Harman Kardon AVR 147 - stays on standby mode

[BVG]

Hello everyone,

Last week I was watching a movie, and the amplifier switched off (I heard the relay open).
Now, when I hook the amplifier in the wall, it stays on standby mode (amber color).
When I push the button to turn it on, the light stays blue for about 10 seconds, and goes to standby mode again. The relay doesn't close, when I push the button. The front LCD doesn't show anything during the 10 seconds (ON mode).

I already looked inside, and made some tests.
The fuse is OK.
I do not see any blown component.
I already measured the 12V transform and looks OK.
The main transformer have a small resistance, so I supposed the coil is OK.
I measured the relay coil resistance, and have the right value.

Any thought's?

The manual service for the HK AVR 147 is available here.

Any help will be welcome!

 

[TLS Guy]

Hello everyone,

Last week I was watching a movie, and the amplifier switched off (I heard the relay open).
Now, when I hook the amplifier in the wall, it stays on standby mode (amber color).
When I push the button to turn it on, the light stays blue for about 10 seconds, and goes to standby mode again. The relay doesn't close, when I push the button. The front LCD doesn't show anything during the 10 seconds (ON mode).

I already looked inside, and made some tests.
The fuse is OK.
I do not see any blown component.
I already measured the 12V transform and looks OK.
The main transformer have a small resistance, so I supposed the coil is OK.
I measured the relay coil resistance, and have the right value.

Any thought's?

The manual service for the HK AVR 147 is available here.

Any help will be welcome!

As described in the manual the first thing to try is a reset back to factory default, as described in the manual you linked.

If this does not solve it unless you are an experienced tech and have the required service equipment you are not going to fix this.

There are thousands of possibilities. The reasons for this fall into two broad categories.

I). Primary power supply failure.

2). Failure of a device causing excess current flow to ground causing the power supply to go into protection and shut down.

The commonest reason for number 2 is failure of a power output device in one of the power amps. When they fail they almost universally result in a short through the failed device. Any solid state device can do this including the main processor.

The first step is to disconnect the power amps and see if the power supply shows the correct voltages. If so, then reconnect each amp one by one until you find the one sending the supply into protection and then isolating the fault in the offending board and repairing it.

Any other board failing is not repairable, such as main processor board or HDMI board for instance.

This receiver is not worth a lot of time or trouble and certainly not a trip to a repair center.

Far more likely than not it needs a one way trip to the recycling center and a new receiver purchased.

 

[BVG]

Here's a video:

 

[BVG]

As described in the manual the first thing to try is a reset back to factory default, as described in the manual you linked.

Yes, I did that and it doesn't work.

 

[BVG]

The first step is to disconnect the power amps and see if the power supply shows the correct voltages. If so, then reconnect each amp one by one until you find the one sending the supply into protection and then isolating the fault in the offending board and repairing it.

How can I disconnect each power amp?
I must desoldering some component, or make the circuit open on each power amp?

 

[BVG]

By the way, thanks for your response TLS Guy.
I would like to fix my amp, because I want to learn to fix these kind of amps.
So, taking this amp to the recycling bean is not an option

 

[BVG]

I disconnected the power cords that connects to the power amps and now the LED stays blue, but I don't hear the relay close.

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[TLS Guy]

I disconnected the power cords that connects to the power amps and now the LED stays blue, but I don't hear the relay close.

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So now you know one of the power amps is bad.

So now we need to know what equipment you have.

You need a FET VOM or tube voltmeter, a signal generator, an o-scope and a Variac at the minimum.

Now you need to reconnect each power amp one at a time until you find which one is triggering protection. Make sure the unit is powered from the Variac and bring the voltage up slowly each time, so you do not do more damage.

When you find it, then the output transistors will need replacement at a minimum. For this you need clip on heat sinks while soldering and heat sinking compound. You will also have to determine id the damage stopped at the output transistors as many times the driver stage is blown up as well including the driver transistors and associated diodes.

Once the power transistors are replaced then they have to be re-biased under instruments as described in the manual.

At this stage you bring the unit up on a Variac, which is a continuously variable voltage transformer. This allows you to bring the voltage up slowly so you can monitor the situation under instruments as it comes up. The Variac also isolates the unit from the mains, so you are much less likely to kill yourself while working on it.

