directed d2400

[mike49504]

I have another one of theese amps in for reapir.

The amps light will flash very quickley and the protection light will also flash very quickly like its in protection.

I checked the outputs none test shorted.

I checked power supply fets nothing there either.

Wondering where i go from here?

 

[Perry Babin]

Is it this amp?
Directed 2400d inside - Amp Guts

 

[mike49504]

Heres pics of the board i have.

Also if you mess with the switches sometimes it will stay on for a min then go into protection.

Also if i connect a speaker to it all i get is a squealing noise from the test speaker

 

[mike49504]

Any ideas on where to start looking ? Since there is no output just a squealing noise from the outputs and then it goes into protection

 

[Perry Babin]

When the amp squeals, is there any high frequency oscillation on the output transistors?

 

[mike49504]

Im wondering if someone put the outputs in backwards since it looks like they been replaced at one time.

Wondering how do i tell where the 640's go and the 9640's go?

Also i took the outputs out of the amp already and the amp will power up perfect and idle fine.

 

[Perry Babin]

Are there mixed 640s and 9640s on each side of the amp or do you have 640s on one side and 9640s on the other side?

 

[mike49504]

There are 3 of each on both sides of the amp.

 

[Perry Babin]

If the center legs of each bank of outputs is connected together, the third leg of the 9640s should go to the positive rail. The third leg of the 640s should go to the negative rail. Confirm that none of the source legs (leg 3) of the 640s are connected to any of the source legs of the 9640s.

 

[mike49504]

Next question is do the 640's and 9640's need to be in the amp in order for it to power up?

If i stick the 640's in the amp without the 9640's the amp goes straight into protection

 

[Perry Babin]

With only the 640s in the circuit, it is likely producing DC which is causing it to go into protection. With no outputs, it may power up normally.

 

[mike49504]

with no outputs in the amp it powers up fine.

If i put 9640 and 640's in the amp it draws excessive current .

I checked the outputs all test good.

From all of the dircted amps ive worked on this one is the one from hell.

All the other directed amps ive worked on the 9640's were closet to the power supply fets then the 640's were near the rca jacks.

it seems like all pads are connected together in this amp for some reason.

Any thoughts?

 

[Perry Babin]

Which pads are connected together?

 

[mike49504]

i was getting strange readings between the pads i switched batteries in my meter now its measuring right.


With no outputs in the amp it powers up and idles fine.

On the output pads the reading i get are

1 banks of outputs

Leg1: -68.2
Leg2:0
Leg3:- 71.3

2nd bank

Leg1:72.1
Leg2:0
Leg3 70.1

So that appears to look good.

As soon as i put the outputs back in it it draws excessive current.

So Do you know what they are using for the drivers for the outputs?

 

[mike49504]

Ok the 2 drivers circled are defective.

They are marked.

DK QY

AG QQ

Is there a good sub for theese??

 

[Perry Babin]

See if the 2SA1797 and the 2SC4672 appear to be the same transistors.

 

[mike49504]

Im just wondering i have some other transistors that are new but i lost the packaging on them to tell me what they are.

they are marked
DY
209

CY
209

Wondering if theese will work in this amp or not??

 

[Perry Babin]

The SMD Code Book

Use this page to find the part numbers. Compare the dimensions in the datasheet to the device to confirm that they are the correct parts.