PPI 4400 Help Needed

Bought a used ppi 4400 about 10 years ago but just now hooked it up. discovered that the rr channel is very garbled at low power and then starts to clean up when turned up but still has distortion. did the normal swap of inputs, speakers and wires. still has issue with rr channel. also tried the button that used the front inputs to power the rear outputs and still the same. is there a diagram available for this unit i can get or any help from anyone here on what needs to be changed. much appreciated Paul
 
Hi Paul,
Try the Perry Babin links for basic troubleshooting skills required for working on any car amplifier. Please click the links below this text...Perry Babin has done a great job of pulling all of the skills and basic knowledge together for you to study at your own pace. I recommend it highly especially if your new to this sort of thing..You did not indicate your level of experience so I am sending you to the best basic source I know of. All amplifier failures are not alike so just throwing some general failure modes and solutions to you will just blind you somewhat, and possibly cause root issues to be overlooked...hope this helps some to start you out with.
We here on the DIY also like to see inside picture of any amp your working on so if you can please post a couple clear good res pictures with your questions...

PPI did not release schematics back then so it might be tough for you to get your hands on a schematic. They built all of their amps on one single basic design so they all share common similarities between the different power levels.

Perry thank you for letting me borrow your links...:)


Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links
 
Thanks for the links I will check them out and see what I can come up with. The unit is still installed as 3 ch still work. I was going to wait to see if I could come up with a schematic before removing it. But I can certanily take it out and get some pic's. I dont currently have a gen or scope but I do know a little about componets and their functions. Probably not as much as I used to LOL. Still have my soldering / desoldering station so can change parts if necessary. Looks like the people here are way above my level thought that is why I joined and posted for help. I also know my way around a schematic if one was available. Thanks.
 
Thanks for the links I will check them out and see what I can come up with. The unit is still installed as 3 ch still work. I was going to wait to see if I could come up with a schematic before removing it. But I can certanily take it out and get some pic's. I dont currently have a gen or scope but I do know a little about componets and their functions. Probably not as much as I used to LOL. Still have my soldering / desoldering station so can change parts if necessary. Looks like the people here are way above my level thought that is why I joined and posted for help. I also know my way around a schematic if one was available. Thanks.



You will have three working mirror image channels to guide you by when you open it up. You can always do the old fall back of comparing a known good channel to the bad one with a meter. As I said these are all based on a single design so the three good channels should be enough to guide you with since no schematics are likely available.
look for shorted output transistors, and burnt 2 watt resistors nearby. These amps cost so little to build that replacing everything in the bad channel should only cost you 10 to 20 bucks. Hopefully it does not use the SIP driver cards, while they can be repaired sometimes, when they need replacing they are really tough to find..

Typically a garbled channel mean burnt devices like outputs and emitter resistors nearby. but without pics I am guessing so bear that in mind so I don't misguide you.;)
 
Thanks for the advice. Sorry for the delay in getting back but been reading the info from the links you sent me 1moreamp. They were very informative and helpfull. So I have taken the unit out and apart. First thing I seen was this amp has been worked on before. Found alot of solder splatter, changed componets and torn and missing runners on the main board. yuck. I had to completely remove the board to see if the runners that were missing were replaced with jumpers on the back or not. One between 2 transistors was and one looks like it is still missing. At this point I dont know if pic's would even help. I dont see any signs of burnt componets. The one componet that has been changed with the missing etching is for U1 (7915cv morocco) looks to be a -15v reg. Opposite side of board has orignal U6 (7815ct motorola) +15v reg. I googled their data sheets and they are not excatly the same. If you still think some pic's will help I will try and get some up here. Thanks Paul
 
did you ever fix it and i have more questions

Thanks for the advice. Sorry for the delay in getting back but been reading the info from the links you sent me 1moreamp. They were very informative and helpfull. So I have taken the unit out and apart. First thing I seen was this amp has been worked on before. Found alot of solder splatter, changed componets and torn and missing runners on the main board. yuck. I had to completely remove the board to see if the runners that were missing were replaced with jumpers on the back or not. One between 2 transistors was and one looks like it is still missing. At this point I dont know if pic's would even help. I dont see any signs of burnt componets. The one componet that has been changed with the missing etching is for U1 (7915cv morocco) looks to be a -15v reg. Opposite side of board has orignal U6 (7815ct motorola) +15v reg. I googled their data sheets and they are not excatly the same. If you still think some pic's will help I will try and get some up here. Thanks Paul
 
i think i bougt this amp working but now has failed

You will have three working mirror image channels to guide you by when you open it up. You can always do the old fall back of comparing a known good channel to the bad one with a meter. As I said these are all based on a single design so the three good channels should be enough to guide you with since no schematics are likely available.
look for shorted output transistors, and burnt 2 watt resistors nearby. These amps cost so little to build that replacing everything in the bad channel should only cost you 10 to 20 bucks. Hopefully it does not use the SIP driver cards, while they can be repaired sometimes, when they need replacing they are really tough to find..

Typically a garbled channel mean burnt devices like outputs and emitter resistors nearby. but without pics I am guessing so bear that in mind so I don't misguide you.;)