Harman Kardon AVR130 - Issues

[R_J]

Re: Harman Kardon AVR130 - Issues

Well it looks like you are getting voltage up to the main micro, I'm not sure what to check next, It could be that the micro is locked up or not working? I would think that pressing the stby button should do something, light the display, turn on the relay or show some sighns of life.

[revelations]

Re: Harman Kardon AVR130 - Issues

Well it looks like you are getting voltage up to the main micro, I'm not sure what to check next, It could be that the micro is locked up or not working? I would think that pressing the stby button should do something, light the display, turn on the relay or show some sighns of life.

Hmm well i got this HK from someone and when i first tried to turn it on, it did show blue lights but no display, then i think (hard to remember) checked some voltages or removed the video input board, and then it still showed blue light and i pressed the reset button inside a few times and somewhere in between this it wouldn't turn back on. (i saw a video on youtube) and he basically replaced all the condensators on the main PCB and once he was done with that he tried it again and blue lights came back. so it might have something to do with those condensators? even tho mine aren't blown tho i am aware they can still be broken without visual damage.

Wich was this video https://www.youtube.com/watch?v=HTNC6UvW0NI

[revelations]

Re: Harman Kardon AVR130 - Issues

The small voltage regulator is warming up.
The Cathode has 12 volt
The large green resistor has 12 volt

Doesn't that mean the relay or the small transformator is defect? or not necessarily?

I was thinking maybe i should replace the Condensators + Relay and or small transformer?

[R_J]

Re: Harman Kardon AVR130 - Issues

The regulator is fine, it runs a bit warm because it is regulating the 12 volts down to +5 volts. The transformer is fine also. I'm sure the relay is ok. the relay coil needs 12 volts across it to activate. right now there is 12 volts on one side of the coil (pin 3 of relay)and the other side needs to connect to ground to activate the relay. the way that works is through Q901, when the base of the transistor gets .7 volts it turns on taking the collector (and relay pin 4)to ground
That .7 volts (or POWER_H) is not there
The microprocessor detects the stby button going low, if everyting is ok the mpu should output a signal from ic72 (pin96) POWER_H to the base of Q726, which turns on Q743 which will supply the .7 volts to Q901
The relay is what turns on the main transformer which the supplies all the other voltages

[revelations]

Re: Harman Kardon AVR130 - Issues

I see, ill try to find that voltage where it stops at least. Both pins on the left side of the relay has 15 volts not sure if that's correct?

[mmartell]

Re: Harman Kardon AVR130 - Issues

Is it just my eyes or are there some badly cracked solder joints under the relay and what is going on under the blue cap ?

[revelations]

Re: Harman Kardon AVR130 - Issues

Is it just my eyes or are there some badly cracked solder joints under the relay and what is going on under the blue cap ?

Hmm not sure I could resolder them, the little voltage regulator was lose, had to resolder the 3 solder joints, no idea how that could have happenend

Slightly confused does 0.007v means it has .7 volt or does it mean it's zero?

Shouldn't it say 0.700v instead?

[R_J]

Re: Harman Kardon AVR130 - Issues

That looks like 0.007 volts, which is basicaly 0
Having 15 volts on both sides of the relay coil means it is not energized. you measure the same voltage on both pins because there is no current flowing through the coil, no current = no voltage drop,

Look at the schematic, see that transistor connected between the relay and ground, that transistor needs to have at least .7 volts to turn on. when that happens, the one pin of the relay gets connected to ground through the transistor, that energizes the relay coil, closing its contacts (the other 2 pins) which turns on the main transformer of the unit.

[revelations]

Re: Harman Kardon AVR130 - Issues

That looks like 0.007 volts, which is basicaly 0

Alright so that means it has no voltage, so the standby/power button doesn't give the signal, Think ill follow the whole circuit again based on your previous anwsers and see where it stops giving the correct voltage. before the IC72 or after? if im correct what you meant with .7 volts is basically just under 1volt correct?

Sorry for these questions i'm not that good at reading the schematics.

[R_J]

Re: Harman Kardon AVR130 - Issues

IC 72 is the main microprocessor if its not working or is in a dumb mode, it won't know what to do when it sees that the standby botton is pressed.

[revelations]

Re: Harman Kardon AVR130 - Issues

I see, ive remeasured all of it.

Q901 has 3 pins left and right no voltage, middel pin has 14/15volt
BN80 pin 4 no voltage, pin 5 close to zero
BN88 pin 4 changes voltage to zero when standby is pressed
BN81 PIN6 has 5 volt
BN81 PIN RESET keeps changing voltages rapidly
L702 Has 5 volt
D761 Has 5 volt

Hopefully this makes more sense. There is no 0.7volt anywhere, is there anywhere I can check to see if that voltage is available close to the button? Guessing it should be a problem some where close to that?

