Sony Audio Receiver in Protect mode Repair Fix STR-DG720

[@JustBarran]

8 years later and your still helping people 😍

[@daveb40361]

I replaced a blown 125-volt, 6.3-amp slow-blow fuze in my aging Sony STR-DE597 7.1 receiver and when I powered it up, after a few seconds it went into protect mode every time. I was stumped, but I think you may have told me how to fix it. The info and the lesson are greatly appreciated. If you're still checking this video after 5 years, thank you, NorCal715.

[@songreosmenep]

Norcal is one of the top guy in this business such a knowledgeable and professional technician. Following him for years now. Good job my brother. Cheers!

[@jcweiz09]

Enjoyed watching the entire video. I like the feeling of success when there's a fixed equipment after a repair..

[@cobra646]

Thanks for this video. It was a perfect place to start in getting a Sony receiver that I pulled out of a junk pile working. Nothing like checking it after a repair and seeing a unit come right back to life!

[@justinberry3991]

Keep looking around. That's where mines going

[@williamchow1624]

Another great repair video. I have 2 Sony receivers that go into protection mode. Now I am motivated to fix them.

[@terrellbuechner7397]

My Sony str de685 display light is not Comeing on the store comes on but the display light don't how do I fixs that

[@dilbyjones]

Man U are one of the best I’ve seen with explaining how to work these

[@getmoneyhozea2722]

MAN THIS IS A LIFE SAVER!! I HAVE A SONY STR-DH130 RECEIVER !! It is stuck in protect mode and I just so happen to have a solder gun and volt meter I'm going to fix my own receiver ASAP !! NOW I got to order the Transistors !!

[@vivekvivek198]

Excellent video. Well explained all details. Nice to see a professional skills to avoid recycling in electronics.

[@Jamesbond22855]

It's next to impossible to find useful information on this for early 2000's Sony AVR's. Thank you so much! I'm much more confident that I will be able to fix my STR-DE885's center channel now

[@1killersmile]

Absolutely wonderful of you to post a video like this. Much appreciated. We are expected to just throw these out and buy new units, with a little troubleshooting and effort someone could save hundreds in replacement units. I have 3 older units handed down with this same issue, and personally have a

[@davidks3552]

Many thanks for sharing your tech skills. My DE425 is back up and running as it should.

[@JahanZeb1976]

Excellent video! Always you are posting high quality and knowledge based videos. I know video shooting and editing is a tedious process but by this way we are helping our friends. Great effort. Regards,

[@vinaykamble3275]

LearningZone hi. I m vinay I got one receiver. Model ...STR- K870P in protection mode. In cold testing every part normal condition. Problem is after starting Showing PROTECTION. What can I do.

[@johncunningham5435]

Nicely done Steve; When logic is deployed, troubleshooting becomes easier.

[@Big_Old_Dog]

I have an Sony SR-k750P with the same problem. Happened to find your excellent video and sure enough the exact same problem with the same readings even. Ordered replacement transistors off Amazon and will soon be trying the repair. You certainly saved this Receiver from the dump as without schematics I didn;t even no where to begin except looking for the obvious. Thank you for taking them time to share.

[@cb3475]

Did it work?

[@Big_Old_Dog]

Unfortunately, No. It must have been something more.

[@BioCybergoth]

@@Big_Old_Dog i have the same amp but it got much worse, some problem before, a transistor almost burned, the heat compound got darker and smell very bad, even some smoke got out, but weirdly enough, re solder every transistor, put everything back, power and got sound, but then i tested the headphone connection to find any parasitic signal but suddenly, the screen showed PROTECT but before blinking, the unit went off, the transformer got killed, nothing blow yet, replaced the step down converter to power it up again, relays work but now i have no image on the VFD and i don't know what went wrong here.

[@dirtydon8661]

Very informative video. You you tube producers are really helping teach people like me....well some of you are. Peace

[@vhm14u2c]

I have a Sony reciever str-av570, that keeps going into protect mode intermittently, even when the reciever is off, will intermittently do relay click and amber leds on the front will glow gradually, off, and repeat till I unplug it. Back in 2003-2004(before KZbin), I took my reciever to a authorized sony service center that did not know how to fix it, but charged me $35 to inspect device anyways. From this vid you posted, looks like a good place to start. Thanks for sharing!

