Hi im new here. i have a problem with an mtx thunder 2300 the power supply is shot and i think the mosfets are p50n06 im not too sure cause they was all cracked, but i cant find them anywhere, I emailed mtx for the schematic cause it needs a resistor too and i got no response.
If you guys know of any replacements for the power mosfets in the power supply please tell me any help will be greatly appreciated, oh and if anybody has the schematics for that amplifier please send it to mikelee3@atlanticbb.net
Thanks and I appreciate it,
Mike
If you guys know of any replacements for the power mosfets in the power supply please tell me any help will be greatly appreciated, oh and if anybody has the schematics for that amplifier please send it to mikelee3@atlanticbb.net
Thanks and I appreciate it,
Mike
The gate resistors are either 68 or 75 ohm metal film resistors. The fets vary as I have seen from 50n06's to 60n06's, I use 75 ampere rated replacements from Intersil.
The 50n06's are listed on e-bay, but the seller believes they are made of gold by his price for them. $3.25 each + shipping
you can use just about any mosfet as long as it is rated at or above the current demand of the old ones.
If this seems fresh I just repaired a four channel MTX yesterday. Don't be suprised if a rectifier chip on the secondary side is blow also, or possible a blown output or two.
Generally speaking the power supply usually does not fail for no reason, so look around on the other side of the toroid for other issues leading to this failure.
Good luck, hope this info helps.....
The 50n06's are listed on e-bay, but the seller believes they are made of gold by his price for them. $3.25 each + shipping
you can use just about any mosfet as long as it is rated at or above the current demand of the old ones.
If this seems fresh I just repaired a four channel MTX yesterday. Don't be suprised if a rectifier chip on the secondary side is blow also, or possible a blown output or two.
Generally speaking the power supply usually does not fail for no reason, so look around on the other side of the toroid for other issues leading to this failure.
Good luck, hope this info helps.....
There were a couple of versions. If the amp is like the one in the attached image, the value is 22 ohms.
I use IRF3205s as replacements for the power supply FETs.
If it has 4 power supply FETs on one side of the amp and the two rectifiers on the opposite side of the board, check the legs on the rectifiers to make sure that they're not broken. This was a very common failure.
The amps with power supply FETs on both sides of the board (6 FETs) were more reliable and had a lower incidence of broken leads on the components.
As justonemoreamp mentioned, the outputs have likely failed. Even if you don't find any failed outputs, when you initially power up the amp, do so through a current limiter. If you don't have a limiter, power it up through a 10 amp fuse. Also make sure that you have the transistors clamped down before applying power. Components can fail within seconds if there are more problems.
I use IRF3205s as replacements for the power supply FETs.
If it has 4 power supply FETs on one side of the amp and the two rectifiers on the opposite side of the board, check the legs on the rectifiers to make sure that they're not broken. This was a very common failure.
The amps with power supply FETs on both sides of the board (6 FETs) were more reliable and had a lower incidence of broken leads on the components.
As justonemoreamp mentioned, the outputs have likely failed. Even if you don't find any failed outputs, when you initially power up the amp, do so through a current limiter. If you don't have a limiter, power it up through a 10 amp fuse. Also make sure that you have the transistors clamped down before applying power. Components can fail within seconds if there are more problems.
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On the mtx I restored yesterday a FEP16CT dual rectifier diode had failed. So it dead shorted the amp internally.
So follow Perry's recommendations about fusing and or limiter usage.
His selection of the 3205 fet is also fine, and they can be found on e-bay for 79 cents each just type the number in the ebay search bar it will come right up with at least 5 listings from Activeparts. Tom is a good supplier of fets and other devices.
Hope this is found helpful
So follow Perry's recommendations about fusing and or limiter usage.
His selection of the 3205 fet is also fine, and they can be found on e-bay for 79 cents each just type the number in the ebay search bar it will come right up with at least 5 listings from Activeparts. Tom is a good supplier of fets and other devices.
