Harman Kardon AVR1700 won't power up

[tibimakai]

I have picked up this receiver really cheap and I'm thinking to keep it if I'm able to repair it.
The only thing happens is the power light turns on, nothing else. Display is completely black.
I have done some measurements and found a missing +/- 45V, +/-12V, D+5V at the power supply.
Here are all the voltages at the three connectors:
CN66:
34V= 34.2V
DGND= 0V
ST+5V= 5V
+12V= 0.002V
AGND= 0V
-12V= 0.215V
D+5V= 0.024V

BN65:
Vol_Sel_1= -0.013V(keeps changing a bit)
Vol_Sel_2= -0.013V(keeps changing a bit)
GND=0
GND=0
GND=0
D+5V= 0.025V
D+5V= 0.025V
D+5V= 0.025V
-12V= 0.002V
AGND= 0
+12V= 0.002V
ST+5V= 4.978V
ST+5V= 4.978V
Power_Hi= 3.28V
AMP_Vcc_On= 0.006V(on)/ 3.28V(off)
Power_Down= 1.966V

CN20:
Vcc -45V= 0
Vcc GND= 0
Vcc +45V= 0V

Soon I will have some pictures too with the power board.
First time I'm, working on an audio equipment, but I have some experience with LCD TVs and monitors.
Any help would be appreciated.
I have the PDF file for it, but it's to big for this forum.
I will have to do something, to be able to put it here.

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

Here are the pictures of the PS.
For now, here is the link from elektrotanya:

PS is page #96.
It's not the best quality, but I don't know how to get a page out of a PDF file.

[Khron]

Re: Harman Kardon AVR1700 won't power up

Judging by those voltage readings, i'm thinking that only the stand-by section is working (as it would be, for as long as the receiver's plugged into the mains).

Can you figure out where each of the voltages from CN66 are coming from? ie. from which transformer. ST+5V is definitely coming from the smallest transformer, but what about the rest?

As a second step, you'll want to see where the PSU gets is "turn on" signal, and trace that back to its source.

What brands are those capacitors?

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

CN66 goes to the display PCB which is a pretty big board.
It seems, that the voltages: ST+5V, +34V are coming from the smallest transformer.
The +/-12V comes from the middle transformer.
I think that the turn on signal is coming from the HDMI board. If I unplug that connector (BN65) it won't turn on.
I'm not home right now, so I will check the capacitors when I get home.
They don't seem bad, but I know that it's not enough to just look at them.
Thanks for you help.
I have picked up another one and it should arrive next Thursday. That one has a blinking power light.

[tom66]

Re: Harman Kardon AVR1700 won't power up

Check for shorted diodes on the +/-12V transformer.
Very poor quality for Harmon Kardon, disappointing!

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

It's made in RPC.
I will check when I will be home.
I'm just wondering why is missing the 12V and 45V. One is dependent of the other?

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

Here is a PDF page of the PS.

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

Main filter capacitors are Samyoung and the rest is Acon. Samyoung I know for sure that is a bad brand.
I never heard of Acon.
The 12V supply is made with two 7812 ICs.

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

I have done some measurement in the primary area and I have noticed that the PWM IC ICE2QS01 doesn't have any voltage at it's pins.
https://cdn.badcaps-static.com/pdfs/...482e511f29.pdf
This power supply should have 400V? The main filter caps are 250V.

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

I have measured all the diodes and transistors and I haven't found anything bad.
I haven't checked the ICs yet.
What else could I check?

[tom66]

Re: Harman Kardon AVR1700 won't power up

Check C933, C953 voltage across each should be more than 14V.
Check TS92 and TS91 for continuity. They appear to be thermal fuses, mounted to heatsinks. They should appear shorted.

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

Capacitors show 0V.
The thermal fuses show 0.3 Ohm.
Tom, I don't have voltages in the primary section. PWM IC shows at each pin 0V.

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

Tom, at each transformer at the output, what kind of voltage should I expect?
It should be AC, no? Value wise, I'm only getting a couple of milivolts and they keep dropping.
That is what I'm getting at the 45V section and I'm getting 0V at both diodes D942, D952. I have measured both diodes and they check out good.

[dmill89]

Re: Harman Kardon AVR1700 won't power up

Main filter capacitors are Samyoung and the rest is Acon. Samyoung I know for sure that is a bad brand.
I never heard of Acon.
The 12V supply is made with two 7812 ICs.

I would have expected better than that from Harmon Kardon. Nothing like "high end" equipment having the same components/build quality of the $99.95 Wal-Mart specials.None of those caps are a good brand.

My Kenwood VR6070 which is in a similar price class (though several years old) has 100% Cornell Dubilier, Elna, and UCC cap. It also appears to be much better/more heavily built in general. Sadly such quality equipment seems to be getting harder and harder to find, especially in the sub-$1000 price point.

[tom66]

Re: Harman Kardon AVR1700 won't power up

To turn on, PC2 must go low. This is triggered by AMP_VCC_ON going HIGH. This in turn switches on transistor Q902, if the thermal fuses are intact. Q902 passes the voltage from C920 to the Vcc of the +/-45V rail switcher. It looks like the Vcc is dependent on the +/-12V supply starting first, so let's look there.

There's also a PC1 signal, which looks to be triggered by POWER_HI, which should turn on the +/-12V. Is this signal going HIGH? High signal pulls down PC1, lighting LED of PC91, turning Q903 on. Q903 passes voltage stored on C921 to Vcc of IC92.

So, what do you have:
- across C921 (volts)
- across C920 (volts)
- at Vcc pin of IC92 (negative probe on negative lead of C930, C921 or C920.)

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

On C921 I have -15.11V and on C920 I have only 0.04V.
At the IC92's Vcc I have the same -15.11V.
The -15.11V starts higher, like -16.09 and keeps dropping until reaches -15.11V.

[tom66]

Re: Harman Kardon AVR1700 won't power up

Negative? Where is your ground going?
COM probe in right position?

ICE2B365 IC92 appears defective. It has 15V on Vcc, it requires at least 13.5V, so it is getting what it needs.

Check C903 on SS pin 1 for shorts. Consider freeze spraying it.

Check R908 on CS pin 3, should read less than 1 ohm.

Check snubber diode D903 for shorts.

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

C903 shows 222.2 Ohm. Freeze spray raised it to 226.2 Ohm.
R908 shows 0.6 Ohm.
D903 it's fine also.
I guess, I was holding the probes the other way around. I'm not familiar with these capacitor markings. Today I held them right and I'm getting Vcc 13.75V and 338.8V at D903 in and 338.4V at output side.
The ground that I'm using is the C921 (-).

[tom66]

Re: Harman Kardon AVR1700 won't power up

C903 would appear leaky. Test the voltage across it while in operation (or from pin SS to a good ground.) Is it SMD?

10 blinks on Panasonic plasma TV is caused by leaky capacitor on SS pin, so this could be a similar problem.

[tibimakai]

Re: Harman Kardon AVR1700 won't power up

It is SMD, it's at at the bottom of the PCB.
What should I expect while measuring it?
So the IC92 may still be OK?