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    Transistors for PAT-4



    Transistors for PAT-4

    Post by rce107 on Tue Oct 12, 2010 12:10 am

    I have an old PAT-4 that has a weak channel. Does anyone know what Q3 and Q4 could be substituted for? The #'s on the txistors are ??239 and T7435 respectively. Thanks.


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    You man not still be listening but...

    Post by hvlee on Thu Oct 21, 2010 9:16 am

    My experience with three out of three Dynaco preamps: PAS-3X and two PAT-4's, is that channel imbalance is always the volume control.

    Recapping helped, though not as much as the volume control. I don't believe in recapping without a reason, but all of these preamps gave me a reason. Each had deficiencies in sound, from poor response to squeals and motorboating until they were recapped. Now, if I got a "new" Dynaco preamp I would break my rule and just go ahead and recap it.

    Radio Shack has an inexpensive 100K stereo pot with loudness tap which has done the job for me. I believe the stock pot value is 250K, but the 100K item has worked for me.

    There are those who say that it takes several of the Radio Shack pots to find one which tracks correctly but I haven't found that to be the case. They may be holding the pots to a technical standard inaudible to me.

    It's hard to get advice on solid-state Dynaco gear. The community is biased toward tubes (no pun intended).


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