I have an XRD680 Plus that has an odd problem seemingly on both the main power amps or maybe the power supply? At low power levels the sound is clean & undistorted but as the drive is increased the sound cracks, distorts and reduces in level.
Reducing the drive to the output amps results in a slow restoration of clean sound, just like a slow agc cutting in or out.
I have only been able to find the schematic for the XRD680 (not plus) and it doesn't seem to relate very closely... the Plus Amps have three output pairs (not just two) of Motorola 70483180 & 70473180 and a bridge rectifier at each end of the main pcb. And the pcb layout is very different.
Has anyone got a schematic of the plus power amp & psu please? Or any bright ideas where I should start troubleshooting, could the DDT or thermal protection system be at fault or should I simply check all the output transistors for O/C's or the voltage rails for some form of collapse?
Such a solidly built bit of kit but not the easiest to access for troubleshooting
So any /all advice gratefully received...
Dave G
XRD680 Plus ... Is DDT my problem?
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Re: XRD680 Plus ... Is DDT my problem?
Did you ever figure it out? I have an XRD680 Plus which I have had for about 10 years. I have never had a problem with mine except that I pulled out three of my XLR connectors once when I plugged in some off-brand mic cables. They went in too tight and when I forced them out, it pulled apart the input jacks. Hope you find your solution. Hope I never have your problem.