fender amp problems,reverb and crackling

[mrchrismckay]

hello to anyone reading this. i have just got myself a 4x10 blues deville,wonderful valve amp but my first ever valve amp and its is giving me a couple of problems which i do not have the money to take in to get it fixed just now,so please help!!!

firstly, playing the amp softly it sounds fine, but once u crank the volume on either channel, it crackles like there is no tomoro,esp when u strum hard. at first i thought it was a power issue but nope. i good friend said his Twin had the exact same problems, and what his turned out to be was the connections between the tubes and the amp were ever so slightly dodgey, now, if this is the case, how would i fix it, could i do it myself????

second, aswell as this amp, i also have a solid state fender deluxe 90,now,the reverb on this does not work at all ASWELL as the reverb on the deville,now, am i doing something wrong, coz neither of my fender amps have the reverb working on them, how can i fix this or even begin to find out whats wrong!!!!

please help as i am totally clueless!!!!

chris

[drlowlow]

try this link

check out this FAQ http://ampage.org/htac/faq/tube_amp.html skip to the maintenance issues and it gives procedures for checking and cleaning your sockets if you think that is the problem, it also gives conditions to look for if they need to be replaced. the problem could be many places in the circuitry but a good start is to follow the safety guidelines on that link i sent and get some contact cleaner and clean the jacks and places where a contact could erode. If the simple methods don't work then I would recomend taking it to someone that can signal trace the problem with an O'scope because that can usually narrow down exactly where in the circuitry the problem is, which in the long run will likely be cheaper then changing a bunch of things out that could be the problem until the problem is fixed. Another free little trick that may have some fruitation is to adjust the pots one at a time to see if you are getting and crackling from any of those. Good luck.

[Tom Phillips]

Both the amps you mention are prone to developing cracked solder joints where the jacks and controls are attached to the circuit boards. A symptom is loud crackeling when you pound on the cab with the amp turned on. Also wiggling the input plug in the jack or the vibration caused by playing loud as you mentioned.

If that's your problem then the fix could require removal of the circuit board to repair the joint. Techs have their own methods for finding the trouble spot. It involves pushing on parts, wires and the board with the amp powered up. Not something I would recommend that you attempt yourself if you are "totally clueless" as you stated.

It shouldn't cost much for a competent tech to fix your problem.

Tom

[Two Tone]

I just had a blues deluxe for repair with the same symtoms,
turned out to be the ground to chassis connection of the preamp board.
Resolder this point and make sure you have a good chassis contact

[Amp Kat]

These problems are very common with all the new Fender PCB amps mainly the twins and Deluxes. The Filter caps and grounds on these amps are just a nightmare and you may fix one connection then another acts up. That's why they are called the evil twin's. I've changed all of the sockets in these amps to no avail until you find the connection. As Tom said pushing or tapping mainly on the filter caps will cause loud pops thru the speaker or tapping on any ground will do it. The wires going to and from the preamp tubes to the pcb boards are proned to breaking off very easily so you have to be careful with those also. Something else someone said is your poking around 500 volts so I'm not sure this is something you want to be subject to and it's not hard to get hit and could be lethal. The reverb problems in both could be a connection problem and usually are. You may try swapping the rca connectors around on the pan from input to output. The pans on those two amps are different pans and won't work on the other so you can't test them to isolate a pan problem or driver problem. The SS amp uses op-amps as the driver recovery stage and the tube one uses a transformer and a tube as a recovery stage amp. However the tube one also uses an op-amp to switch the reverb on and off at least on the twin and that op-amp very rarely is bad as it's usually a connection on the gray wire strip.