Cabinet resonance problems with the great little amps is a major nuisance. The cause is the chipboard baffle. This would have been ply in the old days but in Fenders reissue they have gone for a more affordable design choice.
You may be able to fix yours just by tightening the securing screws up a little. It’s a hard life being a combo and they will loosen off in time.
See below for an attempt to solve the problem with a little DIY cabinet rework.
Remove baffle add bracing at top. Some folks like bills used angle aluminium but this model already has had a ply brace added but it is just pinned in. Here I have added several decent screws carefully drilled in, glue and some additional brace.
Refit baffle applying wood glue and adding additional securing screws.
At the back of the amp I added a brace to reduce the rear panel resonating.
Nice little budget amps with a range of built in effects. Seem to suffer from intermittent sound loss and cutting out. The PCB are plagued with bad joints around ribbon cables, regulator U10, and although I have not seen it the numerous large resistors and caps.
Also recently saw one making g a terrible humming or buzzing noise. No signal was coming through at all. Current draw on the amp was about right so quickly able to link to open circuit power supply filter capacitors. Replaced, resoldered and glued into position and amp will be good as gold for another ten years minimum.
My friend Roger’s lovely 1972 Fender DR suffering with smoking front panel looking like a scene out of spinal tap.
Took it apart, powered it on and . . . all fine. So what’s the problem – nothing, it’s fine. Left it on for a while – then fireworks. Bang . . .Bang – bits of electrolytic capacitor all over the place and that curious, quite pleasant smell.
So replaced the caps, and with a meter measured the anode HT voltage, I got worried. Those caps are rated at 500v but the HT is way higher, more like 560vdc – how can this be – is it normal?
So, after a bit more research I reckoned that the rectifier tube could be gone, or breaking down. Replaced it and watched the anode voltage carefully as it was wound up on the variac – this time with protective glasses.
The voltage is still high, think about 520vdc, but Fender Deluxe reverb’s do run hot. I regret not choosing 600vdc caps as they are just as easy to get hold of. However once the amp is being played the power supply sag will lower the HT voltage to perhaps lower than the rating of the caps. If so all well and good. The amp has been giggied a few times since being fixed and is running well. It sounds absolutely awesome really clean, sounds like a bell and very detailed. I do think that Fender might make the best amps.