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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 #20

Subject: Akai GX-646

Date: Mon, 28 Jul 2003 10:51:13 -0500

From: "Mark Brandt"

Hello Steve, after looking at your site, it seems you have alot of knowledge on the Akai's. I bought a 646 at a local auction yesterday, beautiful cosmetically and with the tape dustcover. It is giving me some trouble however!

The only thing I can get it to do is rewind. It will start to fast forward but then reverse automatically. Hoping you may know the symptoms and probable causes or lead me to someone who might.

Thank you for your time and you have a great site!!

Best Regards,

Mark Brandt

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

Hi Mark -

I've never come across that particular symptom, but most 20 year later symptoms are gonna be tough dogs to repair.

My first guess based upon the symptoms you state, would be a blown primary logic chip. This is a proprietary chip that controls all of the operational functions, and unfortunately, it is a part that hasn't been generally available for about 15 years, and so is difficult to come by.

I have a few of those chips, new, unused and still sealed in the factory plastic bags, they cost $75. just for the part.

Of course, your symptoms could be something else. Actually, it could be one of more than half a dozen problems, and one can't really get the right thing fixed when the set is sitting a few hundred miles off.. Repairs by remote control just won't work.

As for a RTR Tech, I don't know of many who still do and are well versed in the later Akai's. Guess that depends where you are located. Local repair people often don't know what to do with these sets now...

In terms of keeping a set going, long term, and for repairs, finding a competent repair person for a treasured Reel to Reel machine can be an arduous task at best... Few among the independent repair places you will find in the yellow pages will still work on these sets.

Among the problems, and reasons, they typically cite are: 1) "Its obsolete equipment." 2) "We can't get parts." 3) "Can't get service data." 4) "Stuff is older than our technicians." 5) "Would likely cost more to repair than the equipment is worth." To some extent, all of the above are true for most service places, which have to make a profit from every technician in the place, every month, to offset their rent and other costs.

Since such service places are likely less than 20 years in the business, they deal with TV's, VCR's, and CD Players, and are likely unfamiliar with Reel to Reel sets, and are less inclinded to know about the proper functioning or of proper repairs for failures.

I have come across repair shops that take in a Reel to Reel Deck, and never finish it; one fellow said, after nearly three years his local repair place not only hadn't finished the repairs, they couldn't even find his Akai, when he demanded it back (he was gonna send it out to me).

Lastly, I specialize in Akai repairs ( and also the Pioneer RT-909, Sansui SD-7000, and the Tandberg 9000 Series ) I am located in Queens, New York.

I do have a minimum fee of $75. plus return shipping costs to evaluate the set ( the minimum fee also includes first hour of labor towards repair ) and I use a 3 check method which I have found to be fair to both myself and set owners, more details if interested.

My own success rate for repairs on these sets tends to vary with their age, and problems. My successes run from 50% to over 80%, again, very dependent on what is wrong with the set. Again I do best for sets where I have the Factory Service literature and info. I have the factory literature on most Akai's, some Tandbergs, Sansui's, and Pioneers.

Typically repair costs run from about $100. to maybe $350. Shipping costs depend on the weight of the set, and some of these older units are quite hefty! I should note that sometimes, my repairs take a long time, one set which was a Pioneer, was here for just over 6 months, but was fully repaired, the owner was so happy to actually get it working, when he came to pick it up, he left his malfunctioning Teac for some work.

So typical turn-around time can be 4 weeks, or less, but there can be a wait as long as six months if it needs parts that are presently unavailable and need to be made up. These sets are typically over 20 years old and parts are unavailable most of the time, neither Akai, Sansui, or Tandberg has supplied parts during the prior 15 years and Pioneer and Teac may have only a few select items available, for one of their sets now.

For the most part, manuals, and technical information, is difficult to come by and this is typical of all companies for products in this genre. Still the situation is not completely bleak.

Special Akai items you should also know about - All, none, or as many of these as you wish can be performed as they are quite independent of each other and serve very different purposes. The most common failure seen in these later Akai tape decks sets tends to be the Servo failure, which is seen as one of four variations:

My Capstan Servo-Fix Upgrade Kit ( and soon my SYSCON Rebuild Kits ) are for those who can wield a hot soldering iron and perform delicate soldering without problems or coaching ).