Hope this is found helpful
Hi,
hey sorry for the poor picture its from my phone the 2 resistors i need are r171 and r172 i ohmed them and they both are 19 ohms 1/4 watt i have half watt 22 ohm here will those work? oh and i checked the rectifiers and they checked good and made sure i soldered them in good the resistors are in the pic they are the 2 between the ground screw you shold be able to see them where i took them out cause they was black i am gonna order so irf540s for the outputs ill get a few of them just in case and a few of irf3205s for the power supply. the amplifier blew up when one of the subs it was driving locked up then it just kept blowing fuses i tool it apart and all 4 power supply mosfets was cracked and 2 outputs were cracked. If you guys think of any other things i should look at feel free to respond
Thanks a Million you helped me out alot
Mike
hey sorry for the poor picture its from my phone the 2 resistors i need are r171 and r172 i ohmed them and they both are 19 ohms 1/4 watt i have half watt 22 ohm here will those work? oh and i checked the rectifiers and they checked good and made sure i soldered them in good the resistors are in the pic they are the 2 between the ground screw you shold be able to see them where i took them out cause they was black i am gonna order so irf540s for the outputs ill get a few of them just in case and a few of irf3205s for the power supply. the amplifier blew up when one of the subs it was driving locked up then it just kept blowing fuses i tool it apart and all 4 power supply mosfets was cracked and 2 outputs were cracked. If you guys think of any other things i should look at feel free to respond
Thanks a Million you helped me out alot
Mike
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at first power up, a good idea for a simple limiter is a 60w car headlight. I use it all the time. wire it in series with the positive supply to the amp.
it allows enough current to do some low power testing or checking if the amp has an audio output. when something is wrong, the bulb will glow and limit current to the amp.
it allows enough current to do some low power testing or checking if the amp has an audio output. when something is wrong, the bulb will glow and limit current to the amp.
If you have outputs that are cracked, they have most definitely failed. This means that you MUST replace all 4 that were in parallel with the cracked FETs. I'd strongly recommend that you replace all 8 outputs in that channel. They were all subjected to the same abuse and if they haven't outright failed, they may be weakened.
Check the 0.1 ohm 2 watt resistors near the outputs. You should remove them and check them out of the board if any are discolored.
When ordering parts, I'd suggest that you order a few each of the MPSW42 and MPSW92 transistors. If I'm not mistaken, these are used as the drivers for the outputs.
The 1/2 watt 22 ohm resistors will work but you may as well order the correct resistor since you have to the order the other parts. I'd recommend a flameproof resistor. If you don't use flameproof resistors, mount the resistor ~1/4" from the board to prevent further damage to the board (if the amp fails again).
Check the 0.1 ohm 2 watt resistors near the outputs. You should remove them and check them out of the board if any are discolored.
When ordering parts, I'd suggest that you order a few each of the MPSW42 and MPSW92 transistors. If I'm not mistaken, these are used as the drivers for the outputs.
The 1/2 watt 22 ohm resistors will work but you may as well order the correct resistor since you have to the order the other parts. I'd recommend a flameproof resistor. If you don't use flameproof resistors, mount the resistor ~1/4" from the board to prevent further damage to the board (if the amp fails again).
ok the only mpsw's i could find was the mpsw92 their a little larger and there is only 2 on each channel and there is smaller mps6523 2 connected to the heatsink when they are clamped down all 4 checked good with my fluke, ok this is odd i looked under the .1 ohm 2 watt resistors on the side that has the cracked mosfets and no black where they are connected to the board but on the other side where none are cracked 3 .1 ohm resistors have black around the solder connection should i desolder it clean it up and resolder it? , oh i also found a few mpsa06 there was others it looks like they are behind the mosfets in pairs, can i check them in circuit because there is alot of them.
