Xtant 603x mosfets

[Beatcoaster]

I have an Xtant 603x(square holed cover) that has a couple fried mosfets that appear to be on the power side of things. One is cracked and one has a big molten metal looking bubble on it. The amplifier plays the 2 main channels fine but the mono subwoofer output is crackly and has very limited volume. Because of this I am thinking the mosfets (locations 30 and 29) are probably linked to that and creating the issue(along with a few popped tiny "220" resistors/diodes?). The mosfets are ST P6ONEO's and appear to be an easy solder/swap. With all of that said, I have a x604(hexagonal holed cover) that is crispy as well and has lots of perfect P6ONE's on it's power side that I could use for replacement. It also has some of the tiny "220" resistors/diodes that I could put onto the 603 since a few of those are popped in half as well. Am I out of line thinking that the P6ONE and P6ONEO are compatible/interchangable? I am thinking that the PCB is only one layer and that I could easily perform the soldering but haven't taken it apart to verify yet. Any info from you experienced guys would be extremely helpful - thanks!

[Perry Babin]

If there are cracked power supply FETs AND the sub channel is distorted, you have two problems. It's possible (rare but possible) that only 2 of the power supply FETs failed and the rest are still driving the supply.

Neither of the FET part numbers are complete. There is another line of characters under the lines you posted.

You can use the parts from one for the other. I would not recommend it if you were working on an amp for a paying customer but if it's your amp and you don't intend to sell it, using used parts for the repair is OK.

The board is at least double-sided.

[Beatcoaster]

After two hours of soldering/swapping 2 mosfets and some resistors the amp is still toast and now just draws current when 12v is put on it / never equalizes - where at least it equalized before and played, now it just arcs on the battery/power source...super bummed, should have just left it alone. I now have a x604 and 603x as paper weights - taking offers from anyone who wants to buy them for parts...

[Dr Zeus]

I believe the sub channel output fets are IRF530, and from what I know, the sub channel goes pretty easy and quick if overdriven; which is a combination of problem with it's lack of beef and the limited power supply circuit of this amplifier. I replaced the sub channel's outputs of the one i repaired with IRF540 fets and the owner has had a working amp since.

I did not have to replace te power supply fets but they were probably ST P60NE06, which are a 60v & 60A n-channel mosfet. I dont know an exact equivalent but I might be able to suggest a replacement.

-What is the value of the gate resistors on each of the first leg of the PS fets? The are probably either 100ohm or less 1/4w resistors.

[Dr Zeus]

Check for solder bridges. Are any fets shorted internally? Test them with your DVM. If one is shorted, remove it and test it again. I usually just clip the shorted ones off the pcb. Be careful not to damage any more components - run tests with a 5A or 10A fuse on your battery.

Can you post a photo of the likely damaged pieces of this amp?

[Dr Zeus]

I wonder if one of the TC4427 PS drivers went bad. From the schematic and the images it may either be U19 or U20. I am also surprised that only 2 fets failed in the one bank.

What happens if you remove the 2 fets in the same bank and next to the ones you just replaced?

[Beatcoaster]

I will try that - my fear is that at some point I managed to mess up the pcb. I'll take some pictures as well...

[Beatcoaster]

Xtant 603x - zero visible issues short of the little resistors and 29/30 bank of mosfets. The front inputs would crank and ran two ohm stable during my testing with zero issues. The subwoofer was weak and crackled.



Already started to remove the two mosfets and 220 resistors(diodes?)I installed from the x604. I'm pretty sure that I cooked the PCB at R19 and all is lost now. Rookie move...



Here is the 604 I am pirating parts from. Couple resistors and mosfets gone. This amp played the front right channel fine, front left at an apparent 1/2 volume and both back channels were dead.

[Dr Zeus]

The blackened section is just a bit of soot. You can probably clean it with something house-hold since the area is so insignificant. I think the board is OK. Check Q28 and Q31. Are there any shorted readings using your Digital Volt Meter?

[Perry Babin]

Start a new thread if you're asking for help with the 604.

The damage at R19 isn't significant. It's not good but it certainly doesn't make the amp unrepairable.

The components marked 220 are 22 ohm resistors, not diodes.

What's the resistance between the B+ and ground terminals of the amp?