Interesting Road Case for Ampeg SVT-CL

[nevetslab]

A new client dropped off five road cases full of gear needing the basic inspection and check-out prior to the group going out on the road. One of them is an Ampeg SVT-CL, and is packaged in its' road case like I haven't seen before. Remove the two covers, and the amp is parked inside ready for use. Now, what should be present and isn't are large rubber mounting feet on the 'bottom' side of the road case, rather than the normal corner-ball corners of traditional case hardware. Although those are only on the front/rear of the removable covers. Still, needs mounting feet, as far as I'm concerned.

There were two cables sandwiched in between the top side foam and the top of the amp. What struck me right off was getting the amp head out of this road case package.



I wondered if they would have left the amp's plastic mounting feet installed. Seeing the void in the rear bottom of the foam told me yes. While there is that gap at the top between the cabinet and the foam inside, I hadn't yet thought of turning the case upside down and trying to push the amp forward and up onto the bench, having parked the road case right in front of it. I did my best to try and pull the amp out of this, as it was a somewhat snug fit. I had to remove the grille, so I could pull on the preamp to draw it forward, though it wasn't much in the mood to leave the safety of it's road case.

I had just about gotten the amp out of the case, when I found one of the feet still attached to the bottom of the cabinet. I was then able to lift it enough to clear, and got it onto the bench. I found another cabinet foot buried in the foam, no mtg screw, and a third foot, also not mounted, on the floor with it's mounting screw. No forth foot found at all. And, looking at the inside of the floor of the road case, it was well torn up from cabinet feet. What I did notice thru the rear grille panel was power tube V3 having a frosty layer at the top of the glass bottle. Obviously this amp isn't going to power up with that in place. Haven't yet pulled it apart, but as it's in for service, and I've never seen this one, it comes completely apart, for the full treatment. I had advised them I would no doubt need to do that, so afterwards, it can be fully relied upon.

I'll have to see what I have in way of large cabinet feet to place on the bottom of the road case. That, of course, would need proper mounting hardware on the inside, while the foam is fully glued into place. I'll have to think about this. I don't have a circular razor saw that could easily pass thru foam, allowing re-use once the mounting hardware is secure, and glue it back into place.



I can see where the cabinet/chassis mounting screws are, having left tears in the foam as did the mounting feet. So, I'm not the first one into this cabinet/road package to do service. Not so well thought out.

[Leo_Gnardo]

Seen, even done this sort of amp case before. I had two made in 1986 or 7, one held 2 Marshall heads, the other 2 Mesa Mk II. One lid had 4 Darnell casters, the other none. Both lids filled with foam so amps had fully cushioned Cadillac ride no matter what position the case wound up in the tour truck. No rubber feet, they would get torn off in transit & who wants a tilty case.

[The Dude]

Just be glad they have a case! I used to do service for a now defunct band that had no cases for anything. They just launched all the gear in the back of a trailer including a digital drum set left completely intact- wiring and all. They'd pull the trailer up to the shop about 3 times a year and have me go through everything- repairing all the damage done in transport. They could have bought cases for everything many times over if you added up all of the repair bills.

[Enzo]

Did they bother to pull the head from the case in use? The amp vents via front and rear rather than top and bottom, so pop the covers and plug it in.

[g1]

From the gap at the top I would guess they originally had the case and head upside down and slid it in there.
A note on top would have saved everyone that had to work on it a lot of grief.

[Leo_Gnardo]

Just be glad they have a case! I used to do service for a now defunct band that had no cases for anything. They just launched all the gear in the back of a trailer including a digital drum set left completely intact- wiring and all. They'd pull the trailer up to the shop about 3 times a year and have me go through everything- repairing all the damage done in transport. They could have bought cases for everything many times over if you added up all of the repair bills.

Sometimes when folks get their gear in cases it still gets trashed. I tell them "you can't handle the gear like it was bowling balls, WITH or without cases." Slamming stuff around never good. Most of the time I even got truck loading crew to cooperate on tour. "Handle it like it was full of eggs & we don't want any to break. PLEASE!"

[nevetslab]

This morning, still pondering how I would tackle installing the 1.5" dia x 3/4" tall rubber case feet. I knew they had 1/4" mtg holes, recessed with healthy flat washers imbeded. I just didn't know if I had mounting hardware, not being well stocked in 1/4"-20 hardware. I knew I had 1/4"-20 T-nuts, and pretty sure the wall thickness of the road case was 1/4" material. When I got in, and spent 10 minutes rolling out the forest of road cases that were now occupying all floor space in the shop to park outside the shop door in the hall, I grabbed the case for the Ampeg, removed the front lid, then flipped it up onto its side. Not seen until now were the remaining 5/16"-18 carriage bolts dangling out of the bottom of the case, that must have previously had feet attached. Armed with my largest X-Acto knife/blade, I pushed on the bolts to find them thru the 1" foam, then cut square holes thru the foam to the case wall, pulled the foam out, then removed the bolts. So, I now had mounting holes for my T-Nuts. I had 1" long 1/4"-20 hex head bolts, so added two flat washers, one large enough not to be pulled thru the deformed holes from before, and pulled the T-nuts on into the panel. Removed the bolt, then one by one, mounted the new rubber feet.



So that worked out better than I had anticipated.

