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bob4333
17-06-2017, 08:18
After a bit of a search and a few dead ends I finally have an AKAI GX-635D. It’s sonic performance is beyond my expectation, no hiss, wide dynamic range and what goes onto the tape comes out through the speakers. Wasn’t expecting it to be this good.

But – it does have a couple of issues that I need to fix / have fixed and would welcome some help and guidance.

1. LH VU meter is intermittently sticky. It’s behaviour is similar to a peak hold meter – except it doesn’t return for sometimes a minute or two. Working below the 0dB level it seems fine but sometimes sticks in the red when things get a bit boisterous. Sometimes stays stuck when the power is switched off.

2. The capstan motor is noisy. Not audible over the music but when the music stops you can hear it. Sounds like humming and changes tone when the pinch wheel engages. Behaviour is common whether playing forward or reverse.

3. The tape counter is fine when playing but sometimes goes into a banshee like howl when approaching speed in FF / REW. Sounds like maybe plastic dry running on a shaft?

The previous owner said it had been “serviced” (whatever that may amount to) 3 months ago. The inside is clean and free from any dust accumulation and from what I’ve seen the linkages look clean and not caked in old lubricant, so some work has been done. The owner also said it had been standing for a while.

Any ideas?

Firebottle
17-06-2017, 09:40
Doesn't sound like anything serious with any of the issues.

I used to have an Akai in my youth, nice machines. Bring it round here and I'll fettle it at no charge.

:)

bob4333
18-06-2017, 13:12
That's an extremely generous offer Alan, even if you can only give me a view.

PM sent.

337alant
18-06-2017, 18:14
Thats very generous Alan ;) isn't AOS a nice place :D

Think Audio Al had one of these decks with similar problems see this thread on tape heads
http://www.tapeheads.net/showthread.php?t=40907

Alan

bob4333
19-06-2017, 07:49
I read Audio Al's "AKAI GX-635D refurbishment" post on Tapeheads a couple of weeks ago but after the first excellent page drawing me in it seemed to come to an abrupt halt.

If the rest is out there I'd love to read it - especially as it has added significance for me now. I also read the other GX-635 posts on the site but they were covering specifics that may (or not?) be a bit further down line for this deck. It has to be getting on for 40 years old, is of unknown provenance but is generally in working order - with a few issues that need resolving to bring it back to it's former peak.

Anyway, here's a gratuitous pic (minus side panels): I hope you'd agree it's worth saving. (Despite the labels the tape on the reels isn't Ampex 406).

http://i1230.photobucket.com/albums/ee481/bob4333/AKAI%20GX%20635/R0010639-Optimized.jpg (http://s1230.photobucket.com/user/bob4333/media/AKAI%20GX%20635/R0010639-Optimized.jpg.html)

And yes, you do meet the nicest people on AOS. :)

Bob

(Off to see Mr Firebottle this afternoon)

337alant
19-06-2017, 08:42
That looks a beautiful machine Bob
Nick Adams did some very good service video's on the GX 656D over on Youtube which is simlar

https://www.youtube.com/watch?v=Bx1e-gFqmx0
https://www.youtube.com/watch?v=swTw25JmGhI

Alan

Cas
19-06-2017, 09:05
That is one lovely looking piece of kit, but I am not jealous, well not much anyway :)

bob4333
19-06-2017, 16:55
Just wanted to say a huge thank you to Alan (Firebottle) for the time he made available to me this afternoon.

Fixed a few things.............
Learned a lot.....................
Drank a little coffee............
Listened to some music......

And I've moved a little closer to getting this tapedeck where it needs to be. There aren't too many ways to better enjoy an afternoon.

My thanks.:)

Cas
19-06-2017, 18:30
Just wanted to say a huge thank you to Alan (Firebottle) for the time he made available to me this afternoon.

Fixed a few things.............
Learned a lot.....................
Drank a little coffee............
Listened to some music......

And I've moved a little closer to getting this tapedeck where it needs to be. There aren't too many ways to better enjoy an afternoon.

My thanks.:)

Great stuff, can I ask what was fixed ?

bob4333
20-06-2017, 08:16
Sure.

