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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.


************ COMMENTS PAGE 4 / ABOUT REEL TO REEL TAPE RECORDERS AND TAPE DECKS ************

Comment #15

Dimitris Rigas wrote:

Hi I had a succesfull bid in ebay of one RT-707 tape deck recorder but the owner informed me last time that there was no switch for the 110 60HZ to 230 50HZ was available on his unit.I have seen some versions that include this option anyway. The question for anybody knows is: Can I use it in Europe (230V 50Hz) with some external adapter or I will have problem with the playing speed due to the difference of frequency of the power line?

I have to know as I am waiting to arrive or this buy will be a dessster for me!!

Thank you in advance

Dimitris

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

Hi Dimitris -

While it might not be a disaster, it could be a hazard.

First, yes you can use a step down transformer, but then all your interconnected audio equipment might be grounded differently, this could possibly cause ground loops ( hum ) or a difference of potential between various sets chassis' that could be up to 120 Volts... so if certain things are happening, caps breaking down, high humidity, etc there could be a serious current leak, and electrocution potential using such a system.

Secondly, the European 50 Cycle current could make the power transformer overheat unless the set was specifically rated for 50 hz. operation. Those CSA type USA/Canada sets pretty much are only rated to operate on 60 Cycle AC current. I know I have an Akai RTR that had a totally burned out and blown open power transformer when I got it. I don't know what the cause was, but it took me 3 years to find a replacement.

While I can't be sure what the transformer blown open was caused by, my guess is that 50 Hz. operation could have done it. Also, such a hookup might also tend to cause failures in the sets internal voltage regulators, and as unknown or unforseen problems resulting that could very well result in a disaster.

I have an RT-707 in my closet that simply blows its internal fuses, and I'm sure it wasn't subjected to anything unusual like what you are planning during its prior 20 years. Too often - twenty years after the warranty ends, these sets blow up or fail, so it just doesn't make sense to start in with experimenting and foolishly hooking them up in ways that are likely to produce either a failure, a hazard, or death... if something went wrong.

-Steven L. Bender



Comment #16

>>> Travis Bearden wrote:

>>> The user nanual for the Akai X-1800SD lists a 15ips adaptor kit. Does anyone know what it contained and the dimensions of the components?

>>> Thanks

>>> Travis

>>> Hi Travis

>>> The adaptor kit is a smaller pinch-roller and different speed-sleeve (located on the storage post above the headcover, usally the sleeve is missing... I don't know the size, sorry...

>>> Best regards

>>> Rolf Houston, TX

>>> Travis -

>> I assume then that the bushing is the same one used for the 7 1/2 ips speed. Is that correct? If that is true, then it is just a matter of finding or having a pinch roller made to the correct diameter. Is that correct?

>> Thanks for the assistance.

> Hi again

> Yes, the same sleeve is used as for 15 ips but a smaller pinch-roller is installed. Some of the Akai models had a extra stored underneath the headcover, but not on this model.

> Best regards

> Rolf Houston, TX

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

NO. NO. NO... The 15 ips capstan sleeve is definately a much, much larger outer diameter as would be needed for the higher speed. If you have the 7.5 ips sleeve, using a caliper you can determine what the correct diameter of the 15 ips sleeve should be. Simply stated, the 15 ips sleeve outer circumference should be exactly that amount larger, that in one revolution it causes exactly twice as much tape to travel past a given point on its circumference as compared to the 7.5 ips part.

Due to the larger diameter of this 15 ips sleeve, the normal pinch roller would NOT be able to engage into its proper mechanical position, either being blocked by some other mechanical parts, or holding the pinch roller solonoid in a partially engaged position.

Its most likely that some internal part needs to hit a microswitch, that indicates to the circuit that it has ended the full stroke of the Pinch Roller solonoid, which then turns the high pull-in current of the solonoid off ( or eventually the solonoid will overheat and then burn out ).

So that larger diameter capstan sleeve is the reason is why the smaller pinch roller is needed, not to burn out the Pinch Roller solonoid.

-Steven L. Bender



Comment #17

chris wrote:

I have a Sony TC 200 Stereo reel to reel portable tape deck which has two internal speakers. The problem is that there is hardly any sound when the reel tape is playing. I had channel 1 and channel 2 volume levels at the max and could just barely hear it. Also, both VU meters lid up but were at a standstill. Do you have any suggestions?

Thanks.

Chris

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

Such older Sony sets (and other brand sets from the 1960's) are likely to have certain known failure modes in common, I've written about many of these in the past but it probably should be restated.

