Today I'm working in one MTX 801D.
When is connected, the led don't turn on
The amp maintain drawing 1.6 AMP
the power source only produce 5-11 v + -
I disordering the 4 mosfets 75339p and are OK
No visible damage in all the amplifier
No shorts in the mosfets outputs or driver
the voltages in the TL494c:
1 0.2
2 4.6
3 0.06
4 1.1
5 1.5
6 3.4
7 0.00
8 10.8
9 0.00
10 0.00
11 10.8
12 11.1
13 5
14 5
15 5
16 0.0
the voltages in the LM339M:
1 4.8
2 4.8
3 11.2
4 5.045
5 6.7
6 3.3
7 5.045
8 1.1
9 3.45
10 4.8
11 3.45
12 0.0
13 0.0
14 4.8
May someone help me? Please
When is connected, the led don't turn on
The amp maintain drawing 1.6 AMP
the power source only produce 5-11 v + -
I disordering the 4 mosfets 75339p and are OK
No visible damage in all the amplifier
No shorts in the mosfets outputs or driver
the voltages in the TL494c:
1 0.2
2 4.6
3 0.06
4 1.1
5 1.5
6 3.4
7 0.00
8 10.8
9 0.00
10 0.00
11 10.8
12 11.1
13 5
14 5
15 5
16 0.0
the voltages in the LM339M:
1 4.8
2 4.8
3 11.2
4 5.045
5 6.7
6 3.3
7 5.045
8 1.1
9 3.45
10 4.8
11 3.45
12 0.0
13 0.0
14 4.8
May someone help me? Please
Sorry by the late response.
Now I can't install the software for mi USB scope in my new computer. (apparently doesn't exist driver for win 7 X64).
ok, lets continue...
I change caps near mosfets, resolder cool solders, and it´s alive again.
+ - 51 V.
but now have another problem.
When amp is running burn the D118.
I remove the 4 transistors for measure everyone and are now OK.
But continue burning D118 and R193 its hot too.
I see something rare, R193 its 10K, but when is soldering measure 2 ohms
Any idea where star to search?
Now I can't install the software for mi USB scope in my new computer. (apparently doesn't exist driver for win 7 X64).
ok, lets continue...
I change caps near mosfets, resolder cool solders, and it´s alive again.
+ - 51 V.
but now have another problem.
When amp is running burn the D118.
An externally hosted image should be here but it was not working when we last tested it.
I remove the 4 transistors for measure everyone and are now OK.
But continue burning D118 and R193 its hot too.
I see something rare, R193 its 10K, but when is soldering measure 2 ohms
Any idea where star to search?
I was working again on this amplifier.
the previous problem wasn´t in the transistor, was in the circuit board, the conductors under the transistor have little metal particles that was shorting, I remove the transistor, the resistor and clean the area, and now it's all fine.
The amplifier doesn't produce sound yet.
I found one operational amplifier with one lost feeding voltage.
Where should be producing this voltage?
the previous problem wasn´t in the transistor, was in the circuit board, the conductors under the transistor have little metal particles that was shorting, I remove the transistor, the resistor and clean the area, and now it's all fine.
The amplifier doesn't produce sound yet.
I found one operational amplifier with one lost feeding voltage.
An externally hosted image should be here but it was not working when we last tested it.
Where should be producing this voltage?
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My scope isn't ready yet.
In a visual inspection, I found R140 burned, I changed and the noise goes!!
But the audio goes too.
Now is drawing 0.8 ampere without audio.
I see differences in the feeding voltage from operational amplifiers:
and the amplifier:
In a visual inspection, I found R140 burned, I changed and the noise goes!!
But the audio goes too.
Now is drawing 0.8 ampere without audio.
I see differences in the feeding voltage from operational amplifiers:
An externally hosted image should be here but it was not working when we last tested it.
and the amplifier:
An externally hosted image should be here but it was not working when we last tested it.
this is the operational amplifier in which I have doubt
An externally hosted image should be here but it was not working when we last tested it.
With Q107 out of the circuit and black probe on the emitter of Q110
With Q107 out of the circuit and the black probe in negative terminal
An externally hosted image should be here but it was not working when we last tested it.
With Q107 out of the circuit and the black probe in negative terminal
An externally hosted image should be here but it was not working when we last tested it.
Last edited:
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