Infinity 7541a Amp
You sent me a request to clarify what is going on with my amp. Anyway I read your page and we have alot in common. I am also ASE certified or should I say was, never renewed. Also I am an electronic tech, I graduated from Tampa Tech which is now called ITT Tech in Tampa Florida back in 1996. Alot has changed but basic electronics is still basic electronics. I want to thank you for replying to my post. First I am having the same problem as another person with the same amp, power and clipping light flashing back and forth. Manual says amp needs to be serviced when it does that. So basicly most of the time the final output transistors are fried or power mosfets are fried, either or. I was seeing if anybody found a solution to this problem yet. I have'nt had much experience in repairing car amps except for replacing some output transistors in a couple of friends' amps that were fried, you could actually see them blown apart so I knew right off that was the problem plus he was running it at 1ohm bridged on a 4ohm bridged amp. Well to begin I was doing a few tests of my own just basic voltage and ohms tests and was trying to ask if you can aproach a car amp just like any other audio amplifire. Say like a home stereo. I used to have a electronic repair shop in a small town here in Florida. I only had a couple of car amps come in so like I said have'nt had much experience in car amp repair. I do have the service manual that some guy I asked to send to me and he did, so at least I have that. Now I also found a site your probably familiar with called bcae1.com Basic Car Audio Electronics. It is a very good site for the novice person wanting to fix thier amps. Gives very detailed info on repair. The guy wants you to buy his DVD rom for $49.95 and I believe it's worth it. Anyway back on the subject brother, I was saying I took some basic voltage and ohms ratings on the output transistors but did'nt know what ratings I was looking for. Even though I know electronics A person can allways continue to learn and it's been 8 or 9 years since I've had my shop and need to brush up and start remembering my tech training, know what I mean. I still know my auto mechanic skills cause I use them still, alot on friends cars as well as people I just happen to run into. So If you can help me or know anything about this paticular amp, it would be greatly appriciated. I can send you the service manual and some pics of the insides if it would help you help me. That site I told you about has been helping out alot but like I said you might know something else thats usefull. So get ahold of me or if you want I would rather call you and talk in person if you don't mind so let me know. I think you can find my e-mail when you click on my name. Well, thanks my brother and hope to speak to ya soon. Later on Bro
Car Audio & Video - Infinity - Reference 7541a Car Audio Amplifier
Answers & Comments
Who ever is having the problem with the crossovers i have the same problem here altho i have found out the cause ...
my amp was mounted upside down and started playing up if i moved the xover switch the speaker would almost pop out of its voicecoil there was that much current being sent to the speaker
after few mins of looking over the amp there is a bord that slides out of the amps mobo (inside) has the xover switches after 20 mins of fiddling i got some glue set the xover to the pass i would like and glued the xrossover switch still now it works like a charm.. took quiet a bit of playing around with the amp on and moving xover swiches till you find the sweet spot ofcorse you could just replace the xoverbord if you dont want to glue your amp
anyquestions feel free to email me
[email protected] . com
Check the speaker terminals for dc, it should be very low,about 100 mV or less, it it is higher you need to find the pots that adjust dc offset to get it down.Also you can compare voltages with the opposite channel to find abnormalities.
i would check the switch with an ohm meter, and the circuits it switches in when the problem occurs,check the solder joints and traces as well as the components. The repair disc you mention is a very good one, worth the money if you work on car amps. I bought it about a year ago but dont really work on car amps very often.And yes a car amp is just like other audio amps to troubleshoot, the main difference is in the power level it works with and the power supply is external to it.which model amp was it you are working on?
although the power supply is external on car amps they still have dc to dc converters to boost the 12vdc up to levels needed for the output stages, i just thought of this after i signed off from my last post.