DC-3 Rackmount Installation Tips?

[LEVEL4]

I already have a Mark IV rackmount. But, I also have a DC-3 short head that I'm planning to put in a Mesa rackmount kit I just bought today. So, I need to pull the DC-3 chassis from its shell and load it into the rackmount kit (I'm probably just going to ditch the reverb tank, since I never use it). Any tips?

1. Should I discharge the capacitors first? Where are they, and how big of a "snap" does it make when I short them out? I just turned the amp "on," then, just turned it "off" while leaving the standby switch still in its "on" position.

2. I know I have to unscrew the four top screws, which hold the chassis in the shell. Should I do this with the shell upsidedown?

3. One last thing. I'm, planning on ditching the reverb tanks on both my DC-3 and Mark IV rackmounts. I want pull the 12AX7s which drive the reverb tanks in each amp. Does anyone know which to pull in each amp?

Thanks for any advice!

 

[LEVEL4]

Okay, I unscrewed the four long screws which bolt the chassis to the shell. I can now lift the chassis and see two blue capacitors the size of 'C' cell batteries. Just throw a screwdriver across each cap's leads and short them out? This doesn't hurt anything?

 

[camsna]

AAAAHHHH! STOP!!!!!!!

Don't touch the caps. Don't worry about them. Don't go sticking screwdrivers into the caps!

Just leave them be, mount the chassis into the rack enclosure, just be sure not to touch any of the circuitry while you do it!

 

[LEVEL4]

Oh, thanks! Someone else said to short them out in some other thread here. I haven't touched the caps (there's four). I haven't touched anything. It's a little hairy, since the whole chassis is exposed, once you pull it out of the shell. Just got the chassis out. Now, I'm going to slide it into the METAL rackmount enclosure. Anyone know which is the reverb 12AX7?

 

[trem]

3. One last thing. I'm, planning on ditching the reverb tanks on both my DC-3 and Mark IV rackmounts. I want pull the 12AX7s which drive the reverb tanks in each amp. Does anyone know which to pull in each amp?

Which version do you have, A or B? In the A, it is handled by V4, which should be a 12AT7. In the B the reverb duty is shared between half of V3 and half of V4. You can't just pull them without killing the lead channel. Don't pull anything. You won't hurt anything even if you don't use the reverb.

 

[LEVEL4]

Which version do you have, A or B? In the A, it is handled by V4, which should be a 12AT7. In the B the reverb duty is shared between half of V3 and half of V4. You can't just pull them without killing the lead channel. Don't pull anything. You won't hurt anything even if you don't use the reverb.

Thanks. Were you talking about the Mark IV, right? It's a 'B' I guess? I bought it "new," but it was sitting in the shop for a few years in a display case. I just swapped V1 and V5 in the DC-3 and it sounds better, FWIW.

. . . mount the chassis into the rack enclosure, just be sure not to touch any of the circuitry while you do it!

DONE! Finally . . . Okay, that was a HUGE pain in the ***! Anyone else need help on this just call me—it'll be easier to explain over the phone. There are these stupid metal spacers screwed in from the inside of the chassis enclosure on the DC-3 that I had to metal-fatigue and hacksaw off. This "simple" shell-to-rack conversion took me over two hours! Now, I gotta build the slanted, 14U, KK Audio rack I got yesterday from Guitar Center so I can load it up with both my new rackmount amps. It's cool. It's black and has textured paint, like an amp. Pics when done!

 

[trem]

Thanks. Were you talking about the Mark IV, right? It's a 'B' I guess? I bought it "new," but it was sitting in the shop for a few years in a display case. I just swapped V1 and V7 in the DC-3 and it sounds better, FWIW.

I was. Even if you don't plug in the reverb tank, no need to pull any tubes. In your case, it's impossible to pull any. I don't get the part about the DC-3 though.

 

[LEVEL4]

Even if you don't plug in the reverb tank, no need to pull any tubes. In your case, it's impossible to pull any. I don't get the part about the DC-3 though.

Thanks! Good to know. On my DC-3, I switched my V1 preamp tube to the V5 position, the reverb position, because I think one of the tubes is bad. I bought new TungSols when I got the DC-3, and one of the tops of the tubes was black instead of silver (it still glows). That's the one I moved. It sounds a lot better now.

 

[Aart]

Hmm, my rackmounting technique was like this(took 15 mins):

1. Dismantle the rackmountkit(2 sides, front, cover). Be sure the fan is already mounted on the inside of the front(there are two bolts to hold it).

2. Get the powertubes out of the amp you want to rackmount(remember in which position they were).

3. take the four screws holding the chassis out and supoort the amp by holding it by the transformers.

4. Take the amp out carefully while holding it by it's transformers.

5. When it's out a few inches you can grab it under the side's of the chassis and put it on the ground.

6. Attatch the side panels of the rackmountkit(they're strong enough to hold the amp).

7. Attatch the front and cover. Put the tubes in. Done.

 

[LEVEL4]

Hmm, my rackmounting technique was like this (took 15 mins) . . .

Yup. I wish mine were that simple. My DC-3 had these nasty little metal spacers, INTERNALLY screwed into the bottom (or was it the top) of the chassis. Since I couldn't open that part of the chassis, I had to use pliers to fatigue the screws (which were screwed from the INSIDE). This took FOREVER, since Mesa chose to use the hardest, strongest, anti-fatigue machine screws known to man! This worked on TWO of the screws. The other two, I had to saw off with a hacksaw. That also took FOREVER, since the screws rotated while I was sawing. Nightmare. But . . . worth it! Wait 'til you see the pictures!

 

[devilrob1979]

That's going to be a heavy rack in more ways than one.Should look pretty awesome. FWIW I velcroed my reverb tank to the top of my rackmount kit and it works great. I installed a vent panel above it to let the amp breathe some anyway so I'm not missing anything.