Tips/Tricks Dealing with Very Heavy MC Amps

[captouch]

I have a heavy MC 2255 coming in toward the end of this month, and I'll be opening it up to compile a cap list for recapping, looking into a meter that isn't working, De-oxiting the controls, and changing the faceplate glass.

It's a ~85lb unit and I anticipate it being a challenge to manipulate (turning this way and that to open top and bottom covers, removing faceplate, accessing boards, etc).

Are there any tips/tricks you all have found effective in dealing with handling/manipulating really heavy units like this?

I'm thinking of putting some pads/towels on a table and making sure not to put any excess weight on the faceplate to avoid damaging the glass - so thinking I'd overhang the face over the edge of the table so it doesn't see the pressure.

But other than that, I'm thinking of maybe rolling it when I need to flip it over instead of trying to lift and flip 85lbs each time.

Does that sound like a reasonable plan, or have others found better ways of dealing with the weight challenge?

Or some things to definitely NOT do to avoid damaging casework/chassis?

I was thinking it'd be really nice to have some jig that you could clamp the amp into and have many degrees of freedom to flip/rotate/etc, but realistically, that's not something that would be readily available or easy to build to support that kind of weight.

Just looking to mine the wisdom/experience of people who've done this before to avoid some pitfalls/mistakes that I can avoid.

 

[damacman]

That's exactly what I've always done - overhanging the faceplate off the bench and rolling it over as necessary. Give yourself plenty of room.

The MC2255 is kind of a lightweight in the big scheme of things! I've got a similar sized MC7300 that is far easier to manage than my MC2300s or MC2600s.

On another note, the MC2255 is one Mc amp that has eluded me - I've just never been able to find one reasonably priced and local. Although I have owned its bigger brother, the MC2500, I'd still love to have an MC2255 in the lair. Have fun and enjoy it.

 

[sKiZo]

Yup ... roll it.

Got a 2205 here, and hard part is getting it into the rack. I've got a sturdy little step stool that's about the right height of the shelf. Piece of plywood temporarily screwed to the top of that, and wiggle/slide the amp in. More or less hernia proof ... ;-}

PS ... did some repairs on it a while back, and used that same setup to get the beast out of the rack. Did the work right there instead of trying to drag it into the basement shop. Only soldered a couple holes in the carpet ... hardly see em if you squint.

 

[Searing75]

Remove the glass face plate first!

 

[captouch]

Ok, I’ll roll it. Thanks for the feedback!

The glass is already cracked and I’ll be receiving a new one shortly.

I know I have to remove the bezel, diffusers, and color filters/lenses from the original glass and apply it to the new one. I was thinking I might leave the cracked glass on while I work on the insides as some degree of protection for the meters which would otherwise be exposed if I took the cracked glass off.

But if it’s a better idea to remove the glass anyway, let me know.

I’ve never worked on a Mac before, so all tips/tricks are appreciated.

 

[sKiZo]

Plan on replacing the color gels long as you're at it. Those tend to discolor over time. Hard to get an exact match to the OEM gels, but stacking these comes real close:

BLUE METER FILTER
Lee Filters Sheets - 118 Light Blue
Lee Filters Sheets - 117 Light Blue

 

[MACKIE1975]

Take a lot of pictures.

 

[damacman]

Ok, I’ll roll it. Thanks for the feedback!

The glass is already cracked and I’ll be receiving a new one shortly.

I know I have to remove the bezel, diffusers, and color filters/lenses from the original glass and apply it to the new one. I was thinking I might leave the cracked glass on while I work on the insides as some degree of protection for the meters which would otherwise be exposed if I took the cracked glass off.

But if it’s a better idea to remove the glass anyway, let me know.

I’ve never worked on a Mac before, so all tips/tricks are appreciated.

I’d likely remove the faceplate as an assy ... otherwise, you’ll be fighting little bits of glass anytime you turn it, etc. The meters themselves are encased so no worry of damage. Keep the faceplate assy together until you’re ready to swap the glass - then you can easily remove things in order to put them on the new glass. Many find these amps look more modern leaving the plastic meter bezel off the front.

