Marshall VS100 Reverb works but ?? doesn't??

[Jon Snell]

The only way to find out is to systematically trace the signal path from one end to the other with your oscilloscope and a signal source.

[GasMask52]

The only way to find out is to systematically trace the signal path from one end to the other with your oscilloscope and a signal source.

Well gents, just before proceeding the the IC tests I re-soldered all components on the Daughter & Pre-Amp & tested it , and **60 cycle hum** with No LED lights - which leads me to believe that I somehow shorted everything slight stench coming from the power module, BDV65 & TIP147 dead??

Did it short cause of the flux in the solder??

[Jon Snell]

It shorted because of the soldering not the flux. Flux is not electrically conductive enough in your amplifier to damage it.
I cannot tell if the transistors are dead from here. Go over your work and look for a solder bridge.

[GasMask52]

It shorted because of the soldering not the flux. Flux is not electrically conductive enough in your amplifier to damage it.
I cannot tell if the transistors are dead from here. Go over your work and look for a solder bridge.

You just cleared another massive doubt that I always had , I always asked that same local tech ,"" is it fine if sometimes I solder some bridges here and there?? "" and he always told me that it wouldn't be an issue , and it wouldn't be harmful - screw him

Yes there are a couple of (lazy) solder bridges, and you're confirming me that bridges causes shorts to the point of eliminating components??

[GasMask52]

At this point I'm not even sure If removing the solder bridges and fixing them is worth it.. I mean the fuse blown, so it means that some components were fried to death

[Jon Snell]

Probably worth a quick going over and then general fault finding may pin point the original fault and the new fault in one go.
If you make a solder bridge across the driver side of a transistor, that may have a catastrophic effect on the amplifier. If it is across one supply rail to ground, then you may get away with just slight damage. There is no way anyone can guess.

[Enzo]

It issn't the ACT of soldering that can damage circuits. Well, too many times and the traces come off the board. But it was the particular soldering job you did. In other words, it is OK to solder, but not if you left a little blob of solder shorting two things together.

A shorted semiconductor is usually behind blown fuses, but that does not mean EVERY semiconductor that shorts will blow fuses. And certainly solder bridges (a bridge means an unwanted connection) can blow fuses and burn uop resistors even if ALL semiconductors are OK.

[GasMask52]

It issn't the ACT of soldering that can damage circuits. Well, too many times and the traces come off the board. But it was the particular soldering job you did. In other words, it is OK to solder, but not if you left a little blob of solder shorting two things together.

A shorted semiconductor is usually behind blown fuses, but that does not mean EVERY semiconductor that shorts will blow fuses. And certainly solder bridges (a bridge means an unwanted connection) can blow fuses and burn uop resistors even if ALL semiconductors are OK.

Tough faacts.. thanks, i might be able to take down a VS100 blindfolded anyday, but i'm no professional when it comes to soldering init - lesson learnt , right now i'm getting rid of ALL soldering bridges I created , which were mostly resistors and small tanlium caps , no transistors involved

[Enzo]

We have all made errors working in there. I have been soldering for over 65 years, and I still make mistakes. But that is why we often urge people not to wholesale remove and replace parts. Every one is another potential for making a mistake.

[GasMask52]

We have all made errors working in there. I have been soldering for over 65 years, and I still make mistakes. But that is why we often urge people not to wholesale remove and replace parts. Every one is another potential for making a mistake.

Well Mighty Enzo , I've removed ALL soldering bridges, mounted the chassis raw , no pots no screws , replaced the fuse and by god it turned on , the LEDs were alive, turned it on a couple of times for 2 seconds , now I turned it off , Didn't test it with a guitar yet , not sure if I should be singing victory yet but i'm scared to screw it up

[GasMask52]

We have all made errors working in there. I have been soldering for over 65 years, and I still make mistakes. But that is why we often urge people not to wholesale remove and replace parts. Every one is another potential for making a mistake.

Tested the amp with guitar and the reverb magically works on both channels now, everything is perfect EXEPT the overdrive channels, they're dead , when I switch to them, either OD1 or OD2 the guitar volume drastically decreases , if I turn up the volume & gain and strike the strings It crackles a lot - Could it be a bad solder joint in the pre-Amp??

[Enzo]

Could it be a bad solder joint in the pre-Amp??

Could be most anything. We need to track it down and FIND OUT what is wrong.

[GasMask52]

Could be most anything. We need to track it down and FIND OUT what is wrong.

I will begin to study the wiring diagram of the VS100, to start , I need to know what components are involved with the Overdrive output signal

[GasMask52]

I will begin to study the wiring diagram of the VS100, to start , I need to know what components are involved with the Overdrive output signal

I mean , logically a TON of components are involved with the OD channel , but i mean the most important and obvious ones first

[GasMask52]

Could be most anything. We need to track it down and FIND OUT what is wrong.

The new issue leads me to believe that:

A - I removed too much solder during a bridge removal
B - There still might be a few micro-bridges that I didn't notice