1) With sets that are 35 to 40 years of age, the heads may be worn down, and there being space between the tape and the gap, there may be reduced output from the head, resulting in insufficient gain.

2) Sets that use pressure pads can have the glue dry out and the pressure pad drops off and gets lost, and the tape is no longer in contact with the head.

3) All of the coupling and bypass caps will likely be dried out and causing reduction in amplifier gain, and/or loss of signal entirely. Other problems can be resistors that have greatly changed in value, which can cause the same symptom.

I suspect the Model 200 is an older Sony tube unit ( the presence of two screwdriver adjust HUM Controls somewhere near the input and output jacks that is a sure tip-off that it is a tube set from the 60's ).

I have a Sony model 262, a model 521, and a 300 ( the 300 appears to be nearly identical to the 521 but without the speakers or case, made for a custom installation ). All 3 of these are tube sets which suffer from dried out caps. Some have one channel working or partially working a bit, or makes motorboat type sounds.

The lack of bass, motorboating, or almost no output at maximum volume can be a symptom of either bad caps and / or tubes. All these old sets are point to point wiring, which are more time consuming and more difficult to work on than later sets that use printed circuit boards.

4) Sets of that age might use tubes, which as they age, or from disuse get a coating on their filament electrode, which interferes and greatly reduces the electron output, or can coat other electrodes and will also interfere with proper amplification, causing reduced high end or maybe causing no amplifier gain.

5) Speakers can get overdriven, overheated, and "blown" causing the voice coils to overheat will cause the wires to deform and melt, causing a short and/or mechanical blockage where the cone will be basically stuck in one place, greatly reducing the mechanical movement and sound output. Also a short may wreck havoc with the amplifier, causing additional failures in there. Either way the sound will be minimal or absent until repaired.

6) Sets of this age, use wheelies, idler wheels, springs, cams, friction cams, and and other assorted mechanical parts for driving the tape and reel assemblies, which can get sticky lubrication, worn or warped rubber idlers, slick wheels surfaces all of which can cause problems in audio reproduction, but more likely will result in things like variations in speed, tape stretching or breakage, wow and flutter.

With unused ( mechanical ) parts generally unavailable for most sets more than five to ten years old, most parts have to be scavenged off a same or similar set, or made up from scratch as one-of a kind parts.

Either way it can be a pretty costly job in terms of parts and labor, and which in the typical situation may greatly exceed the worth or value of the set in question. In the case of a set like the Technics RS-1506, or RS-1700, Pioneer RT-909, or Akai GX-636 or 646, it might be worth investing $350., or $400. to repair it, if needed but I can't say the same thing for a single motor Sony that cost $50. or even $1. at a garage sale, and may have multiple failures to repair.

So many things can go wrong, even in a set which is perfect cosmetically, expect it to have multiple problems, and that bargain set or 40 year old hand-me-down, may well cost in excess of $200. or $300. to repair or bring back to the original level of functionality.

Lastly most repair people these days have never seen the innerds of a Reel to Reel set, most being VCR, Microwave, and TV guys, so know that only a few people, maybe only a few dozen, across the country, are properly qualified to repair these sets thirty or forty years later - if the parts can be found.

-Steven L. Bender



Comment #18

Chris wrote:

I saw an ad in a local online marketplace forum for an Akai Reel 2 Reel tape deck, so I emailed the guy and he said that the deck is an Akai 635D Reel to Reel tape deck and said that it plays the 10 inch reels.

Would I be correct in assuming that it is a GX-635D?

Anyway, the guy told me to make him an offer. Could you please offer me some advice as to what is a fair offer to make him. I am uncomfortable offering too much money for the deck because it can be very very expensive to get these reel to reel decks repaired.

I asked him if it still works and he said that it does.

Thank you very much.

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

Hi Chris -

Yes, it is a GX-635D. It is always best to go locally and pick a set up, I have had so many sets damaged during shipping, cause most people simply don't have a clue about proper packing, and shippers are often quite surprised when things like head covers; corners of the wood case box; and lucite decorative parts are smashed in, or cracked into nine pieces, which can be very dismaying; and nearly impossible to replace.

Also I have had circuit boards which popped their mounting screws or were missing one of three due to a prior shop not bothering to remount the PC Board properly; and in this case it was a GX-635D which arrived here with the SYSCON Circuit Board cracked in half... and quite unrepairable.

