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Old Today, 02:50 AM   #231
ItsAllInMyHead is offline ItsAllInMyHead  United States
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Join Date: Mar 2019
Location: The great state of Minnesoooota.
@flamethrower -



We're rooting for you. You'll get it all back up and going in no time. Curse, Pause, Breathe, and then Curse a bit more over a drink. That works well for me at least.

Then we'll look forward to hearing how you progress in swapping out a few parts.

Now I understand your name though. Too soon?
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Old Today, 02:57 AM   #232
flamethrower1 is offline flamethrower1  United States
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Join Date: Sep 2015
Location: Wisconsin
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ok, here is a pic.
Both .47 watt resistors are smoked and I am sure that is just the beginning.
I do not even know how I am going to sleep tonight.
What a stupid thing to do
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Old Today, 03:13 AM   #233
ItsAllInMyHead is offline ItsAllInMyHead  United States
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Don't beat yourself up. The ridiculous things I've done and that others have shared are pretty comical (in hindsight). It'll be all the sweeter when it's making beautiful music.

Yep those resistors look like they need to be replaced. Others far more skilled than I will certainly chime in with recommendations of proper test procedures to check other parts.

Hopefully it won't nag at you for too long.
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Old Today, 03:28 AM   #234
Dennis Hui is offline Dennis Hui  Canada
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Location: Toronto, Canada
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So back to 6L6's question. What happened when you smoked it?
(Shorted outputs? Slipped probes?...) This will help with figuring out
the damage.
__________________
We are fearless amplifier builders. A little heat doesn't scare us at all.
- NP 2002
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Old Today, 04:52 AM   #235
6L6 is offline 6L6  United States
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Location: Denver, Colorado
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Welcome to the Fearless Amplifier Builder's club. Founding member, N. Pass.

It's fixable. I promise.
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Old Today, 05:01 AM   #236
cubicincher is online now cubicincher  Germany
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Join Date: Mar 2016
Location: Hechingen, South of Germany
Hello flamethrower,


what a sh.t! i can't believe it. Because the numbers I see on the pic with the

DMMs were good.
So you had something around 0,6 V = 600mV over the bias resistors and an
offset at the louspeaker of ca. 18 mV. Those numbers are good.


Did the MOSFETs become extremely hot?
Bias resistors are 3W types? Better 5W?



I am with you. I remember my first start up of my first Amp and problems I had.
Don't give up!

First we have to find out 'what went wrong?'


Greets
Dirk
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Old Today, 05:16 AM   #237
cubicincher is online now cubicincher  Germany
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And I remember from my F5 and F5Turbo-Monoblocks how sensitive they reacted in the upper bias range on the smallest turns of the pots....



Greets
Dirk
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Old Today, 05:28 AM   #238
Extreme_Boky is offline Extreme_Boky
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Join Date: Dec 2003
You may have shorted either side of either resistor (the one you touched with probes to measure the quiescent current) to the ground... with a bit of luck, all you'll need to do is to replace the .47 / 3W resistors and the MOSFETs.

... also, you may have exposed the ZTX's to a high Vbe; so check those as well.

Your wires are soldered onto the PCB from the underside.... they are quite thick and require a lot of heat to solder properly -> this may have burnt the insulation and exposed the wires (underneath)... and they may have touched the heatsink...

Good luck man... keep us posted...
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