Earthquake PHD2 amp

fongman · 21st May 2010, 12:22 AM

I've had the amp for a while. I bought it working and put it away for some years now. So i decide to put it in my truck and the amp won't produce full power? I check the power and its reading 12v. Nothing seems burn. Just not push as hard. All the power and outputs transistor are fine. I've check the 4424 and the 8040 ic and they are ok. The only thing i can see wrong is the outputs reading are: pin 123

40v
80v
40v

on the first 3 and next 3 to the speaker side are

3v
40v
0v

Those last 3 don't look right? Any help please...

Perry Babin · 21st May 2010, 12:36 AM

That all looks OK.

If this was in a different vehicle or was connected to different speakers/enclosure, those could make the difference.

I'll assume that you've checked the gains and crossover point.

Do you have a scope?

fongman · 21st May 2010, 01:00 AM

I was going to buy that scope I talk to you about but it was missing parts so I pass up on it. I try it with two different speaker and it did the same thing. When I used a different amp, it was good. Are the readings ok?

Perry Babin · 21st May 2010, 01:09 AM

I don't see anything wrong with the voltages you posted. I would have expected the pin with 3v to be nearer 5v but since the output is precisely 1/2 of the rail voltage, I don't see a problem. There could be a problem with the preamp section that's not allowing the output to reach full power.

fongman · 21st May 2010, 01:19 AM

I have the gain control too. I will used that and see if it helps?

ppia600 · 21st May 2010, 02:33 AM

Quote:

Originally Posted by fongman

I have the gain control too. I will used that and see if it helps?

I noticed on my phd2 that the amplifier seemed to have higher sensitivity with the gain knob plugged in, kind of weird IMO

fongman · 21st May 2010, 04:23 PM

With the knob plugged in the bass did get louder, but i'm going to test it in the truck. I will let you guys know?

fongman · 3rd June 2010, 05:58 PM

Hello, I want to update you guys that i did put the amp in the truck for testing but the sound was still low. I found that one of the cap by the speaker out was leaking. I will replace the 100v 47uf and retest. I was having a hard time to find a replacment in town.

21st May 2010, 12:22 AM	#1
fongman diyAudio Member Join Date: Jan 2009	Earthquake PHD2 amp I've had the amp for a while. I bought it working and put it away for some years now. So i decide to put it in my truck and the amp won't produce full power? I check the power and its reading 12v. Nothing seems burn. Just not push as hard. All the power and outputs transistor are fine. I've check the 4424 and the 8040 ic and they are ok. The only thing i can see wrong is the outputs reading are: pin 123 40v 80v 40v on the first 3 and next 3 to the speaker side are 3v 40v 0v Those last 3 don't look right? Any help please...

21st May 2010, 12:36 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	That all looks OK. If this was in a different vehicle or was connected to different speakers/enclosure, those could make the difference. I'll assume that you've checked the gains and crossover point. Do you have a scope? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

21st May 2010, 01:09 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	I don't see anything wrong with the voltages you posted. I would have expected the pin with 3v to be nearer 5v but since the output is precisely 1/2 of the rail voltage, I don't see a problem. There could be a problem with the preamp section that's not allowing the output to reach full power. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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21st May 2010, 01:00 AM	#3
fongman diyAudio Member Join Date: Jan 2009	I was going to buy that scope I talk to you about but it was missing parts so I pass up on it. I try it with two different speaker and it did the same thing. When I used a different amp, it was good. Are the readings ok?

21st May 2010, 01:19 AM	#5
fongman diyAudio Member Join Date: Jan 2009	I have the gain control too. I will used that and see if it helps?

21st May 2010, 04:23 PM	#7
fongman diyAudio Member Join Date: Jan 2009	With the knob plugged in the bass did get louder, but i'm going to test it in the truck. I will let you guys know?

3rd June 2010, 05:58 PM	#8
fongman diyAudio Member Join Date: Jan 2009	Hello, I want to update you guys that i did put the amp in the truck for testing but the sound was still low. I found that one of the cap by the speaker out was leaking. I will replace the 100v 47uf and retest. I was having a hard time to find a replacment in town.

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