Faulty infrared remote sensor? - Page 1
Forum section: electronics / repair

author: fritterandwaste
author_rank: Contributor
timestamp: January 09, 2022, 10:41:52 am
content: HiI have a Jamo DMR 60 Dolby Surround DVD/receiver and the remote control is not working properly. I have opened it up, cleaned it, cleaned the sensors and contact pads with alcohol and reassembled. I have viewed the remote's transmitter via my phone camera which confirms that it is transmitting signals. I can see the light flashing for all the controls and clearly the batteries are fine. I have also used my phone in conjunction with the "Quick Remote" Android app to 'learn' and transmit what I assume are the same codes (although if those codes have been corrupted somehow then I guess it will have learned codes that are nonsense) . Once the receiver has been powered up manually, none of the the remote buttons work. However, if I power it off, the remote's power button will often work and so wakes up the receiver - either from the original remote or the Quick Remote App but it does not recognise the button when I try to use it to power down.Is it likely that the infrared sensor/receiver is faulty and needs replacing? Or does the fact that the remote power button works occasionally eliminate this possibility?Also, if I were to replace the sensor within the receiver (which I can access after removing about 20 screws) are there compatibility issues I need to consider or are these sensors pretty standard for household audio/video devices? I have attached a photo of the sensor which has the numbers 6104 on the top (I think) in tiny print.I am no electronics wizard but am game to take on certain jobs and can handle simple soldering tasks.Thanks in advance.

author: madires
author_rank: Super Contributor
timestamp: January 09, 2022, 12:11:40 pm
content: Intermittent issues are often caused by bad solder joints or power supply issues. Which tools do you have (DMM/scope/etc)?

author: fritterandwaste
author_rank: Contributor
timestamp: January 09, 2022, 02:23:49 pm
content: Thanks for your input. I have a DMM (new toy) and a soldering iron but no scope. I would appreciate any further input you might have, thanks.

author: madires
author_rank: Super Contributor
timestamp: January 09, 2022, 03:44:23 pm
content: Then let's start with the power supply. Could you please take a hi-res picture of the power supply PCB/section?

author: fritterandwaste
author_rank: Contributor
timestamp: January 09, 2022, 04:29:58 pm
content: OK Thanks. I will try and attach 2 photos - one of what I believe to be the power supply board and a wider view from above. First attempt failed because photos were too large so I hope they are high-res enough!

author: madires
author_rank: Super Contributor
timestamp: January 09, 2022, 04:46:46 pm
content: That's a switching mode power supply and I see at least two electrolytic caps with bulging tops at the bottom right. The bulging top is a clear sign of a bad electrolytic cap. They need to be replaced. Get new ones with the same specs (important: low-ESR types, known brand). Be careful with the two large caps at the bottom left as they are charged to mains voltage. Make sure they are discharged before working on the SMPSU.

author: fritterandwaste
author_rank: Contributor
timestamp: January 09, 2022, 05:11:52 pm
content: Ah yes I see what you mean (I think) - the two taller black "cylinders" towards the bottom right. That symptom has been mentioned to me on a previous "project" and I should have had the sense to look. Do you think these could be responsible for the remote issues?Thank you so much for your time and patience.

author: madires
author_rank: Super Contributor
timestamp: January 09, 2022, 05:24:54 pm
content: Yes, most likely. The bad caps have lost most of their capacitance and that causes the output voltage to be unstable.

author: fritterandwaste
author_rank: Contributor
timestamp: January 09, 2022, 05:26:32 pm
content: OK thanks again. I will pursue this route.

author: fritterandwaste
author_rank: Contributor
timestamp: January 09, 2022, 07:26:08 pm
content: Final question (I hope) - what would you class as known brands please? I think I've bought capacitors once in my life before (vcr repair).

author: madires
author_rank: Super Contributor
timestamp: January 09, 2022, 07:30:19 pm
content: Nichicon, Nippon Chemicon, Panasonic, Jamicon, Rubycon, or Yageo for example.

author: fritterandwaste
author_rank: Contributor
timestamp: January 09, 2022, 07:49:49 pm
content: Brilliant, thank you once again. Really appreciate it.

author: fritterandwaste
author_rank: Contributor
timestamp: January 17, 2022, 10:13:16 am
content: An update on this...I replaced the two capacitors as suggested (thank you again). When I reassembled and restarted the receiver, the remote seemed OK but one thing I did realise at this pont that, when the input source was set to DVD, the remote was essentially locked and useless but once I changed the source manually, the remote seemed OK as long as I steered clear of the DVD source. In theory this could have been my original problem but I'll never know now! However, the audio was disappointing and only clearly audible on centre speaker, faintly audible on left channel and very quiet and distorted on right channel. After leaving it a while the problem disappeared but when I switched on again the next day it reappeared.I opened up the device again and realised that my re-soldered connections were a bit loose so I resoldered. All seems well at the moment but I'm mildly worried that the audio problem may reappear. It won't read DVDs (which could be why the remote locks up in DVD mode) and it simply ejects any disc I happen to load but I'm not too bothered about that issue.Fingers crossed!

author: madires
author_rank: Super Contributor
timestamp: January 17, 2022, 12:10:16 pm
content: In case you're interested in fixing the DVD drive check out 12voltvids' youtube videos about repairing CD/DVD players.