M44 board opinion...

[NotDeafYet]

I got a newly acquired M44 delivered today. Great job on the packaging by the sender - NOT; got a damaged rca input jack... could of been worse, but it's still Ok. That aside.. I examined the board, and noticed a spot on it that I am concerned about.. what do you gurus think? I'm noticing a heat related board discoloration and the little caps in the area seem to have age/heat related heatshrink wrap issues. I'm guessing I'll need to recap the main caps, as well as these little guys. The discoloration near the diodes/resistors/whatnot in the area are my main concern.

[trickyricky]

Those large 2-3watt resistors get extremely hot, so the shrink tubing on the caps melts or shrinks. There's a simple mod for that, I believe Eric has shown it in his website. But its as simple as replacing those resistors with 5watt-ers and raising them about 3/16 to 1/4 inch off the board. Then replacing those capacitors with heat damage with new ones same values and lean them away from the resistors.

The last picture just shows a revision done by the factory...perfectly normal and fine nothing to be concern about unless you didn't see it lol.

Good thing about those RCA is that they are available unlike the "balanced" jacks for the ZX and Ti lines that have vertical RCA jacks.

[NotDeafYet]

The RCA jacks, it's the plastic casing that got chipped in 2 pieces.. I heard them flinging around in the amp when I unpackaged it. The jacks are still pretty sturdy.

The last pic, it shows the discoloration the best. You're saying I should worry about that part at all??

The first pic, so the fix is replace the caps and lean them away, up the fat resistor to 5watts and raise it from the board, ok. I shouldn't be worried about the other parts and the board discoloration?

[NotDeafYet]

Actually, the seller is going to take back her amp. I think I'd rather do that, than deal with the amp servicing issues!

But one thing I did notice, is a difference of where the speaker leads were connected on the board.

The right side speaker terminals, on this recently acquired M44, the leads inside the amplifier were connected to the board +, -, +, - .. from the center of the board to the right. The other M44 I had for reference, it's inside terminal leads were -, +, +, -. I don't know if any of you can picture how I am describing what I'm asking for properly... which one is wired properly?!

I'm back shopping for another M44.

[kg1961]

Think that is normal for m44 board outputs
Check the forum yes the u it has failed not sure but looks easy to fix good luck

[NotDeafYet]

Think that is normal for m44 board outputs
Check the forum yes the u it has failed not sure but looks easy to fix good luck

Huh?

I think it matters how the leads inside the amp are plugged in on the board - when running in bridged mode! Which is what I plan to do, which is why I need to know which amp is "wired" properly. I can't see either amp being wired properly, but differently!

[trickyricky]

Think that is normal for m44 board outputs
Check the forum yes the u it has failed not sure but looks easy to fix good luck

Huh?

I think it matters how the leads inside the amp are plugged in on the board - when running in bridged mode! Which is what I plan to do, which is why I need to know which amp is "wired" properly. I can't see either amp being wired properly, but differently!

One channel is inverted so when bridging you use the ones that are not signal ground. Which is usually the two outer ones, one easy way to check is with your DMM in continuity and if you have a short (0ohm) between any of two terminals then those are your signal ground terminals (do not use those). I'll draw up a picture if needed, hard to explain with a headache.

But the discoloration is perfectly normal, shows that it has been used. Any M44 you buy will require the mod's I mentioned so don't expect to find another M44 without any heat distress on the same spots/areas. Unless of course it has been serviced by someone who knows about these mods.


In attached picture you can see that the green wires all come from the same location (signal ground) these are not used when bridging, only the two outer red wires. If the amplifier you aquired was wired like in the picture then there was nothing weird or wrong about it.

[Eric D]

On the M44, there are 8 speaker connections. If you look on the board, there are two groups of two near the large capacitors. These are all grounds, and go to the inside two pins of each of the two speaker barrier strips. The remaining outputs are near the large red output filter coils. Each goes to a barrier strip pin in order of how they go across the amplifier. The left most connection goes to the left most barrier strip connection. The next connection (by the coil) in from the left goes to the last remaining connection on the left side barrier strip. Now that barrier strip is full. The right most connection (by the coil) goes to the left most barrier strip connection on the left most barrier strip. Now the only one remaining goes on the only pin remaining. The reason the labeling is the way it is, is because in order to bridge the amplifier, one channel from the front, and one from the rear are inverted 180 deg in phase. This allows them to add together, but you need to connect your wires backwards so your speakers still good if you are running all 4 channels on their own. This is normal for almost every bridgable amplifier made by any manufacturer.

Aside from the broken RCA jack, all the other issues on this amp are normal service on an M44. If you buy a different one, you will still have to address these issues, unless a previous owner did for you.