What comes out should NOT fit back in

[nevetslab]

Fender Deluxe Reverb left for me from the Guitar Dept, so wheeled it into the shop, moved the Audio Research D70 off the bench to make room for this combo amp. Checked the Asset number to see if it was a recent service job. Nope....just before the Pandemic shut us down. Note on the top indicated Rectifier tube was glowing very bright. Removed the upper rear panel, unraveled the power cord....which in mildly cold weather will NOT uncurl, but rather remain curled to trip anyone on a dark stage behind the amps.....and plugged it in, powered it up. Nothing wrong with the 5AR4 rectifier tube....just the heater glow being visible and misinterpreted as faulty. The fuse holder, however, was loose. I'm still finding my way thru all recent generation Fender Combo amps to solve that with a pair of thin ITL washers to lock those down. I'd deal with that shortly.

Powered the amp up, and just checking with residual noise, the Normal Channel had a noisy preamp tube, while the Vibrato Ch was nice and quiet.

I removed the chassis mounting hardware so I could drop the chassis down and slide it out enough to see if I need to remove the chassis, or just enough to unmount the fuse holder. All looked ok inside, so just let it sit balanced on the rear side cleats, and unmounted the fuse holder, added the ITL washers inside/outside, and re-mounted & connected it back up. Went to slide the chassis back in. ABSOLUTELY NO WAY TO GET THE CHASSIS BACK IN. There was clearance between the top of the baffle and the roof of the cabinet, so it wasn't that problem All attempts to get it to slide forward were being stopped. Pulled the chassis all the way out, set it down on the adjacent bench and got my pocket flashlight out to look inside.

In spite prior efforts to staple the inside Tolex covering down flat, what was left had, of course, curled right up away from the cabinet walls, inhibiting ANY attempt to push a chassis back into place. Fetched my staple gun, turned the cabinet on each side to staple the small curly pieces of Tolex down and hammered them flush. Tried again, and still hanging up on the Tolex, but eventually did get the chassis back in. So much for production tolerances, and for proper glue-down of the inside Tolex flaps. And, just to add to the mess, Fender doesn't bother with oversize clearance holes to prevent roof foil from also getting in the way. Why are the long #8-32 screws pointed? To pierce thru the roof foil during the first production line chassis installation.. And it leaves a nice bulge behind, which also allows that foil to prevent chassis' from being slid back into place. At least the baffle wasn't oversized. I have had to remove the baffle, speaker mounted, in order to get the chassis back into place, and THEN remount the speaker baffle into the cabinet. Ah, the problems of Production Fit.

[xtian]

In the back of my mind, I'm always rating cabinets for ease of chassis removal.

[Leo_Gnardo]

Agree, the aluminum foil Fender's been putting in their amps as shielding... I wish they would come up with something else that works. Spent too much time yesterday wrestling an x-pensive RI ptp wired Deluxe Reverb chassis out of then back into its box. Near the front lip, the foil slid back then created a hump upon disassembly. Prior to reassembly, I went back in with a stout putty knife & flattened the foil as much as possible. I'm sure foil is used because it's so easy to install (badly) compared to pesky old window screen & lots of staples. Any elementary school dropout can do it!

Bad enough chunks of foil peel, bubble & in so many other ways become an impediment to servicing the amps, I often find shreds of foil that came loose during previous service work, or in some cases at factory assembly. Never a good idea to have loose metal bits randomly rattling around inside an amp. Murphy's law says, sooner or later, PFZZZZZT!

[nevetslab]

Bad enough chunks of foil peel, bubble & in so many other ways become an impediment to servicing the amps, I often find shreds of foil that came loose during previous service work, or in some cases at factory assembly. Never a good idea to have loose metal bits randomly rattling around inside an amp. Murphy's law says, sooner or later, PFZZZZZT!

Agreed! And, add to that the chiesl-like top edge of the Fender chassis which, once the foil has come loose along the top front, that edge just peels it back, rolling the foil up until it halts, with the chassis now stuck. I've had to remove baffles too many times in order to remove a chassis locked up in that predicament, By the time you've taken the cabinet apart to get the chassis out, then go in and repair the damage, you're an hour into the process....just to get the silly chassis OUT of the cabinet. I've only had one amp actually arc and spit from shreds of roof foil finding its' way into the wrong place, while amazed at how many should have been more exciting events from the potential to do so.

[Mick Bailey]

Sometimes these Fender chassis are jammed in so tight they can't be removed without disproportionate time and effort. I had a Silverface Twin reverb that took most of a day to shift. My theory is the timber with some of these amps shrinks after the amp has been assembled and the tolex, staples and any foil makes things worse. I now have a couple of long .005" hardened shims that I line up inside the cabinet and a really tight fitting chassis will slide in and then the shims can be pulled out. It gets really bad removing a Fender chassis when the fascia panel also get gripped. You don't want that to bend on the way out.

I think one of the worst removal jobs I had was a Marshall combo (can't recall the model). It had 4 hardened M4 screws holding the chassis from the top. The chassis slid into it's own section with a floor, so the only way out was backwards. One screw head was chewed up completely and the thread was striped and it just turned, two came out OK but had damaged threads. The third broke off just inside the chipboard under moderate hand screwdriver use. I ended up machining up a core bit to open up the hole, then made a tubular mandrel with a 4mm hole to centre the drill over the screw. A regular HSS just skated on the remaining thread, which meant grinding up a tungsten carbide masonry drill to the correct angle and rake to cut steel. I got it out but then needed some M4 nutserts which I had to order specially and find some better screws. Then plug and re-drill the enlarged hole. I'm pretty sure I've had a couple of these amps with the same problem.

Then there's the Chinese AC30s with the screws that strip on the way out. I asked Korg and a replacement set of back panel screws was then (about 5 years ago when I asked) £40 ($55) + postage.