Yamaha RX-V573 Receiver - Powers on, no display

[TomC]

I bought a broken Yamaha RX-V573 receiver hoping I could fix it. So far no luck. I'm really hoping someone can shed some light on the issue. It appears to power on. There are some relay clicks after the power button is pressed, and the pins on the main power PCB are carrying current. Cables from the power PCB then connect to another PCB that contains most of the ICs and microprocessors. Let's call this PCB2. The pins on PCB2 where power is coming in from the other board are registering 5V properly. However, the pins for the cables that bring power to the LCD board from PCB2 have no current. Also, a small IC near those pins/cables has no current, whereas several similar ICs on PCB2 have 5V. There are also a couple ribbon cables that connect PCB2 to the LCD board and another board that are registering 3V properly. So power is coming in to PCB2, but it isn't getting to the pins that are supposed to bring the main power to the LCD board.

I looked over all the components on both sides of PCB2 and the LCD board. There are no blown capacitors, and all the soldering points appear solid to me. Yamaha does have a circuit protection feature, which I've tripped during the course of my testing (it can be easily reset), but that is not a factor in this issue. There is something that may be blown on the LCD (see picture). However, I'm not sure it's a factor since the LCD does occasionally come on. Every 4 or 5 times I press Power, the LCD comes on and starts flashing a sort of digital gibberish. It will typically do this continually until Power is again pressed. I have a video of this, but it might be too large to post here. So I tend to think the LCD is working and just isn't getting enough power to function properly.

I tried to make the pictures clear. Let me know if any additional pictures or information would be helpful. Any suggestions are greatly appreciated. Thank you.

 

[shrtrnd]

Could be the display-driver integrated circuit (could be LCD itself. especially if it was damaged by impact).
My first question would be, is the receiver working, and you just have a display problem. Or are there problems with the receiver operation.

 

[TomC]

None of the buttons on the front panel appear to work, other than the Power button. So I haven't been able to get it to function. I get the impression from the relay clicks and power going to other ICs and PCBs that other components would function if they could be properly selected (from the panel).

Sounds like the display driver IC is located on the 'PCB2' in my example. Are you aware of its location?

 

[davenn]

Could be the display-driver integrated circuit (could be LCD itself. especially if it was damaged by impact).

Its a fluoro display

Tom
firstly
welcome to the forums

that burn mark you see in the corner of the display is where they burn of any remaining gas in the tube after sealing it's normal, nothing to worry about ... its NOT an LCD display

I cannot read what the text says on the PCB under the T of no current in the lower left

 

[TomC]

Thank you, davenn. Good to know. In the picture the text in red says no current, and the text next to the right arrow is just indicating that the power comes in to the PCB there and the text next to the down arrow indicates that the power goes out there (to the display).

 

[davenn]

No the white text on the circuit board to the right of the plug and socket with the red and 3 blacks

something, something, GND, GND

 

[TomC]

It says +5USB +5USB, which I noticed before, but now that I think about it that might just be for the USB input on the front panel. Perhaps current doesn't run through there unless something is plugged into the USB port. At least that would explain why their was no voltage on those pins in my tests.

Thanks for pointing that out, davenn. Though, if the above is correct, I now have no idea which component might be causing the issue.

 

[davenn]

would need to see a lot more of the PSU to see if I or others could identify possible faulty components

 

[TomC]

Is the PSU on these receivers just the PCB card where the AC plug connects? Or are you referring to the large yellow transformer?

 

[davenn]

the PSU on these receivers just the PCB card where the AC plug connects? Or are you referring to the large yellow transformer?

Im referring to the whole PSU board

but before we go there, have you tried googling for a service manual or at least a circuit schematic?
its probably going to be essential if we are ever to make any progress

 

[TomC]

I did manage to find the service manual! It's too large to upload here, but I've included some select pages that appear helpful. Please let me know if I should extract and upload additional pages from the manual. The whole thing can be downloaded here: http://elektrotanya.com/yamaha_rx_v573_htr_5065.pdf/download.html (Click link that says "Get Manual")

In the manual, they refer to the PCB with the HDMI inputs and ICs (what I called PCB2 above) as the Digital PCB. They refer to the display screen board as the Operation PCB, and then the largest PCB with all the speaker inputs, large capacitors, main relays, etc is called Main.

 

[Yamaheadache]

Deeeeep Bump!

Let's see if we can finish solving this problem. My receiver is doing the exact same thing as above however after days of googling, I am left with this being the only thread describing my symptoms... particularly the gibberish on the display.

Daveen, maybe your interested in picking up where this left off?