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Blackstar HT Venue MKII

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  • Blackstar HT Venue MKII

    Does anyone have a schematic for this amp? I've got one here, the Kentucky Red or whatever, that is getting no voltage to the preamp. It's fine elsewhere, plugging into fx yields signal out he speaker. All resistors that look like droppers are fine, just getting no supply to the pre.

  • #2
    This isn't for a Venue MKII, but I can't imagine the power supply would be vastly different. I could be wrong but maybe worth a look?

    https://music-electronics-forum.com/...etch?id=910879
    "Yeah, well, you know, that's just, like, your opinion, man."

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    • #3
      Thanks, I did see that one and have been working off of it, but apparently it is different. The last resistor in the PS, a 10K, should feed the pre, and I found that 10K, and it has voltage on both sides of it, but not at the Rp for the preamp. Also that dropper is in parallel with the node before it, on my amp, as opposed to series like the HT40

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      • #4
        Ok, what´s preamp expecting?
        +/-15V for Op Amps?
        Single supply between 25 and 40V?
        that is getting no voltage to the preamp.
        What does that exactly mean?
        Trace it backwards towards power supply, you may have an open dropping resistor, a shorted filter cap, a shorted IC, a bad regulator, a bad connector, cracked open tracks or solder pads .... *guessing* has infinite possibilities, you have it on your bench, start tracing back.

        Post a preamp picture, show the power supply.
        Juan Manuel Fahey

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        • #5
          Or B+ for a preamp tube, if it has any.
          Education is what you're left with after you have forgotten what you have learned.

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          • #6
            If you have heaters on the ECC83s then check R204 10K HT feed for the pre amp valves.
            Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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            • #7
              Here's the schematic. It applies to the HT Venue Mk II as well as the Club 40 and Club 50 models. The Kentucky Red just added red tolex and an Eminence Screamin' Eagle speaker.

              Look at sheet 3 in the upper left hand corner for the power supply for the preamp tubes. I've had R36 (4k7ohm 7W) bad and replaced. That will take out all of your preamp high voltage supply. Also check R69, the two 22uF 450V caps and the diode with that circuit as well.

              I've also found open plate resistors to the preamp tubes as well as a failed open input inductor on the incoming guitar signal on these amps in the past.
              Attached Files
              Last edited by Delta362; 09-15-2021, 12:39 PM.

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              • #8
                If it is the correct schematic by Delta362, check R69 22k in this model, 10k in most others.
                Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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                • #9
                  Originally posted by Jon Snell View Post
                  If it is the correct schematic by Delta362, check R69 22k in this model, 10k in most others.
                  There it is . THANKS!! and Thanks for the scheme Delta32. Fahey you were absolutely correct. I was hastily tracing back, and couldn't find the 22K node that fed the preamp . I mistook it for a 220K balance resistor, and was still scratching my head over the 10K in the same spot in the other amps.
                  Anyways , got it sorted.
                  I was frazzled yesterday over the Park amp, as I had called to discuss the situation with the owner, and he threw a child-like fit, was extremely rude, insinuating I was overcharging him, doing unnecessary work, and ruining his amp. I haven't been at this game long, 5 years or so, but it was the first time that had happened, and it threw me for a loop. On the other hand, just got off the phone with the Blackstar owner, and turns out he owns a fancy restaurant in town, and invited my wife and I to come eat tonight, on the house. Funny how these things work out.

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                  • #10
                    Sometimes you have to be gentle with obstinate customers.
                    Truth be told they couldn't fix it!

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