Symptoms: The presence of wow and flutter at the slow speed... Speed variations at either or both speeds... Capstan motor is stalled or stopped... The capstan motor operates at full speed, regardless of which speed is set... For these problems and failures I designed my Capstan Servo-Fix Upgrade Kit.

1.) The Capstan Servo-Fix Kit is an extension of the parts replacement process beyond what Akai suggested in the 1970's Service Bulletins.

It is a repair and an upgrade that I have designed for those sets mentioned above, which both improves reliability further while it also enhances the performance of the Capstan Motor Servo-system. This alone has repaired many sets which have failures in the servo-system, and doubtless prevented many other sets from future failures; for me to install my Capstan Servo-Fix for later Akai's it costs: $85.

2.) My Syscon Board Rebuilds.

While the Servo-Fix Kit has worked fine in about 95% of cases across all later Akai Decks, those remaining 5% ( usually seen as sets where the motor is running at full speed regardless of the speed switch ) do require a more extensive set of parts replacement - so the more costly and much more extensive Syscon Board Rebuild is something new, which I've been working on recently.

The SYSCON Rebuild Kits must be model-specific because some machines used a proprietary primary logic chip; while others used discrete control circuitry, while somewhat earlier sets used a board filled with power relays.

The SYSCON Rebuild consists of a series of upgrades and part replacements, many of which Akai Factory Service had suggested be done to sets in the GX series, during the late 1970's and into the early 1980's, when it became apparent that time and time again, certain parts Akai used on the Syscon Boards - were failing after a few years. These failures over time increased as sets became 10, 15, 20, or 25 years old...

Syscon Board failures would lead to a number of sets Operation Blocks becoming inoperative. In other words, they would not go into Record, or they would not go into Play, or possibly would not Rewind or Fast Forward. The Syscon Board Rebuild is to prevent these possible failures and to improve the future reliability of the set, and costs between: $175. and $350. which includes labor - depending on which set and which parts are needed.

3.) Set of Audio Capacitor Replacements.

3.) This replaces all the caps in the audio path of both playback channels, and in the record section. Being a labor intensive job takes several hours of work. It costs: $200. ( price is for a Stereo 2 Channel Deck, somewhat higher for a 4 Channel Quad set or 2 channel unit with Dolby B built-in ) which includes parts and labor.

4.) Set of Audio Transistor Replacements.

4.) Another audio upgrade, the Transistor Replacement is something new which I have also designed, to improve both the signal to noise and sonics of the higher end sets.

Since I have found some percentage of the original transistors used by Akai are failing in subtle ways, mostly making the set much more hissy and noisy than would be expected. Often this is seen as one channel being quiet, and the other one very noisy. This upgrade when done at the same time as the Audio Capacitor Replacement, improves the sonics by replacing many of the audio transistors, with more modern twenty-years-later improved low noise devices.

The Audio Transistor Replacement costs $55. ( for a Stereo 2 Channel Deck, higher for a Quad set ).

In any event, it is best to drive the set over here, but if it must be shipped, it is absolutely necessary to pack it properly to avoid shipping induced damage.

The following methods are known to prevent further problems with shipping induced damage. Several layers of quality bubble wrap are required to properly pack this type of set. The best type has 1 inch diameter bubbles and often is used by businesses that package and ship expensive machines.

Less suitable, but still OK, is bubble wrap found at STAPLES SKU 835124 $8.99 for the bag of 5/16" height of bubble 12" x 30', if you don't have large amounts of suitable bubble wrap saved. Wrap two layers top and two layers bottom left to right, then one later top to bottom and around to the top again on each side to form a cucoon.

Foam peanuts can be put in plastic bags and tied, and added underneath and above the cucooned set. Just loose foam peanuts and crushed newspaper are NOT suitable for packing a set this heavy and large. Package it - so it will survive a 12 foot drop off a conveyer belt onto to a concrete floor.

Units should be shipped by Federal Express Ground, or Post Office Parcel Post, or Priority Mail insured for $500. or $600. Use UPS as a last resort ( NOT suggested ) also insure for $600.