 

[chef free]

Consider leaving the plastic bezel off.

 

[captouch]

I’d likely remove the faceplate as an assy ... otherwise, you’ll be fighting little bits of glass anytime you turn it, etc. The meters themselves are encased so no worry of damage. Keep the faceplate assy together until you’re ready to swap the glass - then you can easily remove things in order to put them on the new glass. Many find these amps look more modern leaving the plastic meter bezel off the front.

OK, good idea and thanks for the info about the meters being encased. Tom Manley gave me some detailed, but verbal instructions on the how to change the faceplate, which I'm sure I won't remember when the time comes. So I'll probably end up posting for help here or calling Tom back.

Consider leaving the plastic bezel off.

Yeah, for sure. I was planning on removing the bezel and storing it. I think it looks much more modern without the bezel. I'm getting a case with mine too, but I'm not even sure I prefer the look with the case vs without. The case makes it look more vintage, but case-less seems to look more modern - at least in pics. I can judge better in person I think.

My main "concern" is the non working meter. I'm hoping it's the driving circuitry or a bad component vs a bad meter. If feasible, I may try to switch the wires driving each meter to see if it follows the wires or the meters, and then go from there.

Is that yours?

 

[sKiZo]

Can you get the meter to work if you cycle the meter switch a few times? That usually indicates some corrosion or a loose connection. Another thing to check if you get inside. A good cleaning on the terminals and a bit of dialectic grease should solve the problem.

 

[captouch]

Can you get the meter to work if you cycle the meter switch a few times? That usually indicates some corrosion or a loose connection. Another thing to check if you get inside. A good cleaning on the terminals and a bit of dialectic grease should solve the problem.

Thanks. I don’t have the amp yet, so I’ll try all those things when it comes in.

Will probably start another thread if the simple things don’t solve it to get some suggestions.

 

[Gregory]

By rolling, you mean tipping the amp up from left-to-right (or vise versa) by 90°, then 90° again so it's flipped over on its back? Yes, and hang the glass over the front edge of bench. There are some operations where you might need to stand the amp up on its end. For this use a shim (or two) and be VERY careful not to knock over!

Some examples


Hanging off the LEFT end of the bench.


Upside down with Glass removed.



Standing up on end (use shim under autoformer).



Shim is green sticky-note pad under autoformer.


Custom fixture built from counter top material for 2205 installation.


Glass hanging over front of fixture (stand). These pieces where made from scrap "sink cutouts" bought from the lumberyard for $1 ea. Also recommend using OAK blocks of wood under rails to "stand in" for the feet, and allow cooling air to enter underneath when testing/operating on stand. Also to get your fingers under the Panloc rails when lifting.


Bench mat

Notice ribbed bench mat in above photos. You can buy a 24" wide x 48" long mat from McMaster for $40 bucks and get THREE separate mats from it. That's only 13-1/3 bucks each. Order rubber only for this purpose and forget vinyl. Easy to cut inside a groove with utility knife. Use a piece on the floor to stand on. It's GREAT material and tough!!

https://www.mcmaster.com/6897t511

Only 1/8" thick and that's all you need. Love mine. Can be rolled up for storage and will "relax flat" in just a hour or so. Solder splats easily come off and "component lead cutoffs" fall into the grooves preventing damage to gear. Best to brush or vac debris from mat every hour or two, or when needed. See photos of paint (dust) brush above.


-Greg

 

[captouch]

By rolling, you mean tipping the amp up from left-to-right (or vise versa) by 90°, then 90° again so it's flipped over on its back? Yes, and hang the glass over the front edge of bench. There are some operations where you might need to stand the amp up on its end. For this use a shim (or two) and be VERY careful not to knock over!

Some examples

View attachment 1310925
Hanging off the LEFT end of the bench.

View attachment 1310926
Upside down with Glass removed.


View attachment 1310927
Standing up on end (use shim under autoformer).


View attachment 1310928
Shim is green sticky-note pad under autoformer.


Custom fixture build from counter top material for 2205 installation.
View attachment 1310929

Glass hanging over front of fixture (stand). These pieces where made from scrap "sink cutout" pieces bought from the lumberyard for $1 ea. Also recommend using OAK blocks of wood under rails to "stand in" for the feet, and also to allow cooling air to enter underneath when testing/operating on stand.


Bench mat

Notice ribbed bench in above photos. You can buy a 24" wide x 48" long mat from McMaster for $40 bucks and get THREE separate mats from it. That's only 13-1/3 bucks each. Order rubber only for this purpose and forget vinyl. Easy to cut inside a groove with utility knife. Use a piece on the floor to stand on. It's GREAT material and tough!!

https://www.mcmaster.com/6897t511

Only 1/4" thick, and that's all you need. Love mine. Can be rolled up for storage and will "relax flat" in just a hour or so. Solder splats easily come off and "component lead cutoffs" fall into the grooves preventing damage to gear. Best to brush debris off mat every hour or two, or when needed. See photos of paint (dust) brush above.


-Greg

Thank you Greg, awesome pics!

For the ribbed mat, I was also thinking about using a yoga mat - we have some that aren't being used. I *think* it's rubber, but not 100% sure.

Thanks to everyone for the valuable input on this.

 

[Coytee]

I'm not a mechanic.... I no longer have any Mac amps.... but when working on something, couldn't you fabricate a "Lazy Susan" to set it on and rotate as needed?

 

[captouch]

I'm not a mechanic.... I no longer have any Mac amps.... but when working on something, couldn't you fabricate a "Lazy Susan" to set it on and rotate as needed?

I think rotation is relatively easy - I think rotating it while on a quilted moving pad for instance, would be pretty easy if on a smooth surface table. Though keeping the faceplate/glass overhanging the surface to protect the glass would be an issue, so I think the lazy susan for horizontal rotation while maintaining the overhang would be a good idea for that.

But the challenge is flipping it over to access top or bottom - the gently rolling it seems to be the best solution to the flipping dilemma. I would love to fabricate an easy flipping jig, but that seems non-trivial to do given that it would have to clamp onto the amp well enough to support the 85-90lbs and have some kind of rotation mechanism as well.

 

[sKiZo]

I've got a turntable I use on the bench that I made out of a square of scrap plywood screwed to a heavy duty turntable bearing made for kitchen corner cabinets. Works pretty slick.

 

[Gregory]

Ha! very funny.

Here's the mat on my bench, which is the island in the kitchen.




Here's the 2205 upside-down, hanging over the LEFT end of the bench.. so you can lift, flip, set down with hand underneath the xformer.



There are lots of way to roll-flip the amp LEFT-RIGHT.


Another example:

Here is the 2205 hanging over LEFT edge with heatsink module removed to access the tiny INPUT PCB:


Of course.. BE CAREFUL not to knock the unit over!!

I recommend these grooved mats from McMaster. They're tough and actually for use as high-traffic [walk area] runners in industry. Our design and manufacturing company used them in the shop and shipping areas. I got to take home the scrap cutoffs.


-Greg

 

[Gregory]

This is the amp on OAK blocks on top of a microwave cart – for airflow from underneath when testing and to get fingers underneath the rails.




3/4" thick oak blocks, one each corner:



This was during HEAT SINK temperature tests, playing Skynyrd – Whiskey Rock' a Roller.

See thermal probe in heat sink.


Here in San Francisco 1975 – test track was from Knebworth 1976.

Am I going OT again?


-Greg

 

[motorstereo]

I have a 2255 that I swapped all the lights out to led's in last winter. Mine necessitated carrying it down 2 flights of stairs and across my backyard to where I could work on it. First thing I did was remove the wood case. Next I had a bath towel already put down on a large and empty workspace where I could work on it comfortably. This worked out well and I was able to do the job.
FWIW the MC2255 is a wonderful sounding amp and I think it's much nicer sounding that it's bigger brother the MC2500 which I had a pair of. Good luck to you in getting yours up to snuff