recently repaired this amp had it working perfect until i decided to scrap back down and put some more themal paste because i wiped of alot. After doing same i powered it back on working perfect still until i dropped in a screw driver betweeen two power mosfet. It created a large sparked and killed all mosfets in that section nevertheless replaced again with new driver ic's AGAIN
The problem now is that the output transistors are popping one by one , as i remove the popped one the amp out of protect for a few seconds then pops another mosfet. The amp is a mmats 3500.1
The problem now is that the output transistors are popping one by one , as i remove the popped one the amp out of protect for a few seconds then pops another mosfet. The amp is a mmats 3500.1
Many of these amps are very finicky about the output transistors that will work. The IRF3710Z (<<<Z is VERY important) has been one of the few that seem to work reliably. Using the same exact part as was removed is no guarantee that they will work.
Also, many times when an FET being driven by the 4080 IC fails, it damages the IC.
Also, many times when an FET being driven by the 4080 IC fails, it damages the IC.
Perry I forgot to mentioned DAT it was the power MOSFETs I shorted n replaced, from d burnt mark on d case I guess I grounded one and caused it burn, replaced d pwm IC's also now its d audio FETs DAT are popping one at a time. As I remove d popped one the amps powers on for 3 sec pops another and goes back into protect mode. Did shorting d case kill every thing? Am hoping I cud replace FETs and 4080 ic and be up and running. How much have I killed by shorting d case to PCB perry?
Please use real words. DAT, cud and d are not words.
Shorting the power supply FETs to the case would not affect the output FETs. I've never seen a power supply problem that would cause the output FETs to fail in these amps.
It's possible that one output randomly failed and damaged the 4080 IC and that's causing other output FETs to fail.
Shorting the power supply FETs to the case would not affect the output FETs. I've never seen a power supply problem that would cause the output FETs to fail in these amps.
It's possible that one output randomly failed and damaged the 4080 IC and that's causing other output FETs to fail.
Understood. So could I just change FETs and ic to retest? Is there any way to test the 4080 ic out of circuit?
If the failure was random, you may be able to replace the FETs and IC but if there was another problem like a shorted inductor or some other fault, the FETs may fail again.
You can sometimes check the 4080 to confirm that it's defective by checking between the output pins and the supply pins for that output pin (4 outputs and 8 supply pins per 4080) but it's only definitive when you find a shorted or leaky drive channel on the IC. There are some faults that cannot be easily detected with a multimeter.
You can sometimes check the 4080 to confirm that it's defective by checking between the output pins and the supply pins for that output pin (4 outputs and 8 supply pins per 4080) but it's only definitive when you find a shorted or leaky drive channel on the IC. There are some faults that cannot be easily detected with a multimeter.
hey perry i rechecked the fets and a set of six are good and a set of another six are bad tested in circuit first and then out of circuit individually. I discovered a burnt spot on the board where the last fet came out from(corner) where a very small circular bulb glass/capacitor looking component was, which is broken now and just two leads are sticking up unconnected. I tested one of the leads to be connected to b+ so maybe this also contributed to the problem. I am assuming this is a thermal sensor but honestly dont know, what is it and cant this be replaced?
another question, are those twelve 4710s all identical because it seemed so to me or are they npn and pnp? i removed all with intention to replace them as they had the same number but noticed there are actually irfb4710 and just fb4710
Is the device labeled RT1 or RT2 on the board? If so, it's a thermistor.
All of the output transistors are the same. I've helped several people with this basic amp (several models are very closely related) and none worked with the IRFB4710. If someone else has had success using those parts, please say so.
I've used the IRF3710Z in the most recent repairs but I've also used the IRF3415 in repairs before the 3710Z was available.
All of the output transistors are the same. I've helped several people with this basic amp (several models are very closely related) and none worked with the IRFB4710. If someone else has had success using those parts, please say so.
I've used the IRF3710Z in the most recent repairs but I've also used the IRF3415 in repairs before the 3710Z was available.
its labelled rt1 . Is it replaceable ? The six fets tested bad are the irfb4710 and other six that tested good are the fb4710. What difference would it make to changer over to 3710z in performance?
They are all IRFB4710s. They are probably from two different repairs where only 1/2 were replaced.
The thermistor is replaceable. Is there another one in the amp that you could measure the resistance? You'd need to desolder at least one leg to break the connection to the board.
The main difference in the 37 and 47 is that the 47 is rated for higher current. That would make the 4710 more reliable under low impedance loads. The problem with the owners of these amps is that they all seem to want to run them at 1/4 ohm loads. The 3710s will not hold up to that abuse (or at least not as well as the 4710).
The thermistor is replaceable. Is there another one in the amp that you could measure the resistance? You'd need to desolder at least one leg to break the connection to the board.
The main difference in the 37 and 47 is that the 47 is rated for higher current. That would make the 4710 more reliable under low impedance loads. The problem with the owners of these amps is that they all seem to want to run them at 1/4 ohm loads. The 3710s will not hold up to that abuse (or at least not as well as the 4710).
i placed back the set of six good fets in their original position and the amp powers back on with no popping just the power light pulsing very quickly. What do you make of it so far perry still have to install the other six fets so currently the amp is missing the other six at the moment. Is the pulsing power light because of the fets missing or it sounds like another problem maybe appearing. Will go to the parts store tomorrow to get the fets and see what happens.
I would expect you to have a significant DC offset across the speaker terminals which could make the amp go into protect (if it has DC offset protection).
Im very interested in this case. Have non branded amp with same output mosfets and same 4080aip and couldn't fix it. Very similarly situation. Popping random output mosfets. Have to tell replaced 4080 5 times and very same results. Mosfets too from different sources. And no good results.
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ok perry i replaced the mosfets and hip4080, its up n running just a bit of a buzz on the transformers and a pop/crackly noise on initial start up then running ok. However when no music is playing and the amp in on there is a bit of a buzzing noise through the output and sounds the identical way in which the transformers are buzzing. When i play the music loudly well that buzzing is just drowned out anyway but i would like to know what could be done to eliminate the pop/crackle and get ride of the transformer noise. Also the power and output driver ic's run warm in normal operation?
Do you have your signal source grounded to the 12v power supp;y for the amp?
Is there noise/static with no RCAs plugged in?
Is there noise/static with no RCAs plugged in?
yes there is noise without any rca's plugged in. I am still testing on the bench so a ipod is what am using as signal source at the moment. for the least i would like to get rid of the pop,crackle sound on start up something similar like if you were to connect a speaker directly to a battery or dc power source. if i had to guess i would suspect there is some kind of delay in the turn on circuit maybe a cap taking too long to charge/discharge but again just an assumption. What do you make of it perry?
Pin 3 of the 4080 is generally used to switch the class D circuit on/off. If there is a delay, it will be high (5-12v?) and then drop to near 0v to allow the IC to produce output pulses.
Do you see the noise on the input pin (pin 7 when pin 6 has the triangle waveform) of the 4080 when the amp initially switches on?
Not all amps work well with signal sources that have floating grounds.
Do you see the noise on the input pin (pin 7 when pin 6 has the triangle waveform) of the 4080 when the amp initially switches on?
Not all amps work well with signal sources that have floating grounds.
taking a shot in the dark here without the use of a scope however i can try to see if pin 3 behaves as your describing
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