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Sherwood S-7100A Receiver

After reading thru this thread i guess im very very lucky. I got a 7100a for $10 at a SoCal estate sale, on-off switch working. I have it hooked up to a pair of early ported Wharfedale W70's. I never really get volume past 11 oclock. Loudness off. Gets about 70db at chair.
I also picked up a 7200 for $20 at estate sale months later. Working on-off switch.
I use a power strip and leave the receiver switches on.
You guys are right, these really are off the radar. $10! I couldnt pay fast enough.
 
I hope it's ok if I tack onto this thread.
This thing is so cool, I kind of like the black-out look . . .
IMG_2419.JPG

Just kidding. I need a solution for my scorched blue plastic film things, these:
IMG_2421.JPG

I read another post where somebody flipped them around and trimmed them; that's a good idea but I think mine are washed-out overall from being 50 years old by a hot lamp. I might get a blue sharpie and color them. My other one is actually burned through I think. There has to be something made of blue plastic that could be cut to replace these but I can't seem to find anything. A tab from a file folder comes to mind but I don't see any blue ones here.

The sharpie idea is the best one I have at the moment. What has anyone else done?
 
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fromnowon said:
I hope it's ok if I tack onto this thread.
This thing is so cool, I kind of like the black-out look . . .
View attachment 2042215

Just kidding. I need a solution for my scorched blue plastic film things, these:
View attachment 2042216

I read another post where somebody flipped them around and trimmed them; that's a good idea but I think mine are washed-out overall from being 50 years old by a hot lamp. I might get a blue sharpie and color them. My other one is actually burned through I think. There has to be something made of blue plastic that could be cut to replace these but I can't seem to find anything. A tab from a file folder comes to mind but I don't see any blue ones here.

The sharpie idea is the best one I have at the moment. What has anyone else done?
Click to expand...

This is way late but what I did also was to flip them around and trim the excess from the long side. I then put in some warm white led bulbs I got on Amazon from Parts Express. 5 for $10. I like the look. You may not even need the blue filters. I didn't try the led bulbs without them. I think they are supposed to filter the incandescent bulbs which I removed. I seem to get a nice turquoise color with what I have.
 
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I have a question for the group. I got a free working S-7100A recently with a good on/off switch. I cleaned the pots (not the volume) and replaced the tuning dial bulbs. I measured the dc offset around 50 to 60 mV which I hear is irrelevent for this receiver since it has cap coupled outputs. Anyway, there is a little bit of hum coming from the speakers when turned on. You can't hear it when you turn up the music but wondering what it might be. The output caps? A bad ground? Any suggestions on what to look for? Thanks.
 
fromnowon said:
Hi, just curious if you get the hum with all sources or just certain ones.
Click to expand...
It is the same on all four sources. I hear it through headphones and speakers. Like I said you don't hear it when music plays but it is there when the volume is off. Speakers are hooked to A. I hear hum only when speakers A are on. I don't hear hum when set to Off, B or A+B. I have not tested B yet. Those speaker jacks are a hassle on this thing. :-)
 
Just an observation... This unit does not use a differential pair on the audio input, but rather is single ended. Power supply Rejection Ratio is likely not too good, so I would consider the main filter cap (C851) as a candidate.
 
My S-7100 still isn't finished, but I got far enough to replace C851 with this:
2200 uF @ 63V (c851) FILTER CAP => 647-LKG1J222MESCAK 2200uF 63 Volts 20% 35 mm diameter
I don't recall any fit issues so it must have been ok.

In case that helps.
 
Hi everyone,

I got one of these from a place that fixes up old electronics and love how it sounds and looks, too. I didn't pay much, around $60 I want to say. It worked great for a couple of years but recently, it only plays out of both speakers when in "mono" mode. When I switch to "stereo" mode it will only play out of one speaker. When I turn the balance all the way to the speaker that does not work in "stereo" mode ("right" in my setup) I hear crackles when I turn the volume up and down. For a while, it would play out of that right speaker, but only at one narrow volume range. Now not at all. Any thoughts on what's going on? More clues: It plays fine out of both speakers when in mono. Also, same issue when playing radio or turntable. So obviously speakers and connections are fine. Think it's worth bringing it somewhere to be fixed? Anything someone who does not know how to fix electronics can try? Thanks in advance.
 
MichelleC said:
Anything someone who does not know how to fix electronics can try? Thanks in advance.
Click to expand...
Hi @MichelleC I think there is - you could try cleaning the controls and especially the stereo/mono switch, in case they are not making good contact.
Welcome to AK by the way!
Here is one of the most referenced threads with advice on how to "clean" switches and controls.
https://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/
I hope that helps and let us know what you decide to do.
Not sure how much disassembly you'd have to do to get a good squirt in there. It might even work from the front.

Note: it may not be a good idea to spray cleaner in your volume control as the on/off switch in these are very prone to breaking.
 
The first thing I would try is the clean the stereo/mono switch, volume and balance pots with some DeOxit or another type of contact cleaner. It seems like both channels work in the amplifier section. The switch may be dirty in the stereo position. The scratchiness when adjusting the pots is also due to them being dirty. This is a simple procedure. There are lots of videos on youtube about using DeOxit and lots of threads on here about it.

Edit. I just saw fromnowon's post also. I agree about not spraying the volume knob unless absolutely necessary.
 
Quick look at the schematic, my first guess would be a dirty 'Source/Tape' switch, SW-3. Be sure to clean that one too.
 
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