I have an Ampeg SVT-8 Pro that has a weird story but basically died one day and the Fault and Limit lights stay on constantly. Preamp section tests out good and passes signal. I am somewhat sure that it is the Class D 2500 Watt power amp section that may just need to be replaced entirely.
But... I want to make sure the Power Supply is good. Testing seems fine, the rails have steady voltage and the +/- match fairly closely. Preamp tube section is getting power just fine. There are even LED's that light up.
And... here is the thing, some of the voltages don't match and I don't know enough to tell if/where the problem is or if there is a typo on the schematics.
Schematics for the power supply are attached and they were sent from Ampeg. My concern is at J2 and J3 on the second page, it specifies +/- 120V. But I am getting +/- 138V.
Then the real kicker is J7 on the second page. It specifies +/- 12 V Float and I am measuring +/- 120V!! I triple checked thinking I was crazy!
So is that just a typo on the schematics? Maybe the 138V is still in range? What else could be wrong?
I haven't gotten a quote on the power amp module yet, but I assume it isn't cheap and I would hate to blow it up without making sure the power supply checks out.
Thanks in advance!
But... I want to make sure the Power Supply is good. Testing seems fine, the rails have steady voltage and the +/- match fairly closely. Preamp tube section is getting power just fine. There are even LED's that light up.
And... here is the thing, some of the voltages don't match and I don't know enough to tell if/where the problem is or if there is a typo on the schematics.
Schematics for the power supply are attached and they were sent from Ampeg. My concern is at J2 and J3 on the second page, it specifies +/- 120V. But I am getting +/- 138V.
Then the real kicker is J7 on the second page. It specifies +/- 12 V Float and I am measuring +/- 120V!! I triple checked thinking I was crazy!
So is that just a typo on the schematics? Maybe the 138V is still in range? What else could be wrong?
I haven't gotten a quote on the power amp module yet, but I assume it isn't cheap and I would hate to blow it up without making sure the power supply checks out.
Thanks in advance!
Attachments
i want svt8 amp schematics
i have a worry ampeg svt8. amp part is some worry.but i hanve not schematcs for this part . could you give me svt8 power amp schematis? thank you so much.
i have a worry ampeg svt8. amp part is some worry.but i hanve not schematcs for this part . could you give me svt8 power amp schematis? thank you so much.
J2 ans J3 are about right as it will be off load. J7 is + - 12V floating at 120V or 138V.
I would check your centre point on the power stage before doing anything else. I don't have a schematic on the amp section so if you need any further information, please forward it to my email address and I will help you repair it. jon@jonsnell.co.uk
I would check your centre point on the power stage before doing anything else. I don't have a schematic on the amp section so if you need any further information, please forward it to my email address and I will help you repair it. jon@jonsnell.co.uk
Ampeg SVT-8 Pro Bust
Looks like I have a busted power amp section as well, disconnect the power amp board and it comes out of protect. Changed a shorted FET on the power amp board, but still in protect, so looks like more going on. Pre-amp section works fine. Any schematics for the power amp section available from anyone?
All help greatly appreciated.
Mike
Looks like I have a busted power amp section as well, disconnect the power amp board and it comes out of protect. Changed a shorted FET on the power amp board, but still in protect, so looks like more going on. Pre-amp section works fine. Any schematics for the power amp section available from anyone?
All help greatly appreciated.
Mike
I have a broken Ampeg svt-8 pro as well. I was wandering about the float circuit as well.
On mine j7 1st pin is - 127 2nd pin -108 and 3rd pin is -127, is that correct? I get signal up to the power amp
input ic10.
On mine j7 1st pin is - 127 2nd pin -108 and 3rd pin is -127, is that correct? I get signal up to the power amp
input ic10.
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