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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 12th Apr 2015, 8:43 am   #1
hsbhachu3d
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Default Akai X-2000SD Dead Right Channel

This is not the first case of this deck that I've come across with a dead right channel. Every X-2000SD I've had.. (2 others in the past) and they both had the same issue.

This one is in better condition than the other ones physically but the mechanics need some serious work that I'm currently doing.

without beating around the bush.. I am not that good with fault finding electrically. The deck is a Reel, Cassette and Cartridge combination. On powering up, the right channel is completely dead. after about half an hour of playing, it slowly starts coming in faintly crackling until it gets nearly full gain but still a bit low.

I managed to get a manual off Hi-Fi Engine but it missed the page 30 and 31 that mention Amplifier and playback trouble. If you guys can help me, It is the only thing putting this little tank down.
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Old 12th Apr 2015, 1:00 pm   #2
Restoration73
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Default Re: Akai X-2000SD Dead Right Channel

In the preamp section, each channel had a AA072 thick film IC (orange colour) and these
could fail or go noisy. On the power amp, each channel had a power IC (early type)
which fail to give no or severely distorted sound. You can check the latter by injecting
audio into the volume control, otherwise it's the preamp. Do check that all rec/pb
switches have been cleaned. I'll check if I have the missing pages.
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Old 12th Apr 2015, 1:51 pm   #3
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Default Re: Akai X-2000SD Dead Right Channel

I will check the orange IC. the Main output is done by a pair of mono STK-11 ICs made by Sanyo. And yes. The other 2 models had severely distorted sound on the right channel. This one starts really faint, then gets distorted severely as the gain comes up and then the sound comes probably 3/4 the gain after running for about 45 minutes with little but slightly audible distortion. The left channel is great though.

I have used Deoxit on the switches and they're fine as far as I can tell. I've never had any problem with Akai Switches but this is a benefit of doubt. I will feed sound into the Volume pot and see if it is the amp/ preamp later. It is ****** hectic to get to them though.
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Old 14th Apr 2015, 10:05 pm   #4
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Default Re: Akai X-2000SD Dead Right Channel

Checked the following.. preamp outputs both channels check out good with a 1000hz tape. the preamps give equal reading on both channels with no delay on turning on .

Also swapped the right channel preamp out and connected to the left working amp. Levels check out good then too.

Fed music into amp (at volume pot) and the issue persisted. The low gain and severe distortion was there on the right channel with the music being fed straight into the right and left amp. Left channel checked out good.

Seems like the STK011 Sanyo Right channel main output IC is the culprit then.
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Old 21st Apr 2015, 9:19 am   #5
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Default Re: Akai X-2000SD Dead Right Channel

Ordered a new old stock original IC replacement. Did you get hold of the Pages? @restoration73
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Old 22nd Apr 2015, 1:40 pm   #6
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Default Re: Akai X-2000SD Dead Right Channel

Replaced the STK 011 main output IC and No difference. Even swapped them and still no difference.

Swapped the AA072 orange ones and we're getting somewhere. The initial issue was that there would be a delay in the affected channel in turning on and starts with crackle all the way to full gain. (checked gain at AA072 output) However, the right channel which was the one affected still didn't have as much gain as the left say 3/4 or so.

After swapping the AA072, the right channel sounds flawless from turning on and the crackle and slow gain issue has gone to the left.

What is surprising is that when both channels reach full gain, the gain on the right channel is still showing lower than the left even though the affected IC is on the left now. :/
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