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...
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.
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...
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...
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...
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...
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.
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...
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...
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...
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.
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.