Hifonics GEN X Zeus

[mike49504]

Im in the process of rebuilding 1 of theese amps again since this one came in with no outputs or power supply fets in the board and alot of other stuff missing.

My question is the outputs that are being used in this amp are 2SA1302 and 2SC3281 how do i figure out what outputs go in what locations?

 

[Perry Babin]

What rectifiers are they using?

Are the emitters of all of the outputs in each channel directly connected (less than 1 ohm)?

 

[mike49504]

The rectifiers they are using is FES16JT

All of the emitter resistors are connected together for each channel . I measured from 1 emitter to the last 1 in circuit and get 0.3 ohms

 

[Perry Babin]

Find the rectifiers that have their right leg that read 0 ohms to the non-bridging speaker terminals. The left leg of those rectifiers will connect to the center leg of the NPN output transistors.

If you power the amp up before reinstalling the outputs, you can check the voltage on the center solder pads for the outputs. The NPN transistors will have positive rail voltage on the center pads. The PNP outputs will have negative rail voltage on the center pads.

 

[mike49504]

Ok back to this amp. I replaced all power supply fets, and outputs and a few transistors.

AMp doesnt produce rail voltages or regulated voltages. Heres what i have on the TL494 and the LM324

TL494
1:3.30
2:9.24
3:9.70
4:3.01
5:7.91
6:8.94
7:3.76
8:13.92
9:2.78
10:2.78
11:13.92
12:13.13
13:10.29
14:10.28
15:10.28
16:2.91

LM324
1:0
2:11.72
3:0
4:13.20
5:0
6:6.59
7:0
8:0
9:12.10
10:8.78
11:0
12:12.04
13:6.60
14:11.89

Any ideas on what to check for next?

 

[Perry Babin]

You need to determine why pin 7 doesn't read 0.0v DC. It should be directly connected to ground.

 

[mike49504]

Replaced a couple transistors and heres what i have now. AMP still isnt producing rail voltage.

TL494
1:2.16
2:2.14
3:3.08
4:0.22
5:1.45
6:3.44
7:0
8:13.88
9:0.93
10:0
11.93
12:13.02
13:4.92
14:4.92
15:4.93
16:10.98

LM324
1:11.68 then 0
2:11.68
3:12.01 then 0
4:13.68
5:11.33
6:6.52
7:11.28
8:0
9:11.92
10:8.68
11:0
12:11.99
13:6.54
14:11.85

 

[Perry Babin]

You need to follow the circuit back from pin 16 to see what's driving it high.

 

[mike49504]

Could it be possible i have a bad 494 If i tap it lightly the amp will come on and produce audio and the voltages on the 494 are correct. Then after 1 min it goes dead again and if i tap it it will work again I reflowed the solder to all pins but i have the same issue

 

[Perry Babin]

It's possible but unlikely if the voltage on pin 16 is changing. Do any of the voltages on the 324 change when pin 16 goes low?

Did you determine what was driving pin 16?

 

[mike49504]

I lifted the 494 off the board and found a broken trace under it and amp powers up and plays fine now.

 

[Perry Babin]

Was it on pin 16?

 

[mike49504]

NO pin 7 Amp was working now its doing it again. Pin 16 is high i tracked it back to a diode (1n4148) im gonna lift 1 side and check for leakage.

 

[Perry Babin]

That was the initial open ground that was seen in the first voltages you posted.

The diode likely goes back to one pin on the 324. If you power it up with the diode out of the circuit, be careful.

 

[mike49504]

I got this amp back in for repair the guy said his speaker wires touched when hooking it up.

I opened it up and found a bad output replaced it and now the amp has no output and has the following voltages on the output terminals.

Left channel:0.42 volts

Right channel:0.42 volts

I have 0 volts across every emitter resistor

I have rail voltages -59.8 and positive 54.0

On the op-amps that sit on the input board i have the following voltages
( 2068D)

1:111.45
2:9.76
3:9.42
4:10.0
5:9.42
6:10.42
7:11.46
8:12.21

Any ideas on what to check?

 

[mike49504]

Ok i got the amp to produce output it had a broken leg on a tip 41C

Now the output out of both channels is distorted

 

[Perry Babin]

Do you have negative supply voltage on pin 4 of the 2068?

 

[mike49504]

Well got this thing back again..

It lasted from March to now with no problems.


He said he took the card out and flipped it around with the amp on ..


So now Pin 16 on the 494 is high once again its at 12.94 when powerd up and drops to 10.94 volts and remains constant..


Pin16 connects directly to a diode then branchs off to something else which i havent tracked down yet..


Is Pin 16 usually controlled by a transistor ?

 

[Perry Babin]

Pin 16 being driven high likely means that the amp is in protect mode. Have you checked all of the outputs?

Post a photo of the inside of the amp if you can't find the fault. I'm unfamiliar with this amp.