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Bender Comments Page

These are Reel to Reel Questions, Answers, and comments, things I've posted on several discussion groups, some when people write and ask me questions.


Comment #45

Subject: Akai GX-266D

Date: Fri, 13 Feb 2004 11:23:14 -0500

From: Douglas Barnes

Hi Stephen,

I have owned an Akai GX-266D for a couple of years now. It worked flawlessly until, after leaving it unused and boxed for several months during a move, I finally fired it up and saw that the reel drive motors don't turn at play or record speeds. FF and RW operate normally, as does the pinch-roller motor.

Any idea what's the matter here? I've just been reading on your site about servo failures in Akai decks and it certainly seems plausible that this could be what is ailing my deck. Is there a way to verify that this is the case?

Any advice you can offer is greatly appreciated,

Best regards,

Doug Barnes

New Haven, CT

********** And Bender Sez: **********

Doug -

The servo system ONLY affects the direct drive motor, which is part of the metal capstan which the pinch roller contacts to move the tape at Play speed..

Sounds like all 3 motors work, as the FF, REW, and capstan are at normal speeds if you have checked the operation without tapes on the set ( use some small rubber bands to hold the tension arms in middle position ). Also - - - check that you don't have the "pause" engaged or that it isn't stuck in the pause position, lots of lube in that mechanical control, and if it has hardened, it could possibly get stuck...

You might have to take the front panel off to check that, but you usually can hear the mechanical part disengage and the microswitch clicking in and out so if you know what it should feel like, you'll know if its working or not!

If the reel tables then move properly, during "Play" without reels of tape on them, its likely that they got "pushed inward", very common during a fall on its face or dropping on face during a "move". In which case, the reels hold solid against the front panel, and won't "budge".

In this case the Reel Table Height will have to be mechanically reset as per the service manual proceedure, which requires removing the front panel and top panel and using a long allen wrench to loosen the TWO small set-screws about 1/2 turn to 3/4 turn on each one, and then pull the Reel Table out twards you, say 1/8" or so; to re-align it so that tape is parallel to the front panel to get a Tape Wind that is centered on the reel.

Note that the center of wind points are somewhat different for a Metal Reel than for a Plastic Reel !@@! The Tension Arm and centering of Tape Wind on the reel will guide you in such readjustments of the Reel Table Height, as the tape will bind if either is misadjusted up or downward too much...

If the reel tables still don't move when Play engages, then you might have either a power supply problem, logic problem, or some combination of problems. Actually GX-266D problems are quite rare, it is usually a very reliable machine, the GX-266II usually has the worst record for problems and failures.


Steven L. Bender, Designer of Vintage Audio Equipment

Comment #46

Subject: Repair GX-400D

Date: Mon, 23 February 2004 17:51:00 +0100


Hi Steven

I'm the owner of a Akai GX400 D. Unfortunately the unit is not working anymore. When it's powered up the leds on the wind, rewind and play buttons are lit. No function is reponding. It was serviced by AKAI people in Belgium after the unit was about 3 years old for the same symptons. I remember something about replacing the 'relay unit'. My question: is there a possibilty to buy a kit? I am sure I can do the installation myself with some hints.

Making this unit work again would mean a lot to me and my family

Best regards

Robert Louis, Opglabbeek, Belgium

********** And Bender Sez: **********

Hi Robert,

I do have some information and parts that should be of help. I have no Kit available for this set yet. First, the GX-400D Service Manual might help you greatly in doing your own service. it is a rather lengthy book, with detailed schematics and pictorials of each internal board in the set. This would be very necessary if you plan on doing any work at all inside the set. This GX-400D Service Manual is: $45.usd. plus $12. shipping out to .be.

This may be the same set of symptoms you had 15, 20, or 25 ? years ago, but it is now not necesarily the same cause ( or it could be exactly the same cause ). There are five power relays on the SYSCON Board, which are the most likely parts that you will need. I have gold contact exact replacement power relays for this, and they are drop-in replacements, no sockets, no adapters are needed. They solder right to the PC Boards and are $20.usd.

for each relay, plus International Shipping. OK, I just spent a few minutes with the GX-400D Service Manual, and yes there are five of those power relays on the Syscon board in there. And there are also three more of those identical power relays - one on the Servo board, and two more on the Power Supply Board, making the part problem any number from 1 to 8 relays.

