Fender HR Deville Had a Drink.

[Pryde]

I wish I knew for sure. The kid said it spilled over into the chassis (top facing) so I am sure it ran down pretty much everywhere.

[bsco]

I wish I knew for sure. The kid said it spilled over into the chassis (top facing) so I am sure it ran down pretty much everywhere.

Ok. When you opened it up did you see any signs of where the drink might have landed or traveled inside the amp?? IT probably found it's way down inside tube sockets.....any signs of that on the tube pins themselves?? Also, there are some radial caps in the amp...it is possible some of the liquid could have run down underneath the capacitors and now the residue which you can't see could be causing shorts.......but you are having issues with the voltage dropping resistor which provides voltage to the phase inverter....and when you remove that tube does the resistor still burn up???

P.S. I just read through the posts again......you are also having issues with R68?? SO the problem with R74 is ok now?? Sorry for the confusion......

[Pryde]

Measure the voltage on V3, pins 3 and 8 (the cathodes) - it should be 43V. If it is higher, pull V3.

Now what is it? If there's any voltage at all, check the voltages on the far (from V3) side of C24 and C25 - those should be less than 1V on C24, and 0 (theoretically) on C25. If there's voltage on C25 (and therefore on R68), remove the gray NFB wire from the OPT. If the voltage goes away, you have a primary to secondary short in the OPT. If no change, C24 or C25 may be leaky or shorted.

Oh: The schematic says 14.7V on the plates of V3 - should that not be more like 147?

V3 in:
pin 3: 90vDC
pin 8: 70vDC

V3 out:
pin 3: 70v
pin 8: 70v

C24 far side with V3 out: 91v
C25: 85v

Removed grey NFB wire and C25 still has 85vDC

Transformer toast then?

[Pryde]

Ok. When you opened it up did you see any signs of where the drink might have landed or traveled inside the amp?? IT probably found it's way down inside tube sockets.....any signs of that on the tube pins themselves?? Also, there are some radial caps in the amp...it is possible some of the liquid could have run down underneath the capacitors and now the residue which you can't see could be causing shorts.......but you are having issues with the voltage dropping resistor which provides voltage to the phase inverter....and when you remove that tube does the resistor still burn up???

P.S. I just read through the posts again......you are also having issues with R68?? SO the problem with R74 is ok now?? Sorry for the confusion......

Believe it or not R74 is stable (at the moment). R68 is burning. Another thread suggests the OT might be shorted and so far the tests are leading to that conclusion.

[bsco]

Sounds like the tube socket could be causing problems.....It probably has had a drink of beer......see if you can spray contact cleaner down into the pins or better yet, replace it...if you have a spare one........spraying contact cleaner after a spill like that has dried up would be very difficult to clean anyway.....

If you removed the NFB connection and the voltage is still there, according to the previous post that should rule out the ooutput transformer....check on that tube socket because liquid can go anywhere and you might not see it.....

[Chuck H]

Just because R74 isn't burning doesn't mean it's stable. A lack of smoke doesn't mean everything is fine. What is the current through R74 now?

The PI tube and it's functions cannot cause the problems that have happened to far. Don't bother chasing that. The socket MAY be compromised.

The possibility of a primary to secondary short on the OPT would have made itself evident in more dramatic ways than R68 popping. And besides, for enough current to pop R68 (4.7k) to get to it from the secondary it would first need to pass through R69 (47k). Acting as a 10:1 voltage divider. So if R68 had 97 volts on it FROM THE OT SECONDARY and R69 managed to miraculously survive that would mean over a thousand volts would need to be present on the OT secondary!?! No way.

Lifting the grey NFB lead and still having voltage on C25 would mean that the voltage in that area ISN'T coming from the OT secondary.

That board and all non fixed contacts (pots, tube socket pin holes, switches, rows of ribbon pins, ribbon pin holes, etc. needs to be cleaned again. Better. If you need to lift the board to clean it thoroughly then you need to lift it. It then needs to be completely dry all the way into the ribbon pin and tube socket holes before any testing. It will not be enough to be pretty sure it's clean. You need to be sure it's clean. F'in clean. And dry.

No more testing of anything should happen before this is seen to.

[52 Bill]

With V3 removed there should be no voltages anywhere in the PI circuit, except for the two plates. So the voltage is leaking from somewhere like the plate pins or somewhere on the board or the ribbon cable to the tube board.

As Chuck points out, this needs to be fixed before anything else can be done. There is no easy way to find this leaking voltage other than systematically testing each component in the circuit and possibly by removing parts to see what stops the leaking voltage.