[@erikvianna]

Your video helped me to fix a dead home theater receiver. THANK YOU!

[@ofilippos-carpet]

thank you very much . I am an amateur and you helped me a lot with your video to repair a sony str-de595. Good for you

[@thadjones7261]

Thankyou helped me repair my Sony STR-DH590 same topology just 2 channels less, mirrored you step by step found bad solder joints, Seams to be a sony issue with bad solder due to heating and cooling, but thankyou again.

[@420canada6]

Man, you are an electric surgeon 😷. Ty for this video.

[@BiohazardX9]

Absolutely top notch - clear precise how-to. My STR-KS1300 (slimline 5.1 amp) is now showing the exact same thing. This video gives me a great place to start, and by the looks of it might fix it. the Ks1300 was working but noticed I had a different issue, as it takes random amount of button presses to get it to power on but I'd not hear that relay click but it did produce sound. Although now I get protect mode so I could be a different issue. still work checking the components you showed me though.

[@NelsonBigGunP200Fan]

an update on that HK receiver i had that shut off, it was a bad Center channel transistor. After taking it out, it worked! i got sound and it stayed on. Your video here helped me troubleshoot it! I sold it and the guy is gonna replace the bad parts in it.

[@Jaime_Estevez]

I congratulate you, straight to the problem excellent explanation and proper sequence, and NO drama ... other videos do much theater for something so easy to end up confusing and frightening apprentices, thanks for your videos

[@mendebil]

I fixed a doomed STR-DG520 with this tutorial this is gold! 105Ohm is within tolerance tho I found one that read 2MOhm instead of 100

[@tiktoker_adik]

nice one sir your the best technician i've ever seen your my idol because i learn a lot from you thanks

[@drabara]

Why i like this video ? Because you explain the complete diagnostic procedure... And from that i learn alot ! Thanks ! Looking forward for the next one !

[@terryfictv]

I recently finished repairing a STR-DE135 with protect on symptom. Upon visual inspection, I saw two obvious issues . The driver IC701 area and the Q801 24v regulator had overheated resulting in bad solder connects and a darkening of the circuit board. IC701 did not test bad but I replaced it and c740,741 and c742. Protect still on. Next I replaced c802. Protect still on. Finally, confident that both circuits were restored to fully operational condition I replaced r740 10 ohm and Shazam ! Solid fix ! The takeaway is overheating is often caused by bad capacitors .

[@scotshabalam2432]

These old sonys have the Vacuum Fluorescent Displays(VFD) that I think look beautiful and don't exist as much on newer receivers making these a very beautiful receiver to continue to keep functioning. Another thing I've been a fan of on Sonys is that they take a signal and can be set to put it back out without effects as clean as the signal they were given except amplified for speakers which is great if your DAC or something is an external device that wants to do it's own effects/has better effects.

[@dansibayo4214]

The best video on repair so far. Thank you very much.

[@rajeshbtsol]

Excellent Video, Great effort, let us look into actual remedy information rather than extra sounds,

[@scottk7679]

I have to say that your videos and wonderful instruction have been invaluable to me. I had been reading/studying and doing little "experiments" for several years. Your videos took me to the next level and I am really enjoying repairing now. Thanks again! Just a quick question if you would; I have a Sony receiver that I am working on currently. Power supply is good, power transistors are good, emmitter resistors are good. Something is dragging down the B+ rail voltage by approx 20v then quickly goes into protect mode. I think it is a shorted driver IC. Is it safe for the circuit to take the chip out of circuit to see if the B+ rail normalizes?

[@tvwatcher9291]

Great video and I appreciate your knowledge. I did this myself 35 years ago when I started out but it's just not worth the time and effort to repair these things. Often the driver will be failing or you'll have a heat related drift problem and they'll just blow again after a time. Throw it in the junk pile and buy another one. They are all disposible these days. That's just the way it is.

[@bypass666666]

This video is exactly what I was looking for, many thanks your videos are great.

