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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Of curse!!
D118 was shorted, R193 its 10K same that R194
The operational have now the feeding volages.
And the amplifier have output, but sound distortioned. =(
May you help me plase?
D118 was shorted, R193 its 10K same that R194
The operational have now the feeding volages.
And the amplifier have output, but sound distortioned. =(
May you help me plase?
Does operating all of the pots and switches through their entire range make a difference?
If not, post a photo of the distorted waveform.
If not, post a photo of the distorted waveform.
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.
Check Q110. Confirm that it has two good junctions and is not leaking or shorted. You'll need to remove at least 2 legs from the circuit to check it.
Check Q107. If it's not defective, while it's out of the circuit, see if the amp will power up normally. Be careful (transistors clamped, current limiter inline...).
I remove Q107 and its ok too, no leaking or shorted.
without Q107 the amplifier it's the same. draw 0.8 amps and no output
without Q107 the amplifier it's the same. draw 0.8 amps and no output
Q110 was always in the circuit.
The test just was using or not Q107, but the result was always the same.
The test just was using or not Q107, but the result was always the same.
With Q107 out of the circuit, measure the DC voltage with the black probe on the emitter of Q110 and the red probe on the base.
Measure the DC voltage directly across the following resistors:
R133
R140
R142
R115
Measure the DC voltage directly across the following resistors:
R133
R140
R142
R115
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.
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