Restoreing a model 87 - Printable Version
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+--- Thread: Restoreing a model 87 (/showthread.php?tid=3490)
Restoreing a model 87 - Radioroslyn - 07-17-2011
These are some PM I sent Wendell who has a 87 he is going to be servicing
Hi Wendell
I think I'm a proud new owner of a model 87. Just won it on evilbay. Will go get it tomorrow. It's about 1.5 hour away. Now I can answer your questions with some certainty. Have you found some #45 toobs yet? My set is just in need of some knobs. Form the pics it looks like the cabinet is in good shape, I got a 95 awhile back but the top is chipped up pretty good.Both use the same cabinet and both are the earlier one with the wood sea shell insert in front of the speaker.
As I'm sure you keep us posted on your progress and any questions that may arise. There's a great bunch of guys over on the Phorum with a lot of practical knowledge.
Terry
2:00pm Monday
No problem!
I enjoy working on this old stuff. I drove an hour up and a hour back to get this one. The thing that surprised me was how heavy that darn thing is. The first one I had I got when I was a young teen and don't remember it having so much gravitational pull but that was 40+ years ago.Any way I got it for $40 and it has all the tubes! I mention that because some time you can get a set cheap that has some good tubes in it. I did some work for a customer and she gave me an old Westinghouse that had a pair of globe 45's in it. The cabinet is pretty rough but restoreable.
The cap bank is in the oven should be about done so onward to more fun!
Terry
4:00pm
Well I rebuilt the filter bank! B+ went up about 50v! All good but still not working. One thing nice about troubleshooting a TRF set is all the rf stages are wired in series so you can hook your antenna to any of them to test them to hear which stage is or isn't working.
So I hooked my ant to detector stage(the closest stator plates to the 45's and I got a signal!!! Det,audio driver,and p/p output stage are working.
Now I know that the RF amps aren't working. Checked the B+ and had about 10v Not good! Should be about 100v.
Under the chassis near each rf coil is a thing that LOOKS like a paper cap with solder lugs. Well it looks the a paper cap because it is but it also has a resistor in that unit. The caps are bypasses for each rf amp along with a resistor to feed the B+ to each rf amp. At the last rf stage the cap was VERY leaky and was pulling down the B+ lead 90v. Very easy to test just unscrew the them. That will break the ground connection to the cap, if bad the B+ will go up.
Just getting to replace them and I think that should get this 82 yr old gal working again. Will keep you post with it's progress.
Terry
Hope I'm not putting you asleep!
It's 11:00 here and I replaced the 3 bypass caps. RF amps are getting the proper B+ now. But the volume is low. More poking around is in order. Found the primary of the ant coil is open. Rewound it about 50t of 38g wire. Works better but still volume is a bit low. Check the B+ at the plate pins of the 26's,one got 10v. Rewound primary of 2nd rf amp coil. Now she work like she should. Picks up across the whole dial. Still needs a few minor things, I think the tubes might be a little weak, volume control needs a good cleaning, and the tuning cap could use a bit of oil. Don't want to break the dial cords, they are a pain to restring. My 95 needs that done. So that's the fix the 87 in an afternoon.
Good luck w/your's
Terry
Tuesday 6:30pm
Final installment.
To finish up I did check the tubes two of the 26's and one of the 45's where very weak. Replaced those and did the neutralization adjustment. Now it plays GREAT!!!!. Right now I'm listening to the Whistler on WNAR
Terry
Re: Restoreing a model 87 - Ron Ramirez - 08-02-2011
Congratulations on your work, Terry.
You were very fortunate indeed to find an 87 that still had the 45 tubes in it for $40, even if one of the 45 tubes was weak.
Re: Restoreing a model 87 - TA Forbes - 08-03-2011
All this work on your model 87 is going to make your model 20s (note use of plural) jealous, Terry.
BTW how is it coming along with your model 21? That is a set that has managed to elude me for many years....
Re: Restoreing a model 87 - Radioroslyn - 08-03-2011
>That is a set that has managed to elude me for many years....
I've been eluding it lately. I had it playing but still needs a recap job+just a little cabinet work. haha
So many radios so little time!!
Terry