[@teefer22]

Thanks so much for making this video and the in depth troubleshooting explanations. I was able to get my Sony STR DN1000 AVR back up and running again thanks to your video. I had no experience with any of this and very little soldering experience. Using a $10 multimeter, I was able to find that I had a bad emitter resistor and a pair of bad output transistors. Ordered some new ones from aliexpress and carefully soldered them in and it powered up! I connected all 5 of my speakers and I found that the front right speaker sounded like it was badly blown. I then moved both front speakers from "Speaker A" to "Speaker B" and the sound is perfect again. I don't know if my "blown" front right speaker when using speaker A is due to poor quality parts from aliexpress, my poor quality soldering job, some other small resistor needing to be replaced, or something else, but I only have 5 speakers in a 7.1 channel receiver, so it's not bothering me.

[@iamonearies21]

Best video yet . that's explain and really broke down the process of repairing your receiver...... I ready to buy my pieces and fix my sony and denon receivers.

[@polishpaul]

Thanks! I can't wait go get started on the repair. Do you have any recommendations on a reliable brand or model of receiver/amplifier, based on your experience of repairing them? Are there any to avoid or any that you'd recommend that should hopefully outlast others?

[@zafarkhan7783]

Simply Lovely. Very impressive explanations reflect the work experience.

[@markfassom6768]

Thanks very helpful. What does a repair like this roughly cost in Rands.

[@norcal715]

Appropriate repair cost in USD is $125-$175

[@jix177]

Good job - though have to say I was a little disappointed to find out that it didn't have a Protest mode after all!

[@amilcarmunhoboa9666]

I’m still loving this video

[@DizzzyKipper]

Another very informative tutorial.Thank you.

[@annafan83]

Thanks for all explanations. I need to watch this video again :-)

[@maurissa22hansen]

Hi there. To start off, I am by no means a repair tech but in an effort to "keep' em out of the recycle bin," I pulled the cover off my Sony str-de705 receiver hoping to trouble shoot the "Protected" message shown in the display. Leaning towards a blown amplifier channel, I desoldered and removed all 6 ic's (3 pairs of companion 2488 and 1620 transistors) and tested them on the bench. All show correct bce diode junctions and no shorts. The 3 emitter resistors also check good. With all 6 ic's removed, I powered the unit on to see an "All clear" message in the display followed by the dreaded "Protected" message once again. I removed, tested, re-greased and reinstalled the 79m12 and 7812t voltage regulator ic's with no change in outcome. I visually inspected the 2 large filter caps and they look fine as do all the nichicon caps in the unit. Several fuses on the mains input board as well as the transformer board all have continuity. With all ic's regreased and reinstalled, the "Protected" message remains. The unit will stay powered up however the speaker (safety?) relay never clicks-in. I checked for bridging of the rear speaker terminals and found none. I am back at square one. If you don't mind my asking, where would you point me toward at this point? Any advice is greatly appreciated!! Thanks for your time. Jim

[@choctawironfist8634]

Very precise tutorial,Norcal..well done...Question is,do you regret,making this? Having read through most comments,it seems every other comment is,a request for a diagnosis,on every piece of gear,ever made,in every country on the planet....To which I say....Check the obvious,follow these instructions...if that doesn't work..take it to a pro,or give it away and go get another one to destroy...Receivers were simple 40 years ago...today,not so much...thats why techs charge what they do....not everyone is capable.

[@rayhindle642]

Good communicator, well explained fault finding, loved your tip with the dental pick.............Liked, subscribed, and looking for more. Ray H. from the U.K.

[@kevinbeckenham3872]

Very good documentary and very informative lecture, love see more.

[@magush1982]

Thank you very much for your explanations. I hope i can repair my “Protected” Sony STR-DE597.

[@lucbeauvais1847]

Love the trick with the dental pic . Thanks for the video.

[@Tbuzzing]

Thank you very informative and to the point.

[@AntonisSpirou]

Excellent work, this is a very helpful video and the commentary really good -Thanks man!

[@nozynoz]

Thank you, once again another cracking lesson. Keep up the good work

[@behzadrasteen]

thank you so much of your very informative videos.

[@knunne1]

Thanks for a great video on theSony!

[@int0x13]

Hello norcal, may i know the model of your soldering iron and its power and which temperature you set it? It seems to solder and unsolder so well.

