ogeecheeman 12/15/2017 9:36 PM
Fender Hotrod Deville crackling at turn on
Boy these things are a mess. In addition to the laundry list of items to correct like- plate resistors,power recap,broken solder joints,broken ribbon connectors,bad relays,faulty jacks etc...this guy had one screw holding on the back panel.it fell backwards,the panel pushed into the output tubes breaking the guide pins and knocking them out of the sockets.the guy tried re-using the tubes.put them in misaligned(remember the broken guides).fuse pops.he puts in a 10A fuse. goodbye screen resistors,a few foil traces and a burned hole thru the board.and if that's not enough it looks like a drink has been spilled into it.
1)corrected foil,broken solder joints,ribbon conns,jacks,
2)replaced tubes-returned to customer with understanding that he will return with caps.
amp is back.still crackling
3)faulty power switch, new tubes with....you guessed it, broken guide pins again.
4)replaced ALL plate resistors
5)recap of power supply- 47uf...22uf....100uf
so far...maybe
 
nevetslab 12/17/2017 6:13 PM
Sounds like you still have some solder joints acting up to find. The last Hot Rod series amp I had with crackling was found on the staked-in fast-on terminals over on the primary/secondary side....where I usually DON'T find the trouble. My biggest complaint on this series is the really poor quality PCB material used. The adhesive under the foil breaks down under re-heating of solder pads while changing parts with the greatest of ease. It doesn't help that Fender folds the leads over prior to flow-soldering the board, so you can't use a Pace Desoldering tool directly. (At least you can on the IC's and relays).

You may still have further damage that you didn't find on the tube PCB's down below. Sounds like you're well aware of the normal solder fractures that plague the Hot Rod Series (input jacks, foot switch/pre out/pwr amp in jacks, pots & their support brackets, the tiny solder-masked pads for the power supply caps (I hate how Fender thought it wise to reduce those tinned pads to be so tiny, and NOT use all of the pad dia as should have be done!). I work on Hot Rod series all the time, as there's at least 20 in the rental inventory where my shop is, as well as with other clients. They do come back together and work fine again. And, there's an easy mod to reduce the excessive gain in the More Drive mode.

If you haven't already done so, I'd scrub the PCB wherever you see evidence of the drink being spilled into it, as that also coul dbe your source of the crackling.
 
xtian 12/17/2017 7:21 PM
The Hot Rod series is to amp techs what Microsoft Windows is to IT techs—a constant and reliable stream of income.
 
Mick Bailey 12/18/2017 2:04 AM
Yes - the gift that keeps on giving.
 
Tone Meister 12/18/2017 9:45 PM
Don't overlook the tube sockets either if they're the old black phenolic ones. And I mean the sockets themselves, not just the solder joints. I've seen the old black sockets that lose their grip to where tightening the pins wouldn't help because the metal was compromised by heat over time.
 
ogeecheeman 2/13/2018 4:39 PM
sorry this post took so long.i did solve it. faulty off/on and standby switch.thanks