AKAI GX-636D Service and Repair Part1

AKAI GX-636D Service and Repair Pat1
Complete service and repair if a 1980 Akai.
Part 2 has the full calibration and alignment.

[@jeremytravis360]

A nice job Nick. Akai were very well built for the day. Simply built and easy to access. Not a nightmare of complexity like some other brands.

[@packratswhatif.3990]

Great info Nick, I am taking notes! Trick of the trades .... things you can’t learn from a book. Thanks again ....

[@337alant6]

Nick I like your excellent and informative videos on Reel 2 reel, was really helpful on my Technic's RS1500, keep them coming Alan

[@InflatablePlane]

Just inherited a GX-635D. Hopefully won't have too many issues with it but thanks for this tutorial on basic cleaning and maintenance.

[@navydiving]

I am betting the reason that the spools were out of whack is because at some point the deck fell forward on its face. That would seem to correlate with all the visible damage on the external bits of the unit. Good video - thanks for posting

[@flufycat2748]

So good job!

[@pasdrum666]

Hello NICK. The black akai hubs for the big reels, you can put Them on the deck on 2 ways. You Will notice while turning , at one point they are a bit furder tot the front. Cheers from Pascal. The Netherlands.

[@Raul-yg5oz]

If your wondering the song that Lois is playing in the piano is called - Alley Cat - by “ Muzak “ or “ Al Hirt “

[@felixmotanul5242]

Hi Nick, I hope you are well in these difficult times. Please teach me. Is it absolutely necessary to change the transistors (Akai gx 650d) or replace only the capacitors? I have the complete kit ,transistors + capacitors . Thanks a lot. Greetings from Romania

[@storm-sf5rj]

Excellent video Nick i am just in the process of buying a GX-747 i have wanted one since they came out in about 1981/82 but i had a 1978 Ferrograph Logic 7 and my wife would not let me get one but now i am Divorced i can finally fulfill my Dream lol

[@nickadams5411]

Excellent trade in. You going for the standard colour or Black.

[@storm-sf5rj]

@@nickadams5411 Standard Silver but the one i bought has a Black Head cover never seen one like that before so not sure if the Head assembly has been changed but it sounds fine

[@nickadams5411]

@@storm-sf5rj If it sounds great then you have scored.

[@eddisc4205]

@@storm-sf5rj ...until the crystalline structure of the heads start to fracture internally; and the tension belts are no fun either. Impressive 'looking'

[@carldahlin4624]

Hi Nick! Where can I find that nice service manual that you show in the video? Many thanks!

[@nickadams5411]

Hi Carl The manual is available (free) from: www.hifiengine.com/manual_library/akai/gx-636.shtml You will need to register (also free) and then you can download. All the best. Nick

[@TheTruth-dm8wd]

I just ran into the same issue with the spools not aligned either so when I put a 7 inch reel it started rubbing a lot. I'll be using your suggestion to try to fix it. Thanks!

[@nickadams5411]

Hi, yes, rubbing spools seems a problem on all makes of decks, but is normally fixed with a thin spacer if there is no adjustment. All the best. Nick

[@KevsoldLandy]

Thank you for a very useful cleaning and maintenance guide to the GX 636D. I don't have quite such a sophisticated deck (mine is an older Akai 4000DS) but the guide is still useful in what to look out for. May I enquire? Do you have a link for the useful little Metro Strobe 'strobe' wheel? I have tried Google and eBay to no avail :( Is there an alternative?

[@phonatic]

The best way to measure the tape speed is a speed calibration tape. It comes with a test signal that was recorded on a precisely adjusted machine. Using the Metro Strobe just out of your hand can only give a vague idea of a correct speed as you have to alter the tape path just to use it. A calibration tape will give you the output directly through the machine. You can either then measure it with a scope or simply use a frequency generator app on your phone or computer to compare by ear. You'll be surprised how easy it is to notice the slightest dissonance. You can either look for old calibration tapes or buy a new like those from eBay seller pievox (non-affiliated).

[@nickadams5411]

Hi Ok, but the strobe is very stable. And record decks use them succesfully.

[@1959Berre]

The things you are referring to at 03:00 are not relays, they are solenoids (magnetic actuators) that move things back & forward.

[@eddisc4205]

"interesting" he doesn't know a relay from a solenoid...

[@user-ld9en2td8q]

Cool

[@pnadk]

22:15 You can select one track to play in both channels on the switches under the VU meters on the 625 model, does this not have the same switch?

[@miss.wright3035]

Isn't there terminal with a reference frequency to confirm capstan speed ? Revox uses 800Hz with a trimpot right on the capstan spd ctl pcb.