Bottom line is that if you don't have the proper tools and instruments do not proceed further.

If everything is stable then you can set the bias.

Now you can test the repaired amp with signal generator and o-scope across the whole frequency spectrum and make sure the frequency response is flat and the o-scope tracings are nice and smooth. The amp as you test it need to be connected to beefy power resistors rated to take the power of the amp.

A distortion analyzer is nice at this point but not essential.

 

[BVG]

Well, I only have a Multimeter and a solder station
There's no way I can measure all the components with a Multimeter, in the power amp area?
How can I connect a power amp at a time, if I had only this two plugs? If I desolder the main capacitors I will disable the power amp in that area, right?


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[TLS Guy]

Well, I only have a Multimeter and a solder station
There's no way I can measure all the components with a Multimeter, in the power amp area?
How can I connect a power amp at a time, if I had only this two plugs? If I desolder the main capacitors I will disable the power amp in that area, right?


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You can not fix this with a multi meter and soldering iron. The meter needs to be an amplified high impedance meter or you will do more damage.

It is clear you do not have the training or experience to proceed and I do not encourage it on grounds of safety.

 

[BVG]

OK TLS Guy.
You are right!
I will take the amplifier to repair.

Many thanks.
Have a nice weekend.


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[TLS Guy]

OK TLS Guy.
You are right!
I will take the amplifier to repair.

Many thanks.
Have a nice weekend.


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That unit is absolutely not worth the trouble or cost of repair. It is 9 years old and the expected life span of a unit like that is in the 7 to 10 year range.

Taking it in for repair is good money after bad. It is new receiver time for you.

 

[afterlife2]

I'd take a look at these refurbs instead of repairing: http://www.harmanaudio.com/refurbished-speakers/

 

[BVG]

Oh well.. I don't know
Maybe it's time to make the jump to a higher system for my home cinema.

Thanks people for the advices.


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[TLS Guy]

Oh well.. I don't know
Maybe it's time to make the jump to a higher system for my home cinema.

Thanks people for the advices.


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I would go for Marantz, Denon or Yamaha. An HK would be well down the list.

Choose from no lower than the mid price point.

Refurbs are a risk. A lot of members have had good luck with them, but some have had disasters.

The main risk to me is that quite a few faults are intermittent. It certainly happens that intermittent faults can be missed in refurb/repair departments. The reason being is that you can not find a fault in a perfectly working unit. So the tech thinks it was an open box return or some such. Sod's law says the fault will soon show up when it is in the next customer's hands.

I think refurb or not really depends on the level of risk you are comfortable with. In my view the risk of refurbs is significant.

 

[BVG]

I'm looking for a Denon AVRX1200WBKE2 7.1
It's mid-range?
Maybe for Christmas I'll buy one.


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[TLS Guy]

I'm looking for a Denon AVRX1200WBKE2 7.1
It's mid-range?
Maybe for Christmas I'll buy one.


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That is a 2015 model and NLA. It is not mid price. That is the top of the Denon junk class. Those low end Denons are not well made at all and not recommended.

That one you picked out has grossly embellished misleading specs. To be specific 175 watts 1 channel driven at 10% THD. A spec like that is a disgrace and highly misleading and a massive red flag to avoid like the plague.

Mid price is now $1000 +/- $200. A receiver is a complex affair and if you buy a cheap one you will pay more in the long run.

You might want to consider waiting for the 2017 offerings.

From the current line up I think you are looking at this, or better.

 

[BVG]

That is a 2015 model and NLA. It is not mid price. That is the top of the Denon junk class. Those low end Denons are not well made at all and not recommended.

That one you picked out has grossly embellished misleading specs. To be specific 175 watts 1 channel driven at 10% THD. A spec like that is a disgrace and highly misleading and a massive red flag to avoid like the plague.

Mid price is now $1000 +/- $200. A receiver is a complex affair and if you buy a cheap one you will pay more in the long run.

You might want to consider waiting for the 2017 offerings.

From the current line up I think you are looking at this, or better.

OK, thanks for the info


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