MTX Thunder 2300

[JonFennell]

Spooney, I'm going to surprise you here but I have a MTX2300 thats broken in the exact same way as yours. Check the pics! Mine blew when the Eclipse Titanium sub I was driving popped its voice coil.
I'm no electrical engineer, I'm mechanical and my knowledge extends to knowing that a mosfet is a type of transister, and a transister is a high speed electrical switch. But, I can use a soldering iron and I really want my MTX back working! I blew it 5 years ago and the soundstream, although excellent, just isn't a ballsy.
Do you think you could guide me through it?

The three pictures show 1. Burned out resistors, 2. Swollen capacitor. 3. Two of the fets, fet 4 and fet 7, have holes burned in them.

Can you tell me what components you replaced, or how to check the transisters one by one? Any help would be greatly appreciated.
Jon

 

[spooney]

I'd be happy to try and help you out. If you do a search in this forum for mtx thunder 2300 you will find quite a few threads with some very useful info as well. Can you get me a picture of the entire circuit board of your amp? Also curious to know if you have read Perry Babin's basic amp repair tutorial. It is a must read if you are going to attempt to fix this amp.

 

[spooney]

I was just looking at your pics and based on the date on the circuit board at least our circuit boards were produced on the same day. Crazy.

 

[spooney]

For starters in your first pic those burnt resistors are 22 ohm but I cant remember right this second the wattage rating of them. I think they were 1/4 watt but I believe I used 1/2 watt as replacements but it is going to be a pain to replace them as most likely at least one of the through holes has been completely burned out of the board. I had to solder one leg of the gate resistors into one of the through holes along with the gate leg for the ps fets. the four transistors to the right of those burned resistors are most likely defective as well. Not sure what the originals were but I know I used IRF3205 as a replacement in the power supply. Also I can see you need to replace all of the outputs in at least one of the channels(looks like the right channel?). The originals were IRF540. I used IRF540A as replacements with no issue and they may be easier to find than the IRF540 but either should be fine. Also expect to pull and either check or just completely replace all of the small transistors in that defective channel. Also there is two small driver transistors for the power supply that need to be checked/replaced(I think they are Q52 and Q53). I could ramble all night. Is any of this making any sense to you?

 

[spooney]

Another thing to check would be the rca inputs. This series of amps was notorious for breaking the connections on the rca jacks where they go into the circuit board. Also if you know what they are check the legs of the rectifiers(the two heatsink mounted parts closest to the speaker inputs). These commonly fail as well.

 

[mike49504]

You might also wanna check the diodes in the right channel as i have a mtx 2300 im rebuilding right now. And all of the diodes (1n4150) were blown in the amp i have. Also i have it apart right now so if u need to know the values of any of the resistors. All i need is the board locations. And ill try to help u as well

 

[JonFennell]

Right! Great response guys. I'm on it. I've attached some full shots of the circuitboard for you Spooney. And I've created an actions list for myself.
1. Search and read frelevant posts on MTX2300
2. Read Perry Babins basic amp repair tutorial
3. Replacement parts list
1. 2 x 22 ohm 1/2watt resistors
2. 4 transisters to right of burned resistors - IRF3205
3. Replace output fets - IRF540A
4. Replace all small transistors
5. replace driver transistors Q52 and Q53
6. Check RCA's are still soldered to board
7. Check rectifier legs
8. Check all of the diodes function.

 

[JonFennell]

You might also wanna check the diodes in the right channel as i have a mtx 2300 im rebuilding right now. And all of the diodes (1n4150) were blown in the amp i have. Also i have it apart right now so if u need to know the values of any of the resistors. All i need is the board locations. And ill try to help u as well

Cheers Mike, I might take you up on that, in fact, can you check the number of the small white boxed capacitor nect to RECT2? Mine is blown and reads 153J100 - I think.

 

[JonFennell]

Well, I've started taking the amp apart, as the transisters I've measured are faulty if what I'm doing is right. I'm measuring across the transister legs and hoping to see very high resistance.
RECT 1 & 2 : The two Rectifier diode components (FEP16CT and FEN16CT)do have a 0.5V drop across them in the indicated direction so I assume they are good?

POWER SUPPLY
FET 9. 1-2=17OHM, 2-3=OPEN CIRCUIT, 1-3=OPEN CIRCUIT
FET 10. 1-2=21OHM, 2-3=146OHM, 1-3=167OHM
FET 11. 1-2=OPEN CIRCUIT, 2-3=OPEN CIRCUIT, 1-3=OPEN CIRCUIT
FET 12. 1-2=OPEN CIRCUIT, 2-3=OPEN CIRCUIT, 1-3=OPEN CIRCUIT

AUDIO RIGHT CHANNEL
FET 18. 1-2=OPEN CIRCUIT, 2-3=10MOHMS, 1-3,OPEN CIRCUIT

I've run out of time tonight so I'll keep checking tomorow. I'm enjoying this problem solving. Is that wrong?

 

[spooney]

if I remember correctly those white square capacitors read 123j100. At least on mine they were. They were .012 uF 100 volt caps i believe. If you can wait till tomorrow i will get you the exact number i ordered fr mouser.

 

[JonFennell]

Well, I've started taking the amp apart, as the transisters I've measured are faulty if what I'm doing is right. I'm measuring across the transister legs and hoping to see very high resistance.
RECT 1 & 2 : The two Rectifier diode components (FEP16CT and FEN16CT)do have a 0.5V drop across them in the indicated direction so I assume they are good?

