mmats dhc1400.05

[bikerboy87]

I bought a messed up mmats dhc1400.05 from a guy. It powers up fine has around 49 volts of rail voltage. The problem is it puts out very distorted sound and doesnt get loud, also makes the speaker pulse if i touch the rca jacks. i replaced the 4080 with one from a working amp and its still the same problem. checked the voltage on the speaker terminals is have about .450 DC idle and with sound it goes up to about 2 volts DC. never had much luck working on these 4080 amps so hoping someone could lead me in the right direction.

 

[Perry Babin]

Post the DC voltage on all pins of the 4080. Copy and paste the following:


Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:
Pin 17:
Pin 18:
Pin 19:
Pin 20:

 

[bikerboy87]

Pin 1: 37.2
Pin 2: 13.5
Pin 3: .261
Pin 4: 0
Pin 5: 6.71
Pin 6: 6.09
Pin 7: 1.72
Pin 8: 5.21
Pin 9: 5.22
Pin 10: 36.9
Pin 11: 30.08
Pin 12: 24.25
Pin 13: 6.45
Pin 14: 0
Pin 15: 13.54
Pin 16: 13.54
Pin 17: 0
Pin 18: 6.35
Pin 19: 24.67
Pin 20: 30.56

 

[bikerboy87]

i also just noticed the outputs are just 3710 not the z version and kinda looks like this amp has been worked on before. could that be the issue

 

[Perry Babin]

It could be if they've been replaced. The older non-z would work but the newer ones tend to cause problems. That said, the non-z version 'generally' only causes problems after the amp is power up and a drive signal is sent into it.

 

[bikerboy87]

Do the voltages on the pins of the 4080 look fine i noticed pin 7 lower than what others posted in other threads

 

[Perry Babin]

7 is lower than expected. It's generally about t he same as pin 6. When you measured the DC on the speaker terminals, did you measure across the terminals or from primary ground to the terminals?

Do you have a scope?

 

[bikerboy87]

I dont have a scope i stopped messing with electronics n jus came across this amp from this guy. I measured across the terminals

 

[bikerboy87]

i measured from the amp ground to the positve speaker terminal and i have 24.6 while the rail voltage is at 48.7