Philco model 610 rebuild - by Tim P. - Printable Version
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+--- Thread: Philco model 610 rebuild - by Tim P. (/showthread.php?tid=9048)
RE: Philco model 610 rebuild - by Tim P. - morzh - 06-05-2017
OK, you gotta go and scratch that itch! Let's fire it up!
I can barely wait to fire up mine.
RE: Philco model 610 rebuild - by Tim P. - TV MAN - 06-07-2017
Alright - it's time! Drum roll!!! Lets see what has been accomplished with all this work, time and effort. What's in the box??? Well, here goes, probably for the first time in 50 years, this ol' 610 will see power. Meters in place, plugged into the variac ... 25v ...30...35...40...ok, reposition a meter. 45v ...B+ coming up, 25v. Have meters on the output tube plate, input cap and output cap. Sniffing - so far so good. Up to 50ac, 40 on B+ ... 55v, B+ up to 70, then dropping back to 60 .. huh. Now, 60v line, went up to 90v B+, dropped back to 85. Ok, up to 65 ac, B+ 122, I can hear a very faint squeal when I rotate the volume control - there seems to be life at this point! AC 70, B+ 155, squeal changing. 75v...80...oops! I forgot to put on the tube shields. Well, now I loosened a top cap on a tube UGH!
Ok, tube shields in place, still squealing. This doesn't sound good .... Ok, I flip the tone control in, and the squeal disappears. Interesting. I get some static if I touch the antenna terminal. ...now at 90v rotating tuner with antenna wire connected ... I FOUND A STATION!!! Alright, now 95v ... a little louder and clear. 105v ac, 285 B+. 110ac, 298 B+. Well, it looks like I am on shortwave and picking up some stations - in Spanish!
Now, a "bad" observation. - I have a horrible squeal when I turn the tone control taking the cap out, if I leave it in, it goes away. Obviously some bugs to work out, but there is definatly life in this old thing! Well, this is where I am going to leave things for tonight.
RE: Philco model 610 rebuild - by Tim P. - Steve Davis - 06-08-2017
Tim, the first thing to come to mind, make sure the grid wire to the 75 tube is routed inside the tube shield.
Steve
RE: Philco model 610 rebuild - by Tim P. - TV MAN - 06-08-2017
It's outside. Could be the problem. It is a feedback of some kind. Ill try to running it inside an see if it helps.
RE: Philco model 610 rebuild - by Tim P. - morzh - 06-08-2017
Usually the 75 is next to the output tetrode (or pentode) and so the grid wire picks up the output signal which creates positive feedback and oscillation. Leaving the grid wire inside the shield reduces that feedback.
RE: Philco model 610 rebuild - by Tim P. - TV MAN - 06-08-2017
Steve, Mike, you guys were dead on! I rerouted the grid wire of the 75 inside the shield and the oscillation went away. I don't know if I would have figured that one out on my own or not. Thank you!
I need to get brave and flip the band switch (probably ought to DeOx it) and see what I have on broadcast. I am sure it will need alignment (or at least touched up), and burned in. So far, it sounds good, esp considering the history of this poor thing.
One other question - what to use to clean this dirty thing?
I had read somewhere maybe mineral spirits. I found out real quick that window cleaner cleans really good, including the dial markings. Yea, I fogged it, but thankfully I only rubbed the bottom with the part numbers, which cleaned off nicely. Any suggestions? The worst is a dark spot, which I don't know if it is dirt, sun damage or just age.
RE: Philco model 610 rebuild - by Tim P. - morzh - 06-08-2017
It is likely sun plus dial lght, as it likely was kept there due to being the favorite spot. I don't think it can be cleaned. As for dirt, yes, mineral spirits.
RE: Philco model 610 rebuild - by Tim P. - Steve Davis - 06-09-2017
I learned that one the hard way. It was a 19, it had me stumped for a week before I stumbled onto the cause.
Steve
RE: Philco model 610 rebuild - by Tim P. - TV MAN - 12-30-2017
I finally had a chance to get back on this project. Started feeling nostalgic and had a few minutes to burn, even had the wife's blessing
I decided the original dial needed replaced and found a very nice repro from Radio Daze. I had to slightly enlarge the locating holes with a 5/32 drill bit. It was slightly thicker, but went on fine.
One thing I noted: The two guides at the top of the dial were each bent down, and I discovered that this scratched off some of the lettering before I realized what was happening. They are suppose to be straight out, where they guide the dial on the unprinted edge. Learn from my mistake.
I found the band switch to be dirty so I hit it with deoxit, seemed to help. It works pretty good on the BC band, but not so much on either SW band. I do get some stations, but not very sensitive. It may be my antenna. In the center band I get some bleed through from the BC band, but I dont know if there are really any stations there anyway. The AM is pretty sensitive and picks up a lot of stations. It may need the alignment touched up, but it does work now after how many decades of silence?
More to come ...
RE: Philco model 610 rebuild - by Tim P. - Ron Ramirez - 12-31-2017
Hmmm...maybe we should start gluing some felt to the inside of those metal guides to protect those expensive dial scales?
RE: Philco model 610 rebuild - by Tim P. - TV MAN - 12-31-2017
One thing is for sure, those dials are NOT cheap, so some felt may not be a bad idea. Thanks for the suggestion Ron! I think it is easy to bend those tabs while working on a chassis without even knowing it. I am sure this happened in a previous repair. It's something to watch for at least.
I did an alignment attempt last night. I didn't see a real day or night difference other than I think I had the dial off position a little bit. I may need to move it and touch up. May not make a difference either. I set the dial by tuning in a station that I knew the location. Anyway, I may leave it alone unless there are reasons to reset.