POWER SUPPLY - 5no6hd
FET 9. 1-2=17OHM, 2-3=OPEN CIRCUIT, 1-3=OPEN CIRCUIT
FET 10. 1-2=21OHM, 2-3=146OHM, 1-3=167OHM
FET 11. 1-2=OPEN CIRCUIT, 2-3=OPEN CIRCUIT, 1-3=OPEN CIRCUIT
FET 12. 1-2=OPEN CIRCUIT, 2-3=OPEN CIRCUIT, 1-3=OPEN CIRCUIT

AUDIO RIGHT CHANNEL - IRF540
FET 8. 1-2=OPEN CIRCUIT, 2-3=10MOHMS, 1-3,OPEN CIRCUIT
FET 7. 1-2=1.3KOHM, 2-3=8.9KOHM, 1-3=1.3KOHM
FET 6. 1-20OPEN CIRCUIT, , 2-3=1.4MOHM, 1-3=OPEN
FET 5. 1-2=OPEN, 2-3=OPEN, 1-3=OPEN
FET 4. 1-2=1.6OHM, 2-3=OPEN, 1-3=OPEN
FET 3. 1-2=1.6PHM, 2-3=OPEN, 1-3=OPEN
FET 2. 1-2=OPEN, 2-3=159MOHM, 1-3=160MOHM
FET 1. 1-2=OPEN, 2-3=OPEN, 1-3=15MOHM

AUDIO LEFT CHANNEL - IRF540
FET 13. 1-2=OPEN CIRCUIT, 2-3=600MOHMS, 1-3,OPEN CIRCUIT
FET 14. 1-2=400MOHM, 2-3=0OHM, 1-3=OPEN
FET 15. 1-2=OPEN CIRCUIT, , 2-3=80MOHM, 1-3=OPEN
FET 16. 1-2=OPEN, 2-3=OPEN, 1-3=OPEN
FET 17. 1-2=OPEN, 2-3=0OHM, 1-3=OPEN
FET 18. 1-2=OPEN, 2-3=0OHM, 1-3=OPEN
FET 19. 1-2=OPEN, 2-3=0OHM, 1-3=OPEN
FET 20. 1-2=OPEN, 2-3=0OHM, 1-3=OPEN

I have also checked the diodes on the board. and had between 0.49 and 0.9V drop across them forward. My voltmeter has a diode checker on it. It also has a transister checker if someone can tell me how to use it?

Can anyone tell me whether any of these transisters are still good? Fets 17 to 20 are the only ones that are showing a pattern.
Jon

 

[Perry Babin]

Check the FETs as shown in the FET section of the following page.
Basic Amplifier Repair - Transistor Test Applet Link

 

[JonFennell]

Check the FETs as shown in the FET section of the following page.
Basic Amplifier Repair - Transistor Test Applet Link

I'm such a newbie at this. If this was a engine/chassis forum I would be laughing at someone like me. I'll recheck those transisters again.

 

[Pheadrus]

MTX 2300 & 4320 help for noobie

Hi guys
I'm new to the forum and I'm hoping some of you guys will help me try and fix my MTX 2300's and 4320's. I have a few of them that I bought off Ebay over the years that were suppose to be working but when I got them they were pooched. I've never worked on amps before but have worked on cars for 20 years and usually catch on quickly if given the chance. What section should I post in for repair help for these amps? I'm also looking for any tips or advice on upgrades I can perform on these amps. Any help or insight is greatly appreciated.
Thanks, Steve.

 

[Perry Babin]

Read the two recent 2300 repair threads (this one and one other) then start a new thread. Make a separate post for each individual amp you want to try to repair.

 

[Pheadrus]

Thanks Perry. I'm going to start by reading your basic amp repair article, etc. I just found the box with these amps and I'm going to look at them this weekend and will probably start posting questions and pics next week. I'm stuck with slow 28.8 dial-up living in the country so pics are a pain to upload but I'll do my best.
Thanks, Steve.

 

[Pheadrus]

Thanks Perry

Thanks Perry for the info. I'm going to start by reading your basic amp repair, etc. links. I just found the box with these amps so I'll look at them this weekend. I'll probably post pics and questions next week. I'm stuck with slow 28.8 dial up so uploading pics is a big pain but I'll do my best. I'm still kicking myself for not buying a MTX factory manual for these amps I saw on Ebay years back.
Thanks, Steve.

 

[bega_83]

Start with link in Perry's signature (basic car audio amp repair), you'll find it extremely helpfull, especially if you're newbie like me

 

[ppia600]

I have an Mtx blue thunder pro3002 which appears to be the same amp. Only the power supply fets and their gate resistors were bad. I replaced the fets with irfz44n and the gate resistors with 100 ohm versions because I thought someone had mentioned using them. Will the z44n work in the amp, and if so would the 100 ohm resistors work? I had several z44n's left from other projects so...

Oh yeah and I powered the amp up and it came on without drawing a ton of current. I didn't have it on the sink because I wanted to run it just for a couple of seconds and check the fets to see if any got warm quickly. None did. Of course I didn't have a speaker connected or a signal in, just wanted to see if it would power on.

 

[Perry Babin]

The original gate resistors are 22.3 ohms. The 100 ohm resistors may not work properly in this amp.

The Z44s may not be a good choice. They probably can't handle enough current.