[@adriangaspar8209]

Hi Nick! Really helpful! Using similar tone generator and scope PC software, I carried out a play-head alignment for my AKAI 630D. I bought the machine second-hand this summer, it was probably serviced at some point but I have no evidence of that. I am overall satisfied with the result, but the one thing that I couldnt fix is the crosstalk!. At 7 1/2 ips I get reverse beat from the other side, in the R channel, audible only when volume drops down between the tunes. This was the reason for calibration, I thought it was misalignment (the erase and record are factory painted, so I used own recording of tone to align the play-head). Even that the frequency and phase are correct now, I could not get rid of this effect. I could not be normal, it is so unbalanced - L channel crosstalk is almost unperceptible. Could tou please give me a hint? Could be a leakage in the head itself? Or inside electronic circuitry? The only thing that I touched was the height and azymuth screws, nothing electronic.Kindly look forward for your reply!

[@nickadams5411]

Hi Adrian. A difficult one. You have already used a totally erased tape and just recorded on one track at a time , and there is no breakthrough of those single tracks when tape is played both ways, or tape turned over. It is possible to see with the eye if the heads are perfectly square to each other, and a piece of clear leader tape also can show perfect alignment, just with the eye. It is possible to get crosstalk in the electronics. You will need to swap the left to right connections from the heads to see if it moves with the wires or stays on the same channel. All the best. Nick

[@adriangaspar8209]

@@nickadams5411 It happens to all tapes, recorded on both sides, even on those recorded by another machine too. Therefore I suspected that there is nothing wrong with recording / erase process, but with playback head. Swapping wires looks as a good idea! Before opening, is there somewhere a link to sow how they are phisically wired? Looks kinda confined area.. but I guess is somewhere near to what you need to do to replace head. Thanks for kind reply!

[@adriangaspar8209]

@@nickadams5411 A quick one: could be an effect of tape not ”travelling” correctly under the playback head? If I look from the top, the right spool should come out 1-2 mm to be levelled with the left one, because now the tape is not winding equally spaced between the flanges.

[@nickadams5411]

@@adriangaspar8209 H Adrian. It is important that the tape runs from and to the spools in a nice straight operation. You can adjust the spool heights, and can use shims if necessary. I did show this in one of my videos. The tape must be a nice close fit to the heads without any crinkling of the edges, due to uneven pull.

[@nickadams5411]

@@adriangaspar8209 Not the easiest task, and will probably require some fiddly soldering . You will need the service manual, and take photos before removing any wires. You have the service manual? Free from www.hifiengine.com/manual_library/akai/gx-636.shtml

[@Itsdelaraw]

Could I send you my Akai GX-747 to see if it is working properly?

[@mirish357]

I have been looking for the AKAI GX635 control knob and the 10 inch reel black hubs if possible. I would appreciate any help in finding them. Thanks in advance for the responses about Ebay.

[@nickadams5411]

Hi Mark. They do come up on Ebay etc now and again. It is just a waiting game.

[@mirish357]

@@nickadams5411 Thanks Nick!

[@hennessy4666]

got my 630 db yesterday , clean it up and put a maxell on it.........today i decided to sell all my decks and cd/dvd players..........wtf , i am completely amazed , why people did that HUGE MISTAKE letting reels go?

[@lolita19711]

how many motors?

[@lox_5017]

What country is this video originally from?

[@julioc.vargas2634]

Hi Nick! Great video! I have an Akai GX635D that will not output from the left channel. If I connect a source via rca line in or via 1/4” mic input, the audio is extremely distorted and unusable. What could be wrong with this machine? Please help.

[@nickadams5411]

Hi Julio. is there no output from the tape playing, or when there is no tape but monitor?

[@julioc.vargas2634]

Nick, thank you for the response! There is no output from the left channel when the tape is playing. There is a scratchy and extremely distorted signal from both channels when I am monitoring (both mic inputs and both line inputs) with no tape.

[@nickadams5411]

@@julioc.vargas2634 Hi. The fault is in the electronic board. It could be bad contacts. Clean the input /output sockets with switch cleaner, and plug in/out several times. There may be bad contacts on the cables on the board, which means unplug and clean. It could be a component failure (transistor etc), but that is rare, especially as both left/right have similar faults. Try that first. Nick

[@julioc.vargas2634]

Nick, thanks! I’ll buy some cleaner and give it a go. Could this also be the cause of the dead left channel during playback? I’ve cleaned the heads with no luck.

