Digital Designs Z1

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mike49504

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Joined 2006
#1
Im working on this amp when it came in it had bad outputs and resistors.
Also had bad ic's on the driver board in the output section.

Now upon trying to power it up the red light comes on for a sec and goes dead the power supply is not turning on.

This is what i get on the SG3525

1:0
2:5.15
3:0.1
4:.39
5:2.06
6:3.02
7:3.01
8:.29
9:6.02
10:0.55
11:0
12:0
13:7.50
14:0
15:7.43
16:5.18

Any thoughts on what to look for or check?
 
#2
There appear to be several problems. The 12v supply for pins 13 and 15 is lower than I'd expect. Pin 10 is right on the threshold to shut down the amp. On most amps, this is VERY near 0v. Near 0.6v, the IC may begin to shut down. You'll have to follow the circuit back for these to see if you can find the faults. I'm assuming that you have 12v or more on the power supply terminals.
 
#4
That transistor has very high gain. It's unlikely that you'll have anything close. The pin configuration is the same as most transistors using the Japanese numbering scheme. You could try other transistors with the 2SC prefix but depending on how it's being used, they may not be 100% compatible. Only do this if you know for certain that the transistor is defective.
 
#5
Im rebuilding the driver board in this amp since futher inspection i noticed it has a few defective parts.

There is a A1023 on the board that is a TO-92L package I have some new A1023's that are a TO-92 package so a lil smaller package Will theese be ok ??
 
#6
Ok i found the correct part.

I got the amp to power on now and its producing rail voltage so cool there.

Problem im having now is the relays wont engauge So am i looking for a transistor or diode or what usually turns them on and off??
 
#7
Back to working on this amp again. I just rebuilt the driver board and this is what i get on the Sg3525 AND THE 393 Wondering if you have any ideas on what to check for??

SG3525
1:0
2:2.14
3:0
4:.75
5:.65
6:.86
7:.64
8:.08
9:2.74
10:.43
11:0
12:0
13:3.61
14:0
15:3.61
16:2.14

LM393
1:.02
2:1.75
3:1.28
4:0
5:6.20
6:13.87
7:.05
8:13.84
 
#9
So would the problem most likely be on the driver board?

Pins 13 and 15 on the board go to a cap 47 uf 50 volt then go back to a diode on the board then go back to the main board and the pin is labled VGS which goes to the driver transisors for the power supply.

So wondering do i look for the problem on the driver board or main board?
 
#17
Ok in the circuit the Vgs and the Vdoub connect to a resistor.

I found that the wrong value resistor was in the board its suppose to be a 2.2 ohm (red,red,gold,gold) and there was a 2.2K ohm resistor there (red,red,red,gold) The resistor connects to leg 1 of the 1027

Could that be the cause Of no supply voltage?
 
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#19
Ok the battery - goes to a zener diode (1n4745) then the other side of the diode goes to a disk cap (104) and then goes to the 3rd leg of the 1027.

Diode checks fine I will replace the disk cap ,1027, and the resistor and see what i come up with.
 
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