[The Dude]

I've often used compressed air (an actual compressor for higher pressure- not canned air) to clean spills. You can get liquid out of those places you can't see - i.e. under tube sockets, IC's, etc. If the spill is bad enough, hose the board down with an evaporating component cleaner and give it a good blast of air. Short of removing multiple components for inspection, it's the best way I've found for dealing with spills. Of course some caution and common sense applies. You don't want to be shooting IC's across the room.

[Pryde]

Just because R74 isn't burning doesn't mean it's stable. A lack of smoke doesn't mean everything is fine. What is the current through R74 now?

The PI tube and it's functions cannot cause the problems that have happened to far. Don't bother chasing that. The socket MAY be compromised.

The possibility of a primary to secondary short on the OPT would have made itself evident in more dramatic ways than R68 popping. And besides, for enough current to pop R68 (4.7k) to get to it from the secondary it would first need to pass through R69 (47k). Acting as a 10:1 voltage divider. So if R68 had 97 volts on it FROM THE OT SECONDARY and R69 managed to miraculously survive that would mean over a thousand volts would need to be present on the OT secondary!?! No way.

Lifting the grey NFB lead and still having voltage on C25 would mean that the voltage in that area ISN'T coming from the OT secondary.

That board and all non fixed contacts (pots, tube socket pin holes, switches, rows of ribbon pins, ribbon pin holes, etc. needs to be cleaned again. Better. If you need to lift the board to clean it thoroughly then you need to lift it. It then needs to be completely dry all the way into the ribbon pin and tube socket holes before any testing. It will not be enough to be pretty sure it's clean. You need to be sure it's clean. F'in clean. And dry.

No more testing of anything should happen before this is seen to.

Indeed R74 still has ~100vDC across it so no progress there either.

I have scrubbed the bajeezus out of this board with a toothbrush using denatured alcohol and then naphtha several times in every spot I can reach on the front and back of the board. All I can do is keep trying to clean and scrub it.

It is possible there is residue under components that is still conducting but I can't solve that without removing every part and cleaning under it.

[Chuck H]

I like Dudes compressed air idea. It would help to dry the capillary like spaces too. Really fine stuff like tube socket holes and ribbon pin connections are so super critical. Like toothpick and time critical.

The voltage at R68 is positively getting there via some unintended contact. That R74 is sill passing so much current is also bad. I assume this is with C35 still out of the circuit? Since R75 has a somewhat normal current load that would mean that any current through R74 must also be coming from some unintended contact. There simply must be conduction happening somewhere in the ribbon cable and possibly also the PI tube socket. Toothpicks! CLEAN!!! DRY!!!! If you have an air compressor, use it.

FWIW naphtha won't dissolve old or carbonized beer. Enough with that for now. Alcohol should, but it's very fast. Possibly evaporating before it can do enough dissolving. But stick with the alcohol and use more of it. Keep things wet while abrading them. Douse the tube socket and plug the tube in and out a few times poking in there with a pointy toothpick in between. Twist the toothpick. Be sure the alcohol is wet on the area when all this happens so it can act as a solvent. Do the same with the ribbon pin area of the board and the ribbon pin cable holes. Blast air after or mop up what you must with paper towels and use a blow drier. Be certain the PI socket and ribbon connections are clean and dry. With no visible carbon traces I just don't imagine any other way for the problems you're having.

[The Dude]

On a "too little- too late"note, this is an expensive lesson and why I don't allow beverages of any kind on top of amps in my bands. That's what empty road cases are for. It's kind of funny. I've played with a lot of musicians for so long that all I have to do is just glare at them if they forget. They will remove said beverage without me even saying a word. Every once in a while I'll get "It's my amp", to which I reply, "Yes it is, but it's me that's going to have to fix it."

[Enzo]

I cannot imagine how the OT could put 100v on R68, I seriously doubt it is defective.

My money is still on an arc. Arcs do not always leave big black marks, they can be just the tiniest of sparks. I use a tool similar to the pick your dentist scrapes your teeth with, and I use the point as a feeler. Again, follow the trace from R68 inch by inch looking very closely, run a sharp point along either side of it feeling for any little divot. I wasn't initially thinking the ribbon itself, but even up there is possible.

[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.

This could also have happened between pins of the socket in between the socket and board. I've seen this happen before on an RF amp that had taken a beer hit

[Mark Black]

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...

[bsco]

On a "too little- too late"note, this is an expensive lesson and why I don't allow beverages of any kind on top of amps in my bands. That's what empty road cases are for. It's kind of funny. I've played with a lot of musicians for so long that all I have to do is just glare at them if they forget. They will remove said beverage without me even saying a word. Every once in a while I'll get "It's my amp", to which I reply, "Yes it is, but it's me that's going to have to fix it."

I totally agree...I am always telling fellow musicians...get that drink off that amp.......and they listen.....