Recapping a Sherwood S2000 Tube Tuner - Question

Hey all,
I'm in the midst of recapping a Sherwood S2000. I managed to find a replacement for the big 3x40uF filter cap from AES - it is exactly the same size, but is 4x50uF. I was originally planning to just hook up three of the internal caps in the same way as the 3 original 40uF caps were, but might there be an advantage to using all four of the new caps? Some of the old connections have more than one circuit feeding off one of the cap connections - would I gain anything by separating them and using the extra cap to my advantage? Any advice is appreciated - thanks in advance!

Maxamillion said:

Hey all,
I'm in the midst of recapping a Sherwood S2000. I managed to find a replacement for the big 3x40uF filter cap from AES - it is exactly the same size, but is 4x50uF. I was originally planning to just hook up three of the internal caps in the same way as the 3 original 40uF caps were, but might there be an advantage to using all four of the new caps? Some of the old connections have more than one circuit feeding off one of the cap connections - would I gain anything by separating them and using the extra cap to my advantage? Any advice is appreciated - thanks in advance!

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Are you using 50 ufs in place of 40ufs?

50 uF might be too much for the first filter stage; check the specs for the rectifier (is it a 6X4 or 6CA4 or...? I forget).

Planning to use 50uF

Yes, I'm planning to use 50uF in place of 40uF. As far as I understood, 20% more capacitance shouldn't be an issue - is it? I also found a source for a 3x40uF cap, but it is too large to fit under the cover (the 3x40 is 3 inches long and the 4x50 is only 2 1/2 inches long, same as the stock - go figure!).
The rectifier is a 6X4. Will I be pushing it too hard with 50uF?

Maxamillion said:

Yes, I'm planning to use 50uF in place of 40uF. As far as I understood, 20% more capacitance shouldn't be an issue - is it? I also found a source for a 3x40uF cap, but it is too large to fit under the cover (the 3x40 is 3 inches long and the 4x50 is only 2 1/2 inches long, same as the stock - go figure!).
The rectifier is a 6X4. Will I be pushing it too hard with 50uF?

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It's 25% not 20% and may be.

My data shows a 10uf first cap, for cap input filters. Sometimes manufacturers didn't pay too much attention to tube ratings back then (I think maybe they wanted to sell tubes). If I were doing it, I wouldn't go over what was originally in there, and maybe less. Do you have a schematic you could post?

Yeah, you're right 25%

The funny thing is the spec sheet I found recommends 10uF, but the stock caps were 40uF, and I've seen other references with different values as well. Anyone else ever used 50uF filter caps for a 6X4?

I have a schematic

but I bought it from someone online, so I don't think I'm allowed to post it - there was a warning sheet that came along with it.
Like I said, I would have gone with the 3x40 but it doesn't fit. Funny that a 3x 40 would be bigger than a 4x50, isn't it?

Probably the same as the S-3000...

http://www.mcmlv.org/Archive/HiFi//Sherwood3000.pdf

I imagine the rectifiers in my S-2000 and S-3000 are both original, so I would infer that 40 uF is OK Fifty might be pushing it, though.

Well, come to think of it, I just did one of these for Terry and I'm pretty sure it had the original rectifier too. One thing about it, they're awfully cheap, so it wouldn't hurt to try it.


BTW, I'm fairly certain that the copyright on that literature is long expired, and I seriously doubt if the online seller bought any rights.

Very Similar to the S3000

Looking at my S2000 schematic, the power supply section looks identical to that in the S3000 schematic above, with the same value resistors between the filter caps, only the S2000 has more tubes connected due to it being AM/FM, while the S3000 is only FM. So what is the general consensus - will 50uF fry the rectifier? It has survived for 48 years with 40uF - doesn't seem like it's close to the edge or anything.

I wouldn't hesitate, it'll be fine.:thmbsp:

Thanks, Jay!