Method #2 packing knowledge:

Use only new material except for the filling material between the two boxes. I have found that ALL reel-to-reel decks will fit in the same size boxes and I buy them by the bundles.

First put 15-20 feet of big bubble (2 ft wide)on a flat place at least 4 ft long. Put the bubbles up. Lay the deck on this such that the front is up and whatever dimension seems to fit within the 2 ft bubble wrap is centered. Place 4 inch pieces of cardboard tubing (cut from carpet roll cores available at any carpet place) over the reel tables to protect the spindles and tables from taking loads.

If the deck has delicate switches or other controls elsewhere on the front put a tube on them as well. Roll the deck wrapping the bubblewrap tightly around the deck. Tape the bubble end with some tape other than clear so the buyer can find what to cut to undo the deck. Tape the ends folding the bubbles over the edges of the deck. Make it as tight as you can.

Place this wrapped deck into a 20x20x14 box. It will be tight so the best way is to place the deck face down and put the box over it and turn the whole thing over. Cut the box down until the flaps are tight over the bubble wrap with as little space as possible. If the deck is smaller than the 20x20 part of the box then fill this with something unmashable, but soft like bubble wrap. Tape it all up good. Every crack.

Prepare a 24x24x16 1/2 inch box with a bottom of something like 1 inch foam or peanuts or or lots of crumpled newspapers. Put the other box init and cut down the bigger box until it just will close on the smaller one. Before sealing it all up fill the void between the two boxes with peanuts or crumpled newspapers or more foam or something. Tape the thing up again all cracks and corners.

Note that the top of the deck is protected by three layers of bubble, four layers of cardboard from the inner box and four more layers from the outer box. There is no peanuts or other crushable material between the front of the deck and the ouside world, so it doesn't get a chance to accelerate when dropped.

The front just takes the direct shot and not the inner box moving within the outer box forces. Most decks have the front panel very strong, but the front is full of delicate items and these must be protected. This is what the carpet tube pieces do.

Exact repair costs depend on the set and on the failure encountered.

Let me know, if I can be of help,

-Steven L. Bender

Mark's Reply:

Thanks Steve, your letter is a wealth of information to me! My control board is the one with all the relays and wire-wrapped posts. The unit acts as if it is one of the relays. I do have a technical background, mostly on dental and medical x-ray machines and I do alot of old guitar tube amps for resale on eBay. I actually bought the deck for resale also and probably went too high with my bidding.

I paid 280.00 for it because it looked mint except for a small scratch, it had the remote and dustcover and I was sure it would work like a champ! No place to plug in and test when you are in the middle of a farm field though! I will have to think a bit about whether to spend some money to get it working or just try to recoup what I paid for it.

Thanks again Steve. Will definitely get back to you if we decide to repair. We really do appreciate the reply.

Mark Brandt

Comment #21

Subject: Back at it

Hello Steven:

Well I'm back after surgery. Still a little wobbly but tried of being in bed. I figured to rebuild the hacked amp with your modifications and leave the more stock amp alone for a truer comparison of old vs. new.

Lying in bed I have been wondering if to serve your needs better I should rebuild the second amp to your specs also and that way I have several versions of your modifications to compare. I actually have three (3) 12s in my possession so I could have:

1 stock / 1 built to your exact specs / 1 built with more than required resistor replacement

The up side of the surgery was that I got to listen to the amp for quite some time in varying states of conscienceness and varies levels of pain medication and was very happy with reproduction of vinyl vs. CDs. Not sure why but vinyl sounded much, much better with your amp than CDs. Any thoughts?



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

Hi Dave -

Well welcome back, I hope they didn't remove anything you seriously want... :-).

Glad you seem to be doing OK; and I hope the surgery went fine.

Upon more reflection, I'd also say that in the case of having multiple amps, that is a good idea. Since my kit replaces all the transistors, it is fitting that the worst unit then becomes the best.

Since the main part of the mods is having the ULT Output devices in there, one should be able to switch PC Boards readily to be as stock or mod, but either way, those comparisons would be unfair to any set having "normal" output transistors since the ULT's account for so much of the sonic improvement at loud output levels.

