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Thread: Firing up an old valve amp of unknown provenance

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  1. #1
    GAStronomist Simon Barden's Avatar
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    Well, a quick search for the transformer part number seems to indicate that it is a proper Sound City transformer, probably by Partridge - though this only comes from one hit on an eBay seller in Spain. The part number is T.G. 9875-A265.

    Click image for larger version. 

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    Here's the front of the amp chassis (some valves removed at the time):

    Click image for larger version. 

Name:	whole amp chassis 1 small.jpg 
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    And the back. The PI valve sits between the two EL34s. This is a later arrangement as the PI was originally the other side of the metal shielding plate with the other pre-amp valves:

    Click image for larger version. 

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    Here's the only really suspect cap I could see with obvious cracking (though no leakage):

    Click image for larger version. 

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ID:	25481

    Here's the bottom of the two main smoothing caps. They both seem to have a small bubble in the rubber/plastic covering, so I'm not sure if that's normal or not.

    Click image for larger version. 

Name:	smoothing cap underside.jpg 
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    Haven't had time to do any more real investigation as I need to tidy away all the stuff from the 'indoors workshop' (i.e. the dining room table), as we have friends coming over for a meal tomorrow.

  2. #2
    GAStronomist DrNomis_44's Avatar
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    Quote Originally Posted by Simon Barden View Post
    Well, a quick search for the transformer part number seems to indicate that it is a proper Sound City transformer, probably by Partridge - though this only comes from one hit on an eBay seller in Spain. The part number is T.G. 9875-A265.

    Click image for larger version. 

Name:	Amp transformer 1 small.jpg 
Views:	541 
Size:	394.4 KB 
ID:	25478

    Here's the front of the amp chassis (some valves removed at the time):

    Click image for larger version. 

Name:	whole amp chassis 1 small.jpg 
Views:	544 
Size:	352.9 KB 
ID:	25479

    And the back. The PI valve sits between the two EL34s. This is a later arrangement as the PI was originally the other side of the metal shielding plate with the other pre-amp valves:

    Click image for larger version. 

Name:	back of chassis small.jpg 
Views:	530 
Size:	300.8 KB 
ID:	25480

    Here's the only really suspect cap I could see with obvious cracking (though no leakage):

    Click image for larger version. 

Name:	suspect cap small.jpg 
Views:	501 
Size:	509.1 KB 
ID:	25481

    Here's the bottom of the two main smoothing caps. They both seem to have a small bubble in the rubber/plastic covering, so I'm not sure if that's normal or not.

    Click image for larger version. 

Name:	smoothing cap underside.jpg 
Views:	492 
Size:	573.2 KB 
ID:	25482

    Haven't had time to do any more real investigation as I need to tidy away all the stuff from the 'indoors workshop' (i.e. the dining room table), as we have friends coming over for a meal tomorrow.

    Heard lots of good things about Partridge transformers, apparently they were used a lot in Hiwatt amps.

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