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Cleaning up the Akai GX-630D-SS QR2R - Oh My!

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JonUrban

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So I brought it back downstairs and let it sit overnight (mostly to let myself sit overnight) :)

Went back to it this morning and put the original 10" reel back on the thing that I was using down there and it played fine. Again. However, this reel was recorded at 3 3/4ips. I tested it with both wheels and both wheels played it fine.

I also listen to the rears only with headphones and heard no tik-tik-tik-tik in the rear right channel.

I then took the hubs off and put on a pre-recorded smaller reel recorded at 7 1/2 ips. Boom. Slow, speed got slower. So there's an issue there.

So now it's back to the schematics to look at the speed selection circuitry and the audio out.

Hey, if you're going to have a covid project, why should it be easy? :rolleyes:
 

aludra

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Hey Jon,

Does the inside circuit boards have any molex type card connectors on the edge of them? If so its possible they need cleaning and not making good contact....
 

JonUrban

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Hey Jon,

Does the inside circuit boards have any molex type card connectors on the edge of them? If so its possible they need cleaning and not making good contact....
I've been looking at the schematics and it looks like the audio outs do have some disconnects, so that could be something to look at for the tik-tik-tik, but the speed thing is a little weird. In the schematics, the only difference I see between the two speeds is a resistor and two pots. One speed bypasses a resistor, and the other difference is the switch controls which potentiometer is in the circuit, one for each speed.

Speed Schematic.jpg
 

Circular Vibes

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I know my deck has a speed issue that is related to poor contacts in the speed switch. If I rattle it back and forth it comes back. That switch and maybe the reel size switch may need serious cleaning.
 

aludra

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Have you sprayed the speed selector switch itself? I would also spray the pitch control ..... you say it plays fine with the 10.5 reels....does this include both speeds?
 

aludra

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Not to give you too much too check Jon.......The schematic says the circuit has been changed for certain serial numbers....does your machine fall within that range?
 

par4ken

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So I brought it back downstairs and let it sit overnight (mostly to let myself sit overnight) :)

Went back to it this morning and put the original 10" reel back on the thing that I was using down there and it played fine. Again. However, this reel was recorded at 3 3/4ips. I tested it with both wheels and both wheels played it fine.

I also listen to the rears only with headphones and heard no tik-tik-tik-tik in the rear right channel.

I then took the hubs off and put on a pre-recorded smaller reel recorded at 7 1/2 ips. Boom. Slow, speed got slower. So there's an issue there.

So now it's back to the schematics to look at the speed selection circuitry and the audio out.

Hey, if you're going to have a covid project, why should it be easy? :rolleyes:
That smaller reel wouldn't be warped or anything Jon? You might have to transfer the tape to another reel and try it again.
 

JonUrban

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Hey everyone. Thanks for the tips. I hate to bother you all.

Mike, I have the schematics for all of the revisions and they're pretty much all the same. I just posted one to give an idea of what the circuit looked like.

I haven't tested a 10" reel at 7 1/2 ips yet, but will. As for the smaller reels, I've tried two and they both play really slow at 7 1/2. I do have the other machine so there are opportunities to try different things.

I wonder if my caps have crapped out? Crappy Caps.........
 

DuncanS

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Hey everyone. Thanks for the tips. I hate to bother you all.

Mike, I have the schematics for all of the revisions and they're pretty much all the same. I just posted one to give an idea of what the circuit looked like.

I haven't tested a 10" reel at 7 1/2 ips yet, but will. As for the smaller reels, I've tried two and they both play really slow at 7 1/2. I do have the other machine so there are opportunities to try different things.

I wonder if my caps have crapped out? Crappy Caps.........
Motors aren't really my thing, too mechanical! It says Servo P.C. Board, so I think it operates using pulses. If there are to few, or too many pulses, the motor won't rotate at the right speed. I'm also wondering if at connection (1) by TR1 is a feedback point (so it gets an input from a sensor on the motor) to regulate the speed as D1 is a half wave rectifier, so will give a pulse output which is fed into the low pass filter to give a feedback voltage proportional to speed to correct and maintain the motor at 3.75 or 7.5 ips. At a guess, poor contacts on the connections like for pitch control etc. could also have an effect.
 

JonUrban

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So, long story short, after letting the thing sit for a month or three, I got back into it and low and behold, it was MY MISTAKE. Moron at the helm. Apparently I didn't verify my choice of capacitors when installing the replacements and instead of using 1 1.5 uf and 1 3.5 uf, I used 2 1.5 uf. I was so concerned about making the solder connections neat and that the shrink tubing would look good, I failed to verify which capacitors I picked up to install, as you see, I usually order more than I need "just in case". It's an old habit I have and this time it bit me in the butt.

So, after most of the fall and into the winter, my dining room table has been "occupied"! Fortunately, since we're all sorta locked down, no one was coming over anyway, so the room was mine.

Maybe by the end of the week my wife will finally get the dining room back! Oh well.