There are also about 24 transistors who possibly could be at fault, in that they sink power to these various power relays, and any of those could be a possible secondary problem, giving the same overall "failure symptoms". De-Soldering and re-soldering, of course, will be necessary to change any of these parts; each of the 8 power relays has 14 pins that will be need to be unsoldered, and 14 pins to be re-soldered properly when the replacement is put in.

The GX-400D Power Supply and Servo Boards are hard-wired in and so it would be a little more difficult there to remove the Relays, parts and service. The Syscon Board with the 5 relays, does "plug-in" so it could be unpluged, and if really necesary, be mailed out to me to replace the power relays and the drive transistors, if the task is way beyond your ability.

My quick guess is that replacing these 5 Power Relays and transistors on the Sycon Board would be about $275.usd. for parts, labor, and testing before the cost of return shipping. But international shipping bothways does have a small, but finite risk of loss, and my doing it would increase the cost of the task, for my labor, but at least I could then test it in my own Akai GX-400D, to verify its operation before returning it or them to you.

The other two boards, could, in the extreme case, be removed by unsoldering and marking all the connecting wires and similarly sent in. You would also need a Digital Voltmeter or DMM. to test several areas inside the set for basic operation certain things need to be properly adjusted. There is also the possibility that a failure in the power supply itself, or the power supply board is causing these symptoms, its nearly impossible to diagnose long distance which type of problem exists in your set.

Well there are the options, I'd be guessing at the prices, if I had to do the work. So while it is best if the boards stay with you to be worked on, if destroyed in the process, there is definately no going back, as replacing these boards would now cost many hundreds of dollars to have them duplicated at this point, as well as stuffed and soldered with parts.


Steven L. Bender

Comment #47

Subject: Deep Bass Cross Talk

DATE: Wed, 7 Apr 2004 09:19:56 -0700 (PDT)

From: Harold

Hello everybody,

I have an Akai gx 630 in perfect condition. I have a tape (own recording) with classical music on one side and heavy disco/house on the other. On the classical side I sometimes hear the disco from the other side very slightly backwards through the music. In a silent passage it is just above hiss level. You only hear the deep bass, nothing else. You can't see the Vu meters move, maybe the right one very slightly when you look very well.

The service manual says that you should allow a cross talk of - 45 db. Is that what this is? My cassette deck, an Akai gx 52 has the same problem, maybe even more slightly, but that is a deck with only one rec/play head, so it can't be an alignment problem with own recordings. As the service manual seems to allow this kind of thing, I wonder: is this just a limitation of the system or is there any way to improve this?

What I also noticed is: If I record a 10 khz test tone at -3 db on side A, then record on the same space on side B, the 10 khz tone at side a drops nearly 1 db after recording on the other side (cross talk of the erase head?) It is not really audible, but apparently there. Thank you very much in advance for answering,

Regards, Harald, Amsterdam

********** And Bender Sez: **********

Well Harold -

Crosstalk is indeed the problem here. And the Crosstalk problem is always worse in the lower frquencies, where the magnetized particles can "spread out" thus magnetizing adjacent magnetic particles - actually widening the track ever so much as the tape passes over the gap during recording of loud bass lines. Later heads were designed with thinner gaps resulting in improvements, but this was still mostly at the higher frequencies.

Thus, there is not too much one can do to prevent gap energy from this spreading effect. Also, extremely small alignment effects, even those within the gaps on the heads themselves can effect larger or smaller crosstalk effects, as compared to another identical machine.

Unlike VHS video, where at the faster speeds there is a concise border between adjacent helical scans of a recording, within the 1/4 track audio system, since the tape is supposedly uniform over its surface, adjacent particles do tend to effect those on both sides of them. Crank up the levels in the lower frequencies, and that is what you get.

Crosstalk will tend to be worse in the low frequencies, possibly 15, 20 or 25 dB louder than the residual tape hiss, and thus can be noticeable from the "other" side. Usually crosstalk this bad is found most often on 1/4 track pre-recorded tapes, with head wear problems and alignment problems on high speed tape duplicators that sometimes were used 24/7... way back when... all that exacerbated an already noticeable problem.

The only way to get rid of it would be to have been making recordings on a 2 Track machine like the Akai GX-400D-PRO or PRO-1000; or as suggested, only using tracks 1 and 3 within the 1/4 track system - making a forward recording only. Even erasing the entire reverse tracks 2 and 4 may not cancel it out, as the magnetic energy may have exceeded the nominal physical limits of the reverse tracks when it was recorded, and will remain, even if the disco tracks are repeatedly erased.

