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Spragues original in 210HD130?

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Brian M. Watson (mrroundel)
Username: mrroundel

Registered: 06-2007
Posted on Thursday, September 09, 2010 - 11:00 am:   

I've got a 12AX7 version 210HD130. I pulled the chassis to see if the important caps had been replaced. Well, it had 5 visible larger type capactiors, all Sprague brand. 4 blue, 1 orange ( on fiber board next to tube sockets). Is it obvious that these have been replaced? Thanks.http://home.earthlink.net/~bmw4re3/Music manGuts.JPG
Christophe Le Crom (vignau)
Username: vignau

Registered: 08-2010
Posted on Friday, September 10, 2010 - 04:24 am:   

The blue one are most probably stock. I changed mine recently on my 210HD130, and I have these exactly blue one at the same places. As I bought my amp new in 1980 I know they were stock. For the yellow, don't know, I have the SS driver version.
Christophe
Mike Kaus (mm210)
Username: mm210

Registered: 05-2006
Posted on Friday, September 10, 2010 - 06:48 am:   

Actually, all the tube inverter ones I have seen had the old silver metal mallory's in them(pretty sure they are malllory's). I've attached a couple of pics to show the originals. Not saying they were all like this but this amp I've had from cradle to grave(I sold it so myself in 77 or so.). By the way, the crud on the caps is NOT corrosion-it's sawdust! Could see that when I took the pics. It's down in my shop and I was doing some woodwork. MIke.
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Mike Kaus (mm210)
Username: mm210

Registered: 05-2006
Posted on Friday, September 10, 2010 - 06:50 am:   

Ok, let's try this again.

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Brian M. Watson (mrroundel)
Username: mrroundel

Registered: 06-2007
Posted on Friday, September 10, 2010 - 07:37 am:   

FWIW: B005326 is the serial number of the amp. It seems to me that, with the other larger capacitors pretty much all being Mallories, that it would have had Mallories in these locations as well. If these are the "usual suspects" that are changed out, them being of a different brand than the rest, would indicate that they'd been changed. However, if they were, the tech did a very clean job, as the inside looks quite unmolested.
Related questions: In Mike's second picture there are two trim pots(?). Are they Tremolo(L) and tube bias (Rt)? Also, is that silver transistor (IC?), that looks like a miniature water tank, one of the reverb circuit's components? What number is it, IC1,2,3,....7?
Mike: I know that you are a frequent contributor here, and have a good knowledge of these amps. When you say that you've never seen a tube inverter amp with Spragues, approximately how many have you been in?
Regardless, as I said in the earlier post, despite the fact that I have less fear of death from tampering, I'm going to defer to a professional on this thing. I wonder how they would be able to tell if these caps were replacements? Test? Different look to solder joint?
Many thanks for your responses, guys.
Mike Kaus (mm210)
Username: mm210

Registered: 05-2006
Posted on Friday, September 10, 2010 - 02:33 pm:   

I have worked on dozens but they are ALL very early versions, like mine. I actually have two myself and they are both the same. I have only seen a few of the RD's and ONE RP. The thing is, when a manufacturer gets a deal on compnents, NOTHING is sacred. They'll change at ANY time and you don't know what the hell they will use. I personally would NEVER have used those yellow INDCO mylar caps but they did and sound fine. I sold this stuff back in the day when it was new so I've SEEN hundreds. Kind of wish I had kept a few more.