Sherwood S-7100A Receiver

[birchoak]

Oh man, turns out the S-8900A is the other Sherwood I've been eyeing, partly because of it's incredible interior build---so clean and beautifully laid out, and looks to be built like a tank. It's a perfectionist's private electronic village in there and the care that obviously went into its design and execution reminds me of a Scott R74S, a rare Professional Series receiver that was sold with a TEN YEAR warranty back in the day. That's right, ten years.

Now I'm not going to be able to sleep tonight, thanks a lot (just kidding). If it wasn't for this hobby I'd go crazy; also, I go crazy because of this hobby.

 

[A23gt]

I have some very hungry 4 ohm Ar3a's. It wouldn't run them past a whisper. It was better with my 6 ohm Wharfedale W70d's. I suspect they drop to 4 ohm's. They drained it on bass dynamics at a reasonable volume. It just wouldn't play them. The match put out very smooth mud, but no clipping. The 7100a just can't keep up with the 70's bleeding all the power out. The 70's are not at all hungry. The problem is only noticeable when loaded with a heavy bass line and a hard bass dynamic is added to the load. The dynamic will be absent.
So I got the S-8900a. Now we're cooking with gas. Big orchestra is big. And loud. And clean.
And it runs the AR3a's.
I think the 8900 sounds as good or better than the 7100a. It has the magic too.

AR3a are not exactly efficient. The problem is less the ohm rating than that those speakers are beautiful, power hungry big boy speakers that are acoustic suspension with 12 inch woofers, mids, and tweets.
My little 2 way 8 inch woofer acoustic suspension EPI isn't nearly as hard to drive.

I second you on the S-8900a. Sounds just as good and with more power. It's also more expensive than a 7100a.
The 7100a a really good receiver within its limitations and costs around the price of a good dinner (or pizza if you're lucky)

Slap a Marantz faceplate and controls on it and resell for four times what you paid for it.

 

[birchoak]

I second you on the S-8900a. Sounds just as good and with more power. It's also more expensive than a 7100a.
The 7100a a really good receiver within its limitations and costs around the price of a good dinner (or pizza if you're lucky)

Slap a Marantz faceplate and controls on it and resell for four times what you paid for it.

A new white whale to hunt. And very good points on the 7100A--no power beast, to be sure, but extraordinary sound and affordable. My Marantz 2230, by comparison, has needed a LOT of repairs and is much more difficult to work on, and it was an even cleaner unit, inside and out, than the Sherwood. I'm not knocking Marantz, mind you (note that I own one), but if I'd been aware of this Sherwood I wouldn't have sunk so much time and money into the Marantz.

 

[A23gt]

A new white whale to hunt. And very good points on the 7100A--no power beast, to be sure, but extraordinary sound and affordable. My Marantz 2230, by comparison, has needed a LOT of repairs and is much more difficult to work on, and it was an even cleaner unit, inside and out, than the Sherwood. I'm not knocking Marantz, mind you (note that I own one), but if I'd been aware of this Sherwood I wouldn't have sunk so much time and money into the Marantz.

I feel your pain. I went the Pioneer, Kenwood, and Marantz route too before I gave Sherwood a listen. Now I'm hooked. I have five of them in the house. Don't get me wrong, the big mass market names made great equipment, but at today's prices Sherwood is great bang for the buck. Don't discount their early 80's MOSFET amp and preamp either. 100 watts with lots of headroom.

 

[quiet]

I have a Marantz 2226. It's a good receiver. I like the Sherwood better.

 

[birchoak]

I tried a Sansui 800 and loved its big sound, too, but it is a much more complicated beast to work on and not as neatly laid out. And you always seem to pay more for anything called Marantz, Pioneer, or Sansui. Earlier Yamahas can be had for reasonable money but the CR-1020 and CR-2020 have always been too much money for this man.

There are so many opinions on hi-fi gear that it's nearly impossible to make up your mind by reading what other people write. You have to buy this stuff and listen to it for yourself, and things don't always turn out right. I think some stuff is just too old, is too far gone and cannot be easily repaired by an amateur (me). I think I took a year off my life trying to get a Marantz 2230 to work right and I spent quite a bit of money and time and also had to get professional help (for the Marantz, not me).

 

[A23gt]

I tried a Sansui 800 and loved its big sound, too, but it is a much more complicated beast to work on and not as neatly laid out. And you always seem to pay more for anything called Marantz, Pioneer, or Sansui. Earlier Yamahas can be had for reasonable money but the CR-1020 and CR-2020 have always been too much money for this man.

