Anderton '64 reissue JTM145 - any info?

[Matec]

Yeeessss !!!

Today I will have a heart attack!:lol:

After 1 year of waiting, the same day it arrives !!!!

Uff!

Jazzkramer would be asking too much, if you also make a list of all the capacitors on the motherboard and toneboard?

Thank you !!!!!

[jazzkramer]

Of course it's a pleasure:
Ok guys, than I will shut up and remain in stand by If any question (on the JTM1).
In the case you need to compare to 145 or better understanding here
are the
condenser values: (JTM1) I write as I read because I have to find how to "decode" the values:

MAin Board:

C2: .1J63
C3: (elettr near audio transf) 33uF 500V
C4: 22nK400
C5: (elettr near D5 and D6) 33uF 500V
C6: (small elettr near C5) 1uF 100V
C7: 22nK400
C9: (ceramic) 222 0QK (not sure the 0QK)
C10: 22nK400
C11: 22nK400
C14: (elettr near amp jack out) 33uF 500V
C15: AV .1J400 (not sure the AV, could be A/ or N, maybe is the brand only??)
C17: AV .1J400 (not sure the AV, could be A/ or N, maybe is the brand only??)
C18: 22nK400
C19: (ceramic) 101 KQK
C20: (ceramic) 471 underscored
C21: 2n2 100
C22: .47J63
C23: .1J63
C24: (elettr) 1uF 100V
C25: (elettr) 220uF

Tone board:

Tone pot: B250K
Loud pot: A1M

C108: (ceramic near loudn pot): 221 underscored
C104 (ceramic near blue cables): 221 underscored (the foto is not good here if you need I could try to get the schematic here much more visible if needed)
C102: 22n J100
C103: 22n J100






Bye!

[jazzkramer]

Here in stand by if something is needed, like resistors colors, component identification, part of schematic not clear in the foto... I'm here

thank you all the guys working to understand these amps!

[Matec]

Jazzkramer

Thank you very much!

My big questions (To one another amp ...).

Where is marked R25. I would like to know which terminal V1 it connects?

Where is marked R22. One of the trails going down the large cap C14. You can tell me where this track will stop ?.

Thanks again!

Heart attack, yeesss !!!!


Matec

[jazzkramer]

I;m here:

Where is marked R25. I would like to know which terminal V1 it connects?

you mean the "big plate" under R25, it seems it's not connected to any V1 terminals. Its' for sure connected to the right side of R27 and it seems to anything else. Could it be?



Where is marked R22. One of the trails going down the large cap C14. You can tell me where this track will stop ?.

Ok I think: R22 (not present), goes to the positive terminal C14 big electrolitic, It seems R23 too, 'cause the tester give me o ohm from the positive condenser pins and R23 pin.
ALSO R(19?) that BIG resistor (yellow, purple, red,gold) under the big C14 is connected to the positive terminal of C14 it seems
So it seems the upper trails from R22, R23 and R19?(the big one) all stops to the positive pin of C14


And in the component side there's a trail from the low power switch to C11 an then to R14, I'm sure this is NOT connected to C14 (it's passing under C14 but not in it's terminal)

I should have to unsold the condenser, but I don't have a solder here...

[Matec]

I have to do some changes in the schema of tonestack.

To be practical that you need to measure the values ​​of these resistors R101, R103 and R105. You could measure them directly?

[jazzkramer]

By the tester without unsold the components:

R101 (brown, orange, black, black, brown) 100,5 Kohm (so i think 100Kohm)

R103 (red,red,black,brown,brown) 2,19 Kohm

R104 (green,blue,black,red,brown) 56,2 Kohm

R105 (brown,red,black,black,last is like light brown??) 9.94 Kohm


Still here, so ask if needed

[Matec]

Thanks for the resistance measurements. Is perfect.

This trail leaving the R103, and goes to the back of VR103, arrives to one of the terminals VR102?

I wonder if the terminals of R25, (who also is not on that circuit), be linked to something else, that R22, and the circuit ground.

About R22 if the resistance is 0 to the positive terminal of the capacitor C14? If the answer is Yes I am satisfied, no need to unsolder anything.


Matec

[jazzkramer]

R103: the pin where it's written R103 goes for sure to the middle one of the 3 blue cable connecting to the mainoard.
AND Yes it goes to the first right free terminal of VR102

the other pin of R103 is only connected (on the back) with R105 the pin where it's written R105.


Investigating R25 I discovered that the positive pin of C14 is also connected to C17 to the pin near the speacker out jacks.


Checking R25 it's connected in the pin near C14 to R27 that is the big plate (under where is written R25) and the other side of R25 is conneccting to the not present R22 (R22 the side not connected to the C14 positive pin).

Yes R22 is one side to R25 and the other side to positive pin on C14.


In the case I state somwthing strange, please ask me to check again, becouse it's not so simple to follow the tracks/trails with components soldered to the plate and I could mistake

[Matec]

So now I know that R103 and R105 are connected to ground ... the ground. Has no function in this circuit.

I will ask you to check the newest schema of JTM1 that has left this forum, and probably anywhere in the world forum. Pretty soon I'll post. Take a look and tell me if you find anything strange.

This scheme has a great contribution Her.

Thank you!

Matec

[jazzkramer]

Thank you!!!

I will have the amp at my home for some days (the owner is on holidays) so in the case of dubts, ask me. I will sure check your schematic.

Thanks, jazzkramer.

[Matec]

JTM1 Schematic: (Corrected, 03/09/2014.)

[img625]http://s26.postimg.org/k4sll6lft/JTM1_28_08_2014_B.png[/img]
(To see the full size image, click on the above link and open in new tab.)


As I said before, please check this diagram that there are no doubts about its quality.

This scheme has a great contribution Jazzkramer, among others.

Now I need to create a schema of CS JTM145. But we forget to ask our friend build, to take pictures of Tonestack

Thank you all!

Heart attack !!!

Matec

[jazzkramer]

Ok checking the updated JTM1, I hope "build" could come back to post the Tonestack and the input small board too, to understand the tone differences and the "double input" "double loudness" things

I think the JTM145 is the better sounding of all the 1 watters BUT I had not the money to buy one. If possible I will build one in the future, to play blues LIVE (yes using it as a preamp and reamping by a transistor amp).

Ok checking your schematic. Thanks Matec![/b]

[Littlewyan]

Matec, the schematic looks good, although I'm not sure what R103 and R105 are meant to do. Also putting those tonestack values into LTSpice gives a weird frequency response as there is no mid range but a lot of bass. I have by the way added a 1uF Cap to my 12AU7 Cathode as per the JTM145 Schem and the amp sounds better

[jazzkramer]

Actually I was again thinking about R103 and R105... it's strange they are there if they are not needed.... ??

Checking again the board..