The VU meter came apart, was given a mechanical work through by Alan and reassembled. During the process I'm also pretty sure I saw a small piece of debris dislodged from inside the casing, so maybe it was causing a restriction in not allowing the meter to return. Makes sense. Seems fine now. And I'm also now aware of how to get at the festoon lamps if they fail.

Good news and bad news on the noisy capstan motor. Turns out it's not the motor :) but a noisy transformer :( that's causing the irritation. Luckily it's not audible over the music but something I'd like to find a fix for. Anyone have a 240v GX 635D transformer they'd like to part with? No, didn't think so. I'll keep looking and thinking on this one.

I think I may have fixed the tape counter noise the day before I went to see Alan. It definitely sounded like a plastic "gear on gear" clattering racket. Being careful not to overdo it I'd applied a very small amount of Vaseline on the end of a cocktail stick to the parts of the gearing that would be likely to run at high speed on FF and REW (really the gears that spin on the seconds counters). Had this not have been successful Alan had a spray can of a more specialist lubricant that he would have applied. Have to see how it goes but so far, so good.

I have to keep reminding myself that this is nearly 40 years old and represents thinking and manufacturing from a different age. It's also been goodness knows where in it's life but doesn't look as though it's suffered at the hands of bodgers. It's not perfect and there are probably a few other things to sort out (I don't fully trust the logic controls when anything high speed is involved, so I go from REW to STOP to PLAY rather than as AKAI say "DIRECT FUNCTION CHANGE CONTROL............ The necessity of depressing the Stop Button prior to changing modes is eliminated". That's a refinement for another day as it doesn't stop the deck being used - I just need to be mindful when in use.

So yes, making progress on something I find interesting.

Cas
21-06-2017, 11:23
So everything is going in the right direction, good to hear.

If you have tried it out yet, how does it record and sound ?

bob4333
21-06-2017, 13:48
So everything is going the right direction, good to hear.

If you have tried it out yet, how does it record and sound ?

It's been quite well tried out and getting more so each day. :)

Remember this is my first foray into R2R and I'm still picking things up, but just to get the hang of things I've recorded from a Streamed Input which goes

NAS via Cat5e cable to a
Cyrus Stream X2 into a
Leema Elements DAC into an
Audio Research LS27 pre-amp into the
AKAI GX-635.

It then came off the tape, back out through the LS27 into a Musical Fidelity A5cr power amp to the ProAc speakers.

I was totally surprised. With the LS27 set to monitor and utilising the 3rd head and switching between Source and Tape whilst recording I could not tell the difference. No dulling of the notes, plenty of tightly controlled bass and no tape hiss. Same whichever direction I'm recording / playing. I don't remember cassette being like this

The streaming set up gives a pretty good account of itself so for the tape deck to provide this sort of result straight off is no mean achievement. I'd also throw some credit towards the new RTM LPR90 tape that arrived from Thomann. A little overload into the red doesn't phase the recording - it just sucks it up and carries on.

So yes, sounding pretty good and the "sticky" VU meter performs faultlessly. I mentioned to Alan that at times I can detect a slight instability on some piano notes so have ordered a new pinch wheel. The existing has a tape width wear line embossed into it so could probably benefit from being renewed. Not cheap but at least you can still get them!

Haven't yet tried recording from CD or Vinyl. Should be another interesting comparison................

bob4333
21-06-2017, 13:51
That looks a beautiful machine Bob
Nick Adams did some very good service video's on the GX 656D over on Youtube which is simlar

https://www.youtube.com/watch?v=Bx1e-gFqmx0
https://www.youtube.com/watch?v=swTw25JmGhI

Alan

Thanks Alan, I'd seen the first one and watched it a couple of times. I've now bookmarked the second as well. It's all a bit more meaningful when it's "needs driven".

337alant
21-06-2017, 15:09
Bob I prefer to record direct from the DAC output as the pre amp does nothing in the chain except adds 4 more RCA connections, some tape loops actually colour or attenuate the sound


NAS via Cat5e cable to a
Cyrus Stream X2 into a
Leema Elements DAC into an
Audio Research LS27 pre-amp into the
AKAI GX-635.

Alan

bob4333
22-06-2017, 06:19
You're right. Obvious when I stop and think about it.:doh:

I'll give it a go.