Voltages 1/2 [resolved]
- Thread starter hbonilla
- Start date
fullheadofnothing
Moderator
Were your power transformer secondary voltages (p.31-32) correct?
Natural Sound
New member
I agree with Josh. Sounds like you have the primary of the power transformer set for 220 but feeding it with 110. That would give you roughly half the voltage on the secondary.
Thanks. I checked my wiring on pages 28 and 29 and found a mistake. I had connected 2 to 48U rather than 3 to 48U. Connection is correct now but my readings are still exactly half of what they should be. My input voltage is 122.5
I reviewed my notes and the Power Transformer Secondary test was on target +- 10%
Any other thoughts?
Thanks again
Paul Joppa
Moderator
Look at the high-voltage rectifier connections (and orientation).
If you don't see anything there, somebody will get more meticulous once the work week begins. <eanwhile, it never hurts to re-flow all the solder connections, and that fixes more than half the problems...
If you don't see anything there, somebody will get more meticulous once the work week begins. <eanwhile, it never hurts to re-flow all the solder connections, and that fixes more than half the problems...
What is the AC voltage between terminals A1 and A4? (Put one probe on each terminal to measure)
What's your line voltage?
Can you post a photo of your mains wiring?
122V on 120V mains should give more than 2V. I suppose it's also possible that your meter can't resolve the next digit, so if you had 2.4V, it might just say 2V.
-PB
122V on 120V mains should give more than 2V. I suppose it's also possible that your meter can't resolve the next digit, so if you had 2.4V, it might just say 2V.
-PB
That all looks correct. How about a photo of the terminal strip with the UF4007 diodes and pair of caps.
-PB
-PB
What AC voltage do you have between terminals 19 and 20 on the power transformer?
It is 161.7.
Thanks
Update Sunday Morning.
Yesterday I tracked back all my steps. I resoldered a few connections that I thought might be better and, voila, my numbers improved a lot. My only real problem now is number 7 which throws 407v rather than 170-230. I resoldered but to no avail.
Thanks
Update Sunday Morning.
Yesterday I tracked back all my steps. I resoldered a few connections that I thought might be better and, voila, my numbers improved a lot. My only real problem now is number 7 which throws 407v rather than 170-230. I resoldered but to no avail.
Attachments
OK, well, this is a good indication.
What DC voltage do you see on terminal 44 with no tubes installed?
What DC voltage do you see on terminal 44 with no tubes installed?
OK, I seemed to remember you saying that all the voltage measurements were about half, but it looks like only 1 of the measurements is about half of what it should be. This is a big difference.
408V at 7 can have many causes, one of which is the 12AT7 not getting heated (is it glowing?), a missing ground jumper to the middle of the adjacent 9 pin socket, an incorrect resistor value installed between the center post and pin 8 of that 9 pin socket, etc.
Can you post a photo of that region of your amplifier?
408V at 7 can have many causes, one of which is the 12AT7 not getting heated (is it glowing?), a missing ground jumper to the middle of the adjacent 9 pin socket, an incorrect resistor value installed between the center post and pin 8 of that 9 pin socket, etc.
Can you post a photo of that region of your amplifier?
Try reheating the center leg of the MJE5731 feeding those terminals. Something is not conducting properly.
-PB
-PB
