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    Building, troubleshooting and testing of these amplifiers should only be
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Soundcraftsmen 5050

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@ Jim McShane,
You are correct about the IC cap, it definitely is not original, it's 500V, 22uf. The terminal strip to the left has a white wire coming off the bias pot and a cap 25v 220uf to chassis along with a 68K resistor to chassis. Basically I need to know what wires go where and what is missing. I know there's the filter caps (which I believe was a three in one type) and the large chassis mounted resistor is supposed to be 100ohm (don't know wattage). There are two red leads to each OP x-former, one white lead from the primary PS xformer, one red wire from pin8 of the rectifier tube socket. Once I get it running then I can start with the mods on the rectifier. Here's a closer look at the area in question. Thanks for all the help and suggestions. I've already ditched the JJ rectifier for a GE I had lying around.
 

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I suggest you go to tubesandmore dot com and look at their selection of multisection can caps. You will need a maximum 47 or 50 uf section for the first and then perhaps a bit larger after. I think you will want to use 450V rated caps. I have also used the black JJs that are mounted with clamps with good results.

You do need to arrive at a value for the missing resistor and that part is probably unobtanium. You can however buy a modern wire wound chassis mount part like THIS and mount it inside the chassis.

If you can't find a schematic, you might take a few hours and make a circuit drawing and post it here and it's likely you will get sound recommendations for that resistor value.
 
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Thanks Captn Dave, The missing chassis mounted resistor I believe is 100ohm. The gentleman who gave the amp also gave me 6 or 7 other tube amps in various stages of completion along with many bags of parts some old some NOS some new. He believed that one particular bag contained the parts for this amp. A Sprague electrolytic 40uf-40uf-20uf - 450vdc cap and 100ohm chassis mounted resistor look to be the most likely candidates if that seems plausible according to their values. I'll start a hand drawn schematic, never have attempted that so we'll see how it goes.

thanks
 
The cap values sound plausible. A C-EC40X3-525 from antique electronic (tubesandmore.com) would do just fine if you need a three section can. You can go up on voltage but not down. The first cap is limited to 60uf by the rectifier's design limits (rather than 50 as I said in my first post) and the additional sections can generally be increased in value with positive results. You may connect two or more sections if you desire for the additive value.
 
Yea I acquired a good deal of parts and tube equipment from relative who was an electrical engineer in the US Army in Japan after WWII. A lot of mil spec tubes and NOS tubes. Boxes of PIO caps like Vit Q, Aerovox, Pyramid, Jensen. 4 Bogen pa mixer amps, The Fisher intergrated amp, HH scott, Heathkit, 4 weird Moviola tube amps. I haven't really gone through it all thoroughly but it's a lot of stuff. The Soundcraftsmen is just the first on the list.
 
I think that is a really good idea. I was reading that the Fisher X-100 and the HH Scott 299A that I have are nice sounding amps and schematics are readily available. I think I will be taking your advice Captn Dave. Any suggestions as to which of the two might be a better choice? I'm good at reading schematics and have built one small 6BQ5 single ended stereo amp so I have a little tube experience. thanks
 
Humm, good question. IIRC both of those are 6BQ5/EL84 amps. They both have good iron and they offer about the same complexity. It's a vintage piece, which one will look better to your eye? Somehow the Scott has more curb appeal to me. My beef with the X-100 is that it tries to looks like a solid state amp. Check out a photo of the X-101C and see the difference. But that's just me rambling.

So, I'd take a careful look at the condition and completeness of both amps and pick the one that looks to be the most complete, trouble free and clean. Things like bottom covers, face plates, knobs and power resistors might seem like no big deal today but they can be very hard to find. Hell, I've been looking for a "dog bowl" knob for my Scott LK-72 for 5 years now:) Corrosion's pretty hard to deal with too if it's bad.

Next you'll want to qualify the iron. Check the power transformer with a dead bulb tester and a volt meter to see if it's good and then check the output transfos to see that they are good.

Either of them will sound great if you do a proper job on the restoration.
 
Well then, I didn't remember correctly.

The 7189 in the Scott actually IS an el84 variant; it's an upgraded or premium version that will take greater plate voltages. Same pin out. They were ubiquitous and are still in production. There is a Russian tube 6P14P that is sold as a substitute for both the EL84 and 7189 but I've never check to see that it actually is suitable as a 7189 replacement.

The 7868 is more unique. I think EH is making them again but kind of spendy. You will want to check those tubes.

I say go with the Scott if everything else is equal.
 
I have 4 - Amperex 7189A and 4 - ElectroHarmonix 7868. The Fisher has these "integrated circuit" type components. Basically it has 3 to 6 leads coming off of a component. The schematic shows a series of caps and resistors inside the sealed component. That alone worries me if any of those are bad, I'm sure acquiring replacements would be near impossible. The Scott looks like it needs a little more work, but I'm more comfortable with it's layout. I'll test the iron, hope it's all good. Thank you Capn Dave for your help. I'm sure I'll be posting here for assistance and updates along with photos. Can't wait to get started.
 
The Russian 6П14П-ЕВ (6p14p-ev), AKA EL84M, is a genuine 7189 equivalent that's tough as nails. It also sounds pretty good. The 6П14П-ЕВ is THE tube to use in the 299-A.

The 7189A pins out differently than the EL84 or 7189. Depending on how Scott set things up, you could damage the tubes and/or the amp, if tried in the 299-A. Amperex 7189As are valuable. Think about selling them off to fund other purchases.
 
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