S.E.X. 3.0 [resolved]

[Dana Hinds]

Power and resistance values were all good, finished and powered up.  Heard snapping noise and saw some smoke, only one channel was working.  After looking it over the only problem I found was I missed soldering one resistor to terminal #16U.  Looked like the 680 ohms resistor that goes from 21U-33U was hot.  Looked everything over a hundred times and all else seems ok.  I now do not get proper resistance reading from terminal 17, 18, or 25 to H1.  Not sure what to do next. Any help would be appreciated.

 

[Paul Birkeland]

Can you post some build photos?

Your voltage checks should have been way off if you ended up with that situation.  If the 680 ohm resistor going to 21 got hot, two component leads on that side of the amp are probably touching that shouldn't be.

 

[Dana Hinds]

Here are the pictures. Thank you.
Dana

 

[Dana Hinds]

Here are some more pictures.
Dana

 

[Paul Birkeland]

Remove the red wire from 21, bend it up into the air, then fire the amp up and check the DC voltage at 21. 

 

[Dana Hinds]

From terminal 21 to h1 I get 500v

 

[Paul Birkeland]

If the amp is happy with this wire disconnected, this tends to mean that something is touching around that socket that shouldn't be.  You may want to remove the Solen parallel feed cap and post more pictures and we might be able to see what's causing the problem.

 

[Dana Hinds]

Here are some more.

 

[Paul Birkeland]

I still see no issues.  Something else you could try is to put the disconnected wire and cap back, then run the amp with no tube in that side and recheck the voltage at 21 (it should remain high).

 

[Dana Hinds]

Voltage stays at 500

 

[Paul Birkeland]

Put the tube from the other channel into that socket and see what happens.

 

[Dana Hinds]

I installed both tubes, nothing seemed to overheat and no smoke.Plugged in headphones and only have one channel.I noticed b side plate choke was warm when running and a side plate choke never got warm.

 

[Paul Birkeland]

The voltages are of interest here, not attempting to listen to an amp that isn't working yet.

 

[Dana Hinds]

Doesn’t seem like a side may be getting power

 

[Paul Birkeland]

So the information I'm looking for is something like "The voltage at terminal x is supposed to be y but instead it's z".

Without that kind of information your guess is as as good as mine.

 

[Dana Hinds]

sorry I am going to go back through everything ,just getting frustrated.

 

[Dana Hinds]

I have gone through all assembly to make sure of connections or shorts , found nothing. Wondering if the miissed solder connection on resistor to terminal 16U may have taken out a capacitor or something.Lokking for the next step.

 

[Jameson]

Probably want to start with running the resistance and voltage checks and listing any that are out of spec here.

 

[Dana Hinds]

before power up normal ,now here's what I get
Terminal #1-0 #3-891 #4-240 #5-0 #8-0 #9-0 #11-678 #12-0 #14-0
#15-0 #17-218 #18-5.5 #19-0 #22-0 #23-0#25-0 #26-0 #36-0 H1-0 H8-0
looks like 17,18,25, are way off

 

[Paul Birkeland]

Are those voltages or resistances?