Thoughts on 1/2 and 1/2 M2/AlephJ monoblocks

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Been thinking about my conversion of M2 and AlephJ amps into mono blocks. The change results in each amp modded to contain one M2 board and one AlephJ board, with a heavy duty switch sending the power to one or the other.

All in all, it was a great change, both amps improved over their stereo single amp versions. Down points is the fact that obviously the two amps could not be used in two different systems, at the same time. A slight pain as I run several systems at home.

The other pain that occurred recently, was failure of one of the amps power supply. The amps being in mono block configuration, this failure took TWO amps out of service!

Thinking about this, I believe I will reconfigure the switch and amps like this:

Put both M2 boards back in the M2 and the same with the AlephJ...the switch will now determine if both channels or only one channel is powered up.

Like this I can use them as mono blocks like the 1/2 and 1/2 version, but flipping the switch would let them operate in stereo. Now they could be used in two different systems (switched to stereo), and failure of one wouldn't put both out of service.

Russellc
 
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It ran for a couple years or so and I've bought lots of Antek. So all in all I have received pretty good value. I just bought another of their 500 VA units.

Shoot, I'm not positive it is the transformer, but that's where the smart money bet is I'm thinking. Even if it turns out something else, this transformer will get used somewhere.

Russellc
 
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Almost have M2 put back together as stereo amp. I'm using one of the A-L transformers until the replacement Antek arrives. fire up should be tonight, same power supply and rectifiers. I anticipate it will work fine, then I will put them back in mono block form.

I do plan on first fire up to not have rectifiers connected to the power supply, and will measure DC voltage coming off of them. Then on to hooking up power supply boards and go again.

If it repeats the same fail mode, I will replace rectifiers and re try. At that point if fails again all that's left is the power supply board and the caps on it.

Russellc
 
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"I do plan on first fire up to not have rectifiers connected to the power supply, and will measure DC voltage
coming off of them. Then on to hooking up power supply boards and go again."

Check the diodes first with your DVM diode test function.
Even if you have a true rms DVM, it will measure the average, not the peak. The capacitor bank holds up
the rectified voltage to near the peak. Without that, it will not be pure DC, just a full wave rectified sine.
Instead of say 25VDC, after rectification but without capacitance, you then will get a voltage reading of
25V x 0.707 = 17.7 Vrms on your DVM.
 
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I was only going to do this to prepare for failure event. If one of the diodes are bad, assuming trans will again hum. Voltage as long as symmetrical and in approximate zone is what I'm looking for.

If voltage like that, will hook up cap board and retry.

I think it is transformer failure, but going forward with caution. I expect to see no problem, but have been wrong before and could be again.

Russellc
 
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Probably, first I want to eliminate the other causes. I have never had one fail before, but I have heard of a few here post about it, but I think theirs was bad from the get go.

Restart with variac, eliminate rectifier bridges first, then cap board. If all passes, that leaves only the transformer. I am replacing it anyway, but if it proves OK, it will get used.....of course that would mean this whole thing was just a gremlin. It will work itself out.

Russellc
 
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