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Well I have a EMC schematic but there are some differences. On this amp (Performer II) there are 2 trim pots on the driver board one is a 100 ohm the other is a 50k, but the schematic I have only shows a 100 ohm trim pot. The 100 ohm is tied to the base of the ECG192 and 2n3767 I really am lost other than basics here with this amp, anyone have any suggestions for starters? Most of the power transistors are blown and 2, I cannot read what the RCA numbers are. 2 power transisitors have been replaced with ECG181 the other 2 are RCA, but no numbers left. What looks like driver transistors are 2n3741 and
2n3767.there is a small ECG192 next to one of the ECG181's and it looks like its bad as well. Some EMC schematics are available but not this particular model. There are what looks like 2- .5 ohm (original) emmiter resistors and someone replced the other 2 with a .51 ohm and a .56 ohm... that coincides with the ECG181's. I am trying to repair this for a friend but do not want to pay $200 plus to send it to AudioProz, I have found some transistor cross ref. part replacements but I would really like to know this amp a little better before doing any transplanting of parts. The owner really liked this amp, so that is why I am still searching out any info possible. AudioProz says they replace parts that need to be updated, I think they are replacing electrolytic caps and such and any out of tolerance parts. So is there really any tone improvements other than replacing these old parts, I know its hard to answer without a schematic, but maybe someone has some experience with these amps? I also have his Rogue (Musicians friend special) PRM 1208 mixer PA that mums/buzzes pretty good in the power amp, I checked the transistors which seem ok, no fuses blowing, but the power supply reads +30 vdc and
-40vdc on the neg side, could it be the regulator is bad? I am trying to find a schemo for that too, called MF and waiting to hear back.......
Thanks
Ed
2n3767.there is a small ECG192 next to one of the ECG181's and it looks like its bad as well. Some EMC schematics are available but not this particular model. There are what looks like 2- .5 ohm (original) emmiter resistors and someone replced the other 2 with a .51 ohm and a .56 ohm... that coincides with the ECG181's. I am trying to repair this for a friend but do not want to pay $200 plus to send it to AudioProz, I have found some transistor cross ref. part replacements but I would really like to know this amp a little better before doing any transplanting of parts. The owner really liked this amp, so that is why I am still searching out any info possible. AudioProz says they replace parts that need to be updated, I think they are replacing electrolytic caps and such and any out of tolerance parts. So is there really any tone improvements other than replacing these old parts, I know its hard to answer without a schematic, but maybe someone has some experience with these amps? I also have his Rogue (Musicians friend special) PRM 1208 mixer PA that mums/buzzes pretty good in the power amp, I checked the transistors which seem ok, no fuses blowing, but the power supply reads +30 vdc and
-40vdc on the neg side, could it be the regulator is bad? I am trying to find a schemo for that too, called MF and waiting to hear back.......
Thanks
Ed