Harman kardon hk 970

[homertooties]

Hi there people hope you had a good xmas, well i have a Harman kardon hk -970 amplifier in for service very strange one , plug the unit into 240 volt source and the orange standby light comes on and you here a couple of relays click and thats all , tested the power amps by removing them all good , no fuses blown , transformer is working and giving the correct voltages to amplifiers and secondary power supply , no display and apparently the display is blue but nothing at all , no burning inside and all boards look brand new , appreciate any help and thanks in advance .🙂 Here is a link to the service manual .......http://www.vintageshifi.com/harmankardonhk970.pdf

 

[whizgeek]

If theres is no data to the display, then maybe the processor is not running.
does it need IR remote to turn on?
check +5_MCU. then Reset pin35=5v and INT pin20=5v on remote PCB

 

[homertooties]

Thankyou very much whizgeek will strip out the front fascia and short pin 35 to 20 on mcu after testing for 5 vdc on pin 36 ( vdd ) hope it dopesnt need remote as i dont possess it .

 

[homertooties]

Harman Kardon update

Hi there here is an update tested for 5 volts dc and it is present going through l301 , have shorted the inputs to reset as said before but no difference , any ideas please help thankyou in advance 🙂🙂🙂

 

[whizgeek]

actually its 0v for reset on processor and 5v to run. short out C1 to reset processor.
If the orange power led is on then there should be no power to amps and display off.
Is the standby line 5v or 0v normally, does it change when reset?

try putting 5v into remote input. maybe its just the power on button 😉


i would suspect the processor chip