Ps. Is that right that the reset pin changes voltages rapidly? Or is it trying to reset the whole time? That can't be right haha

[R_J]

Re: Harman Kardon AVR130 - Issues

Do you know how a transistor works? Do you understand how a microprocessor works?
Q901 is a transistor. It has 3 pins, a collector, an emitter and a base.
In this circuit it is acting like a simple switch, thats it. to turn on the switch it takes a minimum of .6 volts.

[revelations]

Re: Harman Kardon AVR130 - Issues

I mostly understand how it works. I'm still a bit new to all of this. I shouldn't have measurred it. Do I need to test the IC72 Somehow? It looks like the problem is on the front board? Or is that incorrect. I mean if it's not sending the .7volts

[R_J]

Re: Harman Kardon AVR130 - Issues

IC72 is the microprocessor, I have no idea how YOU could test it. It needs to have the crystal oscillator (clock) running (pins 82-83) [got a scope?] It needs to have VDD (pin 84,23,35&36) in this case standby 5 volts. It needs to have a reset (pin77) [this is a momentary pulse] so it knows to start its program at the begining, not somewhere in the middle. and thats just the basic idea. Then it reads the data from memory so it knows to look at pin 38 (KEY_1) and say (the button is pressed), I will now turn on the amp by telling pin 96 to (POWER_H) to change state.

It could be as simple as the data got corrupt some how and needs to be reset.

I see there is a built in battery on the front panel, check what the voltage is on it, it should be around 3.6 volts.

[revelations]

Re: Harman Kardon AVR130 - Issues

The battery voltage is 2 volts, ill read the rest of the scheme on your photo.

So I measurred Q743 it's right pin has 5volts and accidentally I hit the middle pin aswell so basically I connected right pin with middle pin and heard the relay switching/clicking and think I heard the large transformer aswell.

[R_J]

Re: Harman Kardon AVR130 - Issues

Thats to be expected, q743 acts like a switch, you basically bypased the switch, so that turned on Q901 and the relay,which in turn powered up the main transformer.
That 2 volts on the battery could be a problem, You could try disconnecting it and see if the amp turns on. That might be stoping the microprocessor from being reset (holding it in a reset state so it won't operate) or it may need to be replaced to supply the 3.6 volts to the reset circuit. you might want to check R777 and make sure its not open and does read 10 ohms, that is the charge line for the battery.

[revelations]

Re: Harman Kardon AVR130 - Issues

Ive checked R777 and it has 10ohm. Ive removed the battery and amp did not turn on, then i put the battery back in (maybe clearing its memory) but still no go
When the device is in standby the battery has a voltage of 4.4v assuming its being charged aswell.

[revelations]

Re: Harman Kardon AVR130 - Issues

I traced back the pin4 from BN88 to the microprocessor and the microprocessor is receiving that voltage (voltages changes on its pin) and from there i traced PIN96 back wich goes back to BN88 but also to J804 wich is bridged/connected (not sure how you name that) to Q726 and Q743, ill still have to test/measure those trails see what it does. i did accidently hit Q726 and J804 with my measure pin and you heard the relay again but also the standby button became blue. (found that interesting)

[R_J]

Re: Harman Kardon AVR130 - Issues

If you are not carefull you WILL (or maybe already did) destroy the microprocessor ic, The base of Q726connects directly to the outout pin of the microprocessor, If you were to give it 5 volts when that pin is in its off state, you can destroy the internal compnent on that port and the microprocessor would need to be replaced and it might not be available anymore so the amp goes to recycle.
forcing POWER_H high, (which you did with the short) also turned on Q725, which turned on Q722 lighting led D707 (blue led)

[revelations]

Re: Harman Kardon AVR130 - Issues

If you are not carefull you WILL (or maybe already did) destroy the microprocessor ic, The base of Q726connects directly to the outout pin of the microprocessor, If you were to give it 5 volts when that pin is in its off state, you can destroy the internal compnent on that port and the microprocessor would need to be replaced and it might not be available anymore so the amp goes to recycle.
forcing POWER_H high, (which you did with the short) also turned on Q725, which turned on Q722 lighting led D707 (blue led)

I think that already happenend when i bought it from someone (it was in a defect state) and i remember when i first plugged it into the wall, the blue lights came up but there was no display, yesterday i found broken solders on the front panel regarding the display unit, wich is odd. ive also found damage near screws. So the previous owner had checked it himself i'm guessing.

Ive also checked J705 and it doesn't have any signal either, so i'm guessing the microprocessor has died or maybe the reset isn't cleared yet? someone told me there's a condensator wich holds a memory? wich i had to clear. but i'm not sure if thats correct or even exists.