Fender Hot Rod Deville 212 - Buzzing with lower frequencies, popping, distortion

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Hello all,

I recently purchased a Fender Hot Rod Deville 212 off craigslist used in Indianapolis. I have video of the symptoms below:

Longer video showing the buzzing produced by large vibrations:

https://vimeo.com/232239804

This video shows the circuitry going crazy, after setting it off with some loud notes:

https://vimeo.com/232244173



My hunch is a bad solder joint or a bad component? I wanted to see if anyone agrees, and if so if there is a specific area of the circuitry I should try resoldering first.


Thanks,
Gary

[nickb]

I see the yellow LED flashing. This suggests a power supply connectivity issue. On the bottom centre of the board are two big white power resistors. These get hot and the solder joints fail. Give them a waggle to see if the problem happens. If it does clean and resolder those. You'll have fun getting the board out to do it.

If not then try try pushing on different components using something insulated to see if you can isolate it.

[Mick Bailey]

+1.

If those resistors are affected, very often the solder pads and tracks are burnt up. In these cases I locate a pair of aluminium-clad power resistors on a small heatsink and wire them back to good points on the board. Sometimes the associated zener diodes have problem joints.

I rarely get these amps with just a single fault. Usually the main electrolytic caps are on the way out. No outward sign of anything wrong initially, but when they deteriorate further a yellow crust appears around the +ve lead where it exits the rubber seal. Additionally, the solder joints on the tube sockets are usually cracked and need resoldering - I go over every one. The input sockets can work loose and crack the solder joints.

[nevetslab]

Besides the Fender Twins & Deluxe Reverbs, seldom does a week go by without one of the Hot Rod series amps coming to my shop. We have around 25 of them in all models in our Rental Depot (CenterStaging Burbank, CA), so I find loads of different ailments with them. The most common ailment is from fractured solder joints. hardest issue on repairing them is getting the main PCB down and out of the chassis. I always unplug the primary and secondary wires, labeling each with a Blk Sharpie so I know where it goes back. I usually have to cut the cable ties off the bundled wires below the PCB coming out of the Output Xfmr, so you can flatten the wires while dropping the main PCB down as low as it can go, to swing out and get the pot shafts to clear the chassis flange.

From there, I"m looking at ALL the solder joints on the board, starting with the input jacks. I wear a surgeon's fiber optic headlight and loupes, so I can see in detail all the solder joints. You're looking for tiny radial cracks around component leads. The input jack terminals are a major common item, as are the pot terminals and the support bracket terminals. Also the Power supply filter caps. On some of the PCB's, where Fender decided to reduce the solder pad with solder mask, I'll un-solder the folded-over leads of the filters, scrape away the solder mask to enlarge the copper area, then fold the lead back down and tin/re-solder the lead onto the larger solder pad area. Fractures on the filter caps cause lots of noises. I've also had AC Mains buzz come and go, that turned out to be solder joint fractures on the swagged 1/4" Fast-on terminals in the Primary and Secondary wiring areas over on that end of the board.

Take your time and be thorough. If the solder joints even look gamey, or maybe it has a ring developing, de-solder and re-solder it. I never just add solder to the original joint. I always de-solder first, then re-solder, using leaded solder 60/40. BTW, I've had loads of problems with the lead-free solder. Hate that stuff.

While you have the main PCB out, dangling by the remaining ribbons and wires, take a good look at the tube PCB's. A lot of the problems I have with the Hot Rod series are on those boards as well., including the ribbon cable wiring.

If the amp also has the stock foot-pedal in the cabinet, take that apart to have a look at the soldering. The TRS phone jack connections fracture a lot. and are an easy fix.

When I'm re-assembling the amp, I'll unravel the transformer secondary wires, and twist the Brn wires together, then the rred wires together, and twist those two bundles together, as well as twisting them with the GRN heater wires, if you had unplugged them from the tube PCB. makes for a much nicer lead dress, and saves on the cable ties. I also twist the primary Blk/Wht wires together separately, and after all have been plugged back into their locations, then I'll add cable ties when needed.