PPI Powerclass PC2350 (Grey) H-Bridge issue?

[Dr Zeus]

I have a prestine show-car condition amp on my bench for a customer. This amp is of course using SG3525 with HIP4081 in H-Bridge.

It won't power up. The current draw is 0.1A.

The SG is putting out clean drive on pins 11 and 14:
Just for good measure;
SG3525
1: 0.139
2: 2.585
3: 0.022
4: 0.176
5: 2.067
6: 3.783
7: 2.062
8: 4.92
9: 6.04
10: 0.002
11: 5.77 (Square wave)
12: 0.002 (GND)
13: 13.41
14: 5.74 (Square wave)
15: 13.41
16: 5.19

No BJTs/FETs are measuring shorted. Board looks perfect. Hesitant to remove it from the sync atm.

Absolutely zero drive at the PS fets.
Should I measure the pins of the HIP4081? Another component? Or is this amp a 'bust'?

Octopart search for HIP4081: HIP4081 | Octopart

 

[goviboo]

I m not sure if you read this thread, it has some useful info - checking the drive waveforms.

PPI PC21400.2

 

[Dr Zeus]

Thanks didn't think to search that amp.

 

[Dr Zeus]

So that amp I think has a few different component labels as there may be some mismatched parts. This amp is not using 2n64xx transistors anywhere as well. I'm guessing just different amps mostly. That being said the PS is likely the same.

He mentioned he found several diodes shorted. I checked -ALL- diodes in this amp and none are shorted/open. In fact all from what I can tell are checking -ok- in curcuit.

Here are the voltages on the HIP4081s.

U3
1: 13.64
2: 0.407 (Square wave from the SG through a resistor)
3: 0.001
4: 0.001
5: 0.407 (Square wave from the SG through a resistor)
6: 0.407 (Square wave from the SG through a resistor)
7: 0.407 (Square wave from the SG through a resistor)
8: 0.001
9: 0.001
10: 13.64
11: 13.26
12: 13.64
13: 0
14: 0
15: 14.03
16: 14.03
17: 0
18: 0
19: 13.64
20: 13.26


U9
1: 13.64
2: 5.98 (Square wave)
3: 0.001
4: 0.001
5: 6.01 (Square wave)
6: 5.98 (Square wave)
7: 6.01 (Square wave)
8: 5.09
9: 5.09
10: 13.52
11: 13.28
12: 13.64
13: 0
14: 0
15: 13.83
16: 13.86
17: 0
18: 0
19: 13.63
20: 13.29

Is the delay start working? Looking that up now...

 

[Dr Zeus]

Its odd that I'm not seeing any waveforms on pins 11-14 and 17-20, while I do see square waves from the SG on pins 2, 5, 6, 7. Makes me thing either these HIP4081s have failed, or something is keeping them from producing any drive.

 

[Dr Zeus]

I found R79 and R172 burnt looking. They're both 10 ohm 1/4w. Both connect from +12 through a diode (36?44? CR18 & CR 31) and then to pin1 of U9 4081, and pin10 of U3 4081. The resistors are still w/i tollerance but something was not cooperating well here-in.

I spoke with the owner, asked him Qs about his setup. He has 1 battery up front with a transfer switch, and 3 batteries in the rear. All Pb, 12v batteries. He said the system/setup was so old, that 2 of the 3 batteries in the rear were stone cold dead (Dead cells?) and so likely this amp suffered severe under-volt/under-amp. He said it wouldnt even turn on after the car sat for a very long long time. He said his other smaller PPI PC amps are now working fine, but this one obviously not.

So, I'm targeting replacing these HIP4081AIP<Z> at this point. Very voltage sensitive I hope.

 

[Perry Babin]

It's odd that you have different voltages on the inputs of the 4081s. Recheck.

 

[Dr Zeus]

Hey Perry,

The output of the SG is good which is about a 13v clean square wave. The 2k resistors are well connected. I have square waves on all HIP4081 inputs, but U3 has a very very weak signal on it's inputs. Either the U3 IC or something else is driving that signal down.

I'm going to take the board out of the sync.

 

[Perry Babin]

Order sockets for the 4081s if you have to replace them.

 

[Dr Zeus]

Thanks for the tip. I removed both HIP4081s and found input pads had great signal from the SG. Time to order new 4081s. I also replaced R79 and R172 10ohm.

 

[Dr Zeus]

New hip4081 ics did the trick. Amp working great on the bench.