I have an Alpine MRX-V70 amplifier here in front of me that turns on momentarily when remote voltage is applied but then dies a second later.
For that second I get:
+ and - 28v on rectifier and proper voltages at regulators.
Gate voltage up to +3.6v on power supply FET gates.
No DC voltage higher than 0.8v on any speaker terminal.
No significant current draw from main supply.
Can someone tell me what I need to check? There is nothing obviously or visibly damaged. Added a picture of the board for reference. If a closeup of any particular area is necessary then let me know.
For that second I get:
+ and - 28v on rectifier and proper voltages at regulators.
Gate voltage up to +3.6v on power supply FET gates.
No DC voltage higher than 0.8v on any speaker terminal.
No significant current draw from main supply.
Can someone tell me what I need to check? There is nothing obviously or visibly damaged. Added a picture of the board for reference. If a closeup of any particular area is necessary then let me know.
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OK, checked again. On the four midrange channels there is a brief pulse up to almost 1.2v before the amp shuts down. I did find however that the 5th channel shows rail voltage (26v) on the + terminal until the amp shuts down.
Does this suggest shorted output transistors for the 5th channel? I have not removed the board from the case yet so I am not sure what it looks like...
Does this suggest shorted output transistors for the 5th channel? I have not removed the board from the case yet so I am not sure what it looks like...
So I took the board out of the heatsink and removed the output inductors for the sub channel. The amp now powers up and remains on with +and - 26v rail voltage. All four midrange channels plays clean and clear audio.
I assume I need to replace the outputs and possibly driver ICs for the 5th channel. Any advice regarding whether there is something else to check, where to get the parts, and how to perform this repair will be appreciated.
I assume I need to replace the outputs and possibly driver ICs for the 5th channel. Any advice regarding whether there is something else to check, where to get the parts, and how to perform this repair will be appreciated.
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So Q3751 is shorted. It is a IRF6662 smd transistor. I assume a hot air rework station is required to replace this part? The terminals are underneath the housing like a turtle in its shell.
I am not likely going to purchase this transistor, a hot air tool and possibly the driver ICs just to fix this sub channel. Is it possible to replace this style transistor with a different style to attempt to get this sub channel functional?
I am not likely going to purchase this transistor, a hot air tool and possibly the driver ICs just to fix this sub channel. Is it possible to replace this style transistor with a different style to attempt to get this sub channel functional?
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You're stuck with that type transistor.
The driver IC often fails when the outputs it's driving fail.
One problem with these transistors is that the inner part is soldered to the case. IT will often shift around when you solder. The easiest way I've found is to use solder paste with hot air. Solder the transistor down with kapton tape, leaving the sides open so hot air can flow under the edges of the case. With kapton tape, you may be able to use a regular soldering iron, heating through the tape,
The driver IC often fails when the outputs it's driving fail.
One problem with these transistors is that the inner part is soldered to the case. IT will often shift around when you solder. The easiest way I've found is to use solder paste with hot air. Solder the transistor down with kapton tape, leaving the sides open so hot air can flow under the edges of the case. With kapton tape, you may be able to use a regular soldering iron, heating through the tape,
Can I use it as a four channel amplifier without causing any problems or further damage?
I will have to source and order the output transistors and driver ICs if I am to fix the 5th channel. I am able to locate the transistors but not the driver ICs, not even at PacParts. Any idea where to get those ICs? They say Anaview.com C1 138P on them.
I will have to source and order the output transistors and driver ICs if I am to fix the 5th channel. I am able to locate the transistors but not the driver ICs, not even at PacParts. Any idea where to get those ICs? They say Anaview.com C1 138P on them.
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I don't have anything on this amp but looking at the V60 manual (may or may not be the same as this amp), the pin out for the IC is the same as for the M500. The M500 IC is the IRS20956. Search the forum for that part number.
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