Question about Sony STR-DB780 Receiver

3 Answers

Protection Problem with Sony STR-DB780 AV Amp / Sony SA-VE535HS speakers

Hi, I have just bought a Sony STR-DB780 AV Amp paired with Sony SA-VE535HS speakers. I upgraded the speaker wire on the fronts centre and rear to 79 strand to replace the supplied wires. But I had a poblem in that the amp kept going into protect mode. Having checked and double checked the connections for shorts without any joy in solving the problem I resorted to the supplied wires which I had had working previously. Problem solved ... The only thing I can think that maybe an issue but being new to this I am not sure if I am totaly off track is that by connecting thicker wires it alters the ohms of the speakers and may be should set the switch on the back of the amp to 4 ohms instead of theh current 8 ohms.( Don't want to flick the switch without advise .. ) Can anyone please point me in the right direction or has anyone come across the problem themselves. Thanks When in TV/SAT mode it cycles through PCM 4B and Unlock before going back to TV/SAT. The sound remains as it cycles through PCM 4B but disappears as it goes through Unlock. This can happen once an hour or every few seconds. I am told the Unlock means it is confused (Sony solution) and the solution is to disconnect it from the mains and reconnect but this does not affect anything. It is only on TV/SAT that it happens not on disc, tape or receiver.

Posted by on

3 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert who has achieved Level 3.

  • Master
  • 788 Answers

How have you checked for shorts in your wires? Did you use a multimeter? Test the resistance of your new wires compared to the old wire, should be close to the same and next to nil on the same wire but if you don't get infinity between pairs then you have a short.

About your second problem, what kind of connection are you using for your TV sound? Sounds like it's a digital connection but is it coax or optical? Sounds as if it loses sync with your signal and has to resync. If you are using optical you may have a bad cable if you are using coax the cable may be picking up interference from something or the cable may be bad.

Posted on May 22, 2008

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Master
  • 3,037 Answers

Hi keith

The thicker wire will reduce the resistance and thus have more power running through it which no doubt tripped the protection mode.

For the unlock, it will do this when it is set to AFD auto format decoding, and is just looking for the best audio to play.

:Let me know if you have any other questions

Posted on May 22, 2008

  • Benjamin Patri
    Benjamin Patri May 22, 2008

    here is a great resource for determining how to wire your speakers

    Have a Great Day and if you need anything else, I am here to help

  • Benjamin Patri
    Benjamin Patri May 27, 2008

    Were you able to fix this, if so then please give me some feedback by
    rating my solution. If you need any more help, I would be glad to
    assist you, just ask.

    thanks and Have a Great Day!


  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 5 achievements.


    An expert whose answer got voted for 20 times.


    An expert who has answered 20 questions.

  • Expert
  • 152 Answers

What you are talking about is impedance matching... it is done to avoid reflection... reflection causes noisy output due to distortion so only wires of specified thickness is being used... you can achieve the desired result by changing the length of the new wire you tried...

Posted on May 22, 2008

1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

My Sony str de335 is in protection mode speakers are unhooked how do I get it out of protection mode?

if you disconnected everything and it still goes into protect, the most likely there is a damaged amp channel that will need to be repaired.

Feb 23, 2015 | Sony STR-DE335 Receiver

2 Answers

STR-DH800 "Protection Mode"

Sounds like a problem in the amp section.

Jun 06, 2013 | Sony STR-DH800

1 Answer

Sony STR-DB780 5.1 Channels Receiver.. I have a problem, i cant get the optical to work.. I can see that on the backside of the reciver "where u put the optical cabel" it kinda not lighting up.....

using the remote for the unit, enter into the "Menu" select Audio options and set it to "Auto". If you still have a problem, post a reply and I can help you further. There are a few more possibilities!

May 31, 2011 | Sony STR-DB780 Receiver

1 Answer

My remote won't work it is locked out some how on a sony amp str db780 how do i fix this. my email

I had a similar problem (apparently 'dead' remote) for which I accidentally discovered the following remedy on one of these specialized sites where you can buy remotes. This site had a 'troubleshooting' section :
Remove the batteries and subsequently press ALL keys of the remote, one by one, for a couple of seconds.
After that replace the batteries.
It worked for me. Good luck

Aug 03, 2010 | Sony STR-DB780 Receiver

1 Answer

Hello! I have problem with my STR DB780. There is no sound out from the amp.(All 5 chanels) I have checked for bad conections on the main bord,(Relay,voltreg. IC801.802) I have supply 52 Volt to the end...

Could we back up a bit?

What started this? Did it ever work? Do you know there is a program flowing through the receiver that could be amplified? Try FM. It's internal and so there are no connections to get wrong. What happens with the speaker setup routines?

Staying with FM stereo:

Still no sound at the speakers? Run an audio cable pair from one of the Video 1 or 2 Audio Out pairs to an input on, say, your TV so you can use its speakers as a diagnostic tool. Assumes you know how THAT works.

Anything there?

NO: Then there are no audio signals circulating inside the unit. Give up on the amplifier diagnostics and get into the preamp area.

YES: You have audio inside, just need to get it to the amps. Check for mispositioned Tape switches, Mute button.

Mar 18, 2010 | Sony STR-DB780 Receiver

1 Answer

My Sony STR-DG500 wont turn on just clicks once and nothing.

Sounds like faulty psu (pwer suply unit) Amp is going into protection mode. Disconnected all speaker and av wires (only power) turn up volume and see if it stays on. If not psu, sounboard or volume function faulty. If on, connect one speaker L or R. Go to tuner mode to tuned radio station an listen for sounds. If on, connect speakers and av cables one by one and test each one on its own until amp switches off, Investigate from there were problem is. Make sure speakerwires is not shorting out.

Aug 29, 2009 | Sony STR-DG500 Receiver

1 Answer

I am looking for a manual for the sony str-db 780 amp but in english can you please help me

Is it a US model? I can't find a listing at all direct from Sony. Is it STR-DB780 or STR-DB870?

For the 870 it's

Hope this helps

Jun 30, 2009 | Audio Players & Recorders

1 Answer

Audio out problem

sounds like your sound output ic may have gone.this is normally connected to a heat sink.also check that sound output settings are ok before you go further

Feb 08, 2009 | Sony STR-DB780 Receiver

2 Answers


Please download user manual of STR-DB870 from Sony Support.

Nov 20, 2008 | Sony STR-DB780 Receiver

1 Answer

Sony amp str-db940 - protection

Somewhere in your speaker wiring, you have a shorted wire. This short can be as simple as a single strand of wire touching the other terminal on one of the speakers.

With a bright flashlight, look carefully at the back of the receiver and then the speakers for any loose strands.

May 27, 2008 | Sony STR-DB940 Receiver

Not finding what you are looking for?
Sony STR-DB780 Receiver Logo

445 people viewed this question

Ask a Question

Usually answered in minutes!

Top Sony Audio Players & Recorders Experts

Donald DCruz
Donald DCruz

Level 3 Expert

17129 Answers


Level 3 Expert

98608 Answers


Level 3 Expert

4678 Answers

Are you a Sony Audio Player and Recorder Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides