Sunday, February 17, 2008

When Good Amps Go Bad III

I hope you haven’t been holding your breath waiting for the next installment of the story of my attempt to repair my Assemblage ST-40 amplifier. It’s been a while. Earlier posts are here and here.

Briefly, after determining that my problem was a shorted power transformer, I contacted PartsConnexion (PCX), the de facto (but not de jure) successor to the old Parts Connection, which had marketed and sold the kit. In a series of emails, the president, Chris Johnson, told me that the transformer had been custom-made by Hammond. Chris said that the price that Hammond would charge for new units would be prohibitive unless he purchased a number of them (I forget how many). He said that several others had committed to purchase units if PCX ordered them, and asked whether I would commit as well. After checking with Hammond (which confirmed that the model was custom-made and that the price of a single unit would be an order of magnitude greater than the price Chris mentioned), I agreed.

Presumably Chris gathered the minimum number of orders he felt he needed and placed the order with Hammond, which then manufactured the new batch of transformers. Last week I received word that PCX had shipped the transformer, and it arrived the other day.

Now, unfortunately, you may have to bear with me again. Although I’m chomping at the bit, we have houseguests this weekend. It’s therefore uncertain whether I’ll have time to get to the project. We’ll see. In the meantime, you can look at the pretty picture of the new transformer at the top of this post.


  1. Hey,

    I'm curious, how did this problem manifest itself? I have my father's ST-40. One of the tubes has always been running extremely hot. And it's not the tube, it's which ever tube is in that socket. I'm getting the tubes sent to me so I can actually start working on it. But seeing this, I figured I'd ask and see what problems you were seeing.

    Btw, I do love the amp.


  2. Btw, I did have one of the resistors blow/crack at one point. I think that it was R53 55 or 56. One of the brown ones.



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