# AV Receiver won't stay on



## Thot

Hello all,
I am a relative newbie when it comes to electronics troubleshooting and repair.
I just purchased a used *Yamaha AV receiver HTR 5240* (USA) sold "AS IS" (you can see it on the Yamaha website, I cannot attach a link, yet) . Externally it appears to be in very good conditions.
When I push the "Standby/On" button, the front panel orange LED display comes on for a fraction of a second and then turns off. I can hear the "click" of the relay when it turns on and when it turns off. It appears that the relay gets energized but does not _stay _energized. If I keep the button pressed it does not make any difference.
I checked the troubleshooting section of the user's manual and made sure the impedance selector on the back was fully on one side (either side did not make a difference).
If feels like may an easy problem to fix but I don't know where to start.
I have some familiarity with multimeters and soldering but that's it.
Any help would be greatly appreciated. 
If need be I can settle for leaving it on when it is powered and switch it off with a power cord switch.


Thank you in advance.


Luca

_______________
There are three types of people in the world: Those who can count, and those who can't.


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## lcaillo

You will need to start by getting the service manual and pulling the diagnostic code from the service mode.

These are not an easy DIY project because of the disassembly. Might just be some bad caps or it could be much more.


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## Thot

lcaillo said:


> You will need to start by getting the service manual and pulling the diagnostic code from the service mode.
> .


Thanks for the prompt reply.
Assuming I can find the service manual (BTW, Where can I find the srevice mamual?) will i be able to pull the diagnostic code given that the machine only stays on for a fraction of a second?


Thanks 

Luca


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## Thot

Hello again,
I was able to find the service manual for the HTR-5250 (mine is a 5240) which looks identical except that mine does not have a S-Video input on the front panel.

I followed the instruction on how to get to the service mode and pull the diagnostic code but, not surprisingly, the unit would not stay on.
I do hear the relay click twice (when it powers on and off) but if I am trying to get to the service mode (as opposed to just turning it on) I don't see anything on the display in that fraction of a second.

The manual states that:_ "If a faulty condition is detected such as excessive current, a bad power supply or excessive amplifier DC offset, the Power will be switched OFF automatically"_ 
In another section, it says:_ "When power is turned on in an abnormal condition, the power relay will come on, protection will operate immediately, and power will turn off"_ which I think is what is happening here, but it does not tell me what to do next.

How do I go on in diagnosing (and fixing) the problem?

I am attaching the manual. minus the figures so not to exceed the 1MB limit. But I can send each of the missing pages individually if you need them.

Thanks

Luca


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## robbo266317

It sounds like the amplifier is faulty. Possible a blown output transistor.
This is not something that I would recommend a home user to investigate due to potentially lethal voltages inside the device.
Have you thought about getting a quote from a local repairer?


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## Thot

robbo266317 said:


> It sounds like the amplifier is faulty. Possible a blown output transistor.
> This is not something that I would recommend a home user to investigate due to potentially lethal voltages inside the device.
> Have you thought about getting a quote from a local repairer?


Well, starting from your last question: No, I haven't gotten a quote and I was not thinking to.
It was on sale for $9.99 - 25% off (I'll let you do the math) :spend: and though it was clearly marked "As is" the fact that it would turn on (albeit for about ⅛ of a second) made me think it might have been something easy to fix.
To be honest, the thrill to be able to fix it and learn something in the process (rather than the need for an amplifier) was the motivating factor to buy it!

I am aware of the high voltage running in these devices and I work on a rubber mat on the floor and place the unit on an anti-static mat connected to ground as well as wearing a grounding wrist strap (am I overkilling it?). The idea being I rather stay alive than die trying to save my $7.50 investment :sweat:

Interestingly, the power cable is not grounded :yikes:

For sake of discussion, if it were the amplifier or a blown out transistor, what could I do to find the faulty component (and replace it)? The service manual lists all the components so I guess is "just" a matter of finding it.....

Thanks

Luca


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## robbo266317

Thot said:


> I am aware of the high voltage running in these devices and I work on a rubber mat on the floor and place the unit on an anti-static mat connected to ground as well as wearing a grounding wrist strap (am I overkilling it?). The idea being I rather stay alive than die trying to save my $7.50 investment :sweat:
> 
> Interestingly, the power cable is not grounded :yikes:
> 
> For sake of discussion, if it were the amplifier or a blown out transistor, what could I do to find the faulty component (and replace it)? The service manual lists all the components so I guess is "just" a matter of finding it.....
> 
> Thanks
> 
> Luca


Hi Luca, 

It sounds like you are quite aware of the risks which is good. :T

A lot of modern equipment is not grounded as it is "Double Insulated". Having said that, I had a Pioneer amp that decided it was a good idea to have the case suddenly run at 120 VAC.  This situation is obviously less than ideal.

As for tracking it down you really need to see how it is configured internally, Often it is not easy to isolate the individual output circuitry. Can you take a pic or two of the internals so we can see what you are faced with?


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