I have an early version of the DSL50 jcm2000 amp to which there is no reference anywhere...printed out the schematics I could find but there are too many differences in denomination of the components and wiring lugs. Anyways I'll state my findings, initial problem is that the channel switching doesn't work at all, the LED doesn't turn on either...so basically its stuck on the clean channel. I tried powering up the amp just to see if it was working at all...it does sound very flimsy and bad so powered off and proceeded to do some tests. HT, heaters and bias voltage seem to be ok. It's just the LV that seems dead. So tracking from the PT LV lugs I'm getting around 21vAC through to the rectifier diodes D6, D7, D8 and D9. On the other sides of D8 and D9 I'm getting around -58vDC and on the other side of D6,D7 I'm getting 0. So I replaced them but still the same readings.
So my question at this point is... am I getting the right AC readings off the PT? If so, since the amp has obviously been tampered with in the past by someone else, did they solder the PT LV wires to the right lugs on the board? W9, W10 and W11 are the lugs used on the board but on the schematic these lugs are denominated W11, W12 and W13. There are other proven factory differences between the board and the earliest schematics so for that side of things I think everything is fine. The other difference I noticed are C6 and C37 are on the board both electrolytic (they have been replaced with 10uf 450v) which I guess is incorrect as C37 on the schematic states 47uf 63v so again too many inconsistencies to be able to rely on any versions of the schematic.
thanks for any help at all
So my question at this point is... am I getting the right AC readings off the PT? If so, since the amp has obviously been tampered with in the past by someone else, did they solder the PT LV wires to the right lugs on the board? W9, W10 and W11 are the lugs used on the board but on the schematic these lugs are denominated W11, W12 and W13. There are other proven factory differences between the board and the earliest schematics so for that side of things I think everything is fine. The other difference I noticed are C6 and C37 are on the board both electrolytic (they have been replaced with 10uf 450v) which I guess is incorrect as C37 on the schematic states 47uf 63v so again too many inconsistencies to be able to rely on any versions of the schematic.
thanks for any help at all
Update: found the problem...compared the readings to another jcm2000 dsl50 and readings were more or less the same except the lv readings on the output board. I managed to trace back to the 2 pcb mount fuses so I replaced them and the amp is back to working conditions....however I still would like to know what made them blow.
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