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COntinued from elsewhere...
With the stuff out of the box, I lay it on the bench looking at the rear. A few screws removes the rear panel. Looking down inside, the power amp module is in front, the PS in rear. Note where they go and pop the wires off the speakons board so the rear panel can be moved more easily. A few screws free the power amp thing. I found enough slack in the wires to flop the module outside the metal chassis, and then I put the rear panel back in place and stuck one screw in it lightly to keep it from moving around. The power amp wires are now "pinched" between panel and chassis wuth the power amp outside. It sits on the bench in front of me. Like the thing is disembowelled. Mixer is to my left. Actually the mixer is propped up with a signal plugged into a channel, and I can reach around there and diddle the volume and also press the power switch. One little piece of cover stayed around the cable, so I kept it out of the way best I could.
The cover comes off the power module, but it is clumsy. Note the wire dress along the rear panel.
Now I can connect a load straight to the PA outs with clip leads, no relays to concern with. I'd check for DC first I guess. No load required. These are digital amps by the way. SO don't look for nice analog waveforms throughout.
Check for power rails. The blue and red wires are obvious, plus I think there is a +15VDC for the ICs.
The unit I had made no output but had mixer action. I found a blown channel. I would power yours down and just measure the outputs for shorted. They are IRF640 and IRF9640 inTO220 - Digikey or Mouser. I think I used a cross for the 9640 from Mouser. Not NTE, just a different maker so it was something like SDP9640, I firget the letters. Also the reason it was not drawing current was the 0.1 ohm ballast resistors were also open on the bad channel. These are little metal film resistors on end with a piece of shrink tube around them, easy to spot. Note each pair of outputs has another TO220 something between them. SO make sure you are checking the MOSFETS and not the other thing.
My experience with these things has been blown MOSFETs and cracked connections. The rest of it seems to be pretty reliable. I had one power module on a PMH5000 - single channel power amp modules, two of them - that had an internittant loss of out, could flex the board for it. Never found it. could have been a cracked via or maybe an internal layer of the pcb. Spent forever agonizing over it. I finally asked if they had modules in stock. Then they told me my cost: $17.50. FOr the whole damned powr amp module!!! I spent hours and hours trying to fix a $17 module I could have replaced. MSRP is $55, so there is a good markup. $17.50 later, the PMH5000 was on its way.
The PMH660 module is dual channel. No idea on cost. Not much I bet. COmsidering the whole mixer sells for $250, I suppose I shouldn't expect the parts to cost a ton.
With the stuff out of the box, I lay it on the bench looking at the rear. A few screws removes the rear panel. Looking down inside, the power amp module is in front, the PS in rear. Note where they go and pop the wires off the speakons board so the rear panel can be moved more easily. A few screws free the power amp thing. I found enough slack in the wires to flop the module outside the metal chassis, and then I put the rear panel back in place and stuck one screw in it lightly to keep it from moving around. The power amp wires are now "pinched" between panel and chassis wuth the power amp outside. It sits on the bench in front of me. Like the thing is disembowelled. Mixer is to my left. Actually the mixer is propped up with a signal plugged into a channel, and I can reach around there and diddle the volume and also press the power switch. One little piece of cover stayed around the cable, so I kept it out of the way best I could.
The cover comes off the power module, but it is clumsy. Note the wire dress along the rear panel.
Now I can connect a load straight to the PA outs with clip leads, no relays to concern with. I'd check for DC first I guess. No load required. These are digital amps by the way. SO don't look for nice analog waveforms throughout.
Check for power rails. The blue and red wires are obvious, plus I think there is a +15VDC for the ICs.
The unit I had made no output but had mixer action. I found a blown channel. I would power yours down and just measure the outputs for shorted. They are IRF640 and IRF9640 inTO220 - Digikey or Mouser. I think I used a cross for the 9640 from Mouser. Not NTE, just a different maker so it was something like SDP9640, I firget the letters. Also the reason it was not drawing current was the 0.1 ohm ballast resistors were also open on the bad channel. These are little metal film resistors on end with a piece of shrink tube around them, easy to spot. Note each pair of outputs has another TO220 something between them. SO make sure you are checking the MOSFETS and not the other thing.
My experience with these things has been blown MOSFETs and cracked connections. The rest of it seems to be pretty reliable. I had one power module on a PMH5000 - single channel power amp modules, two of them - that had an internittant loss of out, could flex the board for it. Never found it. could have been a cracked via or maybe an internal layer of the pcb. Spent forever agonizing over it. I finally asked if they had modules in stock. Then they told me my cost: $17.50. FOr the whole damned powr amp module!!! I spent hours and hours trying to fix a $17 module I could have replaced. MSRP is $55, so there is a good markup. $17.50 later, the PMH5000 was on its way.
The PMH660 module is dual channel. No idea on cost. Not much I bet. COmsidering the whole mixer sells for $250, I suppose I shouldn't expect the parts to cost a ton.
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