Fender HR Deville Had a Drink.

[bsco]

I have had the best luck cleaning water-based drink spills not with high-strength alcohol, naptha or (especially) contact cleaners but with a water-based cleaner like Glass Plus or Formula 409 worked in and scrubbed around with a paintbrush, followed by copious water rinse and compressed air. Basically my thinking is if you spilled a drink on your counter and it dried overnight what would you use to clean it up? Probably not IPA/DNA or contact cleaner...

The more things have dried out and had voltage applied the tougher it gets.

If I was working on the amp at this point I would probably remove the PC boards and soak them in the sink in hot water for a few hours followed by the aforementioned cleaner, rinse & compressed air and then further followed by at least an overnight drying in a warm place. Water-based cleaners usually leave the lube in the pots (if it's not already gone due to other cleaning methods) and judicious use of compressed air will usually get most of the remaining water out of switches, jacks & pots prior to the extended dry-time. Hey - it's already been drenched with beer right?

Once everything is good & clean/dry with conductive sneak paths removed then normal diagnostic technique should prove easier. I like what Chuck said: "You need to be sure it's clean. F'in clean. And dry."

And don't forget to clean the bases & between the pins of the tubes themselves.

One downside of all this is the propensity of these amps to break wires in the ribbon cables at their connection points due to flexing during assembly/disassembly (a problem well known around the forum I think) so try to keep that flexing to an absolute minimum or new problems may be introduced.

Spills are just plain bad news...

I was going to suggest the same thing but you beat me to it....I have done that in the past with excellent results...just remove items such as relays etc.keep both boards attached to each other and let them soak in a warm water and mild dish liquid solution for awhile.....then rinse with clear warm water and dry it.....

[Silvertone Jockey]

There can only be a few normal ways for any voltage to get to R68. Remove V3 and measure the voltage across R68. Hopefully without the tube there will be no voltage there. If there is voltage there then the tube socket or the pc board may be carbonized or there may be a problem with the output transformer.

Try shining a very bright flashlight around the sockets while looking at the opposite side so the light is seen shining through the board and inspect carefully with magnifiers on you might see something, Another thing is to repeat the arc in the dark test but film it this time HTH

[Silvertone Jockey]

And just to reiterate, even if you have excellent eyesight by all means wear a good pair if strong magnifiers when inspecting the board. I can't tell you how many times doing so saved my a$$-ets on a repair job

[Pryde]

OK so back the to nightmare.

I again thoroughly cleaned both boards front/back with DA with toothbrush, dental pics, q-tips, etc. blew it all out with compressed air (from pancake air compressor). cleaned all spade, tube pins, everything I could see. Let dry overnight and here we are:

-C35 still lifted, PI out I am getting no voltage across R68 now. (good). With PI in I am getting about 70vDC across it though. Note this is still an old resistor with some burning on it.
-I am still getting about 80vDC across R75

With the amp powered on there is still loud crackling, popping, etc. The only arcing I can see is in BOTH power tubes (very faint blue arcing that dances with the popping/crackle). I took tubes out, measured pin voltages as follows:

V4:
2/7. 2.3vAC
3. 298vDC
4. 294vDC
5. -25vDC

V5:
2/7: 2.3vAC
3. 313vDC
4. 309v
5. -26v

What next? Really appreciate the HUGE support so far.

[52 Bill]

V4:
2/7. 2.3vAC
3. 298vDC
4. 294vDC
5. -25vDC

V5:
2/7: 2.3vAC
3. 313vDC
4. 309v
5. -26v

What next? Really appreciate the HUGE support so far.

Are you using a limiter for these readings? They all seem low.

There still seems to be too much voltage across R69 with the PI tube installed.

[Pryde]

Wowzer finally found the issue (hopefully not more to follow)!

As suggested by the great pros on this forum we had a small arcing in the ribbon cable by the PI. This however was never apparent until I lightly wiggled the ribbon and then she started smoking a bit and I watched it quickly char up in between the 2 solder points. I scrubbed (again) with DA, blew it out and dried and things are better. Voltage across R75 is ~18v and voltage across R68 is ~7v (this is with current limiter on).

I need to change these resistors, re-attach C35 and test again and see were she stands.

See the attached pic. Would you suggest a bit of silicon in there to seal up the charring between the pins?

