishment - morzh - 02-24-2014

Me too! Is this a current photo?

RE: OK.. so I'm a glutton for punishment - BrendaAnnD - 02-24-2014

I think about 7 years ago. Though I really still look pretty much the same, but with a bit more grey in my hair.

RE: OK.. so I'm a glutton for punishment - morzh - 02-24-2014

Looking good!

RE: OK.. so I'm a glutton for punishment - BrendaAnnD - 02-24-2014

Thanks. Icon_smile Always makes me feel good when someone figures me for 40-ish. (which happens a lot more often that you think.)