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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 13th Feb 2018, 11:59 pm   #1
hsbhachu3d
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Default Akai gx365

I got this deck but it has a peculiar problem and I do not know where to start.

It is a 4 track Auto reverse deck and also has inbuilt amplifiers. It is a 3 head deck and the Play head is moved into a lower position when playing in reverse.

It plays/ records fine. but when you press the reverse the reverse button, it plays in reverse but much faintly from the right channel.

It is obviously not the head because the head picks up 2 tracks and plays fine in forward and not in reverse.

the tape is also fault free, flipped it over, same problem.

Relay bad? Capacitor bad? Switch bad? in the reverse circuit?
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Old 14th Feb 2018, 1:22 am   #2
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Default Re: Akai gx365

If the switching is done by those long slide switches, clean and lubricate them - they always seem to play up. I uses CRC CO then CRC 2.26, but those are probably not available in the UK so others can advise similar products.
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Old 14th Feb 2018, 3:38 am   #3
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Default Re: Akai gx365

Got the culprit. A relay that does not close properly . took it apart and cleaned the contacts with a fine strip of super fine sand paper. done the trick.

BUT also found a new issue. the machine records but the recording is faint. both channels. VU's adjusted properly and source shows alright but when monitoring tape the recording is literally dead. It's like the transistors or something are throwing a fit.
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Old 14th Feb 2018, 4:24 am   #4
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Default Re: Akai gx365

arjoll has it in one!!!

I was service manager for Akai Australia for a couple of years. Those slide switches are the culprit. I actually resigned over that exact problem.

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Old 14th Feb 2018, 4:58 am   #5
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Default Re: Akai gx365

Quote:
Originally Posted by hsbhachu3d View Post
BUT also found a new issue. the machine records but the recording is faint. both channels. VU's adjusted properly and source shows alright but when monitoring tape the recording is literally dead. It's like the transistors or something are throwing a fit.
Are you seeing bias on the record heads?
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Old 14th Feb 2018, 11:33 am   #6
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Default Re: Akai gx365

Seeing bias? if the bias circuit is working? I can assume it is, because I attempted to make a recording with the bias board removed and all I got was faint crackles.

Put the bias board back and it started recording the same low again but I it's something like, If I set the source levels to 0DB, the recording will be something like -6 db on the VUs. Ironically equal on both channels. Increasing the level gets the recording up to nearly 0 db but it starts to clip and I'm way high up on the source input

Last edited by hsbhachu3d; 14th Feb 2018 at 11:47 am.
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Old 14th Feb 2018, 5:02 pm   #7
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Default Re: Akai gx365

I demagged the head and the recording although low is rather clear and very good actually. Just need to figure out why it is so low
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Old 14th Feb 2018, 6:38 pm   #8
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Default Re: Akai gx365

Right, There is the rec amp schematic. I have read on many forums online that the 2SC968 transistors are prone to die or get noisy with age.

Any suggestions on what I can substitute or if these are viable culprits?
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Old 15th Feb 2018, 2:46 pm   #9
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Default Re: Akai gx365

BC549 probably will substitute OK (that's a lower-noise version of a BC547). It has a higher turnover frequency and a lower maximum collector voltage, but still within ratings in this circuit. Package is TO-92 with base in the middle, so should fit a board already laid out for TO-18.
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Old 15th Feb 2018, 7:22 pm   #10
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Default Re: Akai gx365

So far, I've Recapped most of the Play boards and record boards, there are about 2 caps that I've left as I don't have replacements, but It records now. However, it clips on the low end.. say if you record a sine wave between 25-100 hz, it'll sound as though I've maxed it out, anything above that until 18k is good.
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Old Today, 10:20 am   #11
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Default Re: Akai gx365

All new transistors on play board.. Playback is perfect, recording board also all new 2sc 458s , I've left the 454s and 968 on there. Put a new original matched Rec Head. calibrated the whole deck and sounds nearly perfect at 7.5 ips. 3.75 sounds worse than my 4000DS mk1. what shall I do? I think something is up and maybe the record head is not getting the max its meant to get .

was thinking of replacing the 968
2n 2222 is the best equivalent replacement for the 2sc968 which is the record output transie but just worried not to screw anything up.


What shall I do? dead end.
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