Earthquake PHD2 seems to lower output???

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Well since I have the amp out of the car, I'm going to test it with a power supply. I'll use one of my smaller power supplies (10 amps) since I won't be driving any load. I'm not exactly sure where to test for rail voltage but it probably won't take long to find. Currently I'm using my "pro mos" 50 to run the subs (and I'm also wondering if that amp has a built in subsonic filter....) I'm off to open the PHD2 now, be back in a little while...
 
Ok tested a few points:

-diodes soldered on ic - 77.4 vdc regulated
-rail supply output filter capacitors - 81.2 vdc
-output of both power supply rectifiers -78.something vdc??(why is this lower than at the caps??)
-gate leads of power supply fets .5 to .7 vdc
-gate leads of audio output fets about 80 vdc...

I actually had it connected to a small sub playing low so I could watch for any fluctuations even though this was nothing compared to what it would do in the car. Just watching it play those super low notes makes me want to swap it back in and take the ppi out, haha. It is a lot noisier than a class a/b amp on the output. You can actually hear switching sounds through the sub even with no music signal. Its nothing you'd hear inside the car though.
Apparently the diodes aren't connected between the gate and source of the power supply fets, they are connected at the audio output fets which have a really high voltage. Funny thing is they read about 3.75v across the anode and cathode, but if you read them from ground to either side, one side is about 77 and the other about 81. They must be really high voltage zeners or just for reverse polarity protection of some sort. Its pretty kewl that the gate voltage is so high, almost the same as the source voltages. This is apparently the extreme side of switching design which explains the switching output noise.
 
The rectifier is before the inductor. The ripple is probably causing the error. When the duty cycle increases, they will likely be closer.

The zeners are rated at 20v or less. The ones near the outputs are 18v zevers. I'm not sure why they have them on the IC also. They seem to be doing the same thing. Maybe they're rated lower for better protection.

The voltage on the gate of the high side FET is actually greater than rail. It has to be at least ~5v higher if you want to drive the FET to the rail.
 
THe ones on the chip look like 1N5234 (6.2v??)... man I need my eyes done! I can't tell about the ones across the output leads because they are soldered down, but there are two on each fet, one tiny and one larger, both are the clear glass type...

Ok, there are tiny diodes on each output fet, but only one large diode for half of the output fets.. the large ones appear to be 1N4740 (10v??) but its hard to tell, they are all soldered where I can barely see the part number.

I don't understand why the large diodes are there unless they are in series.. The gate voltage is so high, there's no way those are paralled???
 
The smaller diodes are switching diodes. They allow the drive circuit to switch the FET off quickly. When turning the FET on, the drive signal passes through the resistor. When turning the FET off, the drive signal goes through the diode (a tiny current will flow through the resistor on turn off also).

I think the Zeners are there to protect the FETs in case of a short circuit. If the output was shorted and the source was dragged down quickly, the gate may see significantly more than 20v and the FET would fail. The low side doesn't need them.
 
I was looking around on the ampguts site and noticed the phd2 there doesn't have the diodes soldered to the ic.. I'm still searching and haven't found out for sure. I am running the amp currently (giving the ppi a rest) but I'm taking it easy on the alternator for now.
 
i have a amp with a problem unlike yours its a "shredder" phd2, my six of my power fets have blown, it still power up and play too but very weak my outputs is good no resistor or diodes have burn on the circuit, my question is what do i do..im a electronics technician but i dont have access to the original parts but im planning on ordering from the net, thats my personal amp and i want it to be placed back in my car...do i change the tc44cpa? the PWM ic which you identified as 4080? and add my new powerfet to the old ones they are p80ne-06?
i need the help in a hurry please thanks guys.
 
I actually changed every power fet that was clamped to the sink back when I originally burned my amp from accidentally having the speaker short to the car chassis. They were all fairchild mosfets and even after changing them the amp wouldn't power up. The gate resistors were all ok too. Funny thing is I could have probably saved a lot of money just changing the 4080 instead of sending it to earthquake and having them repair it. They threw away all of the mosfets I painstakingly swapped and put all new in, lol. Problem is back when I tried to repair it I wasn't a member here, otherwise I would have tried changing the ic's. The part numbers are ground off both so couldn't change them. Oh well, have to learn somehow
:smash:
 
ph-d2 need more help!

No the fets were three (3) from each side totalling six (6)...they are the ones nearing the output fets.
i need to know what to purchased the resistors checked of fine nutten else visible is burnt just as i say the fets..is the 4080 connected to the powersupply or the output? and just curious what is the IC that is near the tc4424...and the one on the little vertical board?
thanks again!!
 
If FETs faild in both banks, you need to replace all 12 FETs in the power supply.

The 4080 is the audio FET driver IC.

I've never seen an Earthquake that I could read the numbers off of the IC on the vertical board but a similar amp used a TLC271CP for the same circuit if I'm not mistaken. Maybe someone with a schematic could confirm that this is the correct part number.
 
why? if they are still good!!

good day perry
you are saying if fets failed in both banks i must replace all 12, what im saying is 6 fets failed, 3 in each bank and the others tested ok and in fact the amp still plays with the 6 fets missing. no resistor has been burn or any traces on the board the audio output fets are still ok what must i change to get the amp original, i told you guys that im in jamaica the parts arent easily available so i dont want to be flushing anything that can be reused....so do i change the 4080 or not....do i change the 4424 or not do i just put in 6 new fets? i definately dont want to change what is ok.
to be frank i tried the 70n06 and they failed instantly as i power-up the amp i think it should have even turned on and played..so i think that there is something that controls the lower half banks on both side is causing the fets on there to burn...no diodes or no parts around or in the power area is short or open....so please tell me what is the suppected parts to be changed?
 
In virtually all cases, when the power supply transistors fail, they all fail. If one was pushed to the limit, it's possible that the others are not 100% intact from whatever stress that caused the others to fail. If the others fail, you'll have to repair the amp again. Sometimes, when the power supply fails, it damages the board too badly to be repaired. This time you were fortunate and the board was not damaged. There is no good reason not to replace all of them. If they're expensive and the old transistors cause the new ones to fail, it's going to cost even more to repair it the next time.

If there was no damage to the audio section, do not replace the 4080.

The 4424 will need to be replaced. It's probably the reason the new transistors failed.

When you power up the amp, insert a 10-15 amp in the B+ line and have the transistors clamped to the sink. This should help prevent damaging more components.
 
ic erased on the baord

hi, please, i need help, i need the small ic showed on the pict, there are someone that know the ic model. jcaudana@hotmaiol.com. thank you.
 

Attachments

  • earythquake ph d2.jpg
    earythquake ph d2.jpg
    85.7 KB · Views: 369
Great News Guys!!

Ive fixed my Earthquake!! the problem was the 4424 ic, that was what was causing the 6fets to blow each time, but i couldnt get the original P80NE06-10 fets ive used the IRF1010 (wich came up as a replacement under rigorous investigations) and ive still not changed the other 6 that was originally manufactured in the circuit, my amp is running my subs (two Kicker L7 in Solo-X boxes) as powerful as ever, and the good thing from May last year ive just managed to fixed it two weeks ago. thanx again to all you guys that shared experience and knowlege and gave me the ideas.
 
Formas i see you have the same set up as me. 2 kickers L7's 12''s im going to need your help on my blown amp. im working on getting pics to post up. Basically i didnt us an in-line fuse on it and i was bassing HARD at 1 ohm instead of the recommened 2ohm. i think the mosfets on the sides of the two main toroid transformers are gone i dont know. help
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.