There are so many opinions on hi-fi gear that it's nearly impossible to make up your mind by reading what other people write. You have to buy this stuff and listen to it for yourself, and things don't always turn out right. I think some stuff is just too old, is too far gone and cannot be easily repaired by an amateur (me). I think I took a year off my life trying to get a Marantz 2230 to work right and I spent quite a bit of money and time and also had to get professional help (for the Marantz, not me).

I agree 100%. Even though sound is measurable, it isn't processed the same by each persons ears and brains.
A 19 year old may hear details my old ears can't, and have a more favorable opinion of equipment x than I.

The audio equipment we collect is old and sometimes flat worn out. Just too many variables to listen to our individual opinions for buying decisions, but the forum gives us some help because we can average positive responses about equipment. Once I know the members with similar sonic tastes it will help me make some of my future picks.

My Marantz 2226b needed a lot of love to. It turner my bargain receiver into fair market value overnight. I'll never do more than break even.

 

[birchoak]

I agree 100%. Even though sound is measurable, it isn't processed the same by each persons ears and brains.
A 19 year old may hear details my old ears can't, and have a more favorable opinion of equipment x than I.

The audio equipment we collect is old and sometimes flat worn out. Just too many variables to listen to our individual opinions for buying decisions, but the forum gives us some help because we can average positive responses about equipment. Once I know the members with similar sonic tastes it will help me make some of my future picks.

My Marantz 2226b needed a lot of love to. It turner my bargain receiver into fair market value overnight. I'll never do more than break even.

Yes, "flat worn out." I'm learning to not beat myself up because I can't fix everything that I get my hands on. And to go very, very slowly and cautiously when doing ANY work to these electronic Faberge Eggs; man, you blink and there goes a dial string, severed by your soldering iron tip, or you're tired and you put one cap in backwards and it's Game Over. I am trying to do more actual listening to the music and less equipment-acquiring and evaluating. It was supposed to be about the music but since I'm part crow (love shiny things with knobs and lights) that can get lost temporarily.

 

[oldgearhog]

I might as well chime in. I have a 7100A on the bench right now awaiting some recapping. I would like to continue using the metal hoops that hold the large output caps and the main power supply cap but couldn't find anything of that diameter that wasn't way higher in voltage/capacitance/price. Any suggestions would help. As an alternative I was thinking of using zip ties to keep the boys in place.

 

[dly66]

You can often up the capacitance of the filter caps 50% and get close in size and since higher voltage is okay, with some receivers similar sized caps can get rather expensive. You don't want a cap too low in voltage rating or it can blow.

On my S-7200 I used strips cut out of foam sheet, can be found in one of the back aisles of my Local Hobby for less than $1. Stuff comes in handy. Helps take up the gap and hold them tight. Replacements were close but not quite enough.

After replacing the electrolytics and a number of transistors with noise issues now my S-7200 is a sweet sounding unit. As-is auction unit when received had DC on one channel about 200 mV and all sorts of odd noises in the background of one channel - after some time playing that way the differential pair on the channel with high DC started to rat-a-tat-tat after about 10 minutes after turning it on. Took some time and sleuthing to get all of its issues ironed out. It paid off. Now you can have it on aux with no source turn it all the way up and its hard to hear anything. Power switch still works.

Have read a lot of good reviews about their low end S-7100 and S-7100A units along with the higher end S-7900A/8900A (believe 8900A is FM only, 7900A is AM/FM). The S-7200 gets talked about a lot relative to the number that come up on the auction sites.

The old Sherwoods are sleepers, get overlooked in the market so prices can be low but when you hear one they are great units. The British site select45rpm.com reviews a bunch of vintage units and had been harsh on the S-7200. I guess last year they finally restored theirs because late last year the very negative review got replaced by a very positive one.

 

[oldgearhog]

Good ideas dly66. I did get so.e caps and will have to look at the sizes as ss gain, but if they're way off I might go with something else. Otherwise I was pleased with the original unit, but at that age I figured filter caps and the RIAA eq may need a refresh. The tone board looks like a bear to deal with so I decided to leave that one alone.

 

[59volvo]

You can often up the capacitance of the filter caps 50% and get close in size and since higher voltage is okay, with some receivers similar sized caps can get rather expensive. You don't want a cap too low in voltage rating or it can blow.

On my S-7200 I used strips cut out of foam sheet, can be found in one of the back aisles of my Local Hobby for less than $1. Stuff comes in handy. Helps take up the gap and hold them tight. Replacements were close but not quite enough.

