Anderton '64 reissue JTM145 - any info?

[Matec]

Hello odrpol

The pin 5, as you know, is the power of the heaters. If there is a wrong contact, he can do what you said, but it is rare. Make sure the valve pin is not oxidized, and if the socket is in good condition. If so, replace it

The valve 12AU7 heats up more than the others, obvious, there is more current going through it. Of course, too much heat should be avoided, and if so, should be checked.

It would be time for you to make another measurement of voltages, this time with the valves in place.

Cheers

Matec

[odrpol]

Hi Matec.
There is not problem to make the measurement.
I will make it tomorrow. Now is about midnight in Warsaw.

Regards
odrpol

[odrpol]

Hi Matec

Here is the voltage measurement with valves.

Regards
odrpol

[Matec]

Hello odrpol.

Here is the schema "my" JTM1 with the measured voltages to the valves.

There are no mistakes in the assembly, and these tensions were measured several times and remained stable.

An error that exists in my schemes published before is the value of R31. appearing as 2,7k, but it is actually 1.5k. This is the value that appears in this scheme.
I did not see it, this same topic, when it was published the B.O.M. And it seems that no one else noticed. Until our friend, cassoulet, found this discrepancy.

R31 = 1.5k => JTM1, CS JTM145.

R31 = 2,7k => JCM1

Will gradually replacing JTM1 schemes to remedy this.

Cheers

Matec

[odrpol]

Hi Matec
Thanks for the diagram with data.
I must now get the same or similar value.

regards
odrpol

[cassoulet]

Hi everyone,

Odrpol, your output tube V3 draws too much current, about 20 mA per triode and that is way too much for 12AU7. Calculated dissipation for each triode is about 5 watts, but it should not go over 2.5 W.

If you want more output power, use ECC99 instead. It's a good replacement tube for 12AU7. Of course it needs a little more current and your JTM1 will be loud.

[odrpol]

Hi Matec
Once more thanks for the Voltage value.
I was start to analyze the schema with Your`s and Smokebreak layouts and I see one inaccurate, on the schema the signal is thru C22 and R28 connected direct to pin 7 of V1A, but on the layouts (Your`s and Smokebreak) this connection go direct to pin 2 from V1A. What is correct.
The same is at the V2 - on schema pin 7 connection go direct to middle tone pot, at layouts it`s pin 2.
The same is at anode connection - in layouts is inversely than in schema.
Could You be so kindly and explain that. Maybe that is the reason that I have the problems with the amp.

regards
odrpol

[Matec]

Hello odrpol

Would not this inversion amplification stages of the valves, it is the big problem. The amplifier equal work.

What goes wrong on your amp tensions are appearing in places that should not appear.

When you showed the first schemes to measurements without the valves, everything was wrong.

The grids and cathodes should show zero volts. All of them.

The plates, a value close to 295v, all of them as well.

That's what you should focus on.

I did not see anything strange in your layout, but maybe it's best that you post pictures to your board. Detailed photos. Maybe someone sees the problem.

I wait.

Cheers

Matec

[odrpol]

Hi Matec

Than what is correct Your`s scheme,
or maybe the layouts (Your`s and Smokebreak )
I make all seeing Your`s scheme.
Tomorrow I will make the photos and post it.

regards
odrpol

[Matec]

Hello odrpol

At first, the scheme is the most correct.

Not that the layout does not work.

There is information that the "A" section of 12AX7, pins 6,7 and 8, produce less noise. Then, for most assembly the "A" section comes first.

But as the work would not have problems.

Cheers

[odrpol]

Hi Everyone

In my last post I was said that I make the photos from my amp inside.
In the meantime I was soldered all components out, and make it`s from the beginning once more.
I was purchased the new PT with 180 V secondary, and new OT – there are on the road.
When they’re coming I will change both.
Now my request maybe somebody can examine the layout and photo with the scheme.
Maybe somebody will see somewhere the error I was made at the assembly.
I have no ideas what can be wrong.

Thanks in advance

regards
odrpol

[dorrisant]

Odrpol, I don't like where your plate resistors are located, it should work though. In the picture there are some questionable solder joints. Check the continuity of those joints from one component leg to the next component leg, not at the turrets. Then you will know if the joint was soldered correctly. Quite often I have to sand some corrosion of of the turrets before I install them.

If you are going to rebuild this circuit, you should start a new post with your layout and pictures AS YOU BUILD IT. It looks like you have the skills it takes to make this amp work. Maybe there are just a couple of things that need to be corrected to get good results. If the members here on TAG are allowed to see it as it goes together we will get it figured out to work correctly.

If you start a new build post, let us know here with a link and I will certainly help and follow. I don't mean to offend you, I think you are very close to success.

[Ksandr]

its my jtm1. very small. 180x100mm

[cassoulet]

Nice build

How does it sound? Do you have PCB layout?
What TR did you use? I can see a small Hammond for output, but what is the power transformer?

[Ksandr]

attach pcb. PT I was using ordered in the local office (i from Russia). OT i using hammond 125A