Blues JR. "R3000" Know where to get one??

[Steve C]

Okay, last night after the second set my amp blew and it was smoking!!  Took a look at it and the R3000 high voltage diode in the thing is fried.  Mouser doesn't carry them and I'd have to buy 2000 of them to get 'em.  Seen them anywhere?  Anybody happen to have any, or know where else to get one??

Thanks,

Steve C

[e178453]

Steve, try running this by the folks at AX84 and 18 Watt.  I am really curious to know what those diodes are doing there.  Suspect more than just the diode is at fault.
Once you figure out the specs you are looking for you should be able to find an equivalent at Mouser.
scott

[Gus]

If that part burned you might have a few more problems check the output tubes and transfomrer

[Steve C]

Well the problem looks a little more like this

[Ed G.]

You might want to read this:
http://www.fenderforum.com/forum.html?db=&topic_number=584294&lastpost=2006-08-2817:51:45

[Gus]

Go to geofex and look for the shorted winding tester

Thats a good good link to the fender forum.

I think diodes used like that were in a Ken Fisher writeup,  Maybe a few 1n4007? in series?

[Steve C]

Thanks, Guys I appreciate it!!  Great info and I found a couple online.

Thanks Again!

Steve C

[nightingale]

Hi,
It looks like some of your "foils" are dead too. I would ring all of those out that look suspect.

hth,
ry

[Ronsonic]

Thanks, Guys I appreciate it!!  Great info and I found a couple online.

Thanks Again!

Steve C

The diode's a standard part. Don't worry about that. The charcoal is the important thing here. How badly is that board burned? It's hard to see how bad the damage is in the photo, but it's obviously trouble. Have you done that kind of repair before?

Ron

[R.G.]

You have my sympathy.

I think it's almost criminal that PCB based amp companies will persist in not putting in simple protections. I have a few favorite protective devices that I rant about from time to time that would certainly have helped you.

It makes really, really good sense to put a fuse in each winding section of the power transformer. If the fuse is rated under the melting current of the copper foils on the PCB, then you don't get that kind of damage. What clearly happened is that the diode shorted, it sucked all the power that the HV winding could provide and heated up enough to not only start burning the diode, but also to start carbonizing the board.

As someone said, if you're not familiar with repairing burned boards, you have a real problem. In high voltage PCB areas, a burned area starts decomposing the epoxy in the PCB stock into noxious gasses and carbon. If you don't remove the carbonized board from the area, it conducts some from the high voltage once you put it back on, and the carbonized area heats up, and eventually re-ignites as it makes more carbon and the resistance goes down. So you have to be sure to cut away all carbonized board. This may mean dremel tool with a grinding wheel and in severe cases may mean excising a section of board, similar to removing a malignant tumor.

[Steve C]

No, I haven't fixed anything like this before.  The area is very melted (almost all the way through).  I will cut out all the "infected" area and was going to jumper those traces that were damaged.  Anything else I should be aware of besides the usually safety precautions?