As we previously discussed, those 180 ohm, 100 ohm charred or blown resistors, etc., that were in question, simply are not influential to the sonics of the amp. So, my feelings is that they are hardly worth more than just discussing it. I doubt you find much cause for any change of sound between an amp built to my exact specs, or as you did, with some more resistor replacements. I replaced all of the resistors that I felt needed changing, as I didn't want to modernize the sound by too much.

CD vs. Vinyl - I'll have to say: Plenty!! The types of frequency domain and time domain distortions inflicted on sound reproduction by the digital processes are plainly different and possibly much more audible ( especially in the high-end ) than those found in analog vinyl recordings.

As a result, one can measure THD on both, and digital comes out the clear winner, not because its true... but because THD measures things that ignore all the digital forms of distortion and so CD's can "look" clean when it actually sonicaally quite dirty... That is how "specs" lie.

Measuring by ear ( listening ) reveals that which cannot be refuted by lies on paper. In a similar way, there is no easy way to measure how my special ULT Output devices are less distorted in terms of "non-linear distortions" compared to ordinary double and triple diffused bipolar devices ( except by listening ).

As a result - one can easily distingush the better ULT sonics, by increased low-level details, improved clarity, and freedom from changes in apparent frequency response abberations with changes in level, even when the amp is operating at maximum, and even into clipping!

Of course, the source media ( the music ) and the "front end" of the reproduction system ( cartridge, turntable, preamp ) must also be top-notch in order for the overall clarity and improvement to "come through".

So, one can listen to improvements among various cartridges, in turntables, in preamps - in just about all cases tube preamps will sound cleaner than transistor/IC based ones.

One can also distinguish between and among various CD Players and among the various chipsets used in different brands of CD players when using a power amplifier with a much reduced non-linear distortion, as extended listening should reveal to you over the coming months using my Citation 12.ULT. Such differencess probably will not be quite as obvious on a stock Citation 12 or just about any other brand of amp - except maybe an occassional higher-end Levinson, Krell, or Cello unit.

You will find vinyl sounding less distorted in a sense, because it is likely closer to the source sound and the positive attributes of that clearer sonic charactoristic comes though the rebuilt Citation 12.ULT as opposed to getting lost in the low-level blur and grunge of other amps; along with the high-level non-linear aspects of other amps, as they interact with your speakers' inductive and capacitive non-linear aspects, which then are fed back to affect the sonic attributes.

It is probably quite enough to deal with the ULT Rebuilt Amp as you have it, and the second amp ( as made stock ) than to deal with three amps, which will simply make you CRAZY! I'd say the more you listen, the more you will find the relaxing inner detail, speed and clarity of the ULT Amp ( since its actual needed burn-in time is still an unknown probably 25 to 75 hours ) will eventually become second nature to you.

At some point, your ears will simply start to reject the stock amp as sounding more lifeless; lacking "color", space, and depth, even though, as you know, it is the same chassis, same transformers, same circuit and should be essentially equivalent (* like brand name and generic drugs - don't get me started on those! ).

-Steven L. Bender

Comment #22

Subject: Akai 635d Problem

Date: Mon, 1 Sep 2003 14:39:44 -0700 (PDT)

P.S. wrote:


I have a AKAI 635d tapedeck, and the right channel is distorted. I already replaced all the transistors and capacitors in the output circuitry (left and right) and the right channel is still distorted.

Could it be the resistors? (the heads are clean).

If the unit gets warmer the distortion is less noticeable but not gone. Can anyone tell me what this could be.

Thanks Patrick

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

Patrick -

You didn't mention if playing is distorted in both the Forward and the Reverse Direction, or only in one direction.

I'm thinking its pretty ambitious to replace all the transistors and the caps in there, but that its highly unlikely to be the resistors, unless one or more has radically changed its value from nominal.

I'm also thinking that you'll spend a lot of weekends changing all the resistors in there and it will still sound the same - again. So look for some other cause.

-Steven L. Bender

P.S. wrote:


The distortion is also there when playing in reverse mode (both directions)and it is still the right channel. I forgot to mention that i replaced the transistors of the output circuit a few times (for the right channel) the left channel has no problem.

