Itchy's mps2500
Posted: Tue Feb 16, 2010 12:51 pm
ok...this is one of the two amps I picked up in seattle for itchy....knew they didn't work when they were purchased....
So far I've gotten it apart and started the cleaning and polishing process...all the while taking note of what has gone out on the amp...I am getting pretty familiar with the ms power supply so I do believe that I've got most of it sorted out...
Of course I will have to swap out the obviously bad components and power it via dump resistors to really see what it is doing and if I still have more sorting to do...
but so far the right side power supply fets are toast...one cap was bad and the 5401 diodes in the p/s rails tested poorly as I somewhat expected with the hammered fets...of course, if you do one side you have to do both...but that is neither here nor there at this point....r271 and its corresponding rectifiers in the circuit need to be swapped out and the small caps off the right channels output rails all need to go as one blew up when the fet failed...the fuse blew...the one that bridges the output rail to the p/s cap and that cap was damaged...blew a leg off it....all in all the p/s issues are cake as no rails were damaged and the fused did what they were supposed to do...save the bjt's and the core of the audiopath....
of course this amp was filthy...sat open for years in a garage and had a few dead spiders and some dust bunnies in it....in the pics you can tell where and what I've done thru the stages I clean all these amps through and then I will polish it all up...I think the board will be lovely as you can see it is cleaning up nicely....
The pics here are how she sat the day I got it back to town.....in the next post I will load the way she sits now and the damage I've found.....
So far I've gotten it apart and started the cleaning and polishing process...all the while taking note of what has gone out on the amp...I am getting pretty familiar with the ms power supply so I do believe that I've got most of it sorted out...
Of course I will have to swap out the obviously bad components and power it via dump resistors to really see what it is doing and if I still have more sorting to do...
but so far the right side power supply fets are toast...one cap was bad and the 5401 diodes in the p/s rails tested poorly as I somewhat expected with the hammered fets...of course, if you do one side you have to do both...but that is neither here nor there at this point....r271 and its corresponding rectifiers in the circuit need to be swapped out and the small caps off the right channels output rails all need to go as one blew up when the fet failed...the fuse blew...the one that bridges the output rail to the p/s cap and that cap was damaged...blew a leg off it....all in all the p/s issues are cake as no rails were damaged and the fused did what they were supposed to do...save the bjt's and the core of the audiopath....
of course this amp was filthy...sat open for years in a garage and had a few dead spiders and some dust bunnies in it....in the pics you can tell where and what I've done thru the stages I clean all these amps through and then I will polish it all up...I think the board will be lovely as you can see it is cleaning up nicely....
The pics here are how she sat the day I got it back to town.....in the next post I will load the way she sits now and the damage I've found.....