Help on repair Yamaha RX-V496 - won't turn on

[Amaro Leandro]

Hello!
I'm brazilian and firstly please sorry for my english.

I came to tell my sad story hahaha

My son spitted juice on my receiver. At the same time I shut off the equipment.
After the clean there is not powering on. Going on protection mode but show the info percent from DC protection.
Ok. Looked at superficially I found some resistors opened. Removed and soldered the new but at the moment in connect the cables, I've inverted some connections (images 1 and 2) and since then the receiver not display anything (only horizontal lines for 0.5sec).
I hear the relay arming and desarming rapidly.

With tests on the power supply, the line that should have AC12v (image 3), have AC24v. I don't know if it's the problem.

Can anyone help me in this problem?
Thank you in advance for your support.

 

[Amaro Leandro]

anyone?

 

[KilgoreCemetery]

I would definitely recommend not powering the unit on again until we can figure out how to get the AC24v back down to AC12v

 

[Amaro Leandro]

I would definitely recommend not powering the unit on again until we can figure out how to get the AC24v back down to AC12v

Thanks for the reply!
Any tips for repairing the transformer in order to reduce the voltage to AC12v?

 

[KilgoreCemetery]

Actually, after reading this post, it sounds like a transformer may be able to put out a lot more voltage than I would have guessed while not under load.

Let's start over a bit. What's the model number of the receiver?

 

[Amaro Leandro]

Actually, after reading this post, it sounds like a transformer may be able to put out a lot more voltage than I would have guessed while not under load.

Let's start over a bit. What's the model number of the receiver?

Sure. My model it's the RX-V496 Model R.
I watched some videos from receiver repairs but not evolved in that.

Here is some information about what I visualized after the occurred:

- The receiver are powered on and shutdown automaticaly after 2secs. Starting with the hotkeys pressed, the lcd showed DC values and powered off;
- I Substituted some resistor and nothing;
- Then I connected the cables inverted (3 ways: 2 +RYV and 1 VPB) and the state worsened;
- Now the equipment power on and power off at the same moment. The LCD blink.

Thanks for the help and attention.

 

[Amaro Leandro]

Update:
I have tested the voltages in all power supply parts and they are ok
However, I identified some voltage in PRV. Can be it. I'm going continue studying the circuit for kill this problem.

Thanks for any tip you can give me.

 

[Amaro Leandro]

Update:
I found a problem on cap.el. 4700uf/5.5v from display board. The lines are from 5v and this tension drops to 4.5v when the receiver is power on.
I measured the capacitor in 8.8v, in/out of board.

I going buy a new and reinstall. I'll inform.

 

[Amaro Leandro]

Replacing the capacitor not resolved the problem.

 

[Amaro Leandro]

Update
I have analised the pins from IC501 and found the next values:

Pin 12 - RESET - 4.8V (OK);
Pin 16 - VCC - 4.8V (OK);
Pin 20 - PDT (Power down detect input) - 4.8V (4.0V is the correct);
Pin 40 - PRI (Over current protection detect input) - 0V (OK);
Pin 46 - PRY (Power relay output) - 4.8V (OK);
Pin 63 - VCC - 4.8V (on manual the right is -29,3V, but the why I not understand);
Pin 90 - LIMDT (Limitter DC detect input) - 0.6V (0.2V is the correct);
Pin 91 - PRV (PS protection) - 3.0V (1.5V is the correct);
Pin 92 - PRD (DC protection) - 0.9V (0.3V is the correct).

Anyone have any idea what to look or change?

 

[Amaro Leandro]

Update:
I was able to connect and keep the equipment on, disconnecting the flat going to the voltage regulators.
I believe that the reversal of the cable I made may have damaged the central IC. The voltage outputs for image generation on the display do not provide more than 1.5V even when the equipment is turned on.

I'm giving up on getting it back.