Merry Christmas to all, and to all a good night (and exceptional 2021). You all, and me, we deserve that! :)
 

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aminbhatia

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Jon,
I've been following your thread with awe and envy. My Akai 630 D SS is long since in storage and there were some custom mods to it but I'm not going to have the time to really get it back into perfect order. Do you want more parts?
I would feel better knowing it's helping a true Akai lover, than trying to sell it for parts. Let me know.
Amin Bhatia
 

JonUrban

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Jon,
I've been following your thread with awe and envy. My Akai 630 D SS is long since in storage and there were some custom mods to it but I'm not going to have the time to really get it back into perfect order. Do you want more parts?
I would feel better knowing it's helping a true Akai lover, than trying to sell it for parts. Let me know.
Amin Bhatia
Wow. Thanks so much for offering, that's very gracious of you. Actually, I already have a "spare parts unit" that is doing just that, so I'm good. No need to give it up or deal with the shipping.

But again, my thanks, and a very Merry Christmas to you and all!
 

JonUrban

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OK, another questions for you experts out there. Here's the deal:

The machine plays flawlessly on my dining room table. Nice, quiet when there's nothing on the tape (leader, between tracks) but when I bring it upstairs and set it and plug it in near my PC, it seems to be picking up noise as during those silent times on the tape I can hear what sounds like surface noise and maybe a tick or two.

So, instead of plugging it into a wall socket, I plugged it directly into my UPS and it still had the noise in the silent spots, so I am assuming that it's either generated by my PC, monitor, or router, which are all very close to where I keep this machine so that I can record in reels into the PC.

Is there anything that can be done about this? I don't believe it happened before I started the rebuild, but I have since upgraded my router. No, I have yet to try shutting all of those things off and seeing if the noise goes away, that's on my list for today. I am also wondering if the old "lamp cord" power cable that is the original cable from 45 years ago should be replaced with a newer power cord. This one is a two pronger. Suggestions on that?

At least it is now working fine downstairs. Maybe I should just get some 50 Ft RCA cords and play the thing far away from the PC. That would work for sure.

Hope you all had a good Christmas Day. Thinking about Tim and Mike down there in Nashville (and the rest of the folks down there. Horrible situation)
 
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DuncanS

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One possibility is that it could be picking up switched mode power supply noise from the monitor/PC/UPS etc. Try rotating the deck through 90 degrees to see if the noise/ticks vanishes or diminishes, if it does its 'airborne' interference not conductive.
 

aludra

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Thanks Jon for your kind thoughts.....What Duncan suggested above is very good advice.....Also you were wondering about the power cord.....That maybe a good thing to do anyway and swap it out for a 3 prong plug and attach the ground to the frame of the machine or a ground screw if it has one.

I'm sure your were joking about the 50' RCA cords.....If u actually did that it would wipe out the high end and pick up more noise than you have now. 4' or less is best for high impedance cabling...Good luck and let us know how it comes out. :)
 
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JonUrban

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Yeah, I was being facetious. Besides, those 50' cords, if they existed, would probably cost a fortune, and I sure as heck don't want to make my own, even though somewhere in my house is a compression tool for making coax and audio cables with the proper ends (I used it mostly when I was heavy into satellite TV.)

I'll try the suggestions and the turn-offs and report back. Thanks
 

atrocity

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The machine plays flawlessly on my dining room table. Nice, quiet when there's nothing on the tape (leader, between tracks) but when I bring it upstairs and set it and plug it in near my PC, it seems to be picking up noise as during those silent times on the tape I can hear what sounds like surface noise and maybe a tick or two.
I have a Pioneer RT-707 (who doesn't?) that picks up a low-power AM station downstairs but works fine upstairs. The joys of analog!
 

JonUrban

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Oddly enough, after many tests and trial of location and vicinity, it turned out to be that the noise source was my HK 8+ 8 Track Player that sits right next to my PC. Although I have not converted an 8-Track in years, the machine still sits there loyally waiting for the next cartridge to play into the PC.

It was funny. I shut everything off. Modem, speakers, router, PC, Monitor, yet the noise was still there unless I moved away from my desk. I then remembered that an 8-Track player, without an on/off switch, essentially stays powered up but does not become active until the tape is inserted into the slot. All the while it is sitting there, 110vac is inside the unit, live, pulsing through the transformer and a few other power supply parts.

Once I realized that, unplugged the unit from the wall, the noise went away. Figures, legacy vs legacy, vintage vs. vintage. I should have figured that out sooner, but oh well.

So, bottom line is I am recording in a reel as I type and will check the results. I did some tests with the AKAI Demo Q4 and the results through the MOTU are pretty nice, at least with that tape.

My main objective is to get rid of all of my reels and Q8's next year. Probably will have to risk eBay, but those are the breaks.

Anyway, this Lock-Down Saga is pretty much complete now. Thanks to everyone for the assist, encouragement, and pointers. What a great bunch you all are!

Have a great New Year everyone.
 
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