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Hello, I just bought an avt 150hx off ebay, (I know). Anyway, I plugged it in and it doesn't work. The power switch lights up and I can here a sound through the cabinet. Nothing else works, pedal board lights, channel lights on front panel, tube, nothing. My avt 50h with the same cables and cabinet works fine. I even switched the pre amp tubes. I've read alot of posts on this forum and it took me awhile to realize the difference between the 150h and 150hx. I now have the right schematics. I seen alot of posts refer to the tda7293 chips, but i don't think mine has those? Ive also seen posts referrring to low voltage supply rails. The outputs of the tranformer show what their supposed too(32 & 18). What should I be looking for. Thank you for your time. Brian
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How about posting the schematic. -
avt 150 schematics
Here they are,Comment
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It appears , from the schematics, that the AVT150X uses the AVT150 preamp & the AVT100X output section.
If so, the 150X does not have the TDA7293.
It has a discrete component output section.
The test of the transformer is a good first step.
Now follow the schematic to the right where the Vac gets rectified & becomes the Vdc rails.
What are the Vdc readings.
There are two power supply circuits.
One for the high voltage & one for the + - 15 volts.Comment
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AVT 150 HX problem solved
I found out the problem, R223 and R202 were open. I put jumpers on the resistors and it works fine. I called my first year electrical instructor, who is also my Dad, and he helped me. I guess I was sleeping during that class. Anyways, thanks for the help. BrianComment
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Uhmmm.
You are going to replace the 2R2 1watt resistors , right?
A wire is not going to open if there is a problem.
Makes you wonder what demanded enough current to open both resistors.Comment
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Yes i'm am replacing the 2.2 ohm resistors. As for why they opened, the cables might not have been pushed in the whole way and its super sensitive. I'm used to my avt 50 which takes a few seconds to come to life when you hit the power switch. I was hurrying so I hit the switch while i was still plugging cables in. I won't know until I replace the resistors tonight and actually try it out, but last night when I put the jumpers on, everything lit and I had sound on all 4 channels. Hopefully it was just bad luck, but I'll be more careful in the future.-BrianComment
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