I wanted to try and repair a channel on a Rockford amp ive had sitting for months it works great but one side gives me 27 volts. Maybe some mosfets shorted out? Is it possible to buy some new mosfets and just slap em in and will function again? Or will the problem be present again? Could there be anything else short? I measured the big resistors and they read 0.01 is that good? Sorry for all the questions,,,still trying to learn. Thanks
I suppose it's 'rail voltage' I measured it with a dvm. Before that it was pushing the speaker out. It's the left channel that's down. What shout I look for on this??
Set your meter to diode check, check the voltage drop between all three legs of your output transistors, meaning place one lead on leg 1 and the other on leg 2, then check 1 and 3, then check 2 and 3(especially). If you get anything near .0v then the transistor is toast. If you post a picture of the amp we can tell you which transistors are your out puts, or if Perry chimes in he can prolly tell you off the top of his head.
Grab the 40_2 schematic from my site, it should be close to what you have.
https://sites.google.com/site/brandescm/home/projects
Outputs are labelled Q115, Q119, Q215, Q219
https://sites.google.com/site/brandescm/home/projects
Outputs are labelled Q115, Q119, Q215, Q219
Yes I already did that and I got on diode check (IRF9540) .004 according to my meter and it was making a beeping
noise indicating it was shorted and I got for (IRF540) legs 1&2 (gate to drain) .528. Gate to source i got .075.
Can you tell me which ones are the driver transistors? Are they surface mount? I checked the small surface mount resistors and i got 11 ohms for R150 and 12 ohms for R152 they both have 100 marked in them. Are these 10 ohm or 100 resistors? Thanks for the help!
I would replace all the output transistors for the left channel. Also check the large emitter resistors check if there is and discoloration on them.And also check the driver transistors for the left channel outputs.
If all check good replace the outputs and turn the bias pot fully counterclockwise.
Replace the IRF9540's and 540s's with the same part or switch to IRF540A
(A) as the suffix.
The 540N and 9540N's may give you problems as some of the rockford amps ive worked on didnt like the 540n's and 9540n's
Hope this helps
If all check good replace the outputs and turn the bias pot fully counterclockwise.
Replace the IRF9540's and 540s's with the same part or switch to IRF540A
(A) as the suffix.
The 540N and 9540N's may give you problems as some of the rockford amps ive worked on didnt like the 540n's and 9540n's
Hope this helps
They are surface mount transistors for the drivers They are usually marked 1a and 2a set your meter to diode check and test them the same way as you did the outputs. Make sure you pull the bad outputs from the board before u test them.
Also the resistors you tested marked 100 are 10 ohm resistors if you have 11 ohms on 1 and 12 ohms on the other they should be fine
Also the resistors you tested marked 100 are 10 ohm resistors if you have 11 ohms on 1 and 12 ohms on the other they should be fine
Okay gate resistors are off the list, may I ask what are typical readings for drivers transistors? And emitter resistors? .001 that's what i got when i checked them. They don't look burned or anything. Also I have donor RF amp that has good working IRF540s and IRF9540s. The power supply isn't fully working so that's why it's a donator amp
. Thanks for all the help!What's the difference between IRF540 & "IRF540N" because I was browsing for some replacement MOSFETs and all I can is find irf540n's seems like they are the same type? Or can I use some from a donor amp? They still work on this donor amp. I also have a Punch 60x2 that I want to try a shot at. This one is burned up pretty bad. Also if try this can I use BUZ10 mosfets as the power supply?
The IRF540Ns typically don't work properly in Rockford amplifiers.
If the ones from the donor amp are OK, there's no reason that they shouldn't work.
The BUZ10 isn't the best choice but they will work if you already have them. The IRFZ44 would probably be a better choice. Remember to check the gate resistors and the driver transistors.
If the ones from the donor amp are OK, there's no reason that they shouldn't work.
The BUZ10 isn't the best choice but they will work if you already have them. The IRFZ44 would probably be a better choice. Remember to check the gate resistors and the driver transistors.
Hey!! It was a success! The amp played music nice and clear. But how do i set the bias? The left side gets a little warm so I'm not sure to set those.
No I don't it doesn't have one it's just a 10amp 12volt powersuply. Could I use a vom?
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