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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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1st May 2019, 5:14 pm | #1 |
Triode
Join Date: Dec 2018
Location: Southampton, UK.
Posts: 15
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Panasonic AG-6400 Hi-Fi audio problem
Hi all,
I’ve just recently got my hands on a Panasonic AG-6400 portable VCR but unfortunately noticed that the Hi-Fi (or what Panasonic calls HD) audio circuit isn’t working correctly. I can hear the live feed from the headphone jack with perfect clarity, but playback or recording with Hi-Fi audio produces popping when recordings, or a very brief, low level crackly signal that fades into popping when playing a Hi-Fi stereo tape. I have experienced a similar issue on NV-M10 camcorders and know it is capacitor related, but I have never personally carried out the repair before. I have the service manual, but before I go digging through the block diagram and diagnosing each and every cap, I wondered if anyone has done this repair before, and knows of which caps tend to be the most troublesome? All help is appreciated. If no one can help, I will attempt to figure it out myself and post the results for future reference. Many thanks! |
1st May 2019, 6:20 pm | #2 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,185
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Re: Panasonic AG-6400 Hi-Fi audio problem
I don't know the model, but I would suspect every SMD electrolytic between the audio heads and the AF-stage. If there are no SMDs the same goes for miniature wired electrolytics. You could try heating up the suspect area with a hairdryer while listening for improvements. If audio improves, the bad electrolytic is in the heated area.
Does it have a hifi-tracking meter? Is the hifi signal recognised even when it's popping? If so, the first few stages after the head amplifier are probably okay. |
1st May 2019, 6:58 pm | #3 |
Triode
Join Date: Dec 2018
Location: Southampton, UK.
Posts: 15
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Re: Panasonic AG-6400 Hi-Fi audio problem
Thanks for the reply, Maarten.
I had forgotten about the hair dryer method for troubleshooting. It did yield some results. By heating and touching the area in this photo, I got the left channel to come back quite significantly. I could also get some buzzing in the right channel by touching the top of a cap in the area. I think you’re right that I should just go ahead and replace the whole lot there, because if one or two have gone bad, I’m sure there’s a good chance the others have too. Thankfully, they are tiny wired electrolytic ones, so doable with a micro tip iron. i believe this is the FM circuit for encoding the audio to tape. I suppose I’ve got a big project ahead haha! Last edited by TapeTwoK; 1st May 2019 at 6:59 pm. Reason: Spelling mistake |