DENON Denon amplifier PMA-890DGX is a classic old Denon, rich Golden appearance slightly domineering power amplifier stage with two final output to 2SA1490/2SC3854, Mono can be up to 200 watts, that powered the vast majority of brands of three crossover floor box is very easy to do.VvNservice manual download site
VvNservice manual download site
Tian long paying special attention to its power tube amplifier repair, a considerable number of days long instead of ordinary triode amplifier, but Darlington compound pipes, so be sure to replace the original accessories.VvNservice manual download site
Denon amplifier exclusive original power CanalVvNservice manual download site
VvNservice manual download site
Teardown examination revealed the left power supply fuse has blown, judging by the amplifier after a failure, after the level has been a serious short circuit, remove the last-stage power amplifier tube, measured both on breakdown short-circuiting. Further observations of the first-stage amplifier circuit has a resistance burned black, appears to be a comprehensive inspection at every level amplifier circuit, according to amp repair experience, usually in amp amplifier stage will be blackened resistance generally is power resistors or bias resistor, its damage indicate serious excess current phenomenon,VvNservice manual download site
VvNservice manual download site
In most cases, successive levels of zooming in on the tube is damaged. You cannot replace the resistor directly after power on, or you will have a greater range of fault. Secure is pressure maintenance, the indicator parameters for standard voltage are normal again after. After replacing all the amplifier components, test everything. Worth noting is that 2SA1490/2SC3854 original machine using a three tube, if replaced with other models, parameters must be detailed, mutatis mutandis, but should be no less, and poor quality pipes fit even though the same sound, but more or less affect the sound quality.VvNservice manual download site