Digital design

[megael9]

Hi guys:
I'm working on a digital design amp, not sure what the model
Number is all it has is a sticker, see attached picture.
All MOSFET output are shorted out, and the audio driver board
Have 7 ICs all are Burt out, and can not reed the part number, can
Some one please tell me the part number of these ICs,
Thnaks in advance.

 

[megael9]

2nd pic

 

[megael9]

3rd pic

 

[S Merlington]

I believe the amp you have is a Digital Designs Z2

The 4 large IC's are IR21844S

The IC in U6's location is a LM293

U3 is a TL072C

U4 is a LM211

If rebuilding the driverboard also replace all transistors marked 1D,2D,1A,2A

Also Q6 fails sometimes which is a KTD1304

 

[Perry Babin]

It appears that some of the resistors burned. If so, the attached image should help.

 

[megael9]

After rebuilding the driver board, can I test this unit without
Audio output mosfets? Just want to play it save if possible.

 

[Perry Babin]

Without a bit of extra work, you won't be able to tell much without the output transistors. You can check all of the regulators and other supply inputs without the driver board in place. You should do that first.

 

[megael9]

After testing all components of the driver board, I found out that surface mount transistor
Q10 is also shorter, it has printed MAX and 08 on small numbers on it, I think that 08 is for the manufactory year. But can not find the cross reference for that transistor.

 

[megael9]

Hi perry babin, do you have a photo that includes Q10?
Thanks in advance.

 

[S Merlington]

Ive used a 2sc3326 in Q10's location and the amp works fine

 

[luka]

z2?
I see z1a writen on it, and board looks like z1a too

 

[S Merlington]

Sorry didnt look at the first pic i was going by the color of the board your right its a Z1a..

But the driverboard is the same

 

[mbates14]

I have the same amp, same issue. unfortuantely for me, the driver board is fried so bad it burned a hole clean through it.

So its junk.

 

[megael9]

Hi guys:
I rebuilded the driver board and install it,
After power up one of the audio output
MOSFET Shorted out.
I think I also have a problem before the driver board.
My question is, can I use a +- 15 volt power
Supply to troubleshoot the pre amp circuit
Without high voltage?

 

[S Merlington]

If one of the outputs shorted again the driver IC Iss most likely shorted again and will have to be replaced..

What all did you replace on the driverboard??

 

[mbates14]

yea you cant just throw a set of outputs and drivers in there and expect it to work. You have to check around for the collateral damage from the first round. Or, the root cause in some cases.

Check the snubber network near the output coil, ive seen those short and cause failures. You also have to power the unit up with outputs removed, and a current limited power supply. Check the gate drive signals to make sure its present and proper.(wont work on self-oscillating designs of course). This will also allow you to check pre-amp stages as well.

 

[megael9]

I just replaced all 7 ICs and all transistors including Q10 to the driver board.
I want to Check voltage before I install the driver board, but the amp is on
Protect mode, the is no audio output installed and no short Founded,
power supply works when by it self, but not when the audio section is install.
Do I need to chit the amp out of protect mode, If yes, how?

 

[megael9]

I founded R271a open, I replaced R271a, and know the power supply
is working, but after power up the power LED comes up only for 1/2
second and then the protect LED comes on.
eny suggestion?

 

[S Merlington]

Remove the audio driverboard if is is not already removed..

Does this allow the amp to power up normally??


If the audio driverboard is already removed and it still protects try 1 of the following..


Remove all of the outputputs does this make it power up??


If thoose 2 things do not make the amp power up..


You may have a regulator that is shorted or leaking..

If you can get the amp to power up by diabling the output section check the voltages on the regualtors to see if any are shorted or leaking..

To check them leave the in the amp and power the amp up ..


The 7805,7812,7815 place black probe on Leg 1 and red probe on leg 3 ..
The 7805 should read 5 volts
The 7812 should read 12 volts
The 7815 should read 15 volts

The 7905,7912,7915 place black probe on leg 2 (middle leg) and red probe on leg 3

The voltgages should be the same as the others but you would get negative voltages instead of positive..


Are any of theese defective??

Be very careful when doing this DO NOT Slip with the probes this could cause more damage to the amp..

 

[megael9]

Ok thanks for the help, I found a broken pin on la7805.
Now the amp powers up, here are the readings of the driver
Board pins
1 ( between 119 and 122 volts
2 (-149 volts
3 (-160 volts
4 (0 volts
5 (0 volts
6 (-161 volts
7 (0 volts
8. (0 volts
9. (-161 volts
10(between 119 and 122 volts
11(-161 volts
12(.29 volt
13(15 volts
14(5 volts
15(0 volts
16(0 volts
17(-5 volts
18(0 volts
19(-161
20( 0 volts
21(-149 volts
22(-161 volts
23(0 volts
24(0 volts
25(-161 volts
26(0 volts
27(0 volts
28(-161 volts
29(between 119 and 122 volt
Are these voltages about rights?