After replacing the electrolytics and a number of transistors with noise issues now my S-7200 is a sweet sounding unit. As-is auction unit when received had DC on one channel about 200 mV and all sorts of odd noises in the background of one channel - after some time playing that way the differential pair on the channel with high DC started to rat-a-tat-tat after about 10 minutes after turning it on. Took some time and sleuthing to get all of its issues ironed out. It paid off. Now you can have it on aux with no source turn it all the way up and its hard to hear anything. Power switch still works.

Have read a lot of good reviews about their low end S-7100 and S-7100A units along with the higher end S-7900A/8900A (believe 8900A is FM only, 7900A is AM/FM). The S-7200 gets talked about a lot relative to the number that come up on the auction sites.

The old Sherwoods are sleepers, get overlooked in the market so prices can be low but when you hear one they are great units. The British site select45rpm.com reviews a bunch of vintage units and had been harsh on the S-7200. I guess last year they finally restored theirs because late last year the very negative review got replaced by a very positive one.

View attachment 1395609View attachment 1395631

I have a s-7200 really like it. got it off craigslist for $35

 

[birchoak]

I might as well chime in. I have a 7100A on the bench right now awaiting some recapping. I would like to continue using the metal hoops that hold the large output caps and the main power supply cap but couldn't find anything of that diameter that wasn't way higher in voltage/capacitance/price. Any suggestions would help. As an alternative I was thinking of using zip ties to keep the boys in place.

I have done several recaps with the same basic situation: new caps much smaller, don't fit into the space. Pull the old ones, hacksaw off the bottoms, clean them out, mount new cap inside old shell. You can pack out the new cap with closed cell foam, hot glue, etc. so it's not rattling around in there. Have done this many times with no problems. That said, I started a shopping cart at Mouser for the big caps and it looked like the diameters on Nichicon Gold Tunes were pretty close. Not as long but I don't care.

 

[birchoak]

You can often up the capacitance of the filter caps 50% and get close in size and since higher voltage is okay, with some receivers similar sized caps can get rather expensive. You don't want a cap too low in voltage rating or it can blow.

On my S-7200 I used strips cut out of foam sheet, can be found in one of the back aisles of my Local Hobby for less than $1. Stuff comes in handy. Helps take up the gap and hold them tight. Replacements were close but not quite enough.

After replacing the electrolytics and a number of transistors with noise issues now my S-7200 is a sweet sounding unit. As-is auction unit when received had DC on one channel about 200 mV and all sorts of odd noises in the background of one channel - after some time playing that way the differential pair on the channel with high DC started to rat-a-tat-tat after about 10 minutes after turning it on. Took some time and sleuthing to get all of its issues ironed out. It paid off. Now you can have it on aux with no source turn it all the way up and its hard to hear anything. Power switch still works.

Have read a lot of good reviews about their low end S-7100 and S-7100A units along with the higher end S-7900A/8900A (believe 8900A is FM only, 7900A is AM/FM). The S-7200 gets talked about a lot relative to the number that come up on the auction sites.

The old Sherwoods are sleepers, get overlooked in the market so prices can be low but when you hear one they are great units. The British site select45rpm.com reviews a bunch of vintage units and had been harsh on the S-7200. I guess last year they finally restored theirs because late last year the very negative review got replaced by a very positive one.

View attachment 1395609View attachment 1395631

Thank you for sharing that, man. That British site is awesome (and a bit strange--I'd love to meet the guy!). His recommendations are spot on!

 

[dly66]

You have to get used to the British where a valve amp would be tube over here. At first I was like "Valve amp?", what are they talking about.

I am under the impression they disliked the S-7200 so much (but liked the similar NAD) is that they don't like the loudness contour (I don't either) and it has it engaged by default. You have to actually look at the front panel icons to figure out you have to push in the loudness button to turn it off. I think they took some time to figure that out, few manufacturers did it that way.

I collected a few pieces based on their reviews. A Yamaha CR-800, have not recapped it should open it up in sound when I do. Recently finished the infamous Sansui 3000A, once overhauled and service mods done so it shouldn't destroy a woofer (based on the speaker A rocker switch and blown fuses, it had likely already murdered one), it is a really good sounding receiver. Like the S-7100 it has interstage transformers which I believe was used in tube amps too. The S-7100A is cap coupled they got rid of the transformers. The 3000A was an Ebay fix and repair missing a knob only had to beat a bottom feeder to get it for only $37. Poor thing bent shafts massive gouge in tuning knob metal barb sticking out could easily draw blood. Looks like it had been tossed out on the curb as garbage. Ended up being in better shape than I thought when I bought it.

