Harman kardon hk 970

homertooties · 05:31 PM

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 · 21st January 2012, 09:38 PM

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 · 21st January 2012, 10:28 PM

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 · 22nd January 2012, 11:11 AM

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 · 22nd January 2012, 05:41 PM

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

21st January 2012, 05:29 PM	#1
homertooties diyAudio Member Join Date: Nov 2005 Location: suffolk	Harman kardon hk 970 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 __________________ if you strip it for parts keep them for years as soon as you get rid you will want them ..................... Last edited by homertooties; 21st January 2012 at 05:31 PM.

21st January 2012, 10:28 PM	#3
homertooties diyAudio Member Join Date: Nov 2005 Location: suffolk	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 . __________________ if you strip it for parts keep them for years as soon as you get rid you will want them .....................

22nd January 2012, 11:11 AM	#4
homertooties diyAudio Member Join Date: Nov 2005 Location: suffolk	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 __________________ if you strip it for parts keep them for years as soon as you get rid you will want them .....................

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21st January 2012, 09:38 PM	#2
whizgeek diyAudio Member Join Date: Feb 2010	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

22nd January 2012, 05:41 PM	#5
whizgeek diyAudio Member Join Date: Feb 2010	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

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