Hello.
I'm still looking for a Schematic for the Hitachi HA6800 Mosfet
Power Amplifier. I really need it, as there are still a few burnt resistors that I need to know the values of.
In Return, I can offer Drawings / Manuals for many Denon, NAD,
and also a lot of Aiwa Manuals / Schematics.
Thanks, Telnet100.
I'm still looking for a Schematic for the Hitachi HA6800 Mosfet
Power Amplifier. I really need it, as there are still a few burnt resistors that I need to know the values of.
In Return, I can offer Drawings / Manuals for many Denon, NAD,
and also a lot of Aiwa Manuals / Schematics.
Thanks, Telnet100.
Hitachi HA-6800 Integrated Amplifier Service Manual
this website, but probably you will have to pay
http://www.vintageaudiomanuals.com/-H-.htm
this website, but probably you will have to pay
http://www.vintageaudiomanuals.com/-H-.htm
I just repaired a Hitachi HA-6800.
It first looked like a shortcut or burnt through MOSFETS, but ...
In both, left and right power amp, I found (the same) six defective fuse resistors on the main PCB.
R712 (220R, 1/4 Watt)
R714 (470R, 1/4 Watt)
R716 (82R, 1/4 Watt)
R717 (82R, 1/4 Watt)
R718 (470R, 1/4 Watt)
R720 (100R, 1/4 Watt)
They are all part of the current amplification stages.
No visual indication for defects with the resistors, some of them had changed values, most just interrupted.
All transistors, including the four MOSFETs, were OK.
After replacing the resistors, the amp worked again.
Relay cleaning and replacement of the lights.
Because of the serious heat from the 200mA idle current in each of the MOSFETs, one can assume that - over the years - most of the electrolytics have suffered and could use replacement.
I did so and was rewarded with excellent sound quality.
- Poetry2me
It first looked like a shortcut or burnt through MOSFETS, but ...
In both, left and right power amp, I found (the same) six defective fuse resistors on the main PCB.
R712 (220R, 1/4 Watt)
R714 (470R, 1/4 Watt)
R716 (82R, 1/4 Watt)
R717 (82R, 1/4 Watt)
R718 (470R, 1/4 Watt)
R720 (100R, 1/4 Watt)
They are all part of the current amplification stages.
No visual indication for defects with the resistors, some of them had changed values, most just interrupted.
All transistors, including the four MOSFETs, were OK.
After replacing the resistors, the amp worked again.
Relay cleaning and replacement of the lights.
Because of the serious heat from the 200mA idle current in each of the MOSFETs, one can assume that - over the years - most of the electrolytics have suffered and could use replacement.
I did so and was rewarded with excellent sound quality.
- Poetry2me
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