Originally Posted by surface54

1997 Marshall Vs100 valvestate lights works, tubes not lighting up.
My friend accidentally swapped the preamp tube while the amp was on.
The tubes no longer light up and there is no sound from the amp, well maybe 1% with the volume dimed @ 100 watts. since he has the same amp i was able to use board swapping to isolate the problem area, its defiantly the preamp pc board with the tube on it. the rest works fine, transformer, power section, and effects board. he said it was fine if i took parts off his to fix it, but i dont really want to solder anything on my broken board cause any little mishap and the problem could be unfixable. i looked on the underneath of the board and there are no burn marks or any areas that would point me to the problem area on the board. when it happened there was no smoke or sound, it just stopped lighting up tubes. anyone have a similar problem or know what would power the tube?
i dont wanna pay for a tech cause i bought the amp for $239 used 2 years ago and any more money into this amp wouldn't be worth it, even though i love the sound of this thing. i would be fine just using this pc board in mine, he said that was fine but something weird has happened, the sound is a little different, there is less high end detail than my old one, but not much. his is a 2000 and mine is 1997. mine sounded smoother, his sounds boxier and fuller. but i prefer my old sound, but i can deal with it cause i dont have the money to pay for it to be fixed.
just wish i had a magic wand to tell me where the problem part is :T
i dont have the correct tools to test it, only a multimeter, and yes the big capacitors dont drain fast, my hand found that out twice.

thanks for any help, its really appreciated.

Originally Posted by MartyStrat54

If Groove Tubes wants to keep putting it to us, we will smile and say, "Please wear a condom."

Originally Posted by Wilder Amplification

I read it on the internet so it must be true.

Originally Posted by Wilder Amplification

Did you check the fuse in the heater supply?

Originally Posted by surface54

not sure what you mean by heater supply fuse..but the only fuse i see is on the right of the amp near in front of the transformer.
i changed it with the other amps fuse, both work vice versa.
still nothing when i did that.

Originally Posted by MartyStrat54

If Groove Tubes wants to keep putting it to us, we will smile and say, "Please wear a condom."

Originally Posted by Wilder Amplification

I read it on the internet so it must be true.

Originally Posted by surface54

i changed the 2 fuses and got the tube to come back on. but now the 2 ceramic colored striped things are burning hot, and smoking a little. i turn it off before it gets to hot but i can tell thats where the smell of burning is coming from. there are 2 regulators there too but dont want to change them unless i have to.

Originally Posted by MartyStrat54

If Groove Tubes wants to keep putting it to us, we will smile and say, "Please wear a condom."

Originally Posted by Wilder Amplification

I read it on the internet so it must be true.

Originally Posted by surface54

it actually melted the underneath of the 2regulators and the ribbon started coming up.
i thought the fuses would help, all it did was give way to something else broken.
something bad really did happen with this amp, im done working on it. too much for the nerves right now.

serious thanks for your help kind sir

Originally Posted by MartyStrat54

If Groove Tubes wants to keep putting it to us, we will smile and say, "Please wear a condom."

Originally Posted by Wilder Amplification

I read it on the internet so it must be true.

Originally Posted by surface54

it was the stock 250mA fuses

it was weird the tube worked but a stream of smoke came up within 4 seconds of turning it on from those ceramic pieces, now all the lights dont work on the amp, and nothing else changed on the amp. idk im done working on it. i was relieved to see the tube light up, but its what was waiting around the corner hehe. if the ribbon came up some will that ruin the board? its under the regulators, the ring around the solder holes peeled up for some reason when we flipped it over to look at it?

Originally Posted by MartyStrat54

If Groove Tubes wants to keep putting it to us, we will smile and say, "Please wear a condom."

Originally Posted by Wilder Amplification

I read it on the internet so it must be true.

Originally Posted by Wilder Amplification

If it got hot enough, that will happen. But that doesn't mean it's not fixable. I've done many a PCB surgery in my time.

If there's any possible way you can post detailed photos it would help me out immensely to explain exactly what you're looking at as far as the amount of work required to repair it.

EDIT: OK going back through your posts...did you unsolder the fuse? You shouldn't have had to do that...they're typically held in by clamps and you need only a flat screwdriver to pry them up out of the clamps.

If you unsoldered them from one and and then soldered them into the problem amp, you may very well have solder bridged a connection, i.e. "created a short with stray solder", and this could be what ultimately caused the worse problem that appeared after replacing the fuse.

Originally Posted by surface54

i guess the ultimate question now is will the board still be workable with some of the ribbon peeled up and not directly connected to the holes like it was?

the fuses were one whole piece connected to the board. i didnt see anywhere to pry them up at.

im taking the unit back soon so its out of my hands now.
thanks for your help, ive learned alot about amps in the past two days, still dont like working on em though :P

Originally Posted by MartyStrat54

If Groove Tubes wants to keep putting it to us, we will smile and say, "Please wear a condom."

Originally Posted by Wilder Amplification

I read it on the internet so it must be true.

Originally Posted by Wilder Amplification

That's where you and I differ my friend...I live for workin' on 'em. But it's a bit easier when you have the electronics theory and experience and ya know where to look for problems.

The "ribbon" you speak of are the lines on the board that they call "tracings". Those are basically the wires that wire the amp circuit. They are known to pull up off the board when overheated. Problems of this nature are fixable, but it requires some surgery and involves point to point wiring the damaged section of the board to match up with how the tracings wired that section.

So yes it is fixable...obviously it won't look like it did before it was damaged, but it will work just like new once that level of a repair has been done.

Originally Posted by surface54

it probably looks like under the board the area around the two regs are a little burnt, but they look near the same on the working board, my friend said that could of spent .5$ more to add more cooling for them.

Originally Posted by MartyStrat54

If Groove Tubes wants to keep putting it to us, we will smile and say, "Please wear a condom."

Originally Posted by Wilder Amplification

I read it on the internet so it must be true.

Originally Posted by Wilder Amplification

That could've been done during soldering...it's tough to say.

BTW on the component side of the board, I don't see any fuses...I've looked but I can't seem to find any. Where is the fuse that you replaced?

If you've got a resistor in the power supply getting hot like that, this usually points to something in the amp being shorted and you're better off taking it to a tech. Without testing components I couldn't even begin to tell you where to look.

Originally Posted by surface54

in the 1st picture is the two big blue capacitors, the two fuses are black and to the sides of each of them. thats what i replaced.
yeah i get ya, amp tech is the only go for now.

Originally Posted by MartyStrat54

If Groove Tubes wants to keep putting it to us, we will smile and say, "Please wear a condom."

Originally Posted by Wilder Amplification

I read it on the internet so it must be true.