Thanks Your help is Greatly Appreciated,
Mike
Thanks Your help is Greatly Appreciated,
Mike
oh and one more thing.....it looks like someone fixed this amp before i got it because i see different color caps in the filter banks, but i was wondering on this amp the MTX Thunder 2300 do you know if this amp comes with heatsink compound on the mosfets from the factory, it looks like it has a mylar or something pad insulating the mosfets from the chassis. I want to get all that white stuff off of there because it is too messy, i recently fixed a MTX Thunder 240 and it didnt have any heat sink coumpound on it just the little removable pads under the mosfets, they felt rubbery.
I was thinking since i suspect someone was working on this amp before my friend bought it and blew it up now i have to fix it again maybe those black areas around the .1 ohm resistors are from maybe when the amp failed before it was fixed the first time.
I was thinking since i suspect someone was working on this amp before my friend bought it and blew it up now i have to fix it again
maybe those black areas around the .1 ohm resistors are from maybe when the amp failed before it was fixed the first time.The 2300s used both metallic insulators and sil-pads (rubbery pads). All of the old compound needs to be removed. If you use an insulator that's designed to be used dry, you don't have to use compound. The sil-pads are generally designed to be used dry. If you use something like Kapton or mica insulators, you'll need to use compound. Apply just enough to coat the back of the transistors. If you use mica insulators, you have to apply compound to both sides of the insulator.
To get the bulk of the grease out, use a stiff piece of cardboard or plastic. Then clean the remainder with acetone and paper towels (outside with good ventilation).
Any areas that are discolored need to be investigated. If the area under the resistors is black, you should pull them and check them individually. They're connected in parallel on the board so you can't check them reliably in the board. Where the board is discolored, you need to clean it with acetone. Then you should be able to determine if the board is damaged.
When you order parts, you should order ~10 of all of the small transistors (MPSW92, MPSA06, MPSA42, MPSA56...). I can't recall any amps where the 6523s have failed but they're likely inexpensive so you should get 5 or 10. The extra parts will be cheaper than shipping if you have to reorder.
If some of the drivers have failed, you may have to remove many of the small transistors to check them. I've seen them short, open and leak. Leaking and open transistors can be tough to find in the board.
To get the bulk of the grease out, use a stiff piece of cardboard or plastic. Then clean the remainder with acetone and paper towels (outside with good ventilation).
Any areas that are discolored need to be investigated. If the area under the resistors is black, you should pull them and check them individually. They're connected in parallel on the board so you can't check them reliably in the board. Where the board is discolored, you need to clean it with acetone. Then you should be able to determine if the board is damaged.
When you order parts, you should order ~10 of all of the small transistors (MPSW92, MPSA06, MPSA42, MPSA56...). I can't recall any amps where the 6523s have failed but they're likely inexpensive so you should get 5 or 10. The extra parts will be cheaper than shipping if you have to reorder.
If some of the drivers have failed, you may have to remove many of the small transistors to check them. I've seen them short, open and leak. Leaking and open transistors can be tough to find in the board.
ok thanks, ive ordered the parts i needed, when i recieve them what should i do first, pull all the bad fets of the one channel and put the fets in the power supply and try to power it up, oh and i bought a fuse holder for my power supply so i can wire a 10 amp fuse inline so i dont damage anything
Thanks,
Mike
Thanks,
Mike
I got the parts in today but i did not get all of them. I just got in the mpsw92s, irf3205s, and the irf540s. Im still waiting on mpsa06 mpsa56, mpsa53, mpsa42, and mps6523
So heres what i did so far i took a bank of 4 mosfet outputs out
and replaced the mpsw92s and the irf3205s and the unit powered up like normal without the 4 outputs in the left channel, it was the 4 closest to the input ok, so im like ok maybe this thing will work, so i put the irf540s in and tried it, the unit turns on but it is drawing current like crazy, keeps poppin the fuse i take them out no more current draw, so i dont know what to do could u have another bad driver somewhere, because im gonna change all the transistors on the lef channel thats why i ordered all of them, do you think those irf540s could be bad , i tried 4 more 540s and did the same thing, so i dont know i hope its those other drivers, because im having bad luck with this.