Recapping the old ones can really open them up. Electrolytics don't age well, but the solid aluminum and tantalum types don't either. Their ESR seems to go up with age, at least that is what my $20 transistor tester kept telling me. Many tantulums were getting ESR values in the mid teens. Replacing the small value ones with film caps (Kemet R82, Wima MKS2) can enliven them and quiet them down too. I have always found recapping the late 60 and 70s ones it is a substantial before and after difference. My Kenwood KR-7400 did not have noisy transistors just recapping it the background noise is virtually non-existent in the preamp and amp sections. It had a number of tantalums. Fidelity went up too, like it breathed new life into an old tired unit. Looks like the CR-800 has a number of tantalums too.

Noisy transistors can be a problem too. Looking at the schematic there are some potentially problem types in the S-7100A. I have personal experience with the 2SC693F on the tone boards of both the S-7200 (4) and 3000A (2). The 3000A also had its lower gain cousin (looks identical) the 2SC536 as the other pair in the tone section and front end of the amp card. On both receivers replacing those got rid of a lot of background noise. The 2SC693F will hiss in the background much like the noise between fm stations, guessed the similar 536 probably did too. Since they were in the tone section, I found with the S-7200 the hiss from them went up and down in response to the volume control. The 2SC871 design is known for noise issues too. They list two types of transistors in the amp section, the CDC 8002/9002 flying saucers or another pair of transistors. The CDCs were in my S-7200. Sansui used the CDCs too on a few amp models reading forums on those Sansui models they can have issues many like to replace them. For the 2SC693 and 2SC871 the On (formerly Fairchild) KSC1845 works, and for the CDCs the KSA1220 and KSC2690 are recommended replacements. Keep pin arrangements straight so the new ones are put it right. The 2SA666 were in differential pairs at the front of the S-7200 and started making a popping noise on one channel besides causing a high DC offset in that channel. Have found with several units high dc offset (tens of volts) or blown fuses likely a shorted output transistor (may be other components that went with it), smaller more in the range of 200 mV or so the pair at the front of the amp circuit likely culprit.

Basically recap and see how one is from there. Hear audible noise in the background, circuits start making weird noises, sounds increasingly distorted as the volume increases (only sounds right at low volume) there may be bad transistor(s). Have recapped tuner sections, even older discrete ones (no ICs), without noticeable tuner performance degradation. Leave transistors alone in the tuner circuit unless one goes bad and kills tuner performance. Transistor replacement is more likely to require realignment to have the tuner work well again which requires some expensive specialized test equipment and expertise.

The CDCs and tantalums from my S-7200, and the 2SA666 noise.

.

 

[birchoak]

You can often up the capacitance of the filter caps 50% and get close in size and since higher voltage is okay, with some receivers similar sized caps can get rather expensive. You don't want a cap too low in voltage rating or it can blow.

On my S-7200 I used strips cut out of foam sheet, can be found in one of the back aisles of my Local Hobby for less than $1. Stuff comes in handy. Helps take up the gap and hold them tight. Replacements were close but not quite enough.

After replacing the electrolytics and a number of transistors with noise issues now my S-7200 is a sweet sounding unit. As-is auction unit when received had DC on one channel about 200 mV and all sorts of odd noises in the background of one channel - after some time playing that way the differential pair on the channel with high DC started to rat-a-tat-tat after about 10 minutes after turning it on. Took some time and sleuthing to get all of its issues ironed out. It paid off. Now you can have it on aux with no source turn it all the way up and its hard to hear anything. Power switch still works.

Have read a lot of good reviews about their low end S-7100 and S-7100A units along with the higher end S-7900A/8900A (believe 8900A is FM only, 7900A is AM/FM). The S-7200 gets talked about a lot relative to the number that come up on the auction sites.

The old Sherwoods are sleepers, get overlooked in the market so prices can be low but when you hear one they are great units. The British site select45rpm.com reviews a bunch of vintage units and had been harsh on the S-7200. I guess last year they finally restored theirs because late last year the very negative review got replaced by a very positive one.

View attachment 1395609View attachment 1395631

Lovely pic on the right. How does that thing sound? Is it simple inside?

 

[birchoak]

You have to get used to the British where a valve amp would be tube over here. At first I was like "Valve amp?", what are they talking about.

