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In Reply to: RE: Refubishing old Sherwood S-5000, need schematics posted by Son of W5DYV on March 02, 2017 at 16:45:00
The S5000 takes 7189s, not 6BQ5/EL84s, as they will "fry". For all practical purposes, "the only game in town" is the Russian 6П14П-EB (6p14p-ev), AKA EL84M. Fortunately, that variant is tough and good sounding.
The Sovtek 5AR4 will do nicely, IF the series SS diode tweak is employed. Use UF4007s, instead of the 1N4007s shown in the graphic, as that better diode will serve well in future projects.
The clean and quiet Sovtek 12AX7LPS is fine for the phono section. Either of New Sensor's "reissue" Mullard or "reissue" TungSol 12AX7, depending on the voicing preference you and your dad have, will be good in the line section. The Mullard exhibits mid-range accent and the TungSol exhibits "chime".
All of the useful small signal pentode/triode types are out of production. :>( In particular, the 7199 is (IMO) ridiculously expensive. I suggest you rewire the sockets to take 6BL8s/6GH8s/6U8s, without changing parts values. The 3 types are pin compatible and any 1 of them will do. FWIW, I prefer the 6BL8.
Is a "stock" refurbishment contemplated or is something "radical" under consideration. For instance, source selection can be upgraded to remove switches from mV. level signal lines. In today's environment, tape head I/Ps are passe.
Contact AA sponsor Jim McShane for your tube and some of your parts needs.
"I suggest you rewire the sockets to take 6BL8s/6GH8s/6U8s, without changing parts values. The 3 types are pin compatible and any 1 of them will do. FWIW, I prefer the 6BL8."
Or......You can do it the easy way......
Stay calm and return fire.
I've had mixed results with adapters for the 7199, with new/NOS tubes, of a couple different types. In one case, I got really bad distortion on both channels that didn't follow the tubes + adapters to another set, and went away when I put the 7199s back.
IF I hadn't been stockpiling 7199s for a few years, I'd be much more amenable to using these and making them work, but based on mixed success, I'm glad I don't have to!
There's nothing horribly wrong with the adapters. However, the 7199 has gone the way of the Dodo (extinct) and rewiring presents a golden opportunity to install new, mica loaded phenolic, sockets. I like reducing the mechanical connection count, if feasible.
Your post about rewiring tube sockets to accept readily available tube such as the 6BL8 jarred my memory, so I went on a reconnaissance mission into my tube supply.
I came up with 28 of these n.i.b.
Can I use them in the adapter sockets previously posted?
Stay calm and return fire.
You certainly can use those nice 6BL8s in your adapters.
28 of 'em, you say. Methinks you could sell several, for some $, and still have enough to last the rest of your life, while helping other enthusiasts in keeping their equipment functional. Also, 6BL8s are the O/P tubes in McIntosh MR-67 and MR-71 tuners. ;> )
Download and cross compare the data sheets for the 6BL8, 6GH8, and 6U8, from Frank Philipse. http://www.tubedata.org/
Also, check out the schematics for the Scott 233 and 299C regarding interchangeability of the 3 types.
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