By the way, if anyone is interested, I'm recapping the unit with all Sonicap Gen I caps, except for the output coupling cap which is a Dynamicap. I only paid $15.00 for the tuner, and it looks to be in pretty good shape (I'll post pictures when I'm done). The dynamicap cost as much as the whole tuner did!

I've gotten about half-way done, and I'm measuring the old GoodAll paper caps as I take them off. They all measure higher than their rating, from 13 - 25% - is it normal for paper/wax caps to increase in capacitance as they age? I would have thought they would go the other way as leaks developed between the layers.

If they absorbed a little bit of moisture over the years, that might cause a capacitance increase :scratch2:

I'll say one thing; that 2000 I did for Terry is probably the best tube tuner I've ever heard. I kept looking over my shoulder for the DJ when I had it going down here in the cave. It pulled in stations great too.:yes:

Just curious, Jay

What caps did you use to recap it?

offtopic but i think sherwood tuners are still one of the best sleepers out there.they're very selective and have good sensitivity.they also sound great . goodluck with the recapping Maxamillion and be sure to post some pics after your done.

Maxamillion said:

What caps did you use to recap it?

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I honestly can't remember

Recapping is Finished!!

I finished up the recapping tonight, and took a few pictures (below). They show the caps removed (11 paper/wax and one multi-section electrolytic), a view of the S2000 underside (white caps are Sonicaps, the red one at the bottom right is a Dynamicap for the output coupling cap), a view from topside (clean, huh?), and a close up of the new electrolytic can. I tested all the old caps and they were all way off on the high side, from 10% up to 45%, probably due to moisture pickup. I was impressed by the tolerances on the Sonicaps; they were all within 2% of their rated values.

So, I plugged the S2000 into the Variac and brought it up slowly to 120V, and......no smoke or other bad signs. All tubes lit up, so I hooked it up to my old Marantz MR1150 that serves as my shop receiver, through the Aux input, and .... out came static, of course, since I hadn't tuned to any stations yet! So I carefully moved the tuning wheel and voila! MUSIC playing through the Insignia shop speakers. Nice!

So, how does it sound? Very nice in FM, considering the supporting electronics. Very full sound, lots of bass, and sparkling highs, new caps totally unbroken-in. Here's the kicker, though - my shop is in the basement, completely underground, and all I had for an antenna was an old pair of TV rabbit ears I picked up at a flea market for $2. This thing pulled in at least a dozen stations, from both NYC and Philadelphia! FROM MY BASEMENT! It's still playing down there as I write this post.

I live in Somerset County, NJ, about halfway between NYC and Philly, and I have had major problems getting either city's stations on the Marantz's onboard tuner in the past - in fact, when we were first moving in 1 year ago and painting the interior of the house (when we really needed some tunes to keep us going), I could only get 1 station on the ground floor, and it really sucked! Now I can pull in at least a dozen, in crisp clear sound, from my basement, including a few college stations I've never heard before!

AM is hard to say at this point, as I can only tune in 2 stations from the basement. Have to wait to pass judgement on that until I get it upstairs.

Needless to say, I'm impressed. Now all I need to do is re-string the tuner dial and button this baby up. The way it is locking in and holding stations, I don't think an alignment is needed at this point. Next stop - into my main system (Supratek Chenin tube preamp, Gilmore Raven amp, Zu Druid speakers and Mini-Method sub). I can't wait to hear the sound this baby pumps out of the Druids!

Of course, now I need to buy a real antenna - due to WAF, no rooftop antennae are possible. I'm thinking that the APS InTenna should work fine in the attic, since I can get a dozen stations on rabbit ears FROM MY BASEMENT! (sorry, it still amazes me...). Any other suggestions are welcomed.

Did I say I love this tuner! Best $15 I ever spent...

Latest update:

The tuner has been on for more than 8 hours straight now, and continues to produce sweet sounds. It has a very rich tone with nice harmonics - definitely a keeper.
I left it on one station when I finally got to bed last night, and it was still locked onto it this morning, crystal clear, so it's not drifting appreciably, either.