Thanks
So heres what i did so far i took a bank of 4 mosfet outputs out
and replaced the mpsw92s and the irf3205s and the unit powered up like normal without the 4 outputs in the left channel, it was the 4 closest to the input ok, so im like ok maybe this thing will work, so i put the irf540s in and tried it, the unit turns on but it is drawing current like crazy, keeps poppin the fuse i take them out no more current draw, so i dont know what to do could u have another bad driver somewhere, because im gonna change all the transistors on the lef channel thats why i ordered all of them, do you think those irf540s could be bad , i tried 4 more 540s and did the same thing, so i dont know i hope its those other drivers, because im having bad luck with this.
Thanks
It could be a driver. If it's a shorted driver, it's relatively easy to find with your ohm meter.
It could also be that the bias current is set too high. Often when you replace the outputs, the new outputs have a lower threshold voltage. If the bias is not set lower for the new FETs, the amp will draw excessive current. Try turning the blue bias pot fully counter-clockwise. If the current draw is still excessive, it's likely that you have a defective driver.
You said you replaced 4 540s. It's best to replace all of them. Even though 4 may have survived, they were likley subjected to the same conditions that destroyed the other 4. If you don't replace them, you should at least pull them and check them for proper operation.
It could also be that the bias current is set too high. Often when you replace the outputs, the new outputs have a lower threshold voltage. If the bias is not set lower for the new FETs, the amp will draw excessive current. Try turning the blue bias pot fully counter-clockwise. If the current draw is still excessive, it's likely that you have a defective driver.
You said you replaced 4 540s. It's best to replace all of them. Even though 4 may have survived, they were likley subjected to the same conditions that destroyed the other 4. If you don't replace them, you should at least pull them and check them for proper operation.
Is it too burrned to read the color bands?
On the images I have here, it looks like it may serve the same function as R164 on the other side of the board (across the positive and negative speaker terminals). If they are the same, maybe you can read the other one. If it is connected directly across the +/- speaker wires, it should be much higher than 3 ohms.
Did you check the other bias pot? Many times people think that those pots make the amplifier produce more power so they turn them up.
If it's not the biasing, it's likely a defective driver. If you have a lighted magnifying glass, inspect all of the components near the channel that failed. For resistors, look for darkened areas. For the small transistors, look for cracks or bulges in the case of the transistor. This isn't exactly a high-tech way of troubleshooting but sometimes it works.
If you didn't find any shorted drivers, you're going to have to look for open transistors. Most of the transistors have a pin configuration of Emitter-Base-Collector (A06, A56, W92, A42). Look up the datasheets for any others. For the NPN transistors (A06, A42), place the red lead on the center pin. You should read no more than 0.7v on diode check when you touch the black lead to the other pins of the transistor. For the PNP transistors (W92, A56), the black lead goes on the center pin. Again, you should read no more than 0.7v on diode check when you touch the other meter lead to the other pins of that transistor.
On the images I have here, it looks like it may serve the same function as R164 on the other side of the board (across the positive and negative speaker terminals). If they are the same, maybe you can read the other one. If it is connected directly across the +/- speaker wires, it should be much higher than 3 ohms.
Did you check the other bias pot? Many times people think that those pots make the amplifier produce more power so they turn them up.
If it's not the biasing, it's likely a defective driver. If you have a lighted magnifying glass, inspect all of the components near the channel that failed. For resistors, look for darkened areas. For the small transistors, look for cracks or bulges in the case of the transistor. This isn't exactly a high-tech way of troubleshooting but sometimes it works.
If you didn't find any shorted drivers, you're going to have to look for open transistors. Most of the transistors have a pin configuration of Emitter-Base-Collector (A06, A56, W92, A42). Look up the datasheets for any others. For the NPN transistors (A06, A42), place the red lead on the center pin. You should read no more than 0.7v on diode check when you touch the black lead to the other pins of the transistor. For the PNP transistors (W92, A56), the black lead goes on the center pin. Again, you should read no more than 0.7v on diode check when you touch the other meter lead to the other pins of that transistor.
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