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[email protected] themend@gmail.com is offline
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Default Restoring a Sherwood S-5000

Ok, so I guess I can just share the photos and schamtics via dropbox.

https://www.dropbox.com/sh/y4j5cv5ro8o5yja/cvW9ncqTtV#/

Here's what's in there so far:

Pictures of the various twistlock can caps that are there
A picture of the underbelly of the amp
A picture of the unbelievably wrong Sam's photofact of the bias supply
A picture of the -Actual- Sherwood schematic right from a manual, applying to this second rev of Sherwood S-5000
A picture of the selenium rectifier which will be replaced


Regarding the voltages I measured in my last post, it is good to note that Sherwood has different voltages listed in their schematic. However, the Sams schematic is referring to the first rev. of the S-5000, the 'longer chassis' model. These two models can easily be distinguished visually, by the way. The newer one has all the 12AX7s up front mounted flat and underneath a square tube cage with slotted vents and a tube placement sticker. The old version has the preamp tubes at a 45 degree angle, with individual tube shields.

So, let's re-do that chart against the Sherwood schematic since I think that will be more in line with reality in this particular amp. FYI, the Sams schematic has some SERIOUS errors in the bias section, mainly that the capacitors and diodes are in there backwards. Their version magically produces negative volts from positive diodes and caps. Sheesh. So that should never be used for anything.

Sherwood Schematic This S-5000

C53/A - unlisted 442v
C53/B - 425v 438v
C53/C - 350v 365v
C24/A - 270v 285v
C24/B - 250v 204v


That is very telling. We see that the plate voltage is much closer to being 'in-spec' than before, though it is still a tad high, I recall that always being the case in these amps. Nevertheless, we have even more of a problem now in the second section of C24, as we are now 46v shy of the listed value. This is looking even more like a real problem than it did before. Also note that Sherwood calls these two caps C53 and C24, where Sams calls them C1 & C2, which is probably a more logical choice. Nevertheless, from here on out I will refer to the Sherwood schematic. If somebody wants to discuss an older chassis, we can do that too...

I think that's all for today, though I might get around to replacing the selenium rectifier.


-forkinthesocket