[@jimle22]

I really appreciate this video as I have a STR DE445 that is going into protect mode after working on it. I screwed something up as to start I only had a quiet right channel but everything else seemed OK. I took out all the power transistors and checked them out of circuit which seemed like they were OK did not notice any shorts but after a lousy solder job putting back it together it goes into protect now. I need to take it back apart and do it right checking emitter resistors and transistors properly the way you showed us and maybe I can resurrect it? I really needed your guidance in this video, thanks again for taking the time to produce this it will help me tremendously.

[@MarkoVukovic0]

Great video, thank you! I have an STR-DE597 that goes into Protect mode, but seemingly only when it's cold. Can't wait to get stuck in. Could this also be a reason for almost no bass coming from one side? I have swapped speakers and inputs to no avail.

[@vineshv7401]

Marvellous work. Any sprays available in market to protect PCBs from moisture and other contaminants place update

[@barthchris1]

Great vid! Question, would Kapton tape substitute for mica to insulate the fets???

[@charliebrown2454]

appreciated your videos and thanks for the hard work .

[@gabrielmassa]

Like the idea of the stainless steel to clear the hole. I have the same equipment (or very similar) one channel is really weak and shows no protection mode. I do try to test all mosfet and this resistor. But could not find anything I am wondering, could it be a resistor in Th channel, or may be the IC? How can I test the IC? Thank you.. Great video.

[@TheDemoexpert]

Mine is a Sony STR-AV550 and had the speaker wires crossed and activated the PROTECTION mode probably shorted an output transistor ? Good repair presentation!

[@noanyobiseniss7462]

Great explanations and instructions.

[@maurissa22hansen]

As a footnote, I did some voltage checks with the unit powered up, looking at the 6 ic's mounted to the main heatsink. Base idle voltage on two of the three 2488's tested at +1.15v and -1.05v on the 1620's. The 2488 collectors tested +52v and 1620's at -52v. Emitter outputs tested at 0v. On the last pair of ic's (nearest the front of the receiver) the 2488 had -51v base, +52v collector and -50v emitter. The 1620 tested at -51v base, -52v collector and -50v emitter. I tripple checked them for shorts and both tested fine with all diode junctions intact. What would allow 50 volts to show on the base side of the transistors other than a short? I believe the base voltages are effectivly "turning on" the transistors and thru-putting 51 volts (less the v drop thru the diodes) ending up as 50v on the emitters. Hmmm.... Again, thanks ahead of time for any help you or your subscribers may be able to lend to my troubleshooting. Reguards, Jim

[@timerskine249]

What a great video I am still wondering if this fix is above my pay grade. Did you discover the cause for the blown resistors and transistors?

[@norcal715]

Normally it is caused by a shorted speaker wire of defective driver (speaker, midrange or tweeter)

[@urbanocappetta6268]

Congratulations, i was very helpful your lesson, thank you very much.

[@serpentineflame]

Thanks for an informative and interesting video.

[@philmees777LordStarrMees]

I used to be a sparky many years ago, And this sounds like a lot of work. I think Ill just pay the guy to do it. But many thanks for your help. I have the VA555es and it keeps hitt protect, but only if all speakers are plugged in. I know theres no faults with any of my wires or speakers, it just seems having the whole lot in Protect comes on, so many its overload issue. Like all scientific things. Fault finding is the biggest issue. So Ive had it 15 years, maybe its time for a new one!

[@nivaldopinheiro1572]

Very good, clean manutention and correct....

[@alexwda2007]

Parabéns pelo ótimo vídeo. Vou tentar consertar o meu também, um SRT-DE885 que já está parado há mais de 2 anos pelo mesmo problema. Obrigado. Congratulations for the great video. I will try to fix my receiver too, an SRT- DE885 it is stopped about two years with this same problem. Thank you very much.