A GX-635D is a very desirable set with recording in both forward and reverse directions; 6 GX Heads; 3 motors, and servo-controlled direct drive capstan, worth between $300. and $500. depending on cosmetic condition, electrical condition, and mechanical condition; also it should have working hubs, and its certainly worth extra if the Akai remote box or dust cover is included.

Beware, most later high-end Akai's now 20 to 25 years old do have Playback Transistors in the playback circuits, and possibly the recording circuits, which are failing. Also recently, I've seen a larger percentage of the bridge rectifiers failed in almost every recent set I've seen or had come in recently has one channel or both totally noisy, about 20 dB higher noise than would be expected on playback running virgin tape, and these transistors are in the process of totally failing.

Unfortunately, this includes the better sets made from 1978 to 1984 - GX-255, GX-266II, GX-635D, GX-636, GX-646, GX-747, GX-77.

Another problem is floods. The rash of recent flooding has put hundreds of mud and flood damaged "stinky" sets on the market. These I suspect are mostly consignment stuff ending up on ebay, for unsuspecting bidders to bid high and get stunk up! One really stinky set I got as a "parts unit" on ebay ( was also a GX-635D ) was actually working, but was missing the rear plate and a few front panel parts. Anyway, it stunk enough to make you or me sick.

An attempt to clean up such sets usually has been done prior to dumping it on someone else, and my own attempts to get the "stink" out was about 5 hours of cleaning with 91% alcohol, and it still stinks! The ebay seller of course denied any such thing, he didn't notice any smell or anything ( Right! ). Said set was sealed well in plastic garbage bags - which is always a bad sign...

So if you find a mint and well cared for GX-635D, which has zero electronic defects is worth the high-end $500. price. Other later Akai sets that are similar and nearly identical include the GX-636 and GX-646.

I've also seen more than my share of GX-255 and GX-266II's that have bad or catastrophic electronic failures; also the GX-747's tend to have a few more mechanical problems than one would hope. The GX-625's and GX-77's seem to breakdown more than their share. Those last three sets have additional failure-prone circuit's which develop problems twenty or so years later.

So best to test out any of these, and be extra careful in choosing one of those five later sets, if sight unseen; there could be nasty hidden defects.

Lastly, watch out... for instances when some prior owner has engraved their name and ID number somewhere on the metal or wood sides, I hate when people do that !~!~!

-Steven L. Bender



Comment #19

> stephen wrote:

> Hi, I Am Looking For A Pinch Roller For An Akai gx 625 Reel To Reel Tape Deck. Can Anybody Help Me Find One? Thanks

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

Well Stephen -

The Akai line of Reel to Reel tape decks and recorders turned out to be way more complicated and varied than I ever expected six years ago, when I started my trek to learn all there is to learn about Akai Reel to Reels, and collect all the Service Manuals and all the documentation that ever existed.

Among those mundane and mostly ignored items were the Pinch Rollers. There is much more variation than anyone ever expected existed. Despite the possibility of vastly different design teams, the GX-620, GX-625, versions of the GX-630D all are closely related to other sets, except as it turns out, these use a Pinch Roller that is different in size, shape, and rubber from all other Akai's.

The GX-625's Pinch Roller has a much softer durometer type rubber plus has an upper and lower slit going into the rubber surface at about 32.0 mm of circumfrence, and an overall roller diameter of 42.0 mm. Also the height/width of the rubber is 14.0 mm unlike most Akai Pinch rollers. The brass bushing is also different being only 5.0 mm high. Most similar in fact to the GX-650D, GX-400D, GX-400D-ss, and the PRO-1000's PR's but they are a bit too small at 36 mm. diameter.

So don't look to the GX-230D, GX-255, GX-265D, GX-266D, GX-267D, GX-266II, GX-270D, GX-280D/285D/286DB Series, GX-297D, or GX-635D / GX-636 / GX-646 / GX-747 sets or most other commonly seen Akai's for something similar. They are not. These sets have the more common 9.0 mm brass bearing below the rubber part; and 11.0 mm high rubber, which is typical on the "Hard" 37.0 mm; 38.0mm; or 40.0 mm diameter PR's.

While all later Akai's use a resting PR shaft that is around 6.5 mm in diameter - that appears to be the only thing they have in common. I noted that Terry Witt uses a rubber which I would term "super-hard" in terms of durometer, I'm not sure what effect that would have on a system which was designed around a rubber that was clearly "very soft" as on the GX-625.

-Steven L. Bender



This page is under construction ( Like software, the job is never done!....)
Last Update - 6-22-05 7:30 P.M.


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