Your best bet might be to send just the boards to Audio Classics to be updated and tested for you.
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New to me MC2300, replaced driver board
- Thread starter jweaverfl
- Start date
I was able to get reviews these newly built boards previously linked are good quality. But also putting in the original boards causes the same issue. So I’m not sure where the fault is that I’m chasing now.
WIll you please re-write this? I’m trying to figure out what you’re calling an “output capacitor”, and what heatsink hits the power transformer, etc. I have to assume that you mis-typed a few things here.
So sorry brain isn’t working and honestly still learning and mixing up terms. I meant output transistor. Seemingly I solved this issue as one of the wires from the film capacitor bank had a break in insulation and was ever so slightly touching the heat sink only when moved.
Currently still getting a spark from only one side of the film capacitor connections on startup. Seemingly mainly the left side but sometimes also the right side where circled in photo. Seems to have a small spark between the rivet and plate. What would cause this? I cleaned the connections but should I drill out the rivet and put a nut and screw connection on this?
Forgot this photo
Attachments
WHen you say "film capacitor" are you talking about the large round blue capacitors in your picture? If so, those are filter capacitors; they are eletrolytics, not film.
There's a LOT of inrush current when you first turn on that amp to charge up those big capacitors. Not sure if there's enough space between that board and the chassis; if it shorts to the chassis that's really bad. You could try removing the board and re-peening the rivet, or soldering the u-shaped piece with the wire connectors to the piece that goes to the capacitor screws.
There's a LOT of inrush current when you first turn on that amp to charge up those big capacitors. Not sure if there's enough space between that board and the chassis; if it shorts to the chassis that's really bad. You could try removing the board and re-peening the rivet, or soldering the u-shaped piece with the wire connectors to the piece that goes to the capacitor screws.
Yes that is correct. Sorry for my error. I just replaced these and cleaned the board but on the left side specially where the rivet meet the U shape metal and the flat metal that the filter cap connects to is still sparks on the backside on startup and makes a tiny “squeak”.
What actually causes this to happen?
A bad connection. As I said there's a LOT of inrush current charging up those capacitors when you turn it on, if there's a bad connnection you could see sparks at that point. Is the connection getting hot? Those spade connectors might have lost their spring. They should be quite difficult to pull off; usually you need to grab the stem with a pair of pliers and pull them off. If they slide on and off easily they should be replaced or squeezed just a LITTLE bit so they make better contact.
Gotcha, it's only on turning the amp on. I did clean the plate best I could but I wonder if it is tarnished too far. I was mainly concerned something else down the line is wrong and causing it to spark at that joint, would soldering the rivet itself be advised? I do notice this one moves slightly and wiggling (the rivet connection istelf).
If it’s loose, from the look of the metal I expect that there is corrosion between the pieces of metal.
I’d disassemble, drill out the rivet, clean it all up and bolt it together clean.
I’d disassemble, drill out the rivet, clean it all up and bolt it together clean.
sorry to dig up this post but, can I ask how much the replacement cost?
Luckily I still have the old emails. I ordered them from Brian Scott in McIntosh parts department in 2016 and they were $150 each.
(Yikes - 2016 was more than a couple years ago...)
(Yikes - 2016 was more than a couple years ago...)
damacman
Resident Psycho
McIntosh no longer offers them nor does Audio Classics. I also have a pair of the McIntosh reissue boards that I bought in 2009. (Gayle used to assemble these.) I got only 12 years of service from them. Nobody at McIntosh service was able to shed any light on a problem which arose with one that caused the channel to go into oscillation. This problem is wildly unpredictable and much fun when it oscillates at full power! I can pull that board and drop in an original out of another unit and the amp works perfectly.
After two years, I'm done. I have a pair of the new boards from the eBay seller on the way - should be here this week. News to follow.
What replacement did you go with?