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Back in the early 1980s, I bought a nonworking Sherwood S-8900A stereo receiver. This FM-only receiver was rated at 60 watts per channel, not bad for a 1974 receiver.
I took it home and discovered a blown fuse, bad rectifier diodes, and a questionable power supply electrolytic.
Replacing diodes, fuse and one of the big 7000 uF power supply electrolytics...I had a working receiver!
I used it for about fifteen years or so until it started blowing fuses again. Then I did something I now regret...I threw it away and bought a new Pioneer receiver. Pioneers of the 1990s were not as good as their 1970s-1980s siblings, but what did I know at the time.
In retrospect...I should have replaced both of the 7000 uF electrolytics, not just one. It was roughly ten years old, or nearly so, when I acquired it and I troubleshooted at the component level to fix just what was wrong.
Anyway...
Fast forward to 2016. Now on a stereo kick, I had been looking for another Sherwood to replace that S-8900A but until recently had not had much luck finding one.
Finally, an S-7900A popped up on the auction site. This was great for me, as I had wished that the S-8900A I had years ago had been an S-7900A so I could have AM as well as FM.
Unfortunately, USPS did what it does best to vintage electronics...
[Image: http://www.philcoradio.com/images/phorum/S7900A_001.jpg]
[Image: http://www.philcoradio.com/images/phorum/S7900A_002.jpg]
[Image: http://www.philcoradio.com/images/phorum/S7900A_003.jpg]
Not only did I have a damaged cabinet, but the mono-stereo mode switch and the function selector switch were both broken - they rotated like potentiometers with no "clicks".
The seller was very nice and agreed to give me a partial refund.
So...
I decided to try and repair the damage. If it didn't work out, I had already spotted an S-8900A, and I thought I might end up using this 7900A for parts.
--
Ron Ramirez
Ferdinand IN
Posts: 13,776
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A few days ago, I pulled the chassis out of the cabinet and set it on the bench.
Removing top and bottom covers, I soon discovered a couple of serious problems...
[Image: http://www.philcoradio.com/images/phorum/S7900A_004.jpg]
See the gaps between the switch wafers, and between the wafers and the front metal portion of the stereo-mono mode switch? There should be no gaps...all of these parts should be pressed together fairly tightly.
[Image: http://www.philcoradio.com/images/phorum/S7900A_005.jpg]
Looking at the back of the mode switch, see the two holes across from one another with what looks like pins inside? These holes were once the ends of rivets...those rivet ends were broken off from the damage, causing the switch wafers to come loose.
The function switch had identical damage.
What to do?
--
Ron Ramirez
Ferdinand IN
Posts: 13,776
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I considered buying that S-8900A I had found and making this a parts set, as mentioned earlier.
However...
I tried pressing the mode switch together between my fingers and found that, lo and behold, when pressed together it clicked as it should!
So...feeling that I had nothing to lose...I decided to use J-B Weld to glue the switches back together.
[Image: http://www.philcoradio.com/images/phorum/S7900A_006.jpg]
[Image: http://www.philcoradio.com/images/phorum/S7900A_007.jpg]
--
Ron Ramirez
Ferdinand IN
Posts: 13,776
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The next day...
[Image: http://www.philcoradio.com/images/phorum/S7900A_008.jpg]
Everything looked OK. Both switches "clicked" through their positions as they should.
So I reinstalled them.
[Image: http://www.philcoradio.com/images/phorum/S7900A_009.jpg]
I soon noticed that the metal that the mode switch was bolted to was also damaged (bent) - the mode switch was not lined up properly in relation to the function switch.
[Image: http://www.philcoradio.com/images/phorum/S7900A_010.jpg]
Removing the mode switch again, a few well-placed blows with a hammer and long flat-blade screwdriver removed enough of the warp in the metal that the mode switch lined up properly afterward.
--
Ron Ramirez
Ferdinand IN
Posts: 13,776
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Remember that damaged cabinet?
This morning, I decided to try and glue it back together.
[Image: http://www.philcoradio.com/images/phorum/S7900A_011.jpg]
It had really sprung out of place on the right side, so I am not too optimistic about this...but again, I had nothing to lose by trying. I will leave it clamped for 24 hours and find out tomorrow whether or not the gluing was successful.
--
Ron Ramirez
Ferdinand IN
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I polished all of the knobs with Mother's Mag & Aluminum Polish, which really helped them - especially the Tuning and Off-On-Volume knobs, which were really grungy.
I then reinstalled the face plate (after cleaning it up), reinstalled the knobs, and reinstalled the top and bottom covers.
And here it is, playing the smooth sounds of Nat King Cole...
[Image: http://www.philcoradio.com/images/phorum/S7900A_012.jpg]
[Image: http://www.philcoradio.com/images/phorum/S7900A_013.jpg]
How did I get the knobs back on the mode and function switches without breaking them again?
Simple...before I reinstalled the top and bottom covers, I turned the receiver upside down and pushed in on the back of each switch while I pushed its knob back on.
It works!
But I will be rebuilding the power supply in this receiver sooner rather than later...remembering what happened to my S-8900A years ago. Now that this receiver is 42 years old, it's time for preventive maintenance to keep it running smoothly.