[Tom Phillips]

... Would you suggest a bit of silicon in there to seal up the charring between the pins?...

The fix is to remove all the charred material even if is means that you end up with a hole or notch through the board between the pins. Otherwise it will eventually fail again. I use a dremel tool with a small grinding bit. It's much like a dentist would do to remove a tooth cavity. You shouldn't just cover up or try to seal the carbonized material.

[52 Bill]

See the attached pic. Would you suggest a bit of silicon in there to seal up the charring between the pins?

The part of the board that has burned has turned to carbon. Carbon is a great conductor of electricity. You will need to scrape or grind away any of the carbon on the board in order to fix this correctly.

I use a Dremel tool with a tiny burr. If the burning is too bad, you may need to isolate that section of the board and rewire the circuit around it to keep it from continuing to burn and short out the circuit.

[bsco]

The fix is to remove all the charred material even if is means that you end up with a hole or notch through the board between the pins. Otherwise it will eventually fail again. I use a dremmel tool with a small grinding bit. It's much like a dentist would do to remove a tooth cavity. You can't just cover up or seal the carbonized material.

Exactly......If I may be so bold, I would mix up some epoxy and resin and when I had all the carbon scraped away, I would fill the cavity with the mixture and apply it with a toothpick.......

[bsco]

Wowzer finally found the issue (hopefully not more to follow)!

As suggested by the great pros on this forum we had a small arcing in the ribbon cable by the PI. This however was never apparent until I lightly wiggled the ribbon and then she started smoking a bit and I watched it quickly char up in between the 2 solder points. I scrubbed (again) with DA, blew it out and dried and things are better. Voltage across R75 is ~18v and voltage across R68 is ~7v (this is with current limiter on).

I need to change these resistors, re-attach C35 and test again and see were she stands.

See the attached pic. Would you suggest a bit of silicon in there to seal up the charring between the pins?
[ATTACH=CONFIG]33606[/ATTACH]

Great job .....Glad you got it repaired.......Like Tom stated.....get rid of all that carbon......

[Pryde]

Thanks everyone. I have taken some mitchell's abrasive cord and flossed all the carbon out of there. Essentially most of the pcb is also removed between the 2 solder pads as the charring went deep. I will fill the void with a bit of silicon and I think it will be ok. Will update.

[g1]

I would mix up some epoxy and resin and when I had all the carbon scraped away, I would fill the cavity with the mixture and apply it with a toothpick.......

Once I have removed the carbon, I have some GC "liquid tape" that is easy to apply. It's rated for fairly high voltage but I'm not sure if the newer versions still are. MG "super corona dope" is rated for HV insulating.

Edit: GC no longer calls it "liquid tape". Anything branded as such is not sufficient for high voltages so I will try to remember not to call it that anymore.
GC's "insulating coating" is rated 1400V/mil
MG "super corona dope" is rated 4100V/mil so it is a better choice.

[bsco]

Once I have removed the carbon, I have some GC "liquid tape" that is easy to apply. It's rated for fairly high voltage but I'm not sure if the newer versions still are. MG "super corona dope" is rated for HV insulating.

Edit: GC no longer calls it "liquid tape". Anything branded as such is not sufficient for high voltages so I will try to remember not to call it that anymore.
GC's "insulating coating" is rated 1400V/mil
MG "super corona dope" is rated 4100V/mil so it is a better choice.

I never thought about using that stuff...Think I will get some of that to have on hand...Thanks for that tip.....
Cheers

[Tom Phillips]

My feeling is that cleaning off the carbonized material and then just leaving a clean hole behind is OK. The dielectric strength of Air is 3kV/mil so there won't be a problem and the extra effort to fill the hole is unnecessary. The dope won't hurt anything but an epoxy could be worse than nothing if it wasn't rated for electrical use. I have seen PCBs that intentionally had slots milled into the board between HV points.

[Pryde]

Well everything is back together and all voltages check out ok, amp sounds great. I will keep it for a few days and monitor things but initially we are looking good. The last issue was a beer-gummed bias pot that was throwing off bias but I cleaned it up and bias current is good and adjusting well.

I can't thank you all enough for helping resuscitate this one. Although this repair will be a financial bust for me it was a great learning experience so it's all good.