• Disclaimer: This Vendor's Forum is a paid-for commercial area. Unlike the rest of diyAudio, the Vendor has complete control of what may or may not be posted in this forum. If you wish to discuss technical matters outside the bounds of what is permitted by the Vendor, please use the non-commercial areas of diyAudio to do so.

to high negative voltage?

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I keep having problems with my TSE. First the plate voltage on one 5842 went wild and the plate started to glow. Blown current regulator U2? Replaced U2. Plate stopped glowing, but I could only adjust 5842 plate voltage to 160V.
Put in power tubes, as soon as B+ comes up I get a loud hum in both channels. Had neg. 50 or 60 v on the 300B grid. So I replaced both U1 and U2 again and also both mosfets Q1, and Q2. Turn it on and same thing. When B+ comes up I get a Loud hum. So I cleaned up another brd put new U1,U2,Q1.and Q2. This time the 5842 plate voltage adjusted up to 175V. I was encouraged. Put in power tubes, and same thing. B+ comes up and I get a loud hum.
Now enlarging the schematic I notice it says that B- should be about -150 volts. My B- is at about -250V. I suspect that maybe this is blowing the mosfets. Could this be what's happening?
Now in the power supply R5, I have a 270 ohm 3 watt Vishay metal film. C6, I have a 100uf Mundorf poly tube cape. R6, was upgrades to 6 watts. I have in this spot a Vishay 10K, 10 watt wire wound resistor. C7 I have another 100uf Mundorf poly tube cap. R7 is a 100K, 2watt resistor.
Why is my B- so high? Do I have to lower the value of C6? Please help. Thank you all very much.
Just went out to measure B- voltage. It measured neg. 360 volts and then dropped to neg. 325 volts once B+ came up. I measured C6, and C7. C7 measured 100uf as soon as I put the meter on it. C6 read 50uf and slowly climbed to 100 uf. Maybe C6 is damaged? Anyway, I'm sending to Mouser for the stock capos to see if this fix's the problem. Ill let you all know.
For 300B tube it is normal, mine is -312V. Schematic shows B- for 45 tube if I am not mistaken. What is your R14/R25 value? For B+ voltages 350-400V it should be 36k to keep Q1 and Q2 cool.

O.K. So it is normal for me to have a B- of -255 volts with all tubes in and amplifier working? The -360V then settling down to -325V was with no tubes in, except the 5AR4. And yes R14/R25 are 36K.
Yes, it is normal - it depends on B+. Mine is 430V and B- is -312V with amp working.
As I understand you use film caps in psu off board - if it is the case you have a lot of wires that may pick up hum. I suggest making standard build with electrolytics on board and as soon as it works normally start tweaking. My tse is totally silent.
I did have it working with stock electrolytics. I then changed to the film caps with about 5" twisted wires. They will be shorter when in the chassis. I didn't seem to get any hum. When it is working I have a B+ of about 365v, and B- of -255v. that's with 3.5k output tranny's
Well, I got the amp working again. I was mounting everything on the bottom of the Brd. including the Mosfets and the current regulators. I mounted new current regulators and mosfets, and it still wouldn't work. So I decided to mount the Mosfets on top and cut a hole in my plate/top. Powered it up, and it works great. My B+ is +365volts, and B- is -280volts.
Now to package it up, and hope it still works. I'll let you all know, and post pictures when its done.
Are you sure you put the pins in right locations when mounting at underside?

Yes I did. Sometimes it would worked, sometimes it didn't? When last working with mosfets on bottom of brd., it worked for a couple of days, and then stopped. So now they are on the top. I cut a hole in my top plate. And I just ordered some extra heat sinks to attach to the back of the stock heatsink. I think the stock heat sinks are not sufficient.
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.