P.S. I never did buy that S-8900A I saw on the auction site last week. Hopefully, I will not need to now. (Besides, that one has since sold.)
--
Ron Ramirez
Ferdinand IN
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City: Sandwick, BC, CA
(06-25-2016, 08:29 PM)Ron Ramirez Wrote: Remember that damaged cabinet?
This morning, I decided to try and glue it back together.
[Image: http://www.philcoradio.com/images/phorum/S7900A_011.jpg]
It had really sprung out of place on the right side, so I am not too optimistic about this...but again, I had nothing to lose by trying. I will leave it clamped for 24 hours and find out tomorrow whether or not the gluing was successful.
Ron;
All in all, not a great loss to technological history, or humanity, if that cabinet is beyond repair, nothing says 70's ick like simulated woodgrain vinyl over particlboard. Whenever I used to run into furniture/TV/Stereo cabinets covered with this stuff it immediately brought to mind some MacTac peel and stick vinyl shelf covering that was commonplace when I was younger, so I used to say that they were covered with MacTac. I think that it would be almost as easy to make a new box for that Sherwood out of solid wood or baltic birch plywood laminated with walnut veneer, it would look better afterward and would be more in keeping with one of those Fisher receivers from the 60's. I never have had much luck trying to glue broken particleboard back together unless it broke apart at a joint.
With regard to those two switches, if they should break or come apart again I would use a pair of machine screws and nuts of the appropriate thickness and length to replace the rivets. In fact I was sort of thinking that if that metal section on the front of each switch is thick enough it might be possible to tap the two holes that used to hold the rivets and thread a pair of screws into those.
Regards
Arran
(This post was last modified: 06-26-2016, 04:29 AM by Arran.)
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I like the "Loudness" for the volume. Gives it class 
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Posts: 13,776
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Well, it looks like the cabinet gluing was more or less successful...
[Image: http://www.philcoradio.com/images/phorum/S7900A_014.jpg]
More or less?
[Image: http://www.philcoradio.com/images/phorum/S7900A_015.jpg]
You can see the fractured particleboard behind the vinyl covering.
Plus, I discovered that I pulled the clamps a bit too tight...and pulled the right side back a bit too much.
Oh well. It still looks better than it did when it arrived. Not perfect...but it will have to do.
One reason the set was damaged in shipping is because the chassis was not fastened to the cabinet.
Today, I went to the hardware store. $1.03 later, I had four 8-32 x 1-1/4" screws and four large flat washers to correct that issue...
[Image: http://www.philcoradio.com/images/phorum/S7900A_016.jpg]
So here you are - how it looks now.
[Image: http://www.philcoradio.com/images/phorum/S7900A_017.jpg]
Arran, I'm going to have to buy a table saw for another project. Maybe after I get used to using it, I might just try making a reproduction cabinet out of solid wood instead of particleboard...but this will do for now.
That is all for now. This fall or winter, I shall open it up again and give the power supply the overhaul it really should have to keep it happy.
--
Ron Ramirez
Ferdinand IN
Posts: 1,475
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Well considering the damage it had I think you did a good job.  I guess you can consider it fortunate that the circuit boards did not crack or bust a trace during the rough handling.
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(06-26-2016, 06:20 PM)KCMike Wrote: Well considering the damage it had I think you did a good job. ..........
+1
It would look stunning in a real walnut case. I'm surprised Sherwood would use a vinyl covered case back in 1974.
John KK4ZLF
Lexington, KY
"illegitimis non carborundum"
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Thanks, Mike and John.
It really doesn't surprise me that much about the vinyl covering, given that this was one of the last USA-made stereo receivers. I've recently discovered that Sherwood used the fact that the S-7900A and S-8900A were made in the USA as a selling point in at least some of their print advertising.
The cheap vinyl over particleboard was done, no doubt, to cut costs. Even the older 1960s Fisher cabinets were made of particleboard...but they did have real walnut veneer.
I'll have to look at my Fisher 432 again (from the same era) and see if its cabinet is vinyl or real veneer. As the 432 was made while Fisher was owned by Emerson, prior to the Sanyo buyout...it may be vinyl.
--
Ron Ramirez
Ferdinand IN
Posts: 204
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Joined: Sep 2005
City: Newark, Ohio
Hi Ron
Time for you to get a FM Yagi antenna up in the air and do some FM DX!
Ed
Posts: 13,776
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Ed
Would you believe that, although I no longer have the S-8900 I had back in the 1980s-1990s...I still have the Radio Shack FM omnidirectional double dipole that I used with my Sherwood back then? It's funny, now that I think about it...I kept the antenna but didn't keep the receiver. It is sitting, unused, in my garage. Yes, I should put it back up outside...I remember how many FM stations I used to pick up with that antenna on my old Sherwood...
--
Ron Ramirez
Ferdinand IN
Posts: 4,707
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Joined: Sep 2008
City: Sandwick, BC, CA
Ron;
If you are in the market for a table saw, try craigslist, you can get some good deals on 30-50 year old models on there if you are patient, though sometimes the arbor will need the bearings replaced which is cheap.
Regards
Arran
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