Protect mode repair Sony STR-DE675 Receiver amplifier

STR-DE675 Home theater amplifier protect mode repair - in this case all of the amplifier channels were OK and the cause of protect mode was a very easy fix - took a while to work it out, but got there in the end!

[LesFourneaux]

Hi and thank you. Saved a DE475 from the charity shop (different board layout but same design). Worked for a few days then the protection racket started. Followed your video sequence. Exactly the same outcome. Checked that R732 resistor and it showed 1.3 ohms. Not having a 1 ohm job, paralleled two 10 ohms to give me 1.03 by the meter. Guess what, works fine. Simply that resistor had gone out of spec. Thanks for your pointers, appreciated.

[robinfoxx]

Nice repair! Got a Sony reciever with the same problem, hope this video helps! It's always a good idea to fix the old solder joints before they give you problems in the future.

[MrTechnogoodie]

I have a STR-K502P with the same issues. Internals are very similar. Cold/broken solder joints in the same place. All fixed now, thanks to your video. Great info and explanation!

[eddiesomesan]

I had exactly the same problem. Except the one I got was full of water. Believe it or not, I had to wash the biggest pcb with the pressure washer to be able to clean it properly. It was all green inside. I wish I could add some pictures before/after. After cleaning it the problem persisted. But after some soldering rework and changing that resistor, it got back to life. Thank you!

[JorgeTrujillo]

After having it disconnected for 3 or 4 days, it went back to work without having done anything to it. I am placing it in a better ventilated place and removed the self turn-off timer limit because protector mode happened after equipment turned off automatically.

[zukowski]

Nice job and great video, thanks for sharing your "hunt" with us. No doubt will answer a few questions other guys may be having with thier amps. Cold solder seems to be an issue with a lot of these older amps, that about the time manufacturers were switching to lead free solder (like anyone is going to be eating a pcb any time soon) . I had the same issue with my 2016 Jeep Patriot stereo, I had to reflow a cpu chip on the main board (man talk about a pain in the back side). Once I reflowed the connections with "old school 60/40" the stereo worked like a charm, actually a bit better to be honest. Thanks for the video very well done and clear to follow. Cheers!

[stuartsinclair]

Just had a problem with my Sony amp STR K740P, so I’ve brought a replacement STR DE475, a head scratcher but it’s old I brought this amp way back in 1998 fro the Sony store, it’s been absolutely brilliant until now, just checked everything cleaned it out and rechecked some screws, so I’m going to leave it on for a bit, normally trips out at 10mins fingers crossed

[rolandogomez]

Saludos amigo, gracias por tu explicación y metodo de reparación. Tengo problemas de voltaje en un DC-DC board converter de mi Sony SDT-DH-540. No produce los 13.5 voltios requeridos solamente 12Voltios;, ni los 3.5 voltios, solamente 1.6Volt. Me ayudaría usted? (Do you help me? My DC-DC converter is not give 3.5Volt nor 13.5V DC for get up on my Sony HDMI amplifier.) I am from Dominican Republic, I need repair mi Sony, please.

[richarddemers]

@DanTubez, In the video at position 2.50 you found the -52.7 volts. I have also found the same on my amp. Both power transistors and dual resistor check out fine. Was also able to track down the 2 ohm resistor under the two rails but it was also reading fine. All my solder joints appear perfect. Can you offer some direction as to where I should look next. I seem so close because I found the DC volts on the resistor. Its funny because it turns out to be the same set as yours (first from the left). My amp is the Sony STR DE-697.

[saarike]

Great repair! It was a pleasure to watch.

[pikludutta]

I found prob on str de 675 .when I keep it stby there r no memory problem but whet i off main power and sw on after some time demonstration mode apper and memory missing .what to do sir .pls advice

[pauldorschner]

i knew that the receivers sony are good receiver, they have 20 years and still working good, i prefer old technology than new technology because unfortunately everything are made in china and thats not good, congratulations !!! you have a gold technology

[TeacherBrunoOneil]

I had the same issue with mine. I'd highly advise you to redo all the soldering and check the 78XX regulator soldering too. I found some cold soldering on the dolby board. and on the rca board too. the rca has a LM7905 negative 5v regulator. this is a good receiver but with time it melts its on soldering on the pcb.

[richardwalker]

i have the protect mode kick in sometimes, i am using different ohm speakers which probably messes up the power amp
but the preamp output still works, and sometimes the sound quits without the protect kicking in so i increase the volume
and the sound comes back on, could be a resistance problem?

[Luke-V]

good evening, I wanted to ask, what is the function of power amplifier chips? thank you for any answer, and have a nice evening

[Theo_K]

Have similar problem in a 485. IC501 removed and no more protect. Now checking the resistor.

[danielesilvaggi]

Thank you for this video now I have a good idea where to start. My STR-DV10 turns on and sometimes goes to protect after about an hour and sometimes it doesn't all day. Lately it seems to be doing it more frequently like about an hour or so. Would this be a different problem or should I still go after the same things as you describe in this video? Where do you get your service manuals please?

[silviucambesteanu]

I have the same amp but mine has a different problem. I hear all the channels at 1/10 from the original volume, except the center channel. All other functions are working. If you have any idea where to start looking that would be great.

[selwynandrews]

Very helpful - I've got an STR-DE475 and have touched up the solder joints on the board. Quite a lot looked dry, or tending that way, and the joints on that STK IC were particularly bad. I noticed that R732 - mine has gone open circuit as well - is a fusible resistor. Did you use one of those, or just a standard resistor? Want to err on the side of safety, but also want to get the job done, lol.

[hitpoint]

Hi! I did a factory reset on my DN1060 and it got stuck on CLEARING. Any advice please? :/