Bad caps and fets in Hifonics mono amp

[KriszXJR]

pin 7: 94mV
Au-in: -9,9V

 

[Perry Babin]

Do the two resistors with -9.9v connect directly to the au-in pad? If so, what is the voltage on the legs that are not directly connected?

 

[KriszXJR]

Directly connected to au-in pad the R78, R65 and R68.
R78 another leg voltage: -9,7V
R65 another leg voltage: 90mV
R68 connect two 5,6kohm common point (-42,5V), and this resistors go to SP-L (-4V) and SP-R (-85V) pads.

 

[KriszXJR]

I desoldered R68 leg from au-in.
The 4V dc on speaker terminals too.

 

[mbates14]

Check your TVS suppression circuits near the output toroids, these amps love to munch those when the outputs fail.

Also, I dunno about the rest of the people here, but I had poor results when using mis-matched outputs like that. I tend to always match them up, I even go overboard and match them all the way around, even by batch.

 

[KriszXJR]

Do you know what type this diodes?
Only i see KE200...

 

[mbates14]

Thats because its P6KE200A or something of that nature.

Test it, it shouldn't be shorted.

 

[KriszXJR]

Thats because its P6KE200A or something of that nature.

Test it, it shouldn't be shorted.

Thanks!
That was the problem.
Speaker output 0V.

 

[KriszXJR]

I re-installed the driver board, and the amp was working.
But when I connected the speaker the new fets and 15A fuse blown. No protect.




Does anyone have schematic about the power section? (BXi 4000 D)

 

[KriszXJR]

I replaced the output fets (IRFP4229), TVS circuits, 21844s, 1D and 2D smd transistors, TL072 and LMs on audio driver panel. Working, but the sound is lower than normaly. And the speaker crackle about a quarter of the volume.
Anyone have an idea?

 

[tiomilo]

check +/- 15 volts, and those TL072 and LMs you have change, must be around preamp section the faulty. distorted sound and low sensitivity respond to preamp section.

 

[KriszXJR]

+/- 15V ok. TL072 and LMs are new.
How can I verify the correct operation of the preamp? (without scope)

 

[timwebb]

the input and output should be close if i remember right

 

[KriszXJR]

I replaced all NE5532p, but nothing ....
(volume is lower than normal, and the speakers crackle after about a quarter of the volume)
Driver board problem?

 

[tiomilo]

Probably a bad cap too. But is rare.

Sent from my GT-I9300 using Tapatalk

 

[nonprof]

+/- 15V ok. TL072 and LMs are new.
How can I verify the correct operation of the preamp? (without scope)

How about take out the output of pre amp and feed it to another small amplifier? or an aux in of your home hifi system? at that point you will know your pre amp output signal.

 

[nonprof]

I replaced all NE5532p, but nothing ....
(volume is lower than normal, and the speakers crackle after about a quarter of the volume)
Driver board problem?

Can you please replace the coupling electrolytic capacitor between opamp ICs?

 

[KriszXJR]

Someone please tell me the value of:
CL2, CL3
L2, L3
C3, C8
C4, C11
or schematic from board?

 

[bl4ckw1d0w]

I have the same board in a xx thor, I can get you those values when I get to the shop today.

 

[KriszXJR]

I have the same board in a xx thor, I can get you those values when I get to the shop today.

Thank you, that would be good!