[@JasonPrice1]

Hey there. Thanks for the great video! I used this as a guide to check out why my STR-DE575 has decided to only have volume out my center and right surround. It does not matter the input source or the output mode. Only volume from the two mentioned channels. I checked the resistor packs and they all read good for resistance and the centers all had really low voltage. It is difficult to get to the leads reliably on the transistors as my model unit has two shields between the row of resistor packs and the transistors. I set my meter to audible diode mode and it never beeped and I am pretty sure I made contact. If you have the chance to reply, is it most likely that other electronics on the main board are fried/dead? Or if I am lucky one of the driver packs just has a cold solder. I will check that soon but was hoping to not have to tear it all the way down unless it was the same kind of repair as was needed in this video. (I have owned my DE575 for 15 years. Right from original purchase) Thanks in advance for any tips you may have!

[@qwerty-ml8kk]

Jason Price I have the exact same problem! has anyone found how to fix?

[@JasonPrice1]

pyrophantome a Sadly no. I was in need of a new HDMI and component video capable unit and the boxing week sales here in Canada just a few short months later had a great Yamaha unit and I got it. I still have the dead one downstairs so if I ever get the inclination, I may still yet try to fix it. Otherwise, I will salvage out the components for any little diy projects I have.

[@jonsingh90]

Very informative awesome diy video! thanks!!

[@lcagee]

Awesome video. Very clear. Are there any steps you take to make sure the filter caps are discharged or is there a discharge circuit on the unit?

[@عليحمدان-د7ط]

مساء الخير ايها الرائع ....بصراحه لم افهم شيئا ابدا........انت تتكلم بسرعة ر هيبه والتوضيح قليل جدا ..مع انك اكثر من رائع

[@mikeunivers]

I really miss these videos,Why do not you upload more videos?

[@curtward735]

Hey... great video !! I have one question though I am having a hard time finding the rectangular white block that's by the output on the board .....where can I get these ????

[@norcal715]

Do you mean the dual emitter resistor?

[@curtward735]

@@norcal715 yes ......saw your fix by replacing by putting two resistors together making a common in the middle, so thank you very much for that Info...I was kinda stuck !!!!

[@electronicshelpcare]

nice video

[@R0ger007]

Similar symptoms on my STR-DB780. It has a separate bias board attached to the heatsink so access is a ball ache. Your videos has helped me find the problem. Now where can I buy new transistors that aren't fake? (UK).

[@FretsNirvana]

I have a Sony DA80es with the Protect message problem. While not the same as the one in your video I followed your procedure. There are two emitter resisters showing 24 ohms when power is on and all the rest are very low voltages. But the component that emitter resister connects to has 5 leads on it. The component is a Sony NEP250. Could you tell me how I can check this like you did the transistor on the unit in this video. Thank you!

[@marliedpahltr6574]

Please could you tell me if those transistors are expensive or affordable ?

[@SorinG2010]

Hey man great video I just "found" you and subscribed to your channel. What kind of thermal compound did you use? Is it electrically conductive or not? Thanks

[@dj_sorra8605]

Is it ok with the double adhesive thermal insulation tape?

[@vivianwinkel2584]

Do you by chance have a parts list with part numbers

[@lordgalla]

Great Video,I have this same STR-DG720 has been great,all of a sudden the 2 front speakers are very low volume,all others are ok.Even on 2 channel setting,I have to crank volume to like 40 or 50 to get any kind of volume on the 2 front speakers.It's just the 2 front speakers.All others are fine.Have you seen anything like this before on this receiver? Any idea's would be greatly appreciated.The 2 front speakers work,but very low volume.Speakers,wiring,and connections all good.Just noticed this a few days ago.All speaker lights on front panel are lit.Thankyou

[@mr02gixxer1000]

You are a good teacher sir!! I have a onkyo 646 that has no sound 🔊 where sound look and what should I start trouble shooting? Thanks

[@lisandrofarfanherrera6681]

Thank you very much for your detailed explanation! By chance do you happen to remember the number of watt for the 100 ohm resistors? Thanks again!

[@norcal715]

no but I can look them up in the service manual if you need the sony part number. Otherwise just use a metal-oxide flameproof resistor.

[@mattmisanthropy.]