[@nickadams5411]

@@julioc.vargas2634 Hi Julio. The right channel works playing back from a tape, but nothing from the left channel. Clean the potentiometers, and all switches by spraying the contact cleaner into the back of them and rotating./operating. If still no good, it will take some fault finding on the electronic board, which requires some knowledge using a multimeter. Let me know. Nick

[@chanderbhatia541]

Nice video. I have this 635D model that was sitting for about 10 years in my home, It was working fine the last time I used. Today I turned on and the tape got stuck on the capstone spindle and I turned the power off and removed the tape. Now It will power on but none of the switches respond. The sound meter comes on and the right reel switch showing green light. The capstone motor is working fine. When I manually disengage the right brake the right motor turns, but the same does not work for the left motor. Kindly guide me towards the possible problem. I am mechanical person and no electrical knowledge. Thanks in advance

[@nickadams5411]

Hi Chander. Could be a mechanical problem, such as the brake solenoid sticking on. The only way is to expose the operating parts and try and move them by hand and see if any are jammed

[@chanderbhatia541]

@@nickadams5411 Hello Nick. I reset the solenoid and now works mechanically, but no sound output or input . I cleaned up all heads with alkohol. All the switches work but no sound. Sound meters stay at zero. Kindly guide me towards the possible faulty components. I can de-solder and solder parts if I know what to do. Thanks in advance.

[@nickadams5411]

@@chanderbhatia541 Hi. There is no sound when you Record or Play. When you record, there is no sound on the "monitor" and no VU operation. Do the VU meters move when you switch the player on? Are the lights on? Depending on what does not work, the circuit diagram is the only way to trace back to where the sound exists, and where it stops. Best I can say from this distance. Nick

[@chanderbhatia541]

@@nickadams5411 The VU meters have lights on and stay at zero. The VU meter needle do not move. i am sure there is music on the reels. I am a mechanical person who does not understand the electrical circuit diagram. I need a hint to test what possible capacitors or transisters. Thanks for your help.

[@nickadams5411]

@@chanderbhatia541 You must try and record a sound (Line in or Mic) to see if there is any signal reaching the heads, and with "monitor" switch, that the sound can be diverted to line out and VU meters. Without this information, I cannot give any more help.

[@fatarren9075]

I am exchanging The capstan motor on mine, but cant really find out how to get The middle plate of because of that wheel. How do i remove The whhel without breaking it?

[@nickadams5411]

Hi. The service manual is available free at www.hifiengine.com/manual_library/akai/gx-636.shtml

[@tampham-wy7qf]

Hello nick , do you repair akai ?

[@nickadams5411]

Hi Tam. Only in my spare time. What is the Model and what needs doing? Also where are you? I am in the UK.

[@tampham-wy7qf]

Nick Adams Oh too far im in usa Thanks u anyway

[@vfdffdd2675]

Hi. I have 635D. Work normal but have problem with record. One channel is missing /very quite/Suggestion pls

[@animalcorvair]

mine is doing that now hope you fixed it...they had bad 448 transistors i bought mine new in 79,,,,

[@kevinbeckenham3872]

What the machine like on recording

[@nickadams5411]

Hi Kevin. Recording is as good as specification. The tape transport and heads are very stable and high quality.

[@victorsalcedo8127]

Nick Adams, unfortunately the cleaner you used to clean the surface of the player. I have had problems wiping off the lettering due to using the wrong chemicals.

[@nickadams5411]

Hi Victor I agree, that caution when cleaning any equipment. But, most of the lettering was already gone and must have been previously weakened.

[@victorsalcedo8127]

Hi Nick, I just went over my previously sent message. And I noticed I did not asked you what do you use as a surface cleaner. That was my intended question and I sent it incomplete. Thanks and best regards, very informative video. Victor

[@nickadams5411]

Hi Victor I normally use a Baby wipe, such as " Pampers Natural Clean". (Fragrance free). They are good enough for New born babies, but they do remove most surface dirt. For stubborn dirt and grime I have to use other wipes, such as hand cleaners. But as you say, keep away from lettering, and most plastics. But is always best to test it on a small area first. All the best nick

[@victorsalcedo8127]

Nick Adams again, thanks for tge tip. it is so very important to keep our equipment as original as possible and not to erase important logos and lettering.

[@jeanpierremontour8158]

i nick i need he slide switch on preamp bord you have the parts ....

[@nickadams5411]

Hi Jean. Sorry I do not have the part.

[@jeanpierremontour8158]

thank

[@user-wm1cx5ez4h]

Are you interested to repair tascam 52 thx.

[@nickadams5411]

Hi Nice machine What is it's condition? What is wrong with it? Has it been stored for some years.?

[@user-wm1cx5ez4h]

Nick Adams I took my machine tascam 52 to several Serviseman but they could not repair it completely the same problem goes back that the pinch roller does not fit with Capitan and emediatly seperated it needs to cheeked all parts.

[@nickadams5411]

Where are you living?

[@user-wm1cx5ez4h]

Nick Adams I'm living in Iraq where are u located thx?

[@nickadams5411]

I am in the UK So, it is too heavy to post to me?