OK.. so I'm a glutton for punishment
Posts: 1,108
Threads: 89
Joined: Jun 2011
City: Tacoma
State, Province, Country: Washington
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.
(This post was last modified: 02-23-2014, 10:34 AM by BrendaAnnD.)
Posts: 1,562
Threads: 56
Joined: Nov 2008
City: Sedona, AZ/Placentia/CA
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
A friend in need is a pest! Bill Slee ca 1970.
Posts: 1,108
Threads: 89
Joined: Jun 2011
City: Tacoma
State, Province, Country: Washington
Holds the socket for the C-7 dial lamp.
Posts: 1,108
Threads: 89
Joined: Jun 2011
City: Tacoma
State, Province, Country: Washington
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...
Posts: 1,114
Threads: 14
Joined: Feb 2013
City: Irvington, NY
Whats going on with the two output tubes? Does each speaker have its own tube and output transformer, or are they in parallel?
Posts: 15,832
Threads: 554
Joined: Oct 2011
City: Jackson, NJ
It is an FR2 PCB right?
Yeah....you are a glutton for punishment borderline masochistic.
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.
Posts: 1,130
Threads: 78
Joined: Jan 2014
City: Annapolis, IL
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.
If I could find the place called "Somewhere", I could find "Anything"
Tim
Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44
Posts: 1,108
Threads: 89
Joined: Jun 2011
City: Tacoma
State, Province, Country: Washington
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.
Posts: 15,832
Threads: 554
Joined: Oct 2011
City: Jackson, NJ
Was probably a longer time for me - learned that some time end of 70s.....
Posts: 1,108
Threads: 89
Joined: Jun 2011
City: Tacoma
State, Province, Country: Washington
For me it was sometime in the 70's as well. I'm no spring chicken, you know. Just a baker's dozen months till I turn 60.
Posts: 1,562
Threads: 56
Joined: Nov 2008
City: Sedona, AZ/Placentia/CA
Aw BAD, I figured in your 40s! Enjoy your help and your a smart spring chicken.
Jerry
A friend in need is a pest! Bill Slee ca 1970.
Posts: 15,832
Threads: 554
Joined: Oct 2011
City: Jackson, NJ
Me too! Is this a current photo?
Posts: 1,108
Threads: 89
Joined: Jun 2011
City: Tacoma
State, Province, Country: Washington
I think about 7 years ago. Though I really still look pretty much the same, but with a bit more grey in my hair.
Posts: 15,832
Threads: 554
Joined: Oct 2011
City: Jackson, NJ
Posts: 1,108
Threads: 89
Joined: Jun 2011
City: Tacoma
State, Province, Country: Washington
Thanks. Always makes me feel good when someone figures me for 40-ish. (which happens a lot more often that you think.)
Users browsing this thread: 2 Guest(s)
|
Recent Posts
|
Philco 60 Squealing
|
Usually a wave trap is for keeping IF signals from entering the antenna and from leaving the antenna. You feed an IF sig...RodB — 09:30 PM |
Philco 60 Squealing
|
I just peaked it for the best signal at 600.
NULL it for IF frequency, originally it would have been null for 500kh...Chas — 08:05 PM |
Philco 60 Squealing
|
Wavetrap no longer matters.morzh — 05:19 PM |
Philco 60 Squealing
|
Rod, I had checked out your suggestions but did not help. I did solder the ground rivets to the chassis as Chas suggeste...dconant — 04:52 PM |
37-690 Bass Choke Replacement
|
Yeah, I know, Mouser and Digikey don't have "big iron" components. For some reason Philco was messing with the...Radiodial — 04:25 PM |
37-690 Bass Choke Replacement
|
Yes, I just had to deal with that while repairing the 37-604 Philco. Exactly that value choke was gone. And the current ...morzh — 03:52 PM |
37-690 Bass Choke Replacement
|
Ah, now where to find one.
I've into this before on smaller sets, I now recall. Hammond makes one that is only rated...Radiodial — 03:27 PM |
Philco 38-7 Speaker
|
Ask the admins to put them together.
As for the renaming, while inside the thread, you simply press "New reply&quo...morzh — 02:23 PM |
37-690 Bass Choke Replacement
|
This is the parts catalog.
32-7528 choke is 65H, 10mA, 2,250 Ohm inductance.
Find a suitable one.morzh — 02:18 PM |
37-690 Bass Choke Replacement
|
While troubleshooting the no bass amplification issue, I think I found the culprit. The choke #104 is reading 164K ohms....Radiodial — 01:42 PM |
Who's Online
|
There are currently 3322 online users. [Complete List] » 1 Member(s) | 3321 Guest(s)
|
|
|
|