Phoenix Gold MPS-2500 Repair Help, Please
Posted: Sun Aug 30, 2015 7:52 pm
I have (had, in a way, now) a Phoenix Gold MPS-2500. It is a beautiful amp, and I ****** it up. Now I want to cheat death for this poor little guy. Here's the story.
I bought this maybe 6 months back on eBay. It came in pretty goofy condition -- someone had clearly already done something to it (I will be posting pictures, in hopes that you can tell me what exactly was done; I took some when I took this apart for the first time to do the obligatory capacitor replacement). While I was in there, I had to replace the wiring to the RCA jacks. This is I believe revision B, which used the old smaller terminals). I have an MPS-2125 bus bar/terminals/end cover set, that I was using for a while, but I switched back because I could not access the gain control like that; otherwise everything was fine. (this is irrelevant though, the only difference it made was a difference in physical connector sizes). Anyhow, a few weeks ago, I was simply sitting in a parking lot, not listening to anything but radio on, when I smelt The Bad Smell -- the smell that means GTFO your car and flip the breaker, don't wait for the 150A fuse to give out. Sure enough, my amp had turned my custom plexiglass cover a nice nasty soot color, and melted 2 of one channel's transistors nearest the caps. Anyways, I figured that is weird, and simply replaced the transistors (obviously cautiously fuse testing it before powering it up, it worked fine, so I put it back). However, I purchased instead of the original (can't remember 50 or 55v), 57A transistors, some (matching 50 or 55v, can't remember), 70A transistors, at the recommendation for a good substitute from the sales rep (B&D Enterprises, they're close and I get a lot of my parts there).
I replaced the 4 transistors on the damaged side (the channel that is on your right-hand side, if you were looking at the visible side of the circuit board with the bottom off and the capacitors nearest you), and it worked fine after that... For about two days. I noticed it started to sound 'distorted' about 5 seconds before it died completely. When I went to the trunk to see where my bass went, and I found the red (protect) light on. I took the amp out, and inspected, to find no burnt looking anything, but a blown off (literally, off the board) 50v 10uf capacitor (capacitor C221, the one labelled 4.7uf 100v on a MS-2125 schematics diagram, which is not the same as this amp I know -- the capacitor im a matching spot on the other channel is also a 50v 10uf cap) and a blown fuse (the one closer to the edge of the board of the two on that channel). I replaced this capacitor, and fuse, and now get nothing -- no power light, no protect light, nothing.
So, how bad could I have ****** it up, I want to ask (any ideas)? Did my sale's rep's recommendation and my dumb decision to not look further into that, cause this issue? Any clue where to look from here? Also, bonus question -- what are these modifications to this amp? Are these repairs, or some sort of modification? Note: pictures all from before amp blew up.
Last question. Anyone have the schematics diagram of an MPS-2500, preferably early revision? I have the schematics of a MS-2125 if anyone needs those. Can I attach that file here, or is that not allowed? Can email upon request, if that's not okay. Repair materials should be accessible to all, in my opinion.
I couldn't find the original pictures I had taken, so I took some of the board in current state. I have included 'orientation numbers' to help you get an idea of where the zoomed in pictures are. None of these are components I have added, these were all in place when I got it. Any idea what these components added on are for? Any way I can revert this back to 'stock'? Thanks!
Pictures:
http://i.imgur.com/ROFzGBN.jpg
http://i.imgur.com/6bsO8s0.jpg
http://i.imgur.com/vDLazgH.jpg
http://i.imgur.com/PBxmM4V.jpg
http://i.imgur.com/3CQEyDo.jpg
http://i.imgur.com/zXKLJcj.jpg
http://i.imgur.com/1BmZnpW.jpg
http://i.imgur.com/ZBHCHva.jpg
http://i.imgur.com/usDWqEf.jpg
I bought this maybe 6 months back on eBay. It came in pretty goofy condition -- someone had clearly already done something to it (I will be posting pictures, in hopes that you can tell me what exactly was done; I took some when I took this apart for the first time to do the obligatory capacitor replacement). While I was in there, I had to replace the wiring to the RCA jacks. This is I believe revision B, which used the old smaller terminals). I have an MPS-2125 bus bar/terminals/end cover set, that I was using for a while, but I switched back because I could not access the gain control like that; otherwise everything was fine. (this is irrelevant though, the only difference it made was a difference in physical connector sizes). Anyhow, a few weeks ago, I was simply sitting in a parking lot, not listening to anything but radio on, when I smelt The Bad Smell -- the smell that means GTFO your car and flip the breaker, don't wait for the 150A fuse to give out. Sure enough, my amp had turned my custom plexiglass cover a nice nasty soot color, and melted 2 of one channel's transistors nearest the caps. Anyways, I figured that is weird, and simply replaced the transistors (obviously cautiously fuse testing it before powering it up, it worked fine, so I put it back). However, I purchased instead of the original (can't remember 50 or 55v), 57A transistors, some (matching 50 or 55v, can't remember), 70A transistors, at the recommendation for a good substitute from the sales rep (B&D Enterprises, they're close and I get a lot of my parts there).
I replaced the 4 transistors on the damaged side (the channel that is on your right-hand side, if you were looking at the visible side of the circuit board with the bottom off and the capacitors nearest you), and it worked fine after that... For about two days. I noticed it started to sound 'distorted' about 5 seconds before it died completely. When I went to the trunk to see where my bass went, and I found the red (protect) light on. I took the amp out, and inspected, to find no burnt looking anything, but a blown off (literally, off the board) 50v 10uf capacitor (capacitor C221, the one labelled 4.7uf 100v on a MS-2125 schematics diagram, which is not the same as this amp I know -- the capacitor im a matching spot on the other channel is also a 50v 10uf cap) and a blown fuse (the one closer to the edge of the board of the two on that channel). I replaced this capacitor, and fuse, and now get nothing -- no power light, no protect light, nothing.
So, how bad could I have ****** it up, I want to ask (any ideas)? Did my sale's rep's recommendation and my dumb decision to not look further into that, cause this issue? Any clue where to look from here? Also, bonus question -- what are these modifications to this amp? Are these repairs, or some sort of modification? Note: pictures all from before amp blew up.
Last question. Anyone have the schematics diagram of an MPS-2500, preferably early revision? I have the schematics of a MS-2125 if anyone needs those. Can I attach that file here, or is that not allowed? Can email upon request, if that's not okay. Repair materials should be accessible to all, in my opinion.
I couldn't find the original pictures I had taken, so I took some of the board in current state. I have included 'orientation numbers' to help you get an idea of where the zoomed in pictures are. None of these are components I have added, these were all in place when I got it. Any idea what these components added on are for? Any way I can revert this back to 'stock'? Thanks!
Pictures:
http://i.imgur.com/ROFzGBN.jpg
http://i.imgur.com/6bsO8s0.jpg
http://i.imgur.com/vDLazgH.jpg
http://i.imgur.com/PBxmM4V.jpg
http://i.imgur.com/3CQEyDo.jpg
http://i.imgur.com/zXKLJcj.jpg
http://i.imgur.com/1BmZnpW.jpg
http://i.imgur.com/ZBHCHva.jpg
http://i.imgur.com/usDWqEf.jpg