I am under the impression they disliked the S-7200 so much (but liked the similar NAD) is that they don't like the loudness contour (I don't either) and it has it engaged by default. You have to actually look at the front panel icons to figure out you have to push in the loudness button to turn it off. I think they took some time to figure that out, few manufacturers did it that way.

I collected a few pieces based on their reviews. A Yamaha CR-800, have not recapped it should open it up in sound when I do. Recently finished the infamous Sansui 3000A, once overhauled and service mods done so it shouldn't destroy a woofer (based on the speaker A rocker switch and blown fuses, it had likely already murdered one), it is a really good sounding receiver. Like the S-7100 it has interstage transformers which I believe was used in tube amps too. The S-7100A is cap coupled they got rid of the transformers. The 3000A was an Ebay fix and repair missing a knob only had to beat a bottom feeder to get it for only $37. Poor thing bent shafts massive gouge in tuning knob metal barb sticking out could easily draw blood. Looks like it had been tossed out on the curb as garbage. Ended up being in better shape than I thought when I bought it.

Recapping the old ones can really open them up. Electrolytics don't age well, but the solid aluminum and tantalum types don't either. Their ESR seems to go up with age, at least that is what my $20 transistor tester kept telling me. Many tantulums were getting ESR values in the mid teens. Replacing the small value ones with film caps (Kemet R82, Wima MKS2) can enliven them and quiet them down too. I have always found recapping the late 60 and 70s ones it is a substantial before and after difference. My Kenwood KR-7400 did not have noisy transistors just recapping it the background noise is virtually non-existent in the preamp and amp sections. It had a number of tantalums. Fidelity went up too, like it breathed new life into an old tired unit. Looks like the CR-800 has a number of tantalums too.

Noisy transistors can be a problem too. Looking at the schematic there are some potentially problem types in the S-7100A. I have personal experience with the 2SC693F on the tone boards of both the S-7200 (4) and 3000A (2). The 3000A also had its lower gain cousin (looks identical) the 2SC536 as the other pair in the tone section and front end of the amp card. On both receivers replacing those got rid of a lot of background noise. The 2SC693F will hiss in the background much like the noise between fm stations, guessed the similar 536 probably did too. Since they were in the tone section, I found with the S-7200 the hiss from them went up and down in response to the volume control. The 2SC871 design is known for noise issues too. They list two types of transistors in the amp section, the CDC 8002/9002 flying saucers or another pair of transistors. The CDCs were in my S-7200. Sansui used the CDCs too on a few amp models reading forums on those Sansui models they can have issues many like to replace them. For the 2SC693 and 2SC871 the On (formerly Fairchild) KSC1845 works, and for the CDCs the KSA1220 and KSC2690 are recommended replacements. Keep pin arrangements straight so the new ones are put it right. The 2SA666 were in differential pairs at the front of the S-7200 and started making a popping noise on one channel besides causing a high DC offset in that channel. Have found with several units high dc offset (tens of volts) or blown fuses likely a shorted output transistor (may be other components that went with it), smaller more in the range of 200 mV or so the pair at the front of the amp circuit likely culprit.

Basically recap and see how one is from there. Hear audible noise in the background, circuits start making weird noises, sounds increasingly distorted as the volume increases (only sounds right at low volume) there may be bad transistor(s). Have recapped tuner sections, even older discrete ones (no ICs), without noticeable tuner performance degradation. Leave transistors alone in the tuner circuit unless one goes bad and kills tuner performance. Transistor replacement is more likely to require realignment to have the tuner work well again which requires some expensive specialized test equipment and expertise.

The CDCs and tantalums from my S-7200, and the 2SA666 noise.
View attachment 1397789 View attachment 1397790

.

I was tempted to get a Sansui 3000 but did not fancy all the work involved to get it where it needs to be. The Yamaha CR-800 (which I bought based on his review) sounded good right off the bat. I have been slowly recapping it (there are a ton of parts in that thing) it and even tracked down a new relay for it should that ever go bad. It is one of the best built (and complicated) receivers I have ever seen. But the Sherwood (and the JVC 5010) put out incredible sound using so much less----less parts, less power. The Sherwood doesn't even need vents in the cover. I love the pics of the naughty components; they look like teeth that a dentist just pulled. I hear about replacing components with film caps; what is the rule of thumb there? Stuff in the signal path, and lower uF values? I'm chicken to attempt something like that, although I did successfully recap a Marantz 2230 (using irebuildmarantz.com kit), with some help from Catrafter. Ok, a lot of help from Catrafter.

