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Old 24th October 2016, 05:52 AM   #1
6V6dude is offline 6V6dude  Australia
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Join Date: Sep 2014
Default Akai reel to reel channel bias problem?

I have an Akai gx-270d with a problem I've not been able to identify for years. When I record and playback in forward mode, the right channel has more midrange and loss of treble. When I flip the recorded tape around and play it in reverse mode, it's all fine. I've connected test signal on the forward playback head and it comes out the same on both channels which suggests to me that preamps are ok.
I've put it down to two things, faulty head but it looks fine without wear or a Bias. I get similar sound results when I mess around with bias on my Naka 600 - more midrange, treble, etc. But I dont' even know if it is possible the adjust bias only on one channel on the Akai. Maybe it's some other problem, I'd welcome any suggestions, maybe someone has similar experience. I'm sick of playing my tapes backwards only.
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Old 24th October 2016, 09:09 AM   #2
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Location: The Jurassic Coast, England. GB
I would carry out the head adjustment, page 13 & 14 fig 10 of the service manual and demagnetised the head first.
The heads are switched with a relay, I have had issues with this relay. See main schematic page 51.
Download the Akai GX-270-D manuals for free - Hifi Manuals
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Old 1st November 2016, 09:18 AM   #3
6V6dude is offline 6V6dude  Australia
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Thanks for the link. I cleaned the heads, demagnetized, checked alignment, it's all good. SO now the relay and circuit. I'd bet it's something really simple as per usual.
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