Sony STR-DH500 randomly cycling INPUTS on it's own - Page 1
Forum section: electronics / repair

author: SYN80
author_rank: Newbie
timestamp: February 27, 2025, 06:14:40 pm
content: After playing audio for awhile the receiver will randomly go into a rapid INPUT cycling fit, this won't stop until I turn off the receiver for a couple minutes and then power it back on. After a bit the issue will happen again. It seems to be vary random when it starts, I can never predict it.* There isn't a possibility of IR remote interference.* No buttons on the remote or receiver are stuck or sticky.* Opened the case and can't find any visual signs of damage.* Everything is working fine until the random INPUT cycling problem, which I cannot stop until the receiver is turned off for a couple mins and then back on.* The receiver is kept on a specific INPUT all the time. It isn't being switched manually several times per use.I want to save this from the landfill since it works fine, until of the random INPUT issue happens. I'm comfortable soldering in new parts, just don't know what to replace. The receiver I purchased several years ago used for around $60 and I know if I send it out to be fixed (if possible) it's going to cost more than what I paid. Therefore I would like to do the repair myself with some advice from othersHere is a short video of the issue happening

author: benj38
author_rank: Frequent Contributor
timestamp: March 01, 2025, 08:37:03 am
content: This is a tough one. Maybe some BGA IC that has intermittent solder joints.Try to check if you can cause the problem to appear by cooling or heating parts.

author: MathWizard
author_rank: Super Contributor
timestamp: March 04, 2025, 07:46:40 pm
content: If I had it here, I would start by looking at the rotary encoder circuit, which is probably right on the same PCB as the knob/dial, in the front panel. See if that starts acting up. Some part in that could be failing, or bad solder joints. I would solder on wires, and have a DMM and/or oscilloscope setup, to watch it when it starts cycling.Depending on the stereo, you might be able to unhook some wires that goto the rotary encoder PCB. When it's working and set to the correct input, you could turn it off, then unplug the encoder PCB, and then wait and see if the problem returns. I might go as far to cut PCB traces, just to un-power a section of a circuit, and see if a problem goes away.Then I'd check the INPUT selection IC's, and see if they are getting sent all these commands. Some MCU must be sending out the display data, it may or may not be the same 1 that controls the input selection digital switches.But all this would be a big project, I'm modding/fixing my own stereo, but I have a backup one, so it's no big deal when it's out of action.

author: SYN80
author_rank: Newbie
timestamp: March 22, 2025, 04:42:04 am
content: I found thishttps://www.manualslib.com/manual/2054839/Sony-Str-Dh500.html#manualwhich should help.

author: David_AVD
author_rank: Super Contributor
timestamp: March 22, 2025, 05:09:01 am
content: Check for corrosion on the front panel board and top digital board. Also carefully re-seat the various flat ribbon cables that go between those two boards.

author: dbator
author_rank: Contributor
timestamp: March 22, 2025, 02:02:29 pm
content: Hello,I remember, several years ago I had for repair a SONY stereo amplifier/receiver - also STR series and also from that period of time, but an older one judging on the front panel design of STR-DH500. I can't recall what was the symptom, but there were several broken solder joints on THD components, bottom side of course (as usually on SONY PCBAs those days (monitors, TV screens). Resolerding them (incl. cleaning somehow oxidized component pins) solved the issue. In your case the issue looks more induced by temperature. However, temperature can also a bit cause mechanical tension of components. Probability of such cause is not much, but I would inspect bottom part of the board (THD components) for broken solder joints. And then SMD components. I don't know the device, so I can't tell whether there are BGA components, but if yes pushing carefully of the components or PCBA may cause the issue occurs immediately. So benj38 may be right.As MathWizard stated, old rotary encoders can cause such symptoms too, but not after warming up of the device I would say. You can try to touch it before the issue starts to show up again and then when it already is occurring. I would not cut any traces ever.If all that will not move you forward, you have to use service manual, schematic and probe, signal and control path.

author: floobydust
author_rank: Super Contributor
timestamp: March 22, 2025, 05:12:54 pm
content: I remember a repair like this one, turned out it was the IR receiver module sending jibberish to the CPU. The garbage was decoded as phantom key presses on the remote. There was no IR or incoming light involved...I would scope and check for noise coming out of it, or just remove it if there is an external pullup resistor to prevent the data line from floating.Or the module has very noisy power coming in, they usually have a capacitor for that.

author: dbator
author_rank: Contributor
timestamp: March 22, 2025, 05:17:38 pm
content: See, there are plenty of possible causesNow, it's up to SYN80 to find out what is causing that. So, DMM, scope and service manual in hands and to work. Let us know what you discovered.