I have a punch 500a 2 coming in on monday it's non working. I want to know if I can use MMBTA06LT1 & MMBTA56LT1 for replacements for the driver transistors? I remember a while back I had a power 551s that I used some of these in it and worked out good.
And for the channels what main components usually fail? Besides the output transistors? So if I drop in new ones I don't want the power supply to fail again. Thanks all
And for the channels what main components usually fail? Besides the output transistors? So if I drop in new ones I don't want the power supply to fail again. Thanks all
Those should work fine. check with Perry to be 100%.
I usually use the MMBT3906 and the MMBT3904.
Besides the output fets, check the gate resistors, the source resistors, and the protection transistor and diodes. Marked 1A, 2A, 5D, A7 sometimes these fail, and sometimes smd resistors fail or go out of tolerance.
You need to get the amp and trouble shoot it to see what the problem is and go from there.
I usually use the MMBT3906 and the MMBT3904.
Besides the output fets, check the gate resistors, the source resistors, and the protection transistor and diodes. Marked 1A, 2A, 5D, A7 sometimes these fail, and sometimes smd resistors fail or go out of tolerance.
You need to get the amp and trouble shoot it to see what the problem is and go from there.
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A06/A56 shouldn't be an issue, rated for higher voltage and current.
Easiest solution not to blow out the supply is a current limit in B+. The other option is to check the gate signal before populating the outputs.
If the supply is trashed remove the fets, apply remote power and gnd then check the gate signals on the power supply fets.
They are still available but hard to find and expensive. They are just obsolete or discontinued.
The IRF3205 is a better substitute anyway, you just have to change the gate resistors to 47 ohm and get your drivers changed and you will be good to go.
I would bet you have some shorted output fets in this amp unless someone just reversed the polarity and popped the power supply section.
The IRF3205 is a better substitute anyway, you just have to change the gate resistors to 47 ohm and get your drivers changed and you will be good to go.
I would bet you have some shorted output fets in this amp unless someone just reversed the polarity and popped the power supply section.
You dont have to change the drivers they will work fine with the IRF3205's but for ultimate reliability since the power supply has failed I would reccommend changing them.
IRF9540's are available almost anywhere. Active parts from ebay or ARROW.COM has them pretty cheap. You can get them from mouser.com and alliedelec.com as well.
The last 300 I bought were from active parts on ebay. I have put them in at least 60 amps with no issues.
IRF9540's are available almost anywhere. Active parts from ebay or ARROW.COM has them pretty cheap. You can get them from mouser.com and alliedelec.com as well.
The last 300 I bought were from active parts on ebay. I have put them in at least 60 amps with no issues.
+ a shorted power supply. It also appears this amp may have been worked on by RF? Did they still service the "A" series amps around 2001?
Replace the 4 power supply fets with the IRF3205's, change the gate resistors to 47 ohm, change the 2 npn and 2 pnp drivers for the power supply.
Then BEFORE powering it up. Check all the output fets to see if any are shorted. IF you find some that are shorted just clip them out of the circuit. If you find multiple shorted just remove them all and start over.
Once the shorted output fets are removed then power up the amp and you shouldn't have any issues. If there are multiple shorted fets in the output they all have been very stressed and are borderline reliable.
Dont forget to check the gate resistors for the output fets, and the source resistors. Once you get them all replaced be sure to check for DC before hooking the output up to a speaker. Depending how bad the channels are blown you might have to dig in to the protection circuit a little.
Then BEFORE powering it up. Check all the output fets to see if any are shorted. IF you find some that are shorted just clip them out of the circuit. If you find multiple shorted just remove them all and start over.
Once the shorted output fets are removed then power up the amp and you shouldn't have any issues. If there are multiple shorted fets in the output they all have been very stressed and are borderline reliable.
Dont forget to check the gate resistors for the output fets, and the source resistors. Once you get them all replaced be sure to check for DC before hooking the output up to a speaker. Depending how bad the channels are blown you might have to dig in to the protection circuit a little.
Yes those are the ones I'm talking about. It's Q2, Q1, Q5, Q4. Off to install the drivers now....
OK after the drivers, the power supply fets and the gate resistors for the power supply fets are changed then check for shorted output fets.
Not a 100% method for leaky ones but 100% for shorted ones use your DMM and check the resistance from source to gate on the output fets and if you see anything like 1.2, 2.4, etc they are shorted.
If both channels are shorted you might want to consider removing all of them and starting over to ensure the amp will be reliable.
Make sure you dont power up the amp with shorted output fets or you will damage the power supply again!!
Not a 100% method for leaky ones but 100% for shorted ones use your DMM and check the resistance from source to gate on the output fets and if you see anything like 1.2, 2.4, etc they are shorted.
If both channels are shorted you might want to consider removing all of them and starting over to ensure the amp will be reliable.
Make sure you dont power up the amp with shorted output fets or you will damage the power supply again!!
I have a problem, Q11 & Q7 have a little over 12vDC on the gate pads while the other two have 5.14vDC on there pads. I just replaced the drivers. And yes both channels were shorted I removed all the shorted transistors.
No I have not replaced the gate resistors yet I just replaced the driver transistors. I'm trying to find out why I have 12v at Q11 & Q7 on there gate pads.
I don't have any fets installed yet but I did put two test ones in Q10 & Q9 and the amp turned on but if I put two more on the other side amp won't turn on and the fets will get extremely hot fast.
What else should I check? This is weird the last time I rebuilt a amp similar to this everything worked first time.... Could it be a driver IC? TL494C?
You need to make sure all 4 gate resistors have been changed and are 47 ohm resistors. If the old ones are out of tolerance you might get a faulty reading on the gate pad.
Change the all 4 gate resitors to 47 ohm then post your readings on the gate pads.
What are the originals 68 ohm?
If so what is the resistance across all 4 of them?
Change the all 4 gate resitors to 47 ohm then post your readings on the gate pads.
What are the originals 68 ohm?
If so what is the resistance across all 4 of them?
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Hey it's a success !! Turns out I didn't watch closely when I was soldering in the new driver transistors and bridged a connection so I thought I'll just re do the whole thing one more time to see what happens. Now I get 5.22vDC on each gate pad. Also changed the gate resistors to 47 ohms and installed the fets and amp came on ! I am tired out took me 2 hours lol the last punch 500 & 551S I did took less time.
Oh yeah amp has 86.2v on the rectifiers. Now to the output stage.,.,.what do I check for any shorted components before I buy fets? I know on one channel it had two missing source resistors and the rest were burned/open but on the other channel the source resistors where still good. Also checked the gate resistors they all read 10 ohms.
Also one more thing can I use the O.G Harris IRF540 with a modern IR 9540? a ebay seller has the OG Harris IRF540 like the ones used in this amp. I just wanted to try keep it original asap. Funny thing about this amp is that the "warranty void if broken" stickers were uncut when I received this amp and had a couple missing parts and had the smoke stains inside from a previus failor. I'm guessing Rockford may have serviced it back then?
Oh yeah amp has 86.2v on the rectifiers. Now to the output stage.,.,.what do I check for any shorted components before I buy fets? I know on one channel it had two missing source resistors and the rest were burned/open but on the other channel the source resistors where still good. Also checked the gate resistors they all read 10 ohms.
Also one more thing can I use the O.G Harris IRF540 with a modern IR 9540? a ebay seller has the OG Harris IRF540 like the ones used in this amp. I just wanted to try keep it original asap. Funny thing about this amp is that the "warranty void if broken" stickers were uncut when I received this amp and had a couple missing parts and had the smoke stains inside from a previus failor. I'm guessing Rockford may have serviced it back then?
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