DD Z1a damaged

[Perry Babin]

For all ICs, what is the resistance from pin 2 to pin 3?

 

[Achim1409]

61kOhm

 

[Achim1409]

refurbished all solders at that ic´s. Wasnt enough solder. Now i have signal on all ic´s at pin 6. If i measure on the board, some i think low side have signal, high side not. Is that normal?

 

[Perry Babin]

Can you desolder and lift pin 2 to measure all individually?

 

[Perry Babin]

Are the outputs in the circuit?

 

[Achim1409]

No, no mosfets installed.

On both sides allway´s the four center mosfets got signal, the outer one not. Checked on the gate resistors without fets.

 

[Perry Babin]

The reason you don't have high-side drive is because the outputs aren't in. They are used to generate the high side B+. If you use a 9v battery connected across the capacitor across pins 11 and 13, you should get high-side drive. You have to do this for each IC. You can do it individually and check signal then move to the next one.

 

[Achim1409]

Ok, so i found plenty ways, how to destroy the drivers very quick. But now i have on all of them a good signal. High and low tested. I think i can install the fets now.
Previous problem was, that after half our of running the audio part exploded. Power supply i tested allready before. There was no problem. Maybe the filter inductors.
Can i take them out, connect them to my lcr meter and heat them up with a hairdryer?

 

[Perry Babin]

The problem with removing them is that you may clear the short and not find it, only to have it re-short later.

I'd recommend removing the rectifiers and going to a low-voltage supply. Do you have a ±15v (adjustable?) low current power supply?

 

[Achim1409]

No, i havent a Power supply like this.

 

[Achim1409]

I will order or bild such a Power supply. According Google it is not so difficult.

 

[Perry Babin]

Easy to build. You will remove the rail rectifiers from the amp and clean up the solder pads. Read the following thread from the following post. Let me know if you have any questions before applying power.

4000.1

 

[Achim1409]

I dont have that diodes. I will use instead these old double diodes. C25-02C and C25-02N

 

[Achim1409]

Ok, so i used another amp to round the wire around the transformator. Now i have about 20VDC. If i shorten + and -, the lamps starts glowing.

Now i have to connect + to the positive rail, and minus to the negative rail, nothing else?

 

[Achim1409]

In the place for the rectifiers there are marked with + ac -. i think i can connect + and - there, because both sides are bridged.

 

[Achim1409]

So, i have tried. Everywhere a good signal. I can twist and press the inductors. Nothing hapen. No change in signal.... Any suggestions?

 

[Achim1409]

i have reassembled the amp now. Now it seems, there is another problem. Audio Part, Amplitude appears and disappears in every second. Power supply amplitude is rising and lowering. Maybe somewhere a short?

 

[Perry Babin]

Are you still on low voltage?

 

[Achim1409]

No, allready on full. It draws 23Amps

 

[Achim1409]

Maybe something wron with a rectifier, or i didnt worked clean. Before with low voltage everything was allright. The lamps was all the times of (21W Bulbs) Everywhere a good signal.