Sherwood S-9910 Restoration - Progress/Help

[quiko1]

Hey everyone,

I am new to AudioKarma. Well, I have been a member for a short time and read various threads and learned quite a bit from all the experts, but this my first thread! I recently acquired a Sherwood S-9910 receiver from Goodwill and would like to start the process of restoring her.

I have already cleaned her up, as per many recommend, internally and externally including deoxit treatment on all the potentiometers and switches (before and after pics included). Beautiful receiver and the sound is outstanding, at least to me. However, during the process of cleaning her up I noticed that one of the large power caps was damaged. It leaked onto the bottom section of the receiver and so I figured I need to replace these caps. I have ordered the proper caps as per recommended in other Sherwood S-9910 repair threads.

My concern and questions is about some of the details of the older caps and how this would translate to the new caps. The older caps have two terminal with 2 prong on each terminal (pics included). I am assuming that the terminals with the red and blue wires are positive and those with the braided looking mesh are negative. It seem the negatives are connecting to two negative main areas where there are many black wires connected. To many black wires to connect to the negative terminals so maybe it was easier to use this method to allow fore better organization and management.

Are my assumptions with respect to the positive and negative terminals above correct? Should I use the same methodology for the negative or do I need to adapt another way for the new screw type terminals on the new caps? Any information is greatly appreciated. I am a novice, but, not afraid to get my hands dirty and have some fun!

Next steps will be a full recap including transistors. I have developed an issue on the left channel with respect to high frequency and static. At times the tweeter goes out and there is constant hiss only with tweeter not with mid or bass. I am assuming this is due to a capacitor or transistor or both. I have tested my speaker by connecting to another receiver and the issue does not replicate, sounds excellent. So, definitely an issue with the Sherwood. I will keep this thread to show the progress of the full restoration.

Thanks!

 

[6taafondo]

It's easier than what you think. On top of the caps says NEGATIVE BLACK, so the cap terminal painted black is negative.

Watch out that is a dual power supply, that's why the caps connection is opposite to each other and either match the rail on which they are. Connect the new caps just as the current ones are or you may cause a big cap explosion.

 

[quiko1]

Hey Pablo,

Gracias for all your help! Your info is invaluable. I will note the black painted cap on each cap, which should be opposite and I will replicate the original layout.

This weekend I will attempt to replace these power caps and if successful will order the proper caps and transistors to start the full restoration.

 

[6taafondo]

Glad to be of help!

A tip for the restoration project: when replacing parts with new ones go slow and one by one, checking the device works fine after each component change. Replacing a bunch of components can leave you lost in the fog if it fails to work when you turn it on.
When replacing transistors, double -or triple- check the pin out and polarity of the replacements; you don't want to make even one silly mistake that might destroy the unit.

 

[quiko1]

Hey Pablo,

Thank you very much again! I will definitely take your advice and use your approach. I will keep you up to date and share my progress.

Richard

 

[6taafondo]

Cool, Richard, will be following your progress.

 

[just dave]

Beautiful receiver good luck with her.

 

[quiko1]

Hey Fellas,

I replaced the large power caps this weekend. Had about 4 shots of Herradura Anejo (tequila), liquid courage, to give me the motivation to it done. Was a bit afraid of messing the receiver up. However, I took my time and triple checked everything. Before and after pics below.

She turned on and works great! I need to play her to see if she is still having the static issue on the left channel. Do these large power caps have an impact on the sound?

I am working a list of parts, caps and transistors, to update the driver and power boards. However, transistor replacements are not easy. What is the best method to use for viable transistor replacements?

Thanks

 

[6taafondo]

Looks perfect; well done!

These caps do have impact on sound when they go bad, but not as hiss sound, more like hum one.

Is the hiss level affected by any control? (tone, volume, etc..)

You'll embark into a full recap and transistor replacement, and what if the culprit is a bad resistor? Better narrow the stage first.

