how do i tell the difference between a output transistor and a power supply transistor? i am working on a smal MTX amp i have 4 small ones on one side of the amp and 2 large ones on the other side. the 4 on the one side are burnt and look failed. where do i buy them from?
the amp is MTX rtp251d and the numbers on the faild transistor are 18sf2f and 75339p
the amp is MTX rtp251d and the numbers on the faild transistor are 18sf2f and 75339p
One terminal of each of the output transistors will be connected to one of the speaker terminals.
One terminal of each of the power supply transistors will be connected to the power transformer.
The HUF75339P is used in the power supply. Mouser.com has them.
512-HUF75339P3
One terminal of each of the power supply transistors will be connected to the power transformer.
The HUF75339P is used in the power supply. Mouser.com has them.
512-HUF75339P3
i have 4 of these should i replace all 4 of them? one is a complete meltdown and one has no continuity between the outer legs
There should be no continuity between the first leg and either of the other legs.
You should replace all 4.
You should replace all 4.
Go to Perry's site and it shows a basic layout for most amps. Usually 12v comes in through fuses and 16v (or higher) cap(s) and to PS transistors*, they hook to round torrid transformer, then to rectifiers* (usually two), then to large rail caps, then to outputs*, outputs through large resistors in front of them to speakers. Usually PS transistors have torrid close by, and outputs have all the small input circuits next to them. A few amps twist it around, but most are PS/output/input from one end to other. If not then usually that in a circle. Sometimes rectifiers are across from PS transistors (smaller amps), sometimes next to them on both sides (large long amps). Can also look at the numbers on the board to ID them as transistor or diode.
* = on heatsink.
* = on heatsink.
here is a picture of them. what is that thing in the middle of the 4? does it need to be replaced alongside the resistors? should i look for anything else? or just change these 4 and go try it?
of the 4 there are 3 different manufacturers? is this important?
of the 4 there are 3 different manufacturers? is this important?
The two on the left are the rectifiers. They're probably not defective and won't need to be replaced.
If there are only two of the 75339s in the amp, you only need to replace those two. Are there 2 more 75339s on the other side of the amp?
The device under the foam is a thermistor. It's unlikely to be defective.
If there are only two of the 75339s in the amp, you only need to replace those two. Are there 2 more 75339s on the other side of the amp?
The device under the foam is a thermistor. It's unlikely to be defective.
well there are 2 additional transistors on the opposite side but they are much larger. they are both the same and they have the number "IRFP240" on them
i replaced the 2 transistors numberd 75339p and now it will power up if apply power via a resistor but if i apply current directly from a power source it immediatly shuts off the power supply.
It appears that at least one of the PZTA56 transistors has failed. The resistor to the right of it is likely a 10 ohm. Replace both of the PZTA transistors (there should be another one very near the burned one) and both 10 ohm resistors.
Try to read the numbers off of the right-most resistor in the group of 4. All 4 in that group will likely be the same. They will have to be replaced also.
All of the components above drive the power supply FETs. If they were defective, it could have caused the new FETs to have failed. You will need to check the FETs. If they burned only after the new FETs were installed, there was a solder bridge on the FETs or the FETs failed because they were not clamped to the heatsink.
Try to read the numbers off of the right-most resistor in the group of 4. All 4 in that group will likely be the same. They will have to be replaced also.
All of the components above drive the power supply FETs. If they were defective, it could have caused the new FETs to have failed. You will need to check the FETs. If they burned only after the new FETs were installed, there was a solder bridge on the FETs or the FETs failed because they were not clamped to the heatsink.
Those are probably both PZTA56s but I can't read the numbers on them. Do they both have A56 on them?
Are they both connected to the yellow transformer next to them?
If so, they are the ones you need to change.
To get definitive results when checking transistors, they need to be out of the circuit (off of the board).
There are different procedures for checking various types transistors. Go to page 97 of my car audio site and find the section labeled 'Checking Bipolar Junction Transistors'. The images are for NPN transistors. The PZTA56s are PNP transistors so you'd need to reverse the leads to test them. The procedure for testing FETs is above the Checking Bipolar Junction Transistors section.
You need to pull the FETs and check them.
Are they both connected to the yellow transformer next to them?
If so, they are the ones you need to change.
To get definitive results when checking transistors, they need to be out of the circuit (off of the board).
There are different procedures for checking various types transistors. Go to page 97 of my car audio site and find the section labeled 'Checking Bipolar Junction Transistors'. The images are for NPN transistors. The PZTA56s are PNP transistors so you'd need to reverse the leads to test them. The procedure for testing FETs is above the Checking Bipolar Junction Transistors section.
You need to pull the FETs and check them.
i got some parts in the mail today and the resistors i ordered are too large i need the 0805's im not sure what size these ones are but they are about double the size and measure a different resistance.
can someone help me out with the part number from MCM for a smd resistor 0805 with 61R9 marked on it
and yes they are both marked A56.
can someone help me out with the part number from MCM for a smd resistor 0805 with 61R9 marked on it
and yes they are both marked A56.
I couldn't find them at MCM. This is from Mouser:
71-CRCW080561R9FKEB
PZTA56s if you need them.
512-PZTA56
The resistor you have is probably a 1206. The following photo shows the difference between 1206 and 0805.
http://www.bcae1.com/temp/ttIMG_7796b.jpg
71-CRCW080561R9FKEB
PZTA56s if you need them.
512-PZTA56
The resistor you have is probably a 1206. The following photo shows the difference between 1206 and 0805.
http://www.bcae1.com/temp/ttIMG_7796b.jpg
i got my new resistors in the mail and now it seems to power up just fine and it even makes noise now. i am using a portable mp3 player and a small speaker from a home theater system as test peripherials. it is amplifing sound but it seems to only be amplifing low ends like its stuck in low pass. this amp is not equiped with any built in cross over.
is there anything else i should check before trying it in a car?
is there anything else i should check before trying it in a car?
The amp has a built in crossover (low pass, 85Hz fixed).
http://www.mtx.com/caraudio/products/amplifiers/RTP251D.cfm
If it's producing audio with the test speaker/source, it's probably ready for testing in the vehicle.
http://www.mtx.com/caraudio/products/amplifiers/RTP251D.cfm
If it's producing audio with the test speaker/source, it's probably ready for testing in the vehicle.
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