Anderton '64 reissue JTM145 - any info?

[Littlewyan]

I reckon the 10K joins C103 and R101 to ground as that would give more mid range and is often what Fender did in their amps.

[Matec]

About R103 and R105 is simple. I Ask for Jazzkramer, measure the resistance between the terminals of them. If the value is 0, that's right. If you can not give maximum 12,2k

I'm kind of happy. It seems that there were not serious discrepancies in my early schemes ....

Cheers

[jazzkramer]

Yes, if I measure both the value is 12,2K and the connections in your tone schematic seems ok for my understanding.

[Littlewyan]

If you measure both together then you'll get a value of 0 if they're connected together and thus they wont do anything? Am I missing something here?

Jazzkramer, are they connected in series between c103/r101 and ground? If so that would make much more sense.

[jazzkramer]

Ok, maybe I'm understanding, R103 is one side to the mass and the other to R105. But The other side of R105 is not to the mass is.... now trying to dicover....

Ok so, it seams to me that: R101: one side is connected both to the POT and C102, BUT the other side is not to mass but is to R105.

So in your schematic:
1) disconnect the bottom of R105 from the mass.
2) disconnect the bottom of R101 from the mass.

Connect these 2 terminals tooghether. They are a series... total is 112,6K. Could it be?
Does it make sense?

[Littlewyan]

Almost there, C103 would connect to R101 still.

[Matec]

Jazzkramer

Replace the connectors on the motherboard and redo the measurements.

Littlewyan
  These values ​​in the tonestack, equivalent to the midle level a minimum, and the bass at 11:00.
It is not too much bass.

[jazzkramer]

Ok, there something other wrong... C103 does not appear to connect to R103, but it does not appear to be one side connected to the mass.

Checking the board... We will get it!

[Littlewyan]

Matec, you had the resistors R103 and R105 shorted out so they werent doing anything. As a result there was no mid range but a lot of bass. If you connect them in series between C103/R101 and ground then the tonestack will be as if the Bass Control is on 11:00 and middle on 12:00 as you say.

[Matec]

Jazzkramer

I'll need one more picture. Need not be today.

A photo showing the top side of the connector on CON101 tonestack board (where C104), I need to look at the tracks that pass through there.

Littlewyan, your idea is correct, but look at the photos. One side of C103 is directly grounded, has no way to insert here a resistor, however much I want.

Cheers

[jazzkramer]

Ok sure, tomorrow I will take other more detailed fotos of thw tone stack, now I'm trying to solve the things, but anyway, I will take more fotos and post them

[Littlewyan]

We'll get to the bottom of it. Pretty good that you got 95% of the amp correct though Matec, considering you had no one to confirm your values at the time. So well done

[jazzkramer]

Ok, following again with the tester and with the eyes, it seems to me the schematic is like the one I draw on this paper.
I'm definitely not good like you at draw in a better way.

So, my previous correction were wrong, I apologize, I'm sorry.

Does this make sense? I will the same take more good pictures and post
and I will re-check all

Now going to sleep!

Toghether we will get it!!!

Thankyou! Bye!

[jazbo8]

There appears to be very little difference between JTM1 & JTM145, while the PCBs are different (I was wrong about that), most of the parts are the same - on the JTM145, C12, C13 are added, as well as another 33uF next to C5, so its PS is a bit better filtered. The major difference is on the Control PCB, where the TS and the two Loudness controls are located, so we would need to have a few good photos of that board from Build. TIA.

Other than some minor part value changes/re-wires, Matec's old JTM1 scheamtic was pretty much spot on, great job!

[jazzkramer]

Matec
I re-checked by tester and by eyes the drawings I made yesterday night and it's correct. I tried to take more detailed photos but my (shit)camera goes out of focus when I take pictures near the board. I will try again, but I'm pretty sure the drawing is correct.

Of course all af you that have a good understanding of electronic functions will please check to see if what I discover on the board make sense.


You're right jazbo8, I would like to have the 2 different schematic. Maybe in the 145 there is more gain? (I think I remember Anderton's told this in the interview).
Another difference: in JTM1 are added R35 and C23.

We definitely need the schematic of the Tone Pcb of the 145, we will discover the the "hi mid bass thing" and the "2 loudness thing from that.
We need the input Pcb too, to discover the "2 inputs thing".


We would definitely need, if possible, Build to take very detailed photos of the "tone stack" and "the input stack"

So please Build if you could take fotos of the tone pcb and input pcb if possible we will thank you very much, with the list of condenser values as you did for the main board

Thanks!

Bye, jazzkramer.