My JCM800 Just Blew Up

I was at a George Lynch clinic and he used a store provided JCM800, and was pushing the front end pretty hard, not to mention the power section. (LOUD). About 1/2 hour into the clinic and "phhhhhhhhhhhhhhht, snap,......poof". Fire department showed up and all was good. I'll never forget that smell, Uff-Da.

"Gentlemen, we can rebuild him. We have the technology."
 
Rex said:
B+1?
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Amps have a "power rail" to supply various sections/components. B+, B+1, B+2, etc. is terminology that indicates nodes of varying voltage as you move down the rail. B+1 is is normally at or close to B+, or line voltage. As you move down the rail, you will find resistors and capacitors added to step you down to that node's power/voltage supply requirements.

A lot of Fender schematics will use A, B, C, D... instead.
 
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HereToday said:
Amps have a "power rail" to supply various sections/components. B+, B+1, B+2, etc. is terminology that indicates nodes of varying voltage as you move down the rail. B+1 is is normally at or close to B+, or line voltage. As you move down the rail, you will find resistors and capacitors added to step you down to that node's power/voltage supply requirements.

A lot of Fender schematics will use A, B, C, D... instead.
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Heh. I should have known that. I knew about B+, but not the number designations. :)
 
2112 said:
What parameter best replicates the "magic smoke".
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From manual: ”If you don’t like the sound of amp model components breaking, you can adjust the loudness and transient with Amp Component Break Level and Oh Snap -parameters. You can also turn down the level if you don’t want to hear the components break.

In case you don’t like the default smell of the smoke coming out of the amp, you can adjust this with Amp Magic Smoke parameter. Different types include Default, Popcorn, Tar, IPA beer, 420 and Lavender.”
 
Out of curiousity were you running it hard into an attenuator? I’ve always read with attenuators that the tendency is to run amps full on.
 
I have two Canadian versions of the JCM800 50W 2204 amps both built in 1983, a 1x12 combo and a head/4x12.

The only problem I ever had with them was taking them out of standby and they'd blow a fuse. The problem is compounded since the Canadian versions have an additional fuse panel circuit board with several other fuses and those are only accessible after taking the chassis out of the box, and it was always one of those then went...never the one on the back chassis. Backup rig time....

After inspecting/testing the amp changing the internal fuse "held" and there were no issues with the amp; I just assumed I possibly came out of "Standby" at the peak of the AC mains cycle which apparently can do things like that. Fortunately this has only happened a couple of times over the years.

I fire them up every so often for "perspective" but yea both my 800's need a cap job too...they are overdue.
 
Piing said:
Tuba mirum spargens sonum
per sepulcra regionum,
coget omnes ante thronum
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We shall replace "Tuba" with "phhhhhhhhtttt snap".

Phhhhhhhhtttt snap mirum spargens sonum
per sepulcra regionum,
coget omnes ante thronum

The translation would be:

The "phhhhhhhhtttt snap" will send its wondrous sound throughout the sepulchres of the earth, and gather all before the throne.
 
My first experience with a JCM800 curbed my enthusiasm for a while: I was maybe 17, I loaned a JCM800 from music store and carried it to my bedroom. It looked cool and sounded lame at those 75db bedroom volumes. ... ... then all of a sudden it exploded! It quickly ramped up from normal tones to making the loudest possible buzz/hum, perhaps even louder, and the tubes at the back illuminated my whole room with bright blue glow. It was possessed! I jumped and quickly unplugged it and returned it to the store. "Here, take this back I didn't like it". Tube amp gurus later explained me what probably happened, I didn't understand any of it. Something to do with the power tubes.
 
I had two JCM 800 in a stereo setup, I sold both because I preferred the JCM 900 SLX over the 800, what a beast.
 
That's a shame. Someone should let this forum member know that if you buy Fractal Audio's axe3, fm9, etc., you can have everything in the Canadian version of the jcm800...! (No smoke)
:fire: :fire: :fire:
 
flitz said:
If it's referring to the OP forum "member" this is The Member - Boss Member... 😁
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Christopher Reeve Reaction GIF
 
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