Amp fell over. Dood.. where's my bias!?

[Reeltarded]

Short story: Marshall was dropped off full stack. Don't look at me.

Couple things needed some love. It works, but for one thing that has driven me crazy for hours. First fire up the new tubes looked bright.

-11mA.

Ok. Hmmm..

Was @ >-37mA before mono-directional vertical excursion and meteoritic impact. Nothing looks or meters wrong, except for the bias.

Advice? I have chased my tail til my head hurts.

[cbass]

So the bias pot still work and adjusts the negative boltage?

Could just be the new tubes don't draw near as much current as the old ones.

[Reeltarded]

The bias adjusts from less than -11 to max neg rotation about -25 now.

Both tubes match perfectly as seen now, and tested previously as a replacement pair for just such an event.. ya know. They should read -38.2.

I plugged in for a second at medium volume. 60hz in background atypical to this amp.

I am about to throw it at the floor now.

Oh, and I did go outside and curse at the sky, so that's not it.

[Firestorm]

I am about to throw it at the floor now.

No, you gotta throw it up to the ceiling to fix this sort of thing.

I'm not quite following: negative voltage is too low? Current draw is too high?

Did you try replacing the bias pot yet? Most obvious thing with moving, bendable, dentable parts.

[cbass]

I'm confused Are you saying your negative voltage(VDC) not current(mA).
Is adjusting from -11VDC to-25VDC now where it would go to -38VDC before
.

If you are talking about mA. Then it is probaly just a colder set of tubes

[Reeltarded]

Just swapped bias pot. Same thing. Exactly.

Just translating mV to mA and biasing off 1Rs. These tubes tested together previously @38.2 before I reboxed them for a rainy day.

Prrrchhhhhhaaaawww! Booom! Shhhhhhhhhhhhhhhhh! It's raining amps!

Amp was biased in a sure range. Would normally read 38.2 with this set. Read -11 after fall with these tubes. Also tested with second set that bias same. Same results.

What in the bias that would break would cause a change near that amount?

With a multimeter and a soldering iron, I'm pulling teeth; all hair burned off. I reflowed everything obvious 2x or more. I rewired the output sockets, I built the whole rear end without success, one joint at a time. If I weren't already crazy..

It's a 50 watt Marshall ass end. Typical 50w with SS rectifier and 440v and a sick bias reading... and a ppimv.

[Jana]

Pull the tubes. Measure the bias voltage at the bias splitter resistors. What do you get (what is the range of negative volts when you turn the bias pot)?

[Reeltarded]

Excellent. It knows we are plotting. Last round of solder melting fixed it for the moment at least.

It sounds much better than it did before the bad airshow manuver. I would recommend having your hot amp dropped if you want a little more note separation.

Thank you, brothers of the iron. Hopefully I fixed this one with heat.

Anyone have any other shocking moments today? whew.. I have nicer amps, but I love this one.

[Jana]

Okay, now that the amp is fixed, let's have the rest of the story--were you drinking? Calibrating your hinklefarbs with herbal remedies? You said you tried adjusting the pot in the amp--is that what you really meant or was that a Freudian slip? Cough up dude, entertain us.

[cbass]

nevermind

[cbass]

Okay, now that the amp is fixed, let's have the rest of the story--were you drinking? Calibrating your hinklefarbs with herbal remedies? You said you tried adjusting the pot in the amp--is that what you really meant or was that a Freudian slip? Cough up dude, entertain us.

Just look at his Sig.He had a tantrum and knocked the amp off the stack.

[Jana]

I think the tantrum was *after* he was doing helicopters from the ceiling fan and knocked the amp over. I just hope there is video!

[Reeltarded]

Not this time. Not me.

I was showing off my thumpy badassed creation, i went to the other room and my too short to reach up there friend spazzed out and dropped the head input end down on a wooden covered cement floor while trying to swap heads. Lots of intertia. I was just returning. My blood pressure hit about 100x normal, and it took 30 seconds for it to hit the floor. You know when you hold your breath for an instant and your temperature doubles, then it feels like needles all over? Ever see Planes, Trains, and Automobiles? John Candy as Satan when they are going the wrong way between the semis? That was my buddy, except his eyes were WAY bigger, and twice as evil.

Something up front is causing some of that 60hz. It's just a hint, and only when there is a tube in V1, so easy enough to figure out.

I um.. lost my favorite set of 12ax7s, and pair of output tubes. DORKY me just set the chassis in the box after a bias earlier.

I still haven't decided if I should buy a shovel or just dump him in the river.

lol I am kidding.

I already dumped him in the river.

[Reeltarded]

Happy and sad. My buddy won't forgive himself, but my amp sounds better. It also looks great, like it went on a joyride across the country for a month.

Thanks for holding your breath with me. Just talking about it helped a bunch... now off to look at this Leslie..

[rdjones]

I always knew that a full stack was overkill, thanks for giving me a real-world example as to why this thinking is valid.

rd