Onkyo input switch problem?

[Mcraiga]

Hi, I'm new to this forum and am seeking some advice to troubleshoot a problem with my Onkyo Integra A-809. Recently at random times the input selector switch starts switching back and forth between input sources all by itself. It is not a consistant problem - sometimes it works fine for hours and then it will start clicking around to other sources. Then, it may either continue doing this or might stop after a few seconds.

Has anyone else had a problem similar to this? I'm not sure if it is a problem with circuitry in the switch, interference with the infrared remote, or what. I don't have a good repair shop close to where I live so am trying to get some ideas about what might be wrong as a first step.

Any ideas or tips to troubleshoot would be greatly appreciated. I just got done restoring my Sonab OA-14s and am loving their sound with this amp only to run into this new problem.

Thanks in advance for any help

 

[dr*audio]

I think I worked on one of these amps years ago. It has a motorized selector switch, right? I never saw this problem but I have seen similar problems with other equipment. The first thing to look at is the screws that secure the circuit boards. Sometimes manufacturers use these screws to complete the ground path on the boards and when they get loose they can cause it to act flaky as different voltage potentials occur between different points that are supposed to be ground. Tighten all the screws on the pc boards and any that secure a wire to the chassis, particularly on the board the microprocessor is on.
If this doesn't fix it, it's possible that the selector motor is driven by an opamp that may be noisy.
Other Possibilities:
Bad cap in the power supply, particularly the 5V supply, causing noise or low voltage on the supply. You need an oscilloscope to check this one.
A leaky cap in the microprocessor circuit, possibly on the reset line, holding the reset slightly low or an open cap allowing noise to get through.

 

[Mcraiga]

dr*audio,

Thanks for the tips. You are right it is a motorized switch. I'll dig into it tomorrow and try your suggestions. Hope I'm lucky and it is a ground screw connection. I don't have an oscilloscope so if its more than something loose I'll have to try and find a tech to take it in to.

 

[SimpleCAD]

I also have an A-809, agreat unit but with exactly the same problem! Have cleaned unit and checked all screws/grounding that I can see but no improvement. I don't have access to an oscilloscope. Just wondering Mcraiga if you have found a solution?

 

[scvlvidlab]

I know this is an old thread but we have found the fix to this issue. The issue with the selector switch moving back and forth is a noisy transistor Q 852 part number DTA124ES. The transistor is in the protection circuitry on the power amp board.

 

[Bumpalump]

Clean source selector switch on front panel - an element of assigning a function and replace standby microswitch

 

[Soundscape]

I know this is an old thread but we have found the fix to this issue. The issue with the selector switch moving back and forth is a noisy transistor Q 852 part number DTA124ES. The transistor is in the protection circuitry on the power amp board.

Hi & thanks for posting this. Now that it's been a couple years I wondered if that resolved the input switch hunting problem? I have an A-809 that randomly hunts inputs. Wanted to check in before I order the part.
Thanks

 

[TWC]

For those who may have this problem and find this thread, there are a few videos on youtube on how to clean the selector switch, its not difficult and will remedy the switch floating. I found one laying upside down in a pile of scrap at a scrapyard i dump metal scrap for the car dealership i work for at last week, it was in pretty good shape so i took it home plugged it in and the selector switch was jumping all over the place, took it apart and cleaned well with contact cleaner followed up with F5 faderlube and reassembled and works like new. And by the way, this amp kicks some ass and sounds amazing.

 

[Soundscape]

I bought this integrated amp new in 1995. Babied it. I've cleaned the input pot twice over the years. It's happy for awhile then the input selector ghost hunts at random again. It seems to work well when I don't use the Tape 2 and/or Aux 2 inputs. As long I use something in the middle it's less of an issue. It's a very random fault in any scenario.
It's in storage now but if I re-visit this piece again, I'm swapping caps on the input selector board right behind the control switch with some hi temp rated caps. It's a hi temp area so why not. Hard to shoot trouble this random. IIRC, this hunt problem started a year after I had a piece sitting on top of the A809, trapping heat. A few years later after 1995 on other Onkyo models, the company had many warranty repairs/gripes over processors in hi temp areas. Hmmm.

 

[scvlvidlab]

Hi & thanks for posting this. Now that it's been a couple years I wondered if that resolved the input switch hunting problem? I have an A-809 that randomly hunts inputs. Wanted to check in before I order the part.
Thanks

sorry for the late reply but yes that is what it fixed for me

 

[k13n]

Hi - would this be the same issue for Onkyo A9155? - this problem has gotten progressivley worse since this started over a year ago and would love to know how to remedy this.