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Old 01-14-2017, 10:13 PM   #1
tibimakai
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Default Harman Kardon AVR1700 not powering up

Long story short, I'm putting together a receiver, from two receivers. Both had different issues. One missing the power supply, the other had a corroded HDMI board.
The power supply does not work, it had two IC's blown(very visible), D901/D902 and I have found a bad resistor.
I have replaced two blown ICs and resistor, but it still won't power on.
I don't even have standby voltage.
I measure 334V, at the transformer TF93's #7 pin.
Q901 FET is getting 334V.
The ICs, are not getting VCC at all.
D914 zener diode shows .718V one way, but meter is not beeping. That is normal?
Any help would be appreciated.
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Old 01-14-2017, 10:19 PM   #2
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Default Re: Harman Kardon AVR1700 not powering up

Here is my other thread, with pictures of the PS and a PDF file of the PS.
http://www.badcaps.net/forum/showthr...kardon+avr1700
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Old 01-15-2017, 07:08 AM   #3
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Default Re: Harman Kardon AVR1700 not powering up

OK, in the power supply:

On capacitors C901 and C930: what voltage do you have?
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Old 01-15-2017, 06:30 PM   #4
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Default Re: Harman Kardon AVR1700 not powering up

I have 334V, up to the transformer.
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Old 01-15-2017, 07:09 PM   #5
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Default Re: Harman Kardon AVR1700 not powering up

i am wondering why there is 334v ? is it a switch mode supply ?
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Old 01-15-2017, 08:02 PM   #6
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Default Re: Harman Kardon AVR1700 not powering up

Yes. It is a switch mode power supply I believe.
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Old 01-15-2017, 08:05 PM   #7
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Default Re: Harman Kardon AVR1700 not powering up

Yes it is.
I had repaired a couple of these in the past and other similar ones, like 1510 and 1610, but I always had at least the standby blinking.

Last edited by tibimakai; 01-15-2017 at 08:06 PM..
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Old 01-15-2017, 08:18 PM   #8
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Default Re: Harman Kardon AVR1700 not powering up

Quote:
Originally Posted by petehall347 View Post
i am wondering why there is 334v ? is it a switch mode supply ?


Hmm kind of... you have a graetz right before the caps so you should have half of yout AC there.
check page 96 from the service manual.
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Old 01-15-2017, 08:27 PM   #9
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Default Re: Harman Kardon AVR1700 not powering up

It is 334 VDC because it is Voltage double circuit.
So what blown parts did you replace?
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Old 01-15-2017, 08:31 PM   #10
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Default Re: Harman Kardon AVR1700 not powering up

Hi Bud, I'm back with some "put away" stuff, like this receiver, I also came back to the Pioneer VSX-1122k, that nobody could help me(found that a 3.3V is missing) and an Infinity 475A car amp.
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Old 01-16-2017, 08:39 PM   #11
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Default Re: Harman Kardon AVR1700 not powering up

I have replaced: R908, D901, D902, IC91(OB2358L), IC92(ICE2B365).
D914(18V zener), when I measure it, it does not beep(in or out of circuit) and shows .718V.

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Old 01-16-2017, 10:08 PM   #12
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Default Re: Harman Kardon AVR1700 not powering up

If you measure a Zener forward biased, it will read the average silicon voltage drop, so 0.7v is normal. Because this is a little high though, perhaps the meter does not beep. Which way around do you get this 0.7v reading?

You would need to test the zener out of circuit reverse biased with current limiting to check Zener voltage.

Are R926, R927, R922 and R923 OK?
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Old 01-16-2017, 10:21 PM   #13
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Default Re: Harman Kardon AVR1700 not powering up

I believe all four resistors are fine. The 1.2Mohms show a bit weird, though(in circuit) start low and they are going higher and higher in value.
I will have to remove the zener and test it out, that way.
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Old 01-17-2017, 01:14 AM   #14
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Default Re: Harman Kardon AVR1700 not powering up

If there's no voltage supply getting to IC91 pin 1 and 2, then either those resistors are open\high or D914\D911 is shorted, C918 is bad, or IC91 itself is shorted to ground.

I can't see what else it would be.

OR somehow the wire link going between the primary capacitors to R926 is bad.

Last edited by Agent24; 01-17-2017 at 01:18 AM..
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Old 01-17-2017, 07:46 PM   #15
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Default Re: Harman Kardon AVR1700 not powering up

IC91, is getting an oscillating voltage at D914, something between 8-12V.
The voltage should be 18V there, right?
With min/max I'm getting 12.6V.
At pins #5-6(drain), I'm getting 334V.
That is normal to oscillate?
The other two ICs, are net getting any voltage.

Last edited by tibimakai; 01-17-2017 at 07:49 PM..
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Old 01-17-2017, 08:26 PM   #16
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Default Re: Harman Kardon AVR1700 not powering up

The startup Voltage at VDD pin 2 is 12.5V Typ., once the circuit starts running the IC will stop running until vdd drops down to 6.8V typ. see pdf page 4 and 7.
Vrify for sure that those two 1M2 resistors are good, they usually go up in value when they go bad.
You can also lift pin 1 and pin 2 of the IC off the board and check DCV across that 18V Zener.
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Last edited by budm; 01-17-2017 at 08:31 PM..
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Old 01-17-2017, 10:12 PM   #17
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Default Re: Harman Kardon AVR1700 not powering up

I have cut the trace and measured both resistances. Both show, 1.19Mohm. I have also cut the trace, after the zener and the voltage is, 17.97V.
So, everything looks good, in my opinion. Most likely, the "load" has an issue(output source).
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Old 01-17-2017, 10:35 PM   #18
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Default Re: Harman Kardon AVR1700 not powering up

The load in this case is the pin 2 VDD pin of the IC, the startup current is supposed to be 5uA typ., unless the diode that is used for rectifier for the AUX winding that supposed to supplying the running Voltage once the circuit starts running has leakage resistance.
You can not lift pin 2 off the board so anything else connected to the 18v Zener is still in place so you can test the Voltage without the IC load.
Also if you monitor the DCV on the secondary side filter caps, do see the Voltage even jumps up at all?, If it does, it means the circuit did try to star up but goes into shutdown.
Resistance between pin 3 and PRIMARY side GND is?
D910, D928, OPTO PC92, d921, d943 are good?
What DCV do you have on that standby power supply transformer T91 pin 1, pin 2 iwth ref to primary circuit GND? It should a little over 160VDC

Last edited by budm; 01-17-2017 at 10:47 PM..
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Old 01-18-2017, 10:11 PM   #19
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Default Re: Harman Kardon AVR1700 not powering up

Pin #3 and primary grd(pin #7/8) is 5.4 Mohm.
Now, I'm measuring a stable 17.93V at IC91, weird. Yesterday, I had an oscillating voltage.
I have tried C944 at startup and it doesn't show any life.
I'm doing these measurements with the connector disconnected from the HDMI board. The only connector that is connected is for the front panel(power button is there as well). That is correct, or should I connect that one as well? Power connector to the amp, it is not necessary at this time, right?
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Old 01-18-2017, 10:12 PM   #20
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Default Re: Harman Kardon AVR1700 not powering up

How do you test an opto? Some they show as a diode and some don't show as a diode, just a higher voltage ~1-2V.
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