Sony Audio Receiver in Protect mode Repair Fix STR-DG720

The repair of a Sony STR-DG720 audio receiver in the protect mode. involves replacing power amplifier output transistors, emitter resistor and base drive resistors.

[@JustBarran]

8 years later and your still helping people 😍

[@jcweiz09]

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

[@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.

[@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

[@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.

[@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

[@vivekvivek198]

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

[@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

[@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!

[@dilbyjones]

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

[@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

[@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

[@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.

[@dansibayo4214]

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

[@erikvianna]

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

[@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 !!

[@bypass666666]

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

[@nozynoz]

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

[@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!

[@annafan83]

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

[@kikcodog]

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?

[@kikcodog]

Unfortunately, No. It must have been something more.

[@BioCybergoth]

@@kikcodog 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.

[@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 .

[@zafarkhan7783]

Simply Lovely. Very impressive explanations reflect the work experience.

[@DizzzyKipper]

Another very informative tutorial.Thank you.

[@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

[@AntonisSpirou]

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

[@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.

[@kevinbeckenham3872]

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

[@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.

[@tiktoker_adik]

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

[@rajeshbtsol]

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

[@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

[@dirtydon8661]

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

[@knunne1]

Thanks for a great video on theSony!

[@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.

[@behzadrasteen]

thank you so much of your very informative videos.

[@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.

[@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.

[@OttawaOldFart]

Thank you for explaining how to test a transistor. I've been watching videos and everybody does it but no explanation gees.

[@charliebrown2454]

appreciated your videos and thanks for the hard work .

[@Tbuzzing]

Thank you very informative and to the point.

[@420canada6]

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

[@urbanocappetta6268]

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

[@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.

[@serpentineflame]

Thanks for an informative and interesting video.

[@vivekvivek198]

I have similar Sony Muteki 1510 Watts receiver. It looks same as this unit from inside and outside. But this is 6.2 channel amplifier. I have issue with center channel which have some noise and sound is not clear. Rest all channels are working fine. I did check the center speaker in other channel and speaker is good. I strongly suspect the noise is being introduced in center channel. Please guide me how to troubleshoot this issue. Which all components could be problem?

[@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.

[@magush1982]

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

[@amilcarmunhoboa9666]

I’m still loving this video

[@traviskemp236]

Thanks Bro!! Great lesson and saved my sony!!

[@shafikahmed8374]

thanks man for your time, your video is very helpful

[@noanyobiseniss7462]

Great explanations and instructions.

[@jesselyons2002]

Thanks for doing the videos again

[@jonsingh90]

Very informative awesome diy video! thanks!!

[@ElTexMexAlex]

Thank you so much for this video.

[@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?

[@nivaldopinheiro1572]

Very good, clean manutention and correct....

[@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.

[@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.

[@saarike]

Nice and very professional!

[@rodolfogomez382]

Your video is very didactic and useful, thanks.

[@zaprodk]

Once again a good repair video. The title is a bit funny though. Protest-mode :-)

[@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?

[@electronicshelpcare]

nice 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!

[@lucbeauvais1847]

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

[@ramabamaboomboom]

Thank you so much. Sincerely.

[@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!

[@JohnBenedict-KE5RS]

Great video Steve....

[@norcal715]

hey John whats up in Austin? have not heard anything in a while from you, since the tower climbing video some years ago!. still at 3M????

[@JohnBenedict-KE5RS]

Hi Steve. Yes still there but not quite as long you been with PL. You have quite a lot of really good instructive videos. Nice job.

[@mvazquez2616]

awesome this is the first vid i watched of you...and I'm happy to have found you!! ? I have a de335 with same issue...i guess i need a multimeter first!

[@shemnemaire3312]

Thank you for the lesson.

[@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.

[@hervefaro4450]

Excellent job.Thanks.

[@shaunbaxter412]

thanks man this was very helpful

[@darkside69cf]

Awesome video brother!

[@ryanclucas84]

Awesome vid friend. You rock.

[@Jetski270]

He's Back!!!!!!! Yeah!!

[@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

[@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?

[@alia176]

Good video, thanks!!

[@normanwaithe3311]

Thank you very much you have been a great help

[@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

[@zoelynnkendrick1708]

thanks for your response, I have done all of what your said, except the iphone carmera to remote..I try that today, and let you know..I know this remote is old, but it was working just find..I don't know if it can be programed again but I am trying everything to get it back, I appreciate your returning a response to this problem I am having..grateful:

[@zoelynnkendrick1708]

I tried the phone to the remote didn't see any light..it failed so I guest I'll get a universal remote and see if that help..again thanks for your help..

[@errolwilliams65]

good instructive video.thanks a lot

[@s55user]

Thanks for video. I will try repair my receiver.

[@giorgostexnikos6976]

profesional explained.very nice video

[@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.

[@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!

[@ndlovini3505]

Thank you. I have a 5.2 Channel which just cuts power. It's an STR-KM3000

[@Kennynva]

My Fluke will calibrate the leads when you switch it on and put it on the 40 ohm,diode, continuity location, then hit range, and CAL will come up on the meter,,,then its takes into account the meter leads...Its a Fluke 79III I have...nice video.

[@bogartsandoval]

Very useful! Thanks!

[@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

[@travistaylor3186]

excellent video, I'm trying to repair a similar sony unit.

[@salzamora3378]

thank you for your help.

[@barthchris1]

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

[@diezzler]

Do you have any suggestions on tracking down popping and crackling sounds coming from only one channel of a Sony Receiver (center to be exact)? Although my Sony amp is not same (has 9.2, with bi-amplification option on the front channels), I'm sure you would have an idea. I followed your process of diagnosing a receiver (this particular problem), and it doesn't seem to be the issue for me (although I realize this amp was in protect mode). Your understanding and explanations are very clear and precise, and I wish you had (if I can request) a video of common receiver/amplifier problems, and your process to diagnosis them (I realize you have a few videos with a few of the problems). Thanks for any help! Btw, I have a STR-Da2800es

[@discoecultura76]

Good Job man.

[@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.

[@loonieverse6406]

Thanks for the help