There really is not much you can do at this point...

As for recording on side B causing a reduction in level of a high frequency tone already recorded on side A... Ah yes, well I'm not surprised. If its "only" 1 dB, that isn't bad; yes, usually the Erase Head traces a slightly wider track than the nominal width of the track laid down by the Record Head, and a slight head height discepancy from perfect is to be expected... so a 1 dB effect isn't all that bad.

While I've never tried that test on any machine, I'm sure I would find similar things happening.


Steven L. Bender, Designer of Vintage Audio Equipment

Comment #48

Subject: Question about an Akai GX-77 - Sound plays backwards in reverse mode

Date: Wed, 07 Apr 2004 00:57:40 -0400

Kevin wrote:


I have an Akai GX-77 that I recently purchased and am in the process of refurbishing. I have one odd problem, maybe you have the parts/expertise to help me understand. Basically when I play the unit in reverse mode, it plays the same side, backwards. It seems that the econd set of heads are not getting power. I don't know whether ether is a mechanical part that shift the power supply to the second st of heads that is failed or of the heads on that reverse mode are just dead ( doubt it ).

Also if that were the case, why would the other heads still continue to output sound in reverse mode? Any help would be greatly appreciated.



********** And Bender Sez: **********

Hi Kevin -

Seems like the circuitry that changes from one set of heads to the other set is not doing the job.

As heads don't get power, it is the associated circuits that do; so either those circuits aren't powered, which means there is either some power supply problem; or some switch, relay, or activating circuit that is no longer functional, or it isn't getting powered. I don't recall the details of the GX-77 circuits, its been several years since I looked at its circuitry or schematics.

In any case, the forward heads continue to work, but since the tape now is traveling in the other direction, the sound is backwards.

I can supply the reprint of the original GX-77 Akai Service Manual with schematics for $44.00 shipped, for check / MO. or hidden cash ( $45.50 for Paypal sent to: ) if you need that. As for parts, I don't have many parts for the GX-77, other than perhaps some relays, transistors, and capacitors.


Steven L. Bender, Designer of Vintage Audio Equipment

Comment #49

Subject: RT-909 Repair

Date: Tue, 23 Mar 2004 16:45:05 -0800 (PST)

Ray Phillips wrote:

I need to find someone in the North Alabama area that can repair my RT-909. It plays very slow for a few seconds and then stops completely. Either direction. Please advise.


********** And Bender Sez: **********

Hi Ray -

If you haven't found anyone willing to take the RT-909 set on, it is because the parts needed to repair this are propraitary, and are no longer made, due to high failure rates of the original parts.

I have been able to fix most problems involving motor intermittant stoppage and failures in this set. Since the parts to repair this known failure mode have long been unavailable from either the OEM or from Pioneer, I've had special parts made up to replace the original ones. This was expensive, so frankly, the repair is expensive.

Typical cost of inspection, repair, and return shipping is: $300.

Unit must be packed in either a cuccoon of 3 more more layers of bubble wrap or heavy foam. If bubblewrap, type with 1" diameter bubbles to prevent shipping damage ( more layers of bubblewrap if smaller bubble size product is used!! 1/4" diameter bubbles = 10 layers! ). Assume it will fall off a 12 foot high conveyer belt onto a concrete floor at an obtuse angle. Pack accordingly!

My Initial Inspection of the set to determine the actual faults costs: $75. Typical repair as per your descriprion costs: $200. Return shipping sent Federal Express Ground is typically: $25. - $35.

I use a 3 check method, and have found this to be useful and problem free. The total estimated and contingent cost should be sent in 3 checks with the set... Check #1 $100. ( covers $75. for: disassembly and inspection, plus $25. for return shipping ). Check #2 - Repair check: $200. ( covers the expected cost of repairs ). Check #3 Contingency check - if set is found to need additional repairs: $125.

Check #1 will be cashed upon recept of the set; then you will be contacted with specific information.

Sets which arrive here ( I'm in Queens, New York ) showing physical damage will be inspected and NOT repaired. Shipper files claim. If claim is denied; claim is your problem as you are the shipper who will have to fill out and fax claim forms and supporting information.


Steven L. Bender, Designer of Vintage Audio Equipment

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