new JTM45 build, problem Testing Part 1, steps D and E

[Bern1]

Hi all,

Bernie here, thanks for reading and shedding light on the matter if you can.

Took my time building this thing and I'm reasonably sure it's put together correctly, however if it really were put together correctly, I'm sure I would not be having these problems, ha:

Steps A and B checked out ok. In step C I got 3.5V AC at all the points that are supposed to be 3.15V AC. Between pins 2 and 8 of the rectifier I get 4.9V. Not sure if these values are acceptable, within tolerance.

In Step D I get -49.9 V DC on pin 5 of each power tube socket with the bias pot all the way clockwise. Not sure if that is excessive. With the power on and the standby off I get 314V DC at the switch with one meter and 380 with another meter. Not sure if this is a problem either.

Can I live with these mentioned values?

The real problem seems to rear its head in Step E: the values for V1 and V2 vary somewhat for pins 1,3,6 and 8 but at least they are in the ballpark.

for V3 however I've got:
383 V DC at pin 1
5.8V at pin 3
383V at pin 6
5.8 V at pin 8

None of these seem remotely correct, seems prudent to figure this out before going any further.

Any idea where I should start looking?

Thanks!

Bernie
http://www.Turn9Band.com" onclick="window.open(this.href);return false;

[Flames1950]

For the V3 problem, check for a 470K resistor where there should be a 470ohm resistor -- the yellow wire from pins 3 and 8 goes back to the resistor in question. Switching to the proper 470ohm resistor should get your voltages at V3 back in line.

Guess I'd stick with the meter that reads 380V and check the batteries in the other.........

[Bern1]

Thank you, I will check it out and post!

[Bern1]

Flames, nice job of remote troubleshooting, thank you. Indeed I installed a 470kohm resistor where there should have been a 470ohm resistor. I swear I checked that resistor 3 times. Each time I checked it, I guess I made sure it was a 470kohm resistor!
The values at V3 are now more or less correct and nothing seems to be broken, onto biasing!
Cheers, see you all soon...
Bernie

[Bern1]

All right, it works! Can't wait to put a little bit of volume through it!

[Roe]

this is a classic mistake

[Bern1]

Ha! I had no idea that mistake was so common, yet when I cruised through some posts I can see that is indeed the case.
I triple checked it and still made the mistake!