Migz Posted February 15, 2012 Report Share Posted February 15, 2012 (edited) Bought a used amplifier as untested in the hopes that maybe it worked. Plugged power, rem and earth in, power light came on and i was about to start having a party in my head, then when i connected the rca and cables to my sub it wouldn't play anything, absolutely gutted! I was really looking forward to hearing this amp with my subs, atm i have 400w @ 2ohm to two subs. This amp runs 750w @ 2 ohm. I know its nothing compared to you guys but car audio is alot more expensive over here in the uk. So i want to see if i can fix it, but i can't afford to send it away, nor do i know anywhere in the uk that fixes them. I took it apart to see if maybe i could work out whats wrong with it, the only obvious thing i could find was a dark mark on the board. This is what it looks like From a bit further away. On the otherside it was directly under one of those donut looking things, i was reading a tutorial about fixing amplifier last night and i think its the power supply transformer? Does anyone know if this could be an easy fix? Im also going to check all the 3 pronged resistor things later to see if any of them have a broken circuit. I apologise if any of the terms i've used are incorrect but im not an expert in resistors, capacitors and all the rest of that, i can only guess what i think they are from the brief tutorial i read. Edit: Its a Vibe VP4 amplifier just in case anyone needs to know that. Edited February 15, 2012 by Migz Quote Link to comment Share on other sites More sharing options...
Skullz Posted February 15, 2012 Report Share Posted February 15, 2012 (edited) If you can take better pics of the fets which are on the outside of the board and maybe some of the board in the middle to see if we can if see anything is smoked and or burnt. Edited February 15, 2012 by Skullz Quote 01 Ford focus ZX3 Pioneer AVH-X491BHS PPI PC 4800.2 Morel Maximo 6.5" x2 Link to comment Share on other sites More sharing options...
Migz Posted February 15, 2012 Author Report Share Posted February 15, 2012 Wil do when I get home. Will take it with a better camera as well. Quote Link to comment Share on other sites More sharing options...
bobobass Posted February 15, 2012 Report Share Posted February 15, 2012 3 pronged resistor????? Do you mean the transistors? Quote 2000 Subaru outback 2.5l Head Unit: Pioneer deh 4300ub front stage: tbd subwoofer: Stock Fi Q 18" amp: Audio que 1200d Link to comment Share on other sites More sharing options...
timwebb Posted February 15, 2012 Report Share Posted February 15, 2012 thats the inductor. the always run hot. it looks singled layers so im sure its good. u have a better description of what the amp does when first powered up? Quote Link to comment Share on other sites More sharing options...
Migz Posted February 16, 2012 Author Report Share Posted February 16, 2012 thats the inductor. the always run hot. it looks singled layers so im sure its good. u have a better description of what the amp does when first powered up? Powers up fine, power light comes on, when i had it plugged in my girlfriends car the subwoofers just had no output at all. Tried different set of RCA's, same problem. Got home and wired it to a spare computer PSU i have and plugged it into a 6x9, started making a sort of static noise, like the noise you get when you're not on a radio channel. Although i didn't hear that noise when it was in the car, couldve been because i wasn't close enough to the subs or could be interference from the PSU. I twiddled with everything on the amp (gain, lpf, subsonic, phase) to see if it would affect the volume of the static noise but it didn't. It also made the noise when there was no rca's plugged in. 3 pronged resistor????? Do you mean the transistors? Yeah sorry, don't actually know the proper names of any of them, i just read a tutorial that went over the basics of what they are but couldn't remember exactly what it was. Also going to get photos up sometime in the next hour, just need to upload some videos to youtube. Quote Link to comment Share on other sites More sharing options...
timwebb Posted February 16, 2012 Report Share Posted February 16, 2012 u might have a bad opamp. check the rca shield for dc voltage. Quote Link to comment Share on other sites More sharing options...
Migz Posted February 16, 2012 Author Report Share Posted February 16, 2012 So im checking the outer bit of where the RCA plugs into the amplifier on the inside? I'll do it tomorow as it's 4:30am here so i need to go to bed. But will post back here with the results tomorow. Also i've uploaded more pictures. They can be found here. Hopefully those are good enough. Thanks. Quote Link to comment Share on other sites More sharing options...
Migz Posted February 17, 2012 Author Report Share Posted February 17, 2012 I googled how to check rca shield, and it said that to do that i needed to put my negative probe on the amplifier ground, and my positive on the outer bit of the female RCA in on the amplifier. I used that method and checked the outer metal of the female RCA area on the amplifier and i checked the center bit of the female RCA area on the amplifier. I did this on both the input and output. All of them measured 1.3v (give or take 0.1) I also tried measuring with my negative probe on the outer metal and my positive probe on the inside center bit, there was no voltage like that. I just tried that incase that mightve been a different way to do it. Quote Link to comment Share on other sites More sharing options...
STEvil Posted February 17, 2012 Report Share Posted February 17, 2012 if nothing is obviously burned then you need to check the RCA connectors to make sure the solder joints are not cracked. Quote MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..." Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through. Hammerdown... 1% no links to outside websites, business related FB/YT pages allowed. Link to comment Share on other sites More sharing options...
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