Yamaha RX-V485 turns off automatically after 3 secs

[qamarahsan]

Hi Folks, I am looking to troubleshoot my Yamaha RX-V485 which is showing the error DC PRT 000 when put in diagnostic mode. I can't seem to figure out what is causing this.

Can someone help me find out the service manual so that I can start troubleshooting.

[PKTKS]

https://www.hifiengine.com/manual_library/yamaha/rx-v485.shtml

Try the 483 service manual

Yamaha is pretty much consistent although
not simple to deal with

Paul

[qamarahsan]

Been trying to register on this site but gives me an error. If you are registered, can you download it for me and send me a link where I can retrieve it?

[PKTKS]

Usually it does not...

File is way too big for attachment here.
Not even in parts.  Limits are too low

Try again  - if it fails drop me a note here
Paul

[mzacharias]

The service manual has a "protection cancel" mode to allow troubleshooting.

This is good for all protection modes except high-current, such as a blown channel, shorted filter cap etc.

Engage this mode, then I would suggest checking the output of all voltage regulator IC's.

DO NOT connect speakers at this time as there is a high likelihood of DC offset from the speaker terminals.

There is also a small chance of a bad electrolytic capacitor in the regulated power supply area, either open circuit or shorted - either condition will trigger the protect.

[kawal]

I repaired a few Yamaha recievers and  a lot have issues with power transistors. Must be a design flaw. The older V series did not fail on the output stage but failed regulators on regular basis. Putting the receiver in test mode helps pinpoint the issue. 
 

[qamarahsan]

So I got me a multimeter and tested the voltages on each of the speaker outputs. All were the same value except the Surr L which was giving a 48V as opposed to 13mV in the rest of the outputs. At least its a start. I still am however not able to get my hands on the service manual. Paul, can you please help sending me the one you have. I have never tried this before, but will give it a shot since the place I am currently in, I will not be able to find any warranty on the box.

[kawal]

Well that is easy now  . Power stage is broken. Very common thing I find in these.  Take out transistors and figure out which one is broken and replace. Most likely the big power transistor on positive rail. 
This is not the exact manual but should be close

https://elektrotanya.com/yamaha_htr-5140_rds_rx-v495_rds.pdf/download.html
https://elektrotanya.com/yamaha_rx-v481_htr-4069_rx-v481d_sm.pdf/download.html

The power stages are pretty generic and should look like the one attached.

[kawal]

BTW the amps that have 2SC5198/2SA1941 dont seem to fail as much as the weeker 2SA1694/2SC3856 pairs.