Explanation of the protection circuits in an A/V Receiver

[@williamhall2103]

Brother that explains so much. I've only been in audio repair for about four years. (Self taught and KZbin). Great video. Thank you.

[@izzzzzz6]

I believe there is also a voltage sensing pin. if there are multiple ic's and multiple voltage rails they can all meet at a resistor network which creates a sum or an average of all of these voltages. If one rail should fail, if this final sum voltage falls out of a certain range it triggers full protection.

[@scottymont4438]

Thank you for the video. I have a Sony AV Receiver STR-DH820. It is in "Protector" mode. The 8A fuse isn't blown. All the resistors and transistors are good. I made sure all the screws are tight. I touched up the solder joints. I'm confused why the fuse isn't blown, yet it's in "Protector" mode. Do you have any insights or suggestions? Thank you very much!

[@mikesradiorepair]

Good description of the protection circuit.

[@Mark19960]

+MikesRadioRepair .CBRadio Thanks. I try but sometimes articulation is a challenge for me. Describing how something works in a simple form is hard for me at times.

[@paulspencer214]

Hi mark. Could you help please. I have a yamaha rx-v650 that goes into protection. Now it will do it only when ohms selector is set to 8ohms. Having replaced all output staged i still get 21volts from SBL channel on powerup when set to 8 ohms. If 6ohms is set then i get no volts on powerup. Any ideas please as its doing my nut in. Many thanks

[@mdimenke]

Thank you! Great video.

[@souhailla10]

wow your explenation is so clear !! nice .. i own a Bladelius thor MK2 but it does not come out the protection mode.... before when it was hot .. after a couple of minutes cool down it turn back on again.. but this time not at all..any idea what this could be ? or know where to find schemetics for this amp?

[@Electrolab28Ag]

Hi Mark, I have a Sony STR-DN1050 and the problem that I am getting is that the unit powers on fine but from the time I raise the volume it goes into protect. If I switch to FM or Am it works fine. I have toggle the speaker off and the problem geos away, I have also disconnect the power transistor and the problem geos away. I have check the protection circuit but could not fine any bad component. Any suggestion?

[@vernonbosshard9317]

Where can I get a service manual for my RX V477, a good one, not one that is blurred out when you zoom in.

[@Mark19960]

Sorry for the late reply. I am trying to catch up. Once upon a time I was working in consumer electronics as a field engineer and I had contacts that I could get this information. I have been out of that field for many years now. I really don't know. I would suggest calling Yamaha parts. They may have copies of the manual. They may be able to point you in a direction.

[@vernonbosshard9317]

@@Mark19960 I found one online, but I'm still struggling to get this thing fixed.

[@Walczyk]

brilliant comments! im starting of my own journey, repairing my 2-3 pre-amps that only produce sound from one channel. The odd thing about one of them, HK citation 21, the right channel would put out loud signals but distort and stop with low signals, and when the right channel was onyl plugged in, but mono was pressed then sound came from both speakers. so it is receiving the right channel. the other one, kenwood basic c1, just won't output the left channel. where should i begin?

[@zeroonezerofour3179]

Had Teac AV receiver AG-D9260 model. Sounds ok when in stereo mode, sets to 3 stereo and prologic mode ie 5.1, audio is like rumbling soundlike a backmasking. What component possibly the culprit? All power transistors and all the channels are ok. Thanks.

[@IIWII9]

Hi Mark, I have a Yamaha RX v 659. It powers up but shuts down after 3 seconds. The error code is “DC PRT 026 HI”. Does this indicate a power supply fault or a problem with the amp output transistors? Thanks.

[@aaronc2681]

Hi Mark. Would you be able to shed some light on power supply protection circuits and troubleshooting? I have a Yamaha RX-A1060 that goes into ps prt mode. Specifically ps1 154 value. I could use the help if you wouldn’t mind. Thanks!

[@mihaibalint8183]

Hi! In my case on a yamaha rx-v430 and rx-v377 the power supply relay goes nuts clicking forever by touching the standby button. The v430 sometimes it works, sometimes shuts down and sometimes goes nuts the same way that the v377 does. On the v430 the voltage that goes to the micro is arround 11-12v (before the 5v regulator) but after turning on, it drops to 6.5 or 7 or 7.5 and all of this by changing surround effects or changing to 6ch mode. Having it just on stereo, will work ok but the display will freeze after 15 minutes and will not work any button and than I have to unplug the amp. I firstly will do another voltage testing on the micro and will do what you said in this video too. And there is no dc voltage on any channell neither on the big resitors too. I'm kind'a confused and output bipolars are ok. I should check everything again. Did you have any of these issues like I had? Thx

[@izzzzzz6]

Check the capacitors in the startup power supply, they may be going bad, warm the area gently for 5 mins with a hairdryer then try, if it improves temporarily change all caps in the supply. Also check everywhere for dry solder joints.

[@pablolucero9821]

Excellent description. How did you get the service manual? I can't find the DENON AVR-S720W

[@abelabner]

Im trying to absorb this, if you can take a look at a service manual and some pics of amp board could you or anyone tell me what to test. I think I have found bad output transistors and some thermal regulation transistors also.

[@srini_vasanb7694]

I have RX-V675 standby not power on...

[@narmadadistrict2206]

My Onkyo TX-SR875 works only in pure audio or direct audio mode in TAPE/AUX/Video stereo input only. Not works with digital input. No Preout signal available. How to repair it?

[@techtimebd7471]

chk and change your digital to analog audio convert ic. i had a same case. it was solved mine.

[@mand6029]

Thank you for this useful video

[@srini_vasanb7694]

Happy day sir

[@edgardodiaz4183]

Hi Mark good night, I am writing to see the possibility of your help in repairing Receiver Technics sa-da8 I have it 15 years ago, its sound was wonderful until I stop doing it, this was very sad, I want to recover my faithful friend and that is why I am writing to you if your answer is YES I would tell you the details of the problem so as not to get bored with it. Good heavens ..

[@Leroy1995]

Thanks!

[@samuellarbie6383]

Keep up

[@srini_vasanb7694]

If you can help me i will very thsnk ful sir