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Old 13th August 2014, 02:54 PM   #1
kfx5050 is offline kfx5050  United States
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Default Mtx ta81001 resistor problem

Can someone help me out on a repair? Have a mtx ta81001 have 5 off them fix 4 of them.but the fifth one is giving me trouble. Resistor r147 and 148 burn up as soon I apply power to the remote input on the amp.do anyone know what might be my issue or hack fix the problem. I also can post pictures if the bord parts if any needs help replace a burnt part.
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Old 13th August 2014, 10:41 PM   #2
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Post the resistance of R318 and R319 near the RCA op-amp.

Does it burn the resistors if you disconnect the preamp board?
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Old 14th August 2014, 12:10 PM   #3
kfx5050 is offline kfx5050  United States
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Yes it burns the resistors. R318 is 1.000 kohms and R319 showing .991kohms
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Old 14th August 2014, 08:18 PM   #4
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Those are 100 ohm resistors so they have failed. That generally indicates that the voltage regulators have failed. Have you replaced all of the failed components around the two regulators?
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Old 14th August 2014, 08:42 PM   #5
kfx5050 is offline kfx5050  United States
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No. I only replace them two RESISTOR. R147 and R148 I dont see any ather burnt components. Where are the voltage regulatory at?
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Old 14th August 2014, 10:19 PM   #6
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Those large resistors and all of the components in the immediate area form the voltage regulators. The transistors and SMD diodes won't generally have any visible signs of damage. Some of the smaller resistors have visible damage when they fail but you often need a magnifying glass to see it. The transistors clamped to the heatsink (likely IRF540) may also be damaged. The negative regulator may have additional components near the opto-couplers.

You should also know that there is likely extensive damage to the preamp board.

Do NOT apply power to the amp without having all components tightly clamped to the heatsink.

If this amp drives the fans from the positive regulator and it has failed as well, all fans will likely need to be replaced.
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Old 14th August 2014, 11:08 PM   #7
kfx5050 is offline kfx5050  United States
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Ok. I replace all the irf540 on the side where the Rca jacks are at. So I need to replace both side?
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Old 14th August 2014, 11:14 PM   #8
kfx5050 is offline kfx5050  United States
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If I power up the amp woth out the irf540 that's right in fornt of the two resistor they dont blow. But onces k soldier on in them two blow.
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Old 14th August 2014, 11:22 PM   #9
kfx5050 is offline kfx5050  United States
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I will by some replace parts and see what happens. Will keep you posted
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Old 14th August 2014, 11:25 PM   #10
kfx5050 is offline kfx5050  United States
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But the fans do works. If the power left hook up and I unhook the remote wire after about 2 mins the fan kick on
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