Calling all clever electronics people.

Right, disaster has struck (in my world atleast). Some may recall i started a thread about building a small all valve powered guitar amp, brilliant, had it built, tested it - all good, turned it on - all good. Then i got cocky and started moving switches from the back to the front for design reasons (will be rack mounted so needs access) and didnt think about the love connections on the switch touching the conections on one of the power transformers. Now these transformers run at around 350V so needless to say it went bang, sparks went flying and no longer was there power to the amp.

First things first, check the fuse - all was left was shards of glass. Ok so i replaced that and still the amp wont turn on.

Now comes in the disaster aspect, this is my final dissertation for uni, which needs to be handed in by.......next week, and i have no idea where to start looking or what tests to do in order to find the fault in the circuit. PLEASE PLEASE can someone advise me here, im on the verge of a breakdown.

Oh and here is the circuit diagram incase it helps:



Any ideas????

Plenty of beer tokens to the person that makes it work!

Cheers,
Ash.

[anna]

How about a visual inspection of the circuit to see if you can visually see if any of the components are blown?

Check voltages around and about, make sure you haven't got anything else touching where it shouldn't be.

Make sure ground is still 0V.

Isolate sections of the circuit and make sure they work correctly and make your way around the circuit diagram. The current surge could have melted other things, make sure valves are still good.

Sorry I'm not really helping, but don't worry about it, just take it real simple and easy.

You can do it

Originally Posted by anna

How about a visual inspection of the circuit to see if you can visually see if any of the components are blown?

Capacitors have this nasty habit of drooling all over the place when fed too much current (which has obviously happened), don't forget to check / replace them.

[SoulKiss]

Be methodical in your checking and document it all.

After I had it fixed I would add the info to the dissertation, giving you a section on fault finding and repair as well as just the build docs.

Got to be worth a few marks that you managed to repair it, especially if you show how you discovered the fault and then what you did to rectify it.

you know the circuit works (before the bang), so if you're in a real rush, why not throw out the board and knock up a new one the exact same. Will take a bit of time, but may be quicker than fault finding. Just a suggestion (I know nothing about anything).

You could try the amp garage

Dan

Is it hard wired from a plug, if so check where them wires meet your amp and check you have 240v.
The fuse you checked was from the plug right?
I presume the amp has a fuse internally not far from the power incoming, check this if there is.
If the above are ok, have you tried in another socket in your house or tested that socket with another aplliance, i know its basic but you have to eliminate everything.
Generally, if components blow they would be at the start where the power comes in, the whole point of a fuse is to blow before any damage is done to the rest of the system.
Phil

To top it all off, the thing just shocked me

I want to give up!

Originally Posted by specialone

Is it hard wired from a plug, if so check where them wires meet your amp and check you have 240v.
The fuse you checked was from the plug right?
I presume the amp has a fuse internally not far from the power incoming, check this if there is.
If the above are ok, have you tried in another socket in your house or tested that socket with another aplliance, i know its basic but you have to eliminate everything.
Generally, if components blow they would be at the start where the power comes in, the whole point of a fuse is to blow before any damage is done to the rest of the system.
Phil

Your right but the two points that connected were after the internal (and therefore plug) fuses.