I have the model in title and looking for schematics. I know that it could be called by other names bc they use amps in different models. Has 4 6L6GC in output stage.
There was Artist and there was Artist VT The plain Artist had transistors in the preamp, the VT version had op amp ICs in the preamp. Make sure.
Ok thanks Enzo. This is a VT. He is complaining that it sounds "Fuzzy" after it been on for a little bit. So far checked the tubes in the output section. They are relatively new and test great with tube tester. All matched. Have any ideas on this. Havent done the basics yet like looking at PS voltages and such. Bias looks like a little on cold side at 10ma for each tube(6L6GC).
Thanks. Your a DIY treasure.
Thanks. Your a DIY treasure.
Play a pure sinewave through it and scope speaker output.
If you "hear" something ugly, you must also "see" it.
IF not, then it´s a speaker problem, cabinet buzz, etc. , not an "amp" problem.
Show screen captures.
PS: fully agree with your opinion on Enzo 🙂
If you "hear" something ugly, you must also "see" it.
IF not, then it´s a speaker problem, cabinet buzz, etc. , not an "amp" problem.
Show screen captures.
PS: fully agree with your opinion on Enzo 🙂
So looking at the schematic above i'm trying to find the dc power supply for the ic preamp. Voltages not looking right that i can tell. Anyone have any idea??
What does that mean?
Focus on the problem.
Does it sound fuzzy to you?
Do you see any weird waveform?
Obviously there is a +/-9V to +/-17V bipolar DC supply somewhere. You can check for it at the op-amp supply pins. And you can guess that many of the non-supply pins will be "zero" within a tenth volt. However those 604 switching opamps have funny pinout and are notorious failure points (and unobtanium today); don't poke them carelessly.
Stuff is missing. Refer to Fender of the same era. The "TO PREAMP" line goes to two diodes and two good-size caps (small power, not signal). Voltage on these is far too high for these opamps, so there will be a dropper, typically 2 resistors and 2 Zeners, possibly with 2 more caps. That should be pretty obvious.
On the Fenders, the parts were picked to survive a 90 day 24/7 warranty, and after a few years of regular gigs the solder joints are burnt and preamp operation is erratic. With a different purchasing agent you may have blown resistors (low-low voltage) or burnt Zeners (WAY Hi voltage).
You have the Artist power amp schematic with the Artist VT preamp. You need the proper schematic, which includes the 15v supplies. I aattach the VT file. Note the schematic serves several models, not just Artist. The boards are the same.
You have 15v rails to the ICs or you don't. The supplies are as simple as it gets, zeners.
You have 15v rails to the ICs or you don't. The supplies are as simple as it gets, zeners.
Everything becomes easy with the right schematic. I'm only seeing 15volts on 4-8 opamp pins. Looks like I'm missing the negative supply. Anyway i can figure it out now. Thanks for the schematic.
Anybody know what the value should be for C6-C9 in the HV power supply. Doesnt show on the schematic. I'm thinking might be different depending on what version
C6-C9 are simple power supply rectifiers, there would be no reason to complicate the models by changing such basic parts. These are only guitar amps, nothing precise. And beyond that, If you changed them from 100uf to 80uf or to 150uf, it really wouldn't much matter.
OK thanks Enzo. What do you know about the input marked automix. Notice that all the inputs work well now but when I plug into the automix it sounds like it distorts the preamp stage. Even at low volumes.