I realise this is an old video, but hopefully you're still willing to help me. I'm completely new at this so please excuse my ignorance. Yes, I acknowledge you cannot be held responsible and I do this at my own risk. I'll be very careful. With that out of the way, the case with my receiver is that the tower speakers and one rear speaker is very quiet. The subs seem to work, as well as the centre and the remaining rear speakers. To clarify, are you checking the transistors on the diode range in this order?: Pre-powering on: Positive on collector. Negative on emitter. After powering on and then powering off: Negative on collector. Positive on emitter. When I did this, pre-powering on, positive on collector, negative on emitter I got: About .630 on all the negative transistors and 0 on all the positive transistors. After powering on and then off again, negative on collector. Positive on emitter I got: About .630 on all the positive transistors and 0 on all the negative transistors. Does this sound right or am I completely doing this wrong? I was expecting only the transistors for the non working speakers to be faulty. The emitter resistors all read about 1.3 ohms. Didn't find any spikes in volts when testing the centre lead of the resistors.

[@kevin-od6cn]

You really know your stuff, if you were near, I would have you fix mine, but it's a bit much for the average joe.

[@shafikahmed8374]

thanks man for your time, your video is very helpful

[@johnmacdonald1486]

Hello NorCal715, this is a great hands on video. I have a Sony TA-F700ES in protection mode, red power button light stays red after start up instead of turning green. I have no sound on either channel. I checked emitter resistors on one channel and all read good at 0.02 v/dc, the other channel which i suspect has the issues the emitter resistors all read a -55.2 v/dc? I noticed in your video that the emitter resistors were reading +53 v/dc which lead you to finding the bad output transistors. I'm wondering why my readings would have a negative voltage on the emitter resistors? Thanks Alot!!!

[@norcal715]

It just depends on which output transistor had gone bad. The unit rune on a +55 and -55 volt supply. You have the -55 volt transistor shorted.

[@SmartX21]

Hi! Thank you very much for this video. My Sony STR-KM3 (Argentina model) is turning off right after power on, displaying a "USB FAIL" error message, despite the model DOES NOT having any USB connector? (I have once repaired the same model, but with USB. The problem was a faulty relay (RY901)). Any suggestion or hint? Thank you.

[@vineshv7401]

Super from where you got the spares

[@Luke-12V]

Hello, when the transistor is changed to the same one, it is necessary to set the block current, or in what case to adjust it, thanks for the possible explanation

[@norcal715]

Anytime you replace any part in the output or driver stages, you should readjust the bias (idling current)

[@ElTexMexAlex]

Thank you so much for this video.

[@ronniezzzz]

have you discharged caps

[@rodolfogomez382]

Your video is very didactic and useful, thanks.

[@freddiemortos8519]

Nice video as always sir :).. Looking forward to your next video. By the the way,what is the preferred idling current of an amplifier,and how does it affects its operation?How to deal with it when it is too high or too low? I'm a beginner to electronics and i found your video to be good and informative.

[@norcal715]

On this model since there is no bias adjustment trim pot then it would be something in the per amp ic circuit or associated components. on older amps with discrete components then it would just require troubleshooting down to the defective part. the good thing about a stereo amp is you have another channel for comparison if no schematic is available. Thanks

[@jorivera1997]

norcal715 i need some help with my sony tv 5-14-14

[@mat_v]

thanks for the great video. I have an old sony STR-D565 that has gone on protect mode recently. I didnt use it for about a year but it was working great, it did over heat and go on protect mode on a couple of house parties I had. I pulled it apart and did everything you showed, it all checked out good, what would you recommend to check afterwards? Thanks!

[@cryjenshe]

Great video. Picked up a STR-GA8ES for $34 at the Goodwill. It "worked" for about 5 min. Never got any sound. Then it blew the main fuse. Tracked it down to a dual power transistor (NEN250). Pulled it out. Put it back together. Now it has the "PROTECTOR" failure. Based on your video I will check the resistor packs and order the transistor. If it works, great receiver to $42. If not I will have to trouble shoot further or turn it into "spare parts." Again, great video, including your soldering/de-soldering techniques. By the way, where did you get the schematic for yours?

[@normanwaithe3311]

Thank you very much you have been a great help

[@gurambregadze5959]

Great video!I have the same problem with SONY HT-DDW840. There are five big white noble resistors. When I test the central lead with DC voltage range I get the following readings: 3.383v on four of resistors and 0.52.4v on one of them.Based on this, can I conclude that this fifth one is damaged?