Eagle Supre 1st Start-up... Voltages & problems- FIXED!!

[blues junkie]

So I finished my Eagle Supre build this week and built my Lightbulb limiter.

So today I decided to fire the amp up and see if I screwed anything up. Well the lightbulb got bright for a split second and then dimmed to a very soft glow.(SUCCESS!!!!!!!!!!!!!!!!!!!!!!!!) I then took voltage readings and things seemed ok, I then plugged the tubes in took more voltage readings and so far so good. I plugged my guitar in and it sounded great not the slightest bit of hum... very quiet.

I went and ate dinner and decided I would check my voltage readings again and post them here to make sure everything was ok.(Dumb Idea) I was checking my votages at the power tube with the tubes removed and while I was checking voltage at pin 3 my probe slipped off the pin and touched pin 2 at the same time I pulled the probe away... but the 2 pins were arcing, so I quickly turned off the amp,waited till my nerves calmed down and turned the amp back on...everything seemed "OK" I then shut the amp off put my tubes in and thats where the trouble began. The amp has this horrible hum and the power tube got bright orange and the preamp tube seems to be doing nothing. I plugged my guitar in and with the amp hardly turned up the amp has this horrible ratty distortion sound, no clean whats so ever.

Here are my voltage readings without tubes and with tubes. I know I screwed something up...but I don't know what. Hopefully I did'nt smoke my PT or OT. Any help you guys can give me would be very appreciated. I'm so pissed at my self right now I could scream.

Voltages...

Mains:120.3 VAC

PT ( I used the 600v taps) 314.2/313.9 VAC

OT (B+) 436 VDC (W/O Tubes) 345 VDC (With Tubes)

B+1 435 VDC (W/O Tubes) 345 VDC (With Tubes)

B+2 435 VDC (W/O) 320.8 VDC (With)

B+3 434 VDC (W/O) 300.2 VDC (With)

V1...

Pin 1- 430 VDC (W/O) 200.2 VDC (With)

Pin 2- 0V (W/O) 0V (With)

Pin 3- 0V (W/O) 1.48 VDC (With)

Pins 4&5- 3.53 VAC (W/O) 3.38 VAC (With)

Pin 6- 430 VDC (W/O) 191 VDC (With)

Pin 7- 0 (W/O) 0 (With)

Pin 8- 0 (W/O) 1.54VDC (With)

Pin 9- 3.54 VAC (W/O) 3.38 VAC (With)

V2...

Pin 1&8- 0V (W/O) .050 VDC (With)

Pin 2- 3.54 VAC (W/O) 3.38VAC (With)

Pin 3- 435 VDC (W/O) 305 VDC (With)

Pin 4- 436 VDC (W/O) 315 VDC (With)

Pin 5- 0V (W/O) .766 VDC (With)

Pin 6- see pin 4 (jumpered)

Pin 7- 3.53 VAC (W/O) 3.38 VAC (With)

Pin 8- see pin 1 (jumpered)

These are all the readings I got. Let me know what you guys think. I appreciate any insight to this.

Thanks so much.

Chuck.

I did some research, and I think I will resolder those two pins and see if that fixes the problem. Man, I hope I did'nt fry my Phillips 7581a

[im[IMG768]http://i443.photobucket.com/albums/qq15 ... ots002.jpg[/img]g][/img]

[surfsup]

Looks like you havé zéro volts on your cathode pin 8. I'm not sûre chat happened but thaï is a problème. Is your cathode Cap and résister stil good?

WTF nos m'y iPad is SET to Somers weird keyboard langage!

[surfsup]

Let me try this again, you havé zéro volts on your cathode of thé powertube. Lift on end of the bypass cap and check the cap. Check the resistor as well. All your other power tube voltages look okay (to me). Well except your screen is higher than the plate and your input shows 1vdc, should be zero at idle but that could be your dmm.

[Structo]

I did almost the same exact thing about a week ago on my 100w ODS amp.

From now on I hope you do like me and clip on the leads to the meter while the amp is off then turn on the amp to take the reading.

What happened to my amp is that I blew the two 100R artificial heater tap resistors.
They did their job in that respect and I was happy to have that as my only casualty.

Does your power tranny have a center tap on the heater or did you use 100R resistors?

If you did use the resistors, measure the resistance on them.

Mine were completely open.

If not then you will probably have to replace your power tube(s) depending on how many you damaged.

If like you say, it kept arcing after you pulled your probe away, then you will probably have to replace that socket as well because it will be carbonized where the arc was and it will arc there again most likely.

Keep us updated.

[blues junkie]

Problem solved!!!!!!!!!!!!!!!!!!!!!

I removed the wire to pin 3 & 2 of the power tube, cut the ends off and tinned them, cleaned the two pins on the tube socket and resoldered them and that fixed my problem.

I did check voltage at pins 1/8 to see what my voltage was and with the tube in, my voltage was 28.5 VDC. I will double check my voltages when I get an alligator clip adapter for my DMM leads. I don't want to go thru this again... allthough I did learn a valuable lesson.

Also I put my Phillips 7581a back in and it seems to be working fine after red plating, is it a good idea to use that tube or should I just junk it? The amp sounds great and has very little hum, It's very loud and has some nice dynamics. Though it does seems a little stiff right now... but I will play it for a while before I make any changes.

Also thanks to Surfsup & Structo for all the helpfull tips on this build.

[rogb]

I did almost the same exact thing about a week ago on my 100w ODS amp.

From now on I hope you do like me and clip on the leads to the meter while the amp is off then turn on the amp to take the reading.

What happened to my amp is that I blew the two 100R artificial heater tap resistors.
They did their job in that respect and I was happy to have that as my only casualty.

Does your power tranny have a center tap on the heater or did you use 100R resistors?

If you did use the resistors, measure the resistance on them.

Mine were completely open.

If not then you will probably have to replace your power tube(s) depending on how many you damaged.

If like you say, it kept arcing after you pulled your probe away, then you will probably have to replace that socket as well because it will be carbonized where the arc was and it will arc there again most likely.

Keep us updated.

You know, I think there is definitely a case for using the 2x100R artificial center tap as opposed to the PT heater CT for this very reason.

Looking at the schematic, I would also fuse the HT CT that going to ground, I have a 160mA in my 5W SE amp, everything you can do to protect the expensive components in your amp helps, ask me how I know this
But can you still use the artificial even if the PT has the heater CT? Isolate it and secure it out of the way, maybe?
If so, I am going to retro fit them on my 86 Special...