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 Post subject: Akai X360 D motor capacitor questions.
PostPosted: Mar Thu 28, 2019 6:01 pm 
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Joined: Jan Sun 12, 2014 10:51 pm
Posts: 44
I decided to do a more or less complete overhaul of my Akai X360 D reel to reel after it started to misbehave, occasional speed drift, a hot electrical smell, and the occasional buzzing from some of the solenoids as though they were stuck on. I have those issues pretty well pinned down to completely toasted spark quenchers which I learned can cause that from another thread on the forum. Some of the old ones had melted down so badly that they now test only as resistors.

Where I'm having an issue is the capstan motor run capacitor. It's a dual value electrolytic which I thought always shared a common negative, except this one doesn't... It's got five terminals where I would have expected three. I've got two brand new motor capacitors here which test at the correct values but I'm kind of lost as to how to wire them. The schematics I've found for this unit online may as well have been finger painted. Absolutely unreadable.

What I know about the capacitor for sure is that the RED terminal is 2.0 Uf, the WHITE is 1.0 Uf and supposedly the YELLOW is common negative. But as you can see by the third picture that means I've still got wires hooked up to two extra terminals that seem to do nothing.

Any chance anyone else has tackled this same problem?


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File comment: Toasted spark quenchers
Photo Mar 22, 8 09 24 PM.jpg
Photo Mar 22, 8 09 24 PM.jpg [ 129.97 KiB | Viewed 247 times ]
File comment: Capacitor values
Photo Mar 22, 7 12 59 PM.jpg
Photo Mar 22, 7 12 59 PM.jpg [ 211.95 KiB | Viewed 247 times ]
File comment: Capacitor Terminals
Photo Mar 23, 1 57 27 PM.jpg
Photo Mar 23, 1 57 27 PM.jpg [ 212.85 KiB | Viewed 247 times ]
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 Post subject: Re: Akai X360 D motor capacitor questions.
PostPosted: Mar Fri 29, 2019 5:01 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11403
Location: Powell River BC Canada
The schematics I've found for this unit online may as well have been finger painted. Absolutely unreadable.

Finger painted :D

And thank YOU for reminding.. the machine with more relays than
a telephone exchange.

Attachment:
Akai  sch Reg  O 101.jpg
Akai sch Reg O 101.jpg [ 184.05 KiB | Viewed 223 times ]

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Akai X360 D motor capacitor questions.
PostPosted: Mar Sat 30, 2019 12:19 am 
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Joined: Jan Sun 12, 2014 10:51 pm
Posts: 44
Okay so maybe I exaggerated just the tiniest bit about the quality of the schematics, but that is way better than anything I could find. That and and some poking with my meter confirmed to me that those two extra terminals are just another example of Japanese efficiency. "These wires are related to these other ones and they have to join anyway, why not add two extra terminals?"

Now all I have to wait on are the spark quenchers to arrive from Taiwan. I could have made them using a .1 cap in parallel with a 120 ohm resistor but I figured I'd just buy the direct replacements. It's really going to be nice to hear this thing at it's full potential, I'm not sure I ever have. It had always been a little wonky since I bought it.

Thanks for the help!


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 Post subject: Re: Akai X360 D motor capacitor questions.
PostPosted: Mar Sat 30, 2019 2:42 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11403
Location: Powell River BC Canada
I think the resistors are in series with the capacitors as transient suppressors.

Register pages 95 through 116 are the various schematics for the twelve different issues
of the X-360 and X-360 D.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Akai X360 D motor capacitor questions.
PostPosted: Mar Sat 30, 2019 5:49 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 4355
Location: Sunbury, Ohio 43074
The REALLY fun thing with relay systems..... arcs, and reverse EMF from de-energizing coils. I used to design automated museum exhibits with only relays, because pretty much that's what there was. :). .....back then.

RC arc suppression worked fine for most things unless it introduced a timing issue with something .. then next in line was a diode backwards, which also had it's share of issues, although worked fine for most things.

The GOOD thing about relay systems is that, if properly designed and minimally maintained, they worked seemingly forever. You couldn't fry one if you tried, and I did occasionally try, when attempting something a bit outside normal design rules lol.

Just look at the old telephone exchanges and elevator control systems. Nuttin but relays, honey. :)

Oh well... good luck with your restoration. Always nice to see an old deck come back to life. I wish I'd kept the Ampex PR10 decks we pitched at the studio. :(.

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 Post subject: Re: Akai X360 D motor capacitor questions.
PostPosted: Mar Sat 30, 2019 7:28 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11403
Location: Powell River BC Canada
The back EMF diodes interfere with the release time of a relay. Timing
with the telephone relays in a Strowger switch are slugged tops on coils.

That is how the switch knows that the pulses from the dial have stopped
for each digit, commanding the vertical stepping to start , as rotary magnet,
searches for the next idle selector.

The whole damn system depends on the governor in the dial.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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