I thought that the transistors blew every time i placed new ones in the machine, but when i considered that this was going a little to far i thought that maybe the resistors or at least one of them was faulty. (because of faulty voltage supply to the transistors) If a resistor is defective can this be seen on the outside or can it only be measured.

Thanks Patrick

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

Check if the DC voltages in the power supply are correct; then check for individual voltages in the playback circuit, at the equivalent points in the left and right channels.

Incorrect voltages would indicate a problem of some sort, at that point. This would require the schematics of that board. I have the GX-635D service manual and/or schematics available if you want to buy a copy, if you don't have them.

Some of the transistors in some of the later Akai Playback circuits are known to get noisey after fifteen or twenty years, this can be manifested as loss of signal and a big HISS; I guess it could also become a symptom of audible distortion.

So now the question is: Exactly which transistors have you changed on the circuit board ? Typically, in the later Akai Playback circuits, there are six or seven transistors in each channel between the Playback head and the VU Meter, one of them is an FET in some of the later sets.

While resistors can be seen to be charred or burnt in some cases, mostly they fail without physical indications, but such failures are kinda rare.

Two other things that could be causing the problem given the symptoms you describe... a Playback head with bad soldering to its connections, but since its unlikely both the forward and reverse Play head right channels both suddenly go bad at the same time, I'd think both Play heads can be ruled out as the problem. Likewise for the head changing relay, so I'd think somewhere in the playback circuit or power supply is your problem.

-Steven L. Bender

Comment #23

Subject: AKAI 1730D-SS Problem

Date: Mon, 1 Sep 2003 14:39:44 -0700 (PDT)


Joe wrote:

When "tape" is selected, a loud noise which sounds much like pink noise comes through the speakers. However, when I engage "source" this problem goes away. This leads me to beleive that there is a problem in the playback amps, I just dont know what to look for as far as the problem. This machine also records a low level hum. When I play back a tape that I recorded on this machine, on another machine, the hum is present.

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

Hi Joe -

The 1730D-ss used a bunch of crummy Sanyo LD-3141 IC's in the circuit path, "8 of 'em" if I recall correctly. Yes, these are known to go totally noisey, and they are discontinued, and pretty much unavailable.

Of all the Akai's, the 1730D-ss uses more of these failure prone IC's than any other set. The 1730D-ss having no redeemable social value, very little resale value, and a high failure rate, is probably not worth repairing, or even the cost of shipping.

You could maybe use an O'scope on the set and find the bad one, and get a replacement, I have a few in various boards, and even some unused NOS parts, but they are quite pricey.

This little single inline part was used in quite a few Akai RTR sets, almost all of the quad units, from the mechanically simple, single motor, low end 1730D-ss to even the high priced GX-630D-ss and GX-400D-ss, and a number of the lower end 2 channel stereo sets too.

My own suggestion would be get a better set to begin with, at least then, if it is another Quad Akai which also has the Sanyo IC's, if it fails, it might be worth repairing.

In that case, the 1730D-ss could serve as a parts source, as some of the other 7 Sanyo IC's might still be working.

Good luck with it.

-Steven L. Bender

Comment #24

Subject: Tandberg 9200XD Problem

Date: Mon, 1 Sep 2003 14:47:08 -0700 (PDT)

From: Steven L. Bender

Brian wrote:

I am looking for a VU meter for this model. It seems to be dead. Was this a common problem? Is there an easy fix?

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

Hi Brian -

The meters do die, sometimes the pointers fall off, sometimes they just go dead. Nearly impossible to find a replacement these days - unless one takes it out of another 9200 or similar machine. I've a used 9000x parts set, but I think I used both VU meters and two more someone in europe sent me to repair other Tandbergs, so I don't think I have any left to spare.

You can test the VU meter by using disconnecting one lead and using a battery in series with a 1000 ohm resistor ( or any resistor in that range ) note polarity as you do want the meter to go upscale to prevent busting the pointer off.

The good thing is, several Tandberg sets used those same VU meters, the 3500, 3600 if I recall correctly, along with the 9000, 9100, and 9200.

-Steven L. Bender

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