Lets start with this question first, who on this forum try to repair a Musical Fidelity f15 before?
Ok, so I got my hands on a F15, well the one that was posted 2/3years ago on the forum that I requested a person to do the repairs on the left side channel for someone. Repairs was done by local in cape town but cost a pretty :2c: :2c: . This amp end up by last month. The owner gave it to me after the Right side channel went belly up and don't want it anymore. It will play for 15/30sec normal and then it will go super loud on the right channel but the left channel is stable and play normal level.
Open the amp and hooohoooooo, it's crazy inside. It's like a lucky packet. This amp in his life time went up to JHB for repairs/upgrades to what I founded out by old owner, and the repairs the person did in cape town side 2/3 years ago and he informed me to that there was some crazy stuff done on this board and the tracks was coming loos of age. This amp was build in 1993.
Right side channel.
Left side channel:
I Check the output terminals on the rights channel, 16v!!!!! :sweat: left channel. 0v. try to adjust the the offset but can only get it down in to the 12v range. Not good. the Right side channel gets super hot to and fast. So I pulled the amp apart to see what's going on and to check for dry joints, didn't look good either there and you can see they try to save some of the tracks . Re-solder some joints just to check if I can safe it this way, start the amp up, no good. The 2 of the 4 10w resister on the PSU gets super hot, if I disconnect the right side channel wiring from the board, then it runs cool with no problems. Left side and right side rail shows +- 46v on both sides and is stable from the PSU side.
Well, if you cant find a 10w resister, lets slap one together. Will replace all 4 resisters with new ones.
Ok, next step, duplicate everything from the left channel that's working to the right side channel and see if I can get it sorted. So the parts arrived on Monday, busy de-soldering and testing with the multimeter and replacing as I go. I spotted that the one MJ15004 is showing open circuit so my guess is it started there. Other problem, with the age of the board, the tracks is busy getting loos when you de-soldering stuff, so it looks like I will have to run on some spots point to point wiring to help. Will give progress report as I go to see if I can get the right channel fixed.
Funny thing was, this is a F15 amp but it's running the A1000 boards. You can't really find info on this amps on the net. You will find photos with two different boards and even 3de on to. Got in contact with JC repairs in the UK side. The F15 first addition came out with A1000 boards in there first addition , this the one I got, then the second and 3de addition used f15 redesign boards. The Pre and PSU shows F15 on them on my one.
You can find Clone boards online and blank boards for this unit but the problem is, the rated volts for them are 24-26V.
Oooooo yes, and Thanks for [member=13623]fredeb[/member] for his help and info to.
Ok, so I got my hands on a F15, well the one that was posted 2/3years ago on the forum that I requested a person to do the repairs on the left side channel for someone. Repairs was done by local in cape town but cost a pretty :2c: :2c: . This amp end up by last month. The owner gave it to me after the Right side channel went belly up and don't want it anymore. It will play for 15/30sec normal and then it will go super loud on the right channel but the left channel is stable and play normal level.
Open the amp and hooohoooooo, it's crazy inside. It's like a lucky packet. This amp in his life time went up to JHB for repairs/upgrades to what I founded out by old owner, and the repairs the person did in cape town side 2/3 years ago and he informed me to that there was some crazy stuff done on this board and the tracks was coming loos of age. This amp was build in 1993.
Right side channel.
Left side channel:
I Check the output terminals on the rights channel, 16v!!!!! :sweat: left channel. 0v. try to adjust the the offset but can only get it down in to the 12v range. Not good. the Right side channel gets super hot to and fast. So I pulled the amp apart to see what's going on and to check for dry joints, didn't look good either there and you can see they try to save some of the tracks . Re-solder some joints just to check if I can safe it this way, start the amp up, no good. The 2 of the 4 10w resister on the PSU gets super hot, if I disconnect the right side channel wiring from the board, then it runs cool with no problems. Left side and right side rail shows +- 46v on both sides and is stable from the PSU side.
Well, if you cant find a 10w resister, lets slap one together. Will replace all 4 resisters with new ones.
Ok, next step, duplicate everything from the left channel that's working to the right side channel and see if I can get it sorted. So the parts arrived on Monday, busy de-soldering and testing with the multimeter and replacing as I go. I spotted that the one MJ15004 is showing open circuit so my guess is it started there. Other problem, with the age of the board, the tracks is busy getting loos when you de-soldering stuff, so it looks like I will have to run on some spots point to point wiring to help. Will give progress report as I go to see if I can get the right channel fixed.
Funny thing was, this is a F15 amp but it's running the A1000 boards. You can't really find info on this amps on the net. You will find photos with two different boards and even 3de on to. Got in contact with JC repairs in the UK side. The F15 first addition came out with A1000 boards in there first addition , this the one I got, then the second and 3de addition used f15 redesign boards. The Pre and PSU shows F15 on them on my one.
You can find Clone boards online and blank boards for this unit but the problem is, the rated volts for them are 24-26V.
Oooooo yes, and Thanks for [member=13623]fredeb[/member] for his help and info to.
