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  1. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Thanks Andy, I don’t play so I go OCD in building them.
  2. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    I’d say very well explained as well!! I’m gonna try and follow the grounding scheme. I will probably have an exception or two. The amp is going to be for my son and believe it or not he really doesn’t mind hum. He will probably mod it anyway, but for now it’s mine and I like them quite...
  3. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Now that I think about it I was measuring the heater winding, it doesn’t have a CT, I don’t know what I was thinking when I said 3.15 per leg, I do have 6.3. I am going to put the 100 ohm resistors on each leg to ground.
  4. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    I am putting it in a JTM45 chassis 😆
  5. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Thanks man, I know it’s not a Marshall. But this is where I like to hang out. Mark so let me see if I have your suggestions right. The numbers on the schematic are the order of how they are to be connected to the ground buss, or are you saying 5 different grounds throughout the amp. I did...
  6. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Thanks ELS, the board is going to have Turrets, everything will be mounted on the side you’re looking at. I haven’t drilled it for turrets yet. I am going to make a ground buss for the grounding. Here are 2 different ways I’ve done it. Both ways are grounded by the inputs. One style is...
  7. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Very nice ELS, that’s what I’ll do split the plates and the screens. I’ve been building guitar amps from kits for a while now and this one is my first scratch build. I’ll say it’s much more enjoyable. So here is a question for anyone. Here is the mounted circuit board. It extends a little...
  8. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    ELS, as far as the filters go I’m just going close to what Fender did(3-16uf and an 8uf in the preamp)F&T didn’t make those values so I went with 3-22uf caps and for the preamp it’s an 10uf. I did see in other schematics Fender did split up the plates before and screens after the choke. I...
  9. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Hey danfrank, thanks for the info. Looks like there are 3- .047 caps and 2 .1 caps. Both are rated for 600v. I can use the .1s for the coupling caps for the power tubes. If they check out I’ll use them thanks. Here are the components bolted on with the tubes in.
  10. Rotorcraft230

    Marshall JVM410H intermittent sound cutting out

    Sounds like it could be a loose solder joint. If the vibration from hitting the amp causes it to come and go it sounds mechanical. May be hard to find. Look at the PCB with a good magnifying glass. May be difficult to see with the make eye. Downfall is gaining access th the solder side of...
  11. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    There is the chassis, that was a little work, very satisfying though.
  12. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    I got an undrilled chassis, Marshall JTM45 faceplates. The rest is pretty much gonna be Fender like, oh minus the turret board. The OT extends into the chassis so I had to raise the circuit board off the floor and went with turrets. Still waiting on the filter caps, went with F&T The preamp...
  13. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Thanks for helping Neikeel, the 75v is actually labeled 70v and it’s on the secondary of the OT and it had 13.38vac on it when I was doing the WR calculations. Here are some pics of what I removed the transformers from. Oh and also the transformers are SNC, their EIA code is 6. Eminance...
  14. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    So here is what I came up with. Doesn’t quite look ideal. If it has been used since 1961 and is still working I’m go to assume that this OT and tube combination will continue to work together.
  15. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Yes it’s surely will help. I plan on doing that when I get home and I will report back. The PA had 2 12AX 7s, a single 6AV6, 2 6L6GCs and a 5AR4. I’ve never done these types of measurements so it should be fun.
  16. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    A Knight PA with 6L6GCs Plan on using all the secondary taps on the OT 4,8,16 Ohms. It also has a 75v, I think that’s a PA thing.
  17. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Thanks Neileel, I can do that and measure. Here is what I have as far as DC resistance, looks like they are not 40%, but I’ll still measure.
  18. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    Here is a pic of the transformers. I tried looking up the numbers but came up empty, Anyone recognize them?
  19. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    I was wondering what the linear taps would do vs the CT taps used with pin 4 The plate voltages will be in the neighborhood of 420vdc
  20. Rotorcraft230

    building a Fender "Pro-Amp" from scratch

    The PT I’m using is going to be used with the rectifier from the Knight. I believe it’s a 5AR4, Not at home to confirm.

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