spirus said:
Try checking this page:
http://users.aol.com/bluemuse/schematics.html
If the schematic isn't there, it tells you where to get it. The St. Louis Music produced Ampeg stuff pretty much requires you to get the schema right from them.
Re: Re: Any Ampeg SVT-II (non-pro) schematics???
If it comes to that, I hope the OP has better luck with them than I seem to, generally. LOUD Group is now the owner of all the St. Louis Music companies, including Crate, Ampeg, and SLM. In addition, they also own Mackie and EAW, among other companies.
Since the buyout, parts and service info has become like pulling teeth without anesthetics. Many parts are simply not supported, and it can take them as long as a week to get back to you (if at all).
I've started steering people away from any new equipment made by any of the companies the LOUD Group owns. I really hate "disposable" gear...
Regards,
Gordon.
Jim McShane said:
If it comes to that, I hope the OP has better luck with them than I seem to, generally. LOUD Group is now the owner of all the St. Louis Music companies, including Crate, Ampeg, and SLM. In addition, they also own Mackie and EAW, among other companies.
Since the buyout, parts and service info has become like pulling teeth without anesthetics. Many parts are simply not supported, and it can take them as long as a week to get back to you (if at all).
I've started steering people away from any new equipment made by any of the companies the LOUD Group owns. I really hate "disposable" gear...
Regards,
Gordon.
What's the problem you are having with the SVT II.
This amp has a common problem with mosfet bias drift, resulting in noise, dsitrotion or low output, there is a simple procedure that I was given by an Ampeg engineer, if this what you are chasing let me know and I'll dig out the procedure.
Michael
This amp has a common problem with mosfet bias drift, resulting in noise, dsitrotion or low output, there is a simple procedure that I was given by an Ampeg engineer, if this what you are chasing let me know and I'll dig out the procedure.
Michael
well not exactly...
well junction
the problem I'm facing is not exactly that...
the real problem is that they brought it to me and it has no output so I'm searching for a schematic to follow the signal path and see where it's put to gnd!
by the way, what u r refferring sounds "good"...
if you'd like to share that knowledge with us, I'd be more than happy to know what the common problem is and how it is solved, as I may run into this problem as I check the amplifier further on...
well junction
the problem I'm facing is not exactly that...
the real problem is that they brought it to me and it has no output so I'm searching for a schematic to follow the signal path and see where it's put to gnd!
by the way, what u r refferring sounds "good"...
if you'd like to share that knowledge with us, I'd be more than happy to know what the common problem is and how it is solved, as I may run into this problem as I check the amplifier further on...
I must have been brain dead when I read this, because the one I worked on was the Pro version, your's is clearly the non pro version, I'll post the details anyway, because it may be the same circuit in the mosfet power amp stage, maybe??
This info came form someone who used to work at Ampeg;
Adjust the trimpot closest to the mosfets for 25mv across the 0.47 ohm resistors in the mosfet source circuit. Average, so check each bank to be sure they are matching pretty well. No signal no load, obviously.
Be sure to have the pot at the LOW end of the bias voltage range to start with, or it will immediately draw a lot of current...........
If the mosfets are not matched for their Vgs(on), within 0.3V, they will never share well, and may fail at high currents. That was the factory spec, and the mosfets were sourced pre-matched and color dotted.
Before that procedure was followed there was a too-high failure rate. Once we introduced matched mosfets, there were a lot less failures.
.....................................................................
This info came form someone who used to work at Ampeg;
Adjust the trimpot closest to the mosfets for 25mv across the 0.47 ohm resistors in the mosfet source circuit. Average, so check each bank to be sure they are matching pretty well. No signal no load, obviously.
Be sure to have the pot at the LOW end of the bias voltage range to start with, or it will immediately draw a lot of current...........
If the mosfets are not matched for their Vgs(on), within 0.3V, they will never share well, and may fail at high currents. That was the factory spec, and the mosfets were sourced pre-matched and color dotted.
Before that procedure was followed there was a too-high failure rate. Once we introduced matched mosfets, there were a lot less failures.
.....................................................................
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