Hi
I'm from Turkey and I've recently bought a Mesa Boogie Mark IV Combo from a seller on eBay. Actually a friend of mine bought the amplifier for himself but because of his lack of technical knowledge, I'm in charge of the problem solving. Therefore, to keep things a little bit simple I'll talk as if I've bought the amp myself.
Anyway, the amp has some problems. First of all, it doesn't sound like it should, more like a 30 watt solid state amp running on a 18" speaker with volume knob gone to eleven(Muddy lows, almost no highs). I know that the amp doesn't sound like that but this is the least of our problems. The other ones are:
-Master volume knobs don't work. All three channels have a fixed master volume.
-The auto assign button on the right(Rhythm 2 - Lead) switches the channel to Rhtym 2 or Lead(has no effect when it's in the middle), regardless of any other settings on the amp.
-When you pull the Drive Level knob, where it should normally just brighten up the lead channel, it activates the master volume knobs for the channels.
-When that knob is pulled and master volumes are working, their volume levels are reduced from their non-working time. R1 is stays the same, R2 has slightly less volume but noticeable and Lead has 3/4 of the volume(when the master volumes are set to 10).
-When I select the lead channel from the back dial and I play with the Auto Assign switch, R2 position activates the R2 channel. Middle position has no effect(stays in the lead channel), Lead position still has no effect on the channel but channel LED on the Lead channel becomes brighter.
Since I live in Turkey, I can't just go to a Service Center. None of the repairmen here has ever seen this amp before, Boogies are quite rare here. Most of these problems are somehow related to the Fx Loop, except the sound quality and the push-pull issue. I have a limited knowledge of electronics but I checked the schematics which could be found on the internet and I have the impression that these issues could be related to the LDRs used in the amp. I'll probably give the amp to a very skilled repairman I know but he has never worked on a Mark IV before. Do you have any idea about the cause of these problems? Any suggestions?
Thanks for your help and concern
I'm from Turkey and I've recently bought a Mesa Boogie Mark IV Combo from a seller on eBay. Actually a friend of mine bought the amplifier for himself but because of his lack of technical knowledge, I'm in charge of the problem solving. Therefore, to keep things a little bit simple I'll talk as if I've bought the amp myself.
Anyway, the amp has some problems. First of all, it doesn't sound like it should, more like a 30 watt solid state amp running on a 18" speaker with volume knob gone to eleven(Muddy lows, almost no highs). I know that the amp doesn't sound like that but this is the least of our problems. The other ones are:
-Master volume knobs don't work. All three channels have a fixed master volume.
-The auto assign button on the right(Rhythm 2 - Lead) switches the channel to Rhtym 2 or Lead(has no effect when it's in the middle), regardless of any other settings on the amp.
-When you pull the Drive Level knob, where it should normally just brighten up the lead channel, it activates the master volume knobs for the channels.
-When that knob is pulled and master volumes are working, their volume levels are reduced from their non-working time. R1 is stays the same, R2 has slightly less volume but noticeable and Lead has 3/4 of the volume(when the master volumes are set to 10).
-When I select the lead channel from the back dial and I play with the Auto Assign switch, R2 position activates the R2 channel. Middle position has no effect(stays in the lead channel), Lead position still has no effect on the channel but channel LED on the Lead channel becomes brighter.
Since I live in Turkey, I can't just go to a Service Center. None of the repairmen here has ever seen this amp before, Boogies are quite rare here. Most of these problems are somehow related to the Fx Loop, except the sound quality and the push-pull issue. I have a limited knowledge of electronics but I checked the schematics which could be found on the internet and I have the impression that these issues could be related to the LDRs used in the amp. I'll probably give the amp to a very skilled repairman I know but he has never worked on a Mark IV before. Do you have any idea about the cause of these problems? Any suggestions?
Thanks for your help and concern