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Scored an Akai 635D

cableguy2

cableguy2

Well-Known Member
I recently picked up an Akai 635D from a guy I met in a Radio Shack looking for audio cables. We got talking, and I asked the right questions.

I plucked up the Akai 635 complete with the plastic cover, in VG condition, along with the NABS and 4 tapes, and blank reel. The first thing I did was to take the back off and blow it out. After that, it looks pretty decent inside.

It was stiff at first, and the captain rubber wouldn't make it up, but after a little coaxing, I managed to get it to play and record. It also sounded pretty quiet, so maybe it doesn't suffer from transistor meltdown. Let me know if you think otherwise.

Wondering if anybody knows if there are any lubrication points on it. There are a few I noticed on slide areas, like what moves the capstan shaft uo. I took the face plates off, I am going to spray the contacts, but didn't notice any oilers on the motors, I think I saw a small hole on the capstan shaft.

While I have it apart, I figured I would ask so I don't miss something and have to tear it down again.
 
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i havent seen a single 635, that didn't need transistor replacement :) It's a rather simple job, and do replace certain caps , while you're at it - then it'll run for years
 

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jan_stevns said:
i havent seen a single 635, that didn't need transistor replacement :) It's a rather simple job, and do replace certain caps , while you're at it - then it'll run for years
Click to expand...


Do you know what the transistors replacements are? There was a web page by Frank Oomen that had that info, I can't find it now.

It was much easier when I had better eyes, LOL.
 
Love my 635D. although I have not replace the resistors yet (very low hour unit) it is on my short list. Replacing caps looks like more than a 6 pack job. There must be over a hundred of em?
 
I also have a 635D that sounds good to me but maybe it would sound better with new transistors. Thanks for the info, the update is on my to do list as well.
 
Im on the 635D team too - transport seems flawless, perfect condition - but have issues with audio - Im holding off on doing any work on it until I've cut my teeth on the other 4 AKAI decks I have!!
 
stoutblock said:
Love my 635D. although I have not replace the resistors yet (very low hour unit) it is on my short list. Replacing caps looks like more than a 6 pack job. There must be over a hundred of em?
Click to expand...

actually no :)

Those you may benefit from replacing are the ones carrying audio, they are boxed in - in the previous attachment
 
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Part of the team as well with 2 635D's. One from an AK member here and another from the bay. Both currently sound great so I am not inclined to mess with them. Love mine as is but know they may need some attention in the future. Have a real thing for Akai gear. Have the following:

Reel - 2-GX 77's, 2-GX 635D's
Cassette - 1-GXC 570D, 1-GXC 750D, 1-GXC 760D, 1-GXC 706
TTable -1 AP-L45 Linmear Tracker
 
jan_stevns said:
actually no :)

Those you may benefit from replacing are the ones carrying audio, they are boxed in - in the previous attachment
Click to expand...

Good to know. All of them look healthy but...

What caps do you recommend to use?
 
i have no preferences regarding which brand of cap to use - Vishay or Panasonic are normally those i order from Farnell here.
 
if those transistors are used in that model - i'd say yes, and accordingly to the parts list, they are inside a 747 as well ...........

(never had a 747 on the bench though, only lot's of 620, 625 and 635 - all suffered the dissease)
 
I just recently scored one of these units too. Everything seems to work except for the record function on one of the channels. The input level needs to be turned way up to get the left side to record, and when it does it sounds very distorted. I'm guessing that one of the transistor stages is no longer biased correctly due to a faulty cap or drifted resistor. Sounds about right after reading some of the comments in this thread. Can't wait to get inside it and see if I can get it working properly again.

Steve
 
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The solution to your problem is probably allready written in this thread :)
not a capacitor problem, nor a "drifted" resistor - but the usual AKAI problem.

( just finished two more AKAI's today ...... defective transistors ... as usual )
 
jan_stevns said:
The solution to your problem is probably allready written in this thread :)
not a capacitor problem, nor a "drifted" resistor - but the usual AKAI problem.

( just finished two more AKAI's today ...... defective transistors ... as usual )
Click to expand...

Jan,

Seems strange that so many of these transistors are faulty. I've repaired lots of vintage guitar effects pedals and it's usually rare to see a bad transistor. I'm normally replacing small electrolytics or bad switching FETs. IIRC I've only replaced one faulty transistor out of the dozens I've fixed so far.

Any ideas why the transistors in these units seem to be failing so much?


Steve
 
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