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Compiled Ampeg SVT-CL, -AV, -VR, SVT2-Pro & SVT II Svc Notes...347 pgs

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  • Compiled Ampeg SVT-CL, -AV, -VR, SVT2-Pro & SVT II Svc Notes...347 pgs

    Day two of the extreme heat in Burbank, CA...climbing up to 114 deg F, so as the main warehouse at CenterStaging,LLC in Burbank is air conditioned, you BET this is where I've parked my fanny, as there's no air conditioning at home. Nice and cool here at my desk in the shop. So, not having finished my project of compiling ALL of the service notes written on during maintenance/repair of the Ampeg SVT 300 Watt tube amp (SVT-CL, SVT-AV, SVT-VR, SVT2-Pro, SVT II) since I began working here March 2009 thru the present, I've now compiled 347 pages of notes on all those repairs, and now, just beginning to go back thru them to catch the typos, mis-spelling, other edits. Before I got my cataract surgery done in 2019, the degree of typo's leading up to it was horrible. Finger-dislexia, I called it.

    I just looked at the file size....31.6MB, so too large to be uploaded onto this thread in it's current state. It may have to be broken up into yearly chapters before I can upload it. At least now it's all in one file, though it will take time to refine it with an index, derive more details from it all to create a good troubleshooting guide. But, sure a good way to beat the heat outside. I've already completed the present load of repairs on the floor. I haven't yet resumed the loudspeaker cabinet preventative maintenance work, which the Pandemic shut down. No funds to cover all of the speaker replacements needed to manage all that yet.
    Logic is an organized way of going wrong with confidence

  • #2
    Looking forward to this.
    Building a better world (one tube amp at a time)

    "I have never had to invoke a formula to fight oscillation in a guitar amp."- Enzo


    • #3
      Nice job mad scientist!

      Stay cool.


      • #4
        All I can say is DAMNNNN.
        Awesome contribution ...
        When I die I want to go quietly in my sleep like my grandpa did. Not kicking and screaming like the passengers in his car.


        • #5
          You're THE man!
          (You can try uploading on drobpox/google drive - not sharing, just direct link)


          • #6
            This past weekend, I got thru my editing up to around pg around 6/17/18 of my compiled service notes. On one adventure inside an SVT-VR, tracking down why the unit wouldn't reliably power up, I finally got more curious regarding the power transformers used in both the SVT-CL & SVT-VR, and, digging thru all of my notes, I realized I never did draw up anything but an SVT-CL transformer diagram. The outcome of the weekend was now having the rough first drafts of all four transformers used in both models. This morning, I fired up National Instruments Multisim 11 and created fresh drawings of the two transformers for each product.

            SVT-CL power xfmr P/N 94-602-40, which produces the HT and Screen Supply Voltages
            SVT-CL power xfmr P/N 94-602-35, which produces the Bias, Bipolar and Heater Supply Voltages
            SVT-VR power xfmr P/N 94-279-40, which produces the HT, Screen and Bias Supply Voltages
            SVT-VR power xfmr P/N 94-412-40, which produces the Bipolar and Heater Supply Voltages

            I got all of the color codes for the xfmr wires, the secondary voltages (which were based on the Test Procedures at Ampeg when first powering up a completed amp. I haven't yet verified the AC voltage on the HT supply of both products, as the SVT-VR called out 450VAC, while the SVT-CL called out 465VAC. I thought I had unregulated voltage readings on the SVT-VR's Bipolar supply voltages, ahead of their simple zener supplies, so as I open up some more amps during service, I'll make updates to my findings.

            At least finally there are transformer drawings on these amps! Something that has been a mystery to all of us, apart from those of us who sketched them out on the fly.

            Ampeg SVT-CL Power & Heater Xfmrs.pdf

            Ampeg SVT-VR Power & Heater Xfmrs.pdf
            Logic is an organized way of going wrong with confidence


            • #7
              This morning I drew up the Output Transformer diagram for these amps. I managed to catch the error I made on calling out the Primary C/T terminal...which on all but the SVT-VR is J13. On the SVT-VR, it's J18, so I added that note. I've attached this Output Xfmr drawing P/N 94-602-12.

              Ampeg SVT-CL, -AV, -VR Output Transformer.pdf
              Logic is an organized way of going wrong with confidence