 

[quiko1]

I agree with your comments. I have not heard the static and intermittent sound loss since I replaced the power caps, however, I think that I should continue to play and test the receiver to be absolutely sure. If the issue happens again, I will play with the tone and other controls and try to troubleshoot further.

 

[r_deming]

Have the same receiver...been too chicken to really get in there and recap it. good luck and keep posting for us!

 

[Kent fjeld]

was there ever a update to this ? I

 

[Bill Demmer]

was there ever a update to this ? I

Apparently not.
I'll take a whack at it though, as an owner of many Sherwoods, including a S-7910 and S-9910. The static is much more likely to be coming from a potentiometer/switch contacts. Volume control, Tone switch, or a dubbing switch are the most likely. my S-7910 had no right channel until I moved the Tone switch several times. My S-9910 had no left channel until I did the same with the left-most dubbing switch. It's likely that Sherwood used silver-plated contact switches, which while great for many years, after many, many years, that nice silver has oxidized. Deoxit to the rescue!!

 

[quiko1]

Hey Bill, apologize for my lack of a response. So, after many years of intermittent issues and no time to really tackle myself, life stuff, I finally took the unit to a local tech. They performed a complete restoration and repair. After a couple of month of investigating to replicate the issue, they diagnosed the unit with a crack in the Stereo/Mono board/switch. They bypassed the mono function, no longer can use Mono, but, I never would have. Nevertheless, the unit has been functioning great!
I never know about the silver-plated contact switches!

 

[Bill Demmer]

A crack in the board is an easy fix. Scrape the mask off the cracked trace, on each side of the crack, and solder a wire across the crack. Check any traces on either side of the crack, for cracks as well, and reinforce as needed.

Bill

 

[Kent fjeld]

Howdy Bill , Like you I collect Sherwood was hoping to see a list of parts to restore 9910. I have a S110cP also that does have left channel issue
so was hoping the list would help with that also . I have at least 10 other sherwoods that sound great but will need attention unless I decide to sell

https://flic.kr/p/o4jpyP

https://www.flickr.com/photos/17611327@N04/page2y

images from way back . many more since then no picture hope to remedy soon

 

[Bill Demmer]

Very nice stack!!

You may find this post helpful: https://audiokarma.org/forums/index.php?threads/sherwood-s-9910-nudie-pics.404229/post-5295059
from earlier in this thread (page 2).

You know that the S-9910 and S-110CP are the same unit, right?

On your S-110CP, check your 'Tone" and 'Monitor' switches for oxidized contacts. Silver is great for contacts, just not so much after 40+ years, without attention. Break out the DeOxit !


Bill

 

[Kent fjeld]

Thanks Bill Yeah familiar with deoxit's healing powers thanks for the tread wow

 

[Work2do]

Great job on spiffing up those Sherwoods ! I have an S-8500 which I believe is the same as the S-7500 except for an FM only tuner. Beautiful sounding of course and it's 35 W/c seems like at least 60. I took it out of service about 5 years ago when the controls started getting scratchy. This thread made remember how much I love it. Believe it was USA made (?) ca. 1969. My father in law purchased it new as a floor model in 1970. Has a metal chassis with a template to make a wooden one, brochure, manuals. The black part on the face is pretty worn around the tuning dial, kind of wondering how to touch it up or if I should just live with it...

 

[Kent fjeld]

I started with the 7500 was giving to me never heard of sherwood before ( wasn't into audio) hooked it up no sound on am or fm
hooked up mp3 player ( no cell phone at that time ) fell in love have at least 30 pieces now to include totl Sherwood Newcastle stuff P-965 A-965 and R-965 if any one has service manuals for them I would be extremly happy I actully have extra a-965 that UPS dropped and 2 P 965 I need to get working ...

I have bought 5 older sherwoods in last 5 months also I have not really looked at .. recovering from Medical stuff so time is spent gettin life back to normal...the last one I bought was the 972 have\nt had time to look at it yet.... that and I am old lol

I am still looking for the s8500 to go with the 7500 you think you could post the template to make wooden one ? I plan on making some I have CNC that need to be put back in service ....