Earthquake PHD2 seems to lower output???

[ppia600]

I have a PHD2 I bought new from a guy around a year ago. It was great and had way more power than I needed. One day at work the guys and I were bored and we wanted to smoke a speaker for fun. (yeah, I know STUPID ME) Anyways, we screwed this 6" woofer to my back deck, just to see how much bass it would produce before we smoked it. Well, as soon as the speaker burned, the coil must have shorted to the frame and then to ground through the back dash. The amp shut the entire car down it was drawing so much current. I had to go under the hood and disconnect its main fuse.
After sending it to Earthquake in Cali., and spending much dinero to repair it (I had attempted to repair it by replacing every power supply and output transistor with the original part numbers but it still wouldn't come on) I got it back almost two months later. They somehow kept forgetting to send it back to me. Now when I turn the volume up high enough to pound the 12" mtx 7500's it seems to automatically turn the volume down a little even though the car's voltage isn't dropping much and the subs are aok. It never did this before I fried it on the cheezy 6" woofer. The only thing I noticed different on the amp board is a diode soldered across two of the legs of the power supply pwm IC, or at least that's what it looks like. Of course the IC has the part number ground off so I couldn't change it when I attempted to repair it myself. (that was the only part they changed, besides replacing the ones I changed with the SAME part number transistors )
-Does anyone know why they soldered that diode across the top of the pwm ic? Is it some sort of power limiter to protect the amp from me running too low of a load?
-If so, can I just remove it? I never run lower than 2 ohms nominal load, I just made the mistake of having the amp ground to the car's body ground one time. I tried getting ahold of the techs at earthquake to ask about the IC and the diode but couldn't.
-The amp never did this before they repaired it and I want it back to normal. I told them about it and they said "It tested aok and made full power" I was like, yeah, whatever. Thanks

[Perry Babin]

Can you post an image of the defaced ICs that you want to identify? If it has 20 pins, it's likely an HIP4080.

Which PWM are they using in the power supply?

Across which pins is the diode connected?

Which pin is connected to the anode?

[ppia600]

I'll have to remove the amp from under my seat tomorrow at work. I'll get a picture or two but I'm not sure if I can post them yet, maybe my donation helped. The IC is on a socket so it can easily be replaced. Kind of like earthquake knew it is a trouble maker part in the circuit, or maybe swappable to maket the amp 1 ohm stable?? I don't know, but I'm still kind of aggravated that they only changed that IC and removed every original matched fairchild mosfet and diode I replaced, because they "had" to. They could have just swapped the IC, I did a flawless job swapping the transistors IMO.

[Perry Babin]

That's an HIP4080AIP. All manufacturers put them in sockets because they fail virtually every time the FETs fail.

They likely replaced the FETs because not all FETs are created equal. The same part number does not mean the same performance/operation. They used parts that they had confidence in.

[ppia600]

Well they were all the same exact brand and part numbers verbatim. I made sure to ask that the date codes were at least matched. I think they did it for warranty purposes, but it was such a waste, if I'd known it was a 3 dollar IC I could have saved almost $200.
I just need to find out why they put the diode on there, I have a feeling that is the culprit and they may have done it to protect me from myself. I just wish I could find more information about it. This is the first place I have found anyone with good knowledge on these things. I love this place!! Thanks Perry

[Perry Babin]

You can't rely on the exact part number and manufacturer. For example, the IRF3710 that was made a few years ago isn't the same as the one made now. I worked many hours on a few amps trying to find a defective component. I finally determined that the FETs were the problem (same part number and same manufacturer). I had to use a different FET to get the amp working. In another class D amp, RFP40N10s caused the same problem.

There was a thread about this recently.


Justonemoreamp mentioned that he worked on a lot of the PHD2s (if I'm not mistaken). Maybe he can provide some information about the amp.

[ppia600]

/\There's the underside, the IC (ic 4) is to the upper right corner on the left side of the choke.



/\Here's a closer view, it actually has two zeners, I thought there was only one.

Here's an even closer view of the suspect diodes /\

[ppia600]

What would the HIP4080 cross to with say an NTE part? I'm just trying to find the pinout so I can see what's up with the diodes. I should have tried to read the part numbers of the diodes but my vision sucks.

The cathodes appear to be on the BHO and AHO leads (20 and 11) and the anodes appear to be on the BHS and AHS (19 and 12).

[theAnonymous1]

Originally posted by justonemoreamp
I have rebuilt 5 or 6 PHD2's no biggy. Simple HIP4080AIP full bridge output, with dual power supplies. Power supply uses FET drivers IC's that are usual scratched off like the HIP4080AIP output bridge driver.

Earthquake is a local company here in the SF bay area. Some of there stuff was built in Hayward about 12 minutes drive from here.

Let me know if I can be of help, there are several others here also very adept at these amps. Plus you can look in the class D section of this forum for many others that know about these also.

Hope this helps

Well that should at least prove it is a HIP4080.

It's interesting, I know I have seen a pic of that IC with the diodes 3 or 4 years ago when I was into SPL stuff. The pic was part of someones explanation of the "mod" earthquake does to these amps. I can't remember any of what the guy said, but I know it had to do with the diodes.

If they weren't there before, I say just remove them.

[ppia600]

/\ I found the pinout on mouser. Also, the serial number tag on the bottom says its a PHD3, but I believe it says phd2 on the end. Same amp, maybe?