 

[birchoak]

Did the big cap under the board today (I assume that's the main filter cap?) and the two large ones piggybacked on top of the board (output caps? I know, I'm showing my ignorance here). I save the old caps just in case the new sound sucked, but bass sounds deeper and everything else still magical. I am loathe to do anything more to it at this point as I have managed to NOT f--k anything up so far. It is definitely in my top five receivers of all time:

1) Sounds very "big", with a clean, punchy voice, and sounds fantastic on Wharfedale Dentons (speakers notorious for being fussy eaters).
2) Can be had for about $100, unlike just about anything else.
3) Beautiful wooden case--you don't see this on low power receivers usually.
4) Dead simple but sturdy construction--very easy to take apart and work on; no teeny dial pointer bulb / tiny wires to mess with--just a florescent pointer!
5) Simple, uncluttered face and not that many switches, etc. to clean (no switches on the back panel, for example) or give me grief.
6) Solid aluminum lower control knobs!
7) At last, an ON/OFF switch incorporated into the VOLUME knob. No way to accidentally turn it on at full volume and ruin it. Yes, I understand that it's a weak point, but mine is 50 years old and still working, so I'm gonna say a relatively weak point.
8) FM voice is rich and strong.
9) Compact and light compared to other receivers of this era, welcome features when you're always shuffling equipment around like me.
10) No vents in cover = no dust inside the receiver and far better protection against liquid spills.
11) This one may be a fluke, but everything was working clean and strong (ok, some Deoxit was needed) with all original 50 year old parts. I did some caps because I feel like this Sherwood deserves it.
12) Only four bulbs if replacement is necessary, and they're easy to get at (try replacing the bulbs in a Panasonic SA-5800 or a Bose Spatial Control Receiver and you'll choose to drink paint thinner instead).

 

[birchoak]

The British site select45rpm.com reviews a bunch of vintage units and had been harsh on the S-7200. I guess last year they finally restored theirs because late last year the very negative review got replaced by a very positive one.

View attachment 1395609View attachment 1395631

That guy isn't easily impressed, so when he does "rave" about a receiver I'm all ears. I'm on his site frequently, but can find no actual copy on the Sherwood S-7200. What a site, though, huh? Nowhere have I ever found so much detailed information about the build and sound of so many vintage receivers. The JVC 5010 I scooped up on his good opinion blew my socks off. I don't think I've ever been so impressed by the sound of anything, except maybe an SX-1980 playing through tower speakers.

 

[dly66]

The really big cap should be the filter cap. Sherwood had the filter caps tucked on the bottom side of the receiver. Cap coupled amps have one sided power supplies, just the +ve side. The two identical large caps clamped together should the output caps, they basically take out a large dc offset so that a +/- signal goes to the speakers. If an output transistor shorts, the caps should keep a woofer from getting fried. Direct coupled amps like the S-7200 that use fuses and not protection relays can potentially fry woofers in that situation. The fuses are supposed to protect the woofers, but apparently at times the woofer voice coil expires before the fuse does. Many early solid state designs were cap coupled, but the design faded out in the early 70s as direct coupled designs took over the market.

If you did not find the S-7200 review at select45rpm it was on this page. It is listed as 1971 between the Sansui 5000X and the Sony models. Scroll to the bottom of the page then step back up, the review is above the 1971 Sony models.

http://select45rpm.com/pages/hifi/vintage-hifi-reviews.html

Picked up another fix or repair about two weeks ago. Like the 3000A had long been curious about this model. The dismembered picture is on my work table, other picture was from the ad. Tuner works well (fed signal to 3000A out tape monitor and 4-channel out) but very low level signal out of amp. Some sleuthing so far indicates the signal path dies somewhere in the tone control board. Will be pulling some components to check this weekend. Parts order from Mouser should arrive today. Until that is solved won't know how the amp circuit is, at least the relay clicks and dc offset is low. Looking to get this Chicago built S-8900A singing again. Curious about the Dynaquad circuit, part of the 4-channel fad of the 70s. I think it and the 7900A were the last ones built in the US. S-8900A is FM only, 7900A FM-AM. Tuner dial bulbs did not survive shipping, but they were #53 mini bayonet incandescent that most of the local Advance auto parts stores carry according to their website. Not out on the hooks had to ask and they were behind the counter. Apparently an old automotive bulb and easy to replace. Knobs are dark, either very dirty aluminum or could be tarnished bright brass. It should clean up nicely if I succeed in getting its electronic problems solved.