I've got a little work cut out for me here. I'm thinking either this amp suffered from reverse polarity, over voltage, or possible just the Pre-amp FET (BUZ11) overheated. Its got a small sync on it. This FET burned the board pretty good but seems the large traces can be easily reconstructed after cut-out. I'm planning on mounting the new single FET to the main heatsync afterward.
SO, I realize theres not much literature out there on these amps so here goes. The amp is using 4 powers supplies, but the power supplies won't start until the one BUZ11 on the Pre-amp board starts. After which, the main PSs supply the two B&O Icepower A1000 modules.
In previously servicing another one of these; I know the amp should power up with the IcePower modules removed. See reference thread a few months ago: Eclipse DA7232 - ICEpower 1000A?
I dont have that other amp any more.
The failed BUZ11 caused some trace lifting on the Pre-amp board, trace also burned up. Also a trace on the main PS board got hot enough to burn the topcoat but seems to be OK.
LM2574M +5.0 P+ is driving the BUZ11 FET. After figuring out the ground trace was required I can observe clean drive signal to the gate of BUZ11.
I'm at the point where I need to cut and then build-up, but I was wondering what D201 is? Its missing and I dont know what it should be. Anode source and Cathode to drain. Is this just a reverse polarity diode? 1n4004? Or perhaps HER105?
The other missing resistor is a 2w 1ohm which happened to be in a parts bag inside the amp.
Photos coming
SO, I realize theres not much literature out there on these amps so here goes. The amp is using 4 powers supplies, but the power supplies won't start until the one BUZ11 on the Pre-amp board starts. After which, the main PSs supply the two B&O Icepower A1000 modules.
In previously servicing another one of these; I know the amp should power up with the IcePower modules removed. See reference thread a few months ago: Eclipse DA7232 - ICEpower 1000A?
I dont have that other amp any more.
The failed BUZ11 caused some trace lifting on the Pre-amp board, trace also burned up. Also a trace on the main PS board got hot enough to burn the topcoat but seems to be OK.
LM2574M +5.0 P+ is driving the BUZ11 FET. After figuring out the ground trace was required I can observe clean drive signal to the gate of BUZ11.
I'm at the point where I need to cut and then build-up, but I was wondering what D201 is? Its missing and I dont know what it should be. Anode source and Cathode to drain. Is this just a reverse polarity diode? 1n4004? Or perhaps HER105?
The other missing resistor is a 2w 1ohm which happened to be in a parts bag inside the amp.
Photos coming
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I decided to use HER105 seeing as it will be connected between source and drain and its a high frequency device. Here is the remote setup for the new IRFZ44. Will monitor of course and make adjustments to Gate at R201 or pulldown R207 which are both 330ohm.
Plenty of tidy spots to main sync mount that FET.
Plenty of tidy spots to main sync mount that FET.
Attachments
Ok not working well here. I need a new LM2574m+5 now because the drive signal is now pegging at 13vDC.
Also I’m thinking the primary transformer winding is burned as well. Has signs of overheat, gets hot.
Also I’m thinking the primary transformer winding is burned as well. Has signs of overheat, gets hot.
I rewound this transformer as follows:
Secondaryies
Left post to Mid-Left post: 36 turns of 26ga Clockwise
Right post to Mid-Right post: 36 turns of 26ga clockwise
Primary
Left post to Right post: 20 turns of 22ga Clockwise
Also the IRFZ44n wasn't going to work as it was instantly overheating. I used IRF540N and it runs ice cold.
Another note on this amp, I made mention that it would power up without Icepower modules installed but that is actually incorrect. The amp needs at least ONE Icepower module to power up fully.
Once powered, referencing B-; RCA shields have ~0vDC on them. Speaker terminals have +35vDC on them referencing B-. Of course across them is zero. This is normal for this amp. Secondary ground is somewhere on the Icepower module. I didn't need to find it.
This amp should come back together once I secure a permanent mount spot for the IRF540N.
Secondaryies
Left post to Mid-Left post: 36 turns of 26ga Clockwise
Right post to Mid-Right post: 36 turns of 26ga clockwise
Primary
Left post to Right post: 20 turns of 22ga Clockwise
Also the IRFZ44n wasn't going to work as it was instantly overheating. I used IRF540N and it runs ice cold.
Another note on this amp, I made mention that it would power up without Icepower modules installed but that is actually incorrect. The amp needs at least ONE Icepower module to power up fully.
Once powered, referencing B-; RCA shields have ~0vDC on them. Speaker terminals have +35vDC on them referencing B-. Of course across them is zero. This is normal for this amp. Secondary ground is somewhere on the Icepower module. I didn't need to find it.
This amp should come back together once I secure a permanent mount spot for the IRF540N.
Attachments
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The PS is a flyback and the voltage was exceeding that of the Z44.
Use a binder clip to hold it on the metal heatsink that bridges the two modules.
Use a binder clip to hold it on the metal heatsink that bridges the two modules.
The original buz11 has a lower rating than the z44. Maybe that’s why it failed. I also recall the last amp from a few months ago; that part ran hot but wasn’t a failed point. Perhaps irf540n is the way to go.
Are you sure that the BUZ11 was the original (OEM) in this amp?
Did you look at the gate and drain waveforms to see what was happening between the two treansistors?
It's odd that, if the voltage wasn't an issue, that a transistor with a higher RDSon would run so much cooler.
Did you look at the gate and drain waveforms to see what was happening between the two treansistors?
It's odd that, if the voltage wasn't an issue, that a transistor with a higher RDSon would run so much cooler.