Yesterday, having pulled the amp completely apart to check EVERYTHING. It was one of the late generation units...preamp PCB now having double-sided plate-thru holes & lead-free solder, single-in-line I/O cable between the power amp and preamp chassis. I found the usual solder joint fractures along the rear main PCB edge, on the bias pots, XLR terminals, Preamp Out/Pwr Amp input jack terminals, square 0.062" headers 4mm spacing, AC mains input connector on the AC Mains board, and on pots in the preamp. Having had issues with the lead-free solder in the preamp tube connections, I resoldered those just to be sure.

The front standoffs of the main PCB that support that board, all three were loose at the chassis interface. The one corner is the Grounding Path from the main PCB to the chassis, so I already knew this would have had hum issues. Got those restored and tight. The Power and Output xfmrs were loose, but not from the chassis mounting. Core Bolts. I've been finding this generation's xfmrs with loose core bolts, and you can feel them shift when lifting one up. The Philips head drive pattern was full of varnish, so I had to take the time to dig all that out so I could engage the screw to hold it as I tightened the opposite end with an 8mm wrench.

Replaced the clear plastic garden-hose sleeving of the AC Mains and I/O harness wiring with Tech Flex, and then was able to stand up the two chassis, to start measuring the power tubes...less the one that failed. Sovtek 6550's. And, the silk screen was faded, so these had been running very hot. I had another set that I just removed from one of C/S's amps, and after sorting thru all the tubes, ended up replacing two of them and was able to get decent balance. Powered it back up this morning, while getting busy with the road case. Came back and checked the plate current on the six tubes, and they were now very well matched and balanced.

Now I just need to add the hi temp silicone rubber sleeving onto the hold-down clamps so there's no metal-to-glass contact and mount the clamps, install the tubes, and I can put this back together again. First need to check the fit with the SVT cabinet feet mounted again. Might have to change to shorter feet...we'll see.

[Leo_Gnardo]

Nevets you deserve a prize for thoroughness and ingenuity. But... we knew that. Keep on keepin' on!

[nevetslab]

From the gap at the top I would guess they originally had the case and head upside down and slid it in there.
A note on top would have saved everyone that had to work on it a lot of grief.

Just what I was thinking after my futile attempt to force the bloody thing out right-side up. Now that I've loaded cabinet feet onto the road case again, and dug thru my collection of ragged used Ampeg SVT cabinet feet, then sorted thru my box of correct length (and extra-long that Ampeg installed for who-knows-how-long...which disallowed removal of the power amp chassis until finding the fault), I loaded the feet back into the bottom of the cabinet, insuring nothing protruding past the surface. I then opened up the road case, turned it upside down, along with the empty SVT cabinet, and looked to see what the fit was like. As I expected, feet too tall for the gap, but.....it CAN be forced in without doing much more harm to the already damaged bottom surface foam. So, THAT IS how you have to load this into the road case.



Now, on to putting the amp back together, Got the hi temp silicone rubber tubing cut to size and slipped into place, then mounted them onto the chassis, now having replaced those M2 hex-drive M3.5 x 10mm Truss Head screws, which love to make the hex driver strip when they don't want to unthread, now using Philips drive SS truss head screws, still low profile so the tubes don't rock on them (below the surface of the tube base).





Bit by bit, over the years, I get these tiny pesky obstructions taken care of, finding better hardware and getting them into place. Nothing more irritating than encountering locked-up 2mm hex drive clamp mtg screws that refuse to unthread, and radius your decent M2 hex drive tool in the process. Nothing like a proper stainless steel philips drive screw that won't kill your tool, and have the hardness needed to last.

I'm almost there....just pulling the preamp harness connections back out of the chassis, then loading the power amp chassis back in. Stupid cabinet has the older style corner guards, which disallow removal of the chassis without removing them first. I haven't yet heard this amp.

[nevetslab]

As I was sliding the power amp chassis into place, having added split lock washers under the head of each of the five chassis mtg screws, as I engaged one of the side cage nuts, the screw drove the cage nut out of it's square hole! I hate CHEAP ASIAN HARDWARE!! Went to remove the chassis, and it was now locked in place, unable to remove it. Struggled with that for a few minutes, never having had THAT occur before all these years with SVT's. Tipped the cabinet up on end, and finally heard the tinkle sound of metal dropping into the bowels of the unit. I was able to now remove the chassis. And thankfully, the cage nut did NOT disappear into the insides of the chassis! Got it reinstalled, did my best to try and add tension to prevent that again. Put it back into the cabinet, and finally got it all mounted and tight.

Put the preamp into place and connected so I could finally hear it. Speaker connected, switched out of S/B, turned up the master, Gain all the way off, no noises...always a good sign. Turned up the Gain, and hearing hum. Not a good sign. Reached for my shorting plug and plugged it into 0dB input jack. No more hum. Unplugged it, hum back. Figures. While I had the preamp PCB out for inspection, I didn't check those jacks for Muting function with the DMM. Should have, as that would have saved me half an hour tear-down time to remove the jacks, pry up the Tip spring so I could pry up the Normal left in the jack body. Did that on both input jacks, added contact cleaner, verified Shorting, then put it back together.

After listening again to residual noise (very low), then fed burst pink noise briefly, all sounding nominal, I unplugged that and removed my 60's Fender Precision and plugged that in to hammer on it a spell. All sounding solid and fat, growling as I need it to. So, now I just have the task of turning this amp upside down and try to load it into the road case that way. I found part way in, that is a Two-Man task. I managed to get it installed, but won't try that again without help!

So, this took longer than I expected, but will probably be the bulk of the cost on the other four amps I have from the client to go thru and take care of whatever I find.

[Leo_Gnardo]

this took longer than I expected

Like everything around here. I'll have to live to 190 years old to get it all done.