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Louie
Louie, Technician
Category: Home Theater-Stereo
Satisfied Customers: 11442
Experience:  Have been in the business 25+ yrs., down to component level.
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I have a Sony DTR-DG820 HT system. no audio from any input

Customer Question

I have a Sony DTR-DG820 HT system. no audio from any input source. Video from any HDMI source is present. Spent hours doing all kinds of test. Reset/Clear system. Unplug for hours and days. I do not get the "Protector" displayed on the screen. no solution.
JA: What's the exact make and model of your television? And have you done any troubleshooting yourself?
Customer: Sony Bravia
JA: How long has this been going on? What troubleshooting have you tried?
Customer: the HT system has been unplugged for more than a year as we moved and didn't have time to reconfigure the equipment. I reconnected everything about a month ago. the problem happened at that time. it worked properly at the previous location
JA: Anything else you want the electronics expert to know before I connect you?
Customer: no, just to suggest how to resolve the audio problem
Submitted: 3 months ago.
Category: Home Theater-Stereo
Expert:  Louie replied 3 months ago.

Hi, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.

Initially, might the Sony perhaps be an STR-DG820? Even if no sound from any/all speaker terminals, is there sound to/if a subwoofer is connected?

A few tries, checks:

  • • plug in a pair of headphones and determine if there is sound. This is both a test and try of a fix. Do the plug in/un-plug a couple of times. There is a hidden speaker cutoff switch inside the headphone jack. Additionally, consider using compressed air or better yet, plastic safe / non-staining CRC 2-26, DeoxIT DN5 or LPS 03116 Contact Cleaner or equivalent to clean the insides of the headphone jack but allow sufficient drying time;
  • • exercise the SPEAKER button switch repeatedly.

Still, if all external factors have been checked and ruled out, then the described symptom and displayed system message almost always point to an internal hardware issue.

The above would require that the unit be opened up for visual inspection, voltage/continuity/resistance checks, confirm faults and effect repairs.

Are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter and even a soldering iron?

Equally important, could you make use of the repair/Service Manual or at the very least, the schematic diagrams?

Customer: replied 3 months ago.
it is a Sony STR-DG820. I have done the headphone plug in/unplug several times, as you suggested. I have exercised the speaker selector buttons several times. I have done the steps you suggested several times over the past several weeks, prior to contacting you.
When I hook up the satellite box via HDMI in, I get video on my connected Sony TV. I am getting video from all HDMI inputs. NO sound from any of the HDMI sources. If I use the RCA jack for source inputs to the HT unit, I get video but no audio. I get no audio on FM or AM tuners (I have rooftop antennas connected to the HT system. both antennas works as I am receiving radio stations on a Yamaha HT receiver.)
When I do the "tone" test, I hear the tone in the three connected speakers (L+R+C), three distinct pitch and loudness. The display shows E-F:33 message. I have followed various Sony troubleshooting steps.
I am a computer professional for 30 years and is an Electronics Engineering Technologist. I am familiar with electronics, circuit diagrams and have repair various electronics equipment. I have my own multi-meters(2), oscilloscope, soldering iron; everything needed except a circuit diagram. I have been wondering if the audio protectors are malfunctioning. I have no circuit diagram to locate them on the circuit board. I am quite capable of DIY repairs. This seems to be my only option as both Sony and their authorised repair shops in my area are not willing to look at the unit. They claim it is too old and they cannot source parts in a timely manner. Either I fix it myself, with help from a pro like you or throw it out. It has less than 100 hours of use.
Expert:  Louie replied 3 months ago.

Great on the DIY!

Consideration:

  • NO sound from any of the HDMI sources...RCA jack... FM or AM - would indicate a common fault with both analog and digital inputrs;
  • hear the tone in the three connected speakers (L+R+C) - would be indicative of functional amplifier, speaker relay and circuitry all the way to the speaker terminals;
  • E-F:33 message - would indicate a fault in either of the FRONT speakers;
  • OR, the built-in diagnostics is false sensing.

Proposed additional/external checks (if have not been done) even if just as for test purposes:

  • • perform again a RESET;
  • • test for Ω of the speakers connected;
  • • swap left and right speaker / wires;
  • • if able, test/connect a subwoofer.
Customer: replied 3 months ago.
How may I obtain a circuit diagram. I wil be carrying out your instructions later this morning and report back with the results.
Expert:  Louie replied 3 months ago.

I understand and would look forward to an update when able.

Site policy requires that providing schematic diagram / Service Manual be offered as additional / Premium Service with a corresponding (token) fee. Would this still be of interest?

Customer: replied 3 months ago.
What is the $ token fee?
Expert:  Louie replied 3 months ago.

Please see private message.

Customer: replied 3 months ago.
perform again a RESET; - done several times
• test for Ω of the speakers connected; - 8 ohms, tried different speakers as well
• swap left and right speaker / wires; - swapped, no difference
• if able, test/connect a subwoofer, - connected sub-woofer, nothing heard
Expert:  Louie replied 3 months ago.

I understand.

Any sound when in 2CH/A.DIRECT mode?

Internally, carefully check the main board for:

  • visually for possible board discoloration (signs of heat stress);
  • leaky capacitors;
  • -15V @ pin 3 of connector CNP912;
  • +15V @ pins 6 & 7;
  • -7V @ pin 3 of connector CNP500;
  • +7V @ pins 1.