Finally MC2300

nbndtrain

Well-Known Member
I was finally able to find a really nice MC2300. I can't believe how large these are! It simply dwarfs the MC7270 it will be replacing.

This is a 3Y unit with all original outputs and wirewounds. I believe the driver cards have been updated, but not really sure if there are additional updates needed. One side is getting hot, following the card. What replacements are needed to ensure the cards are operating correctly? Is there a common parts list/BOM for Mouser or Digikey?

What are the best options for feet without the rails? I was thinking about adhesive toilet seat bumpers.

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The blue electrolytics on the 'driver' boards need to be replaced. There are probably other similar caps in the power supply and meter circuits that need replacing. Don't wait too long. Many times on the test stand, I used 2-1/4" sq x 3/4" blocks of solid oak, one in each corner under the slide-rails. See in the Manual it will call for a minimum 'space' below the bottom cover. Always be sure your amps have enough airflow for cooling.


-Gregory
 
Wow - that is an exceptionally clean unit. As for feet, there are three threaded holes in the bottom of the amplifier that were originally intended for the bolts to hold the amp to the plywood base in the shipping box. Long ago, I actually found a screw in type foot of the exact same thread and bolt size. You may be able to find some of those locally. If not, hit me up via PM and I may still have them kicking about . . . all my MC2300s are all now rack mounted.
 
Oh, almost forgot. McIntosh does sell a driver board update kit. The OOPS . . . I did it again thread below has info about that kit on pages 6 & 7.
 
Wow - that is an exceptionally clean unit. As for feet, there are three threaded holes in the bottom of the amplifier that were originally intended for the bolts to hold the amp to the plywood base in the shipping box. Long ago, I actually found a screw in type foot of the exact same thread and bolt size. You may be able to find some of those locally. If not, hit me up via PM and I may still have them kicking about . . . all my MC2300s are all now rack mounted.

It is so clean, it's unbelievable. Definitely pampered it's whole life. I paid a little more than market, but it came with shipping box, manual, and a spare set of blue meter glass. Come to think of it, I can take the shipping screws into the hardware store and get some smaller ones for feet. That is the plan. I will check the thread and look into the driver update kit. It seems like this has the new boards, but was never updated. I think I have read there should be a diode or something on the back.

I have not even opened up the bottom yet. I may bring it to a Mac tech to have it gone over, but I can do the simple component replacement stuff where needed in the meantime.
 
You may ask the seller to be SURE they do not have the original side rails. In many cases they will and simply have to remember where they put them.
 
You may ask the seller to be SURE they do not have the original side rails. In many cases they will and simply have to remember where they put them.

Yeah, no dice there so far. Bought it from a reseller in Denver. I will ask them to inquire with the original owner as it sounded like a regular customer of theirs.

One other question. One of the clips that holds the McIntosh badge on the faceplate is missing. Any ideas on a replacement? Is that a common part?
 
Yeah, no dice there so far. Bought it from a reseller in Denver. I will ask them to inquire with the original owner as it sounded like a regular customer of theirs.

One other question. One of the clips that holds the McIntosh badge on the faceplate is missing. Any ideas on a replacement? Is that a common part?

They're simple push on clips. This company has quite an offering: http://www.bakfin.com/
 
Shipping bolts are 1/4 X 20. Just picked up some screws that should work. I will have to drill out the feet I have to accomodate them though. They are the smaller style feet. I need to get some of the bigger ones for this, as well as my preamps and tuner.
 
I would check the value of resistor R17 ( located between the top hat heat sinks right above the diode) Lift one leg....can't remember if it should be 18 or 22 ohms.
 
Oh, almost forgot. McIntosh does sell a driver board update kit. The OOPS . . . I did it again thread below has info about that kit on pages 6 & 7.

Those boards have the upgrade. The black 'Flying Saucer' heat sinks are the giveaway. Those blue caps need to be replaced, as do mine.
 
Here is a Jpeg of an original driver board W/O the new heat sinks. (My upgrade kits have yet to be installed)
 

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Really enjoying the MC2300. Much more power than the MC7270 it replaced, driving JBL L250 speakers. It is however, not quite as detailed and the bass is not quite as sharp. I am sure a lot of this has to do with design, but I imagine that caps have dried up as I don't think it's been used very much over the years.

Recommendations on replacement caps, brands, where to buy, etc? This amp has some crazy values!
 
I'm sure that c_dk or some of the other techs can chime in here, but it's really uncommon for the big electrolytics on the MC2300s to dry up. Mc specs +/- 40 VDC for the rails for each channel. It's easy to measure that to see if you're close. I just checked my 3Y amp about a month ago and it was within .5V of spec for both +/- for each channel at below 120 VAC line voltage.

Popular fixes on these amplifiers are updating the driver boards (mainly for stability) and replacement of capacitors in the signal path. I've upgraded the boards in one of my units but never upgraded capacitors in the signal path of either.

It's certainly plausible that the MC2300 could give up a bit of ground on the bass as compared to the MC7270 as the MC7270 is a much newer design and nearly as powerful. twiiii will definitely concur on that. I had four MC7270s and never used any of them in a direct comparison with any of my MC2300s so that's something that only you can say with your speakers.

Have fun.
 
Before a recap you need to get after the one card causing a side to overheat.

The only reliable way I know how to really determine the need for a power supply recap is a stress test on the bench. Can it put out 450 or so watts at 30 hertz like it should at 1000 hz. Then you can see if the voltage sags......
 
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