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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 7 / ABOUT REEL TO REEL TAPE RECORDERS AND TAPE DECKS ************

Comment #30

Saving Sony Sticky-Shed Tapes!

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

Since the subject of Sticky-Shed Tapes has come up fairly often, as Sticky-Shed Syndrome is now more common than it was years ago... as it is both a time ( and temperature / humidity too ) related problem which affects many brands and batches of Reel Tapes made in the later 1970's through the mid-1980's ( and even later ).

One example of a tape that is very often subject to sticky-shed is the later Sony SLH-180B, SHL-7-550, or ULH. These 1800' shiny brown oxide, and dark bown oxide tapes which are generally well calendered, and backcoated, which usually gives excellent performance, as its surface oxide consistency is superb, giving generally great performance.

One notable and impressive attribute is less "rocks" sound ( under a blank - but erased condition, where a sound much akin to traveling over a cobble stone road is heard as a background noise just above the residual tape hiss ) as compared to competing brands of high output / low noise tapes.

These Sony tapes were made in the early 1980's after Whale Oil was outlawed, and as such, can have the sticky-shed problems related to the ratio of large and small chain hydrocarbons in the binder. The ULH has a much darker oxide, and claims to be a more "energized" version, and apparently suffers from the same type problems. The SLH-7-550 was a later version of SLH seen in beige one piece plastic cases.

Unfortunately, these Sony SLH and ULH Backcoated tapes are notorious for turning into gunky sticky-shed, and also having another problem related to the backcoating, in which the adjacent layers of tape are totally stuck together because the black backcoating had oozed to the outer edges of the tape.

I spent several hours recently, attempting to see if there was a method for "saving" these sticky-shed tapes, which would normally be considered unusable, and can easily stop a three motor deck dead in its tracks...

My attempts were partially successful. I took six Sony sticky-shed tapes and managed to save two, damaging and destroying the other four in the process of determining what is the proper "method" which actually revives the tape without destruction. Now none of this is 100% perfect or guarranteed to work, but pretty much here is the jiffy -

First: Putting the tape through the entire tape path, on multiple tape guides and fast winding is a sure-fire method for destroying the tape. The tape at some point will stick, jerk, pull, and yank, and end up totally stretched at points, stretched almost to a wire thin width. So don't do it!

The best method is very time consuming and requires a deck with a symmetrical tape path and tension arms on each side, suitable units probably include the Akai GX-266D, GX-266II, GX-635D, and GX-636. I used a GX-266II.

First remove the head cover, and thread the tape only between the 2 outer tension arms and along the back of the head cover mounting block. It is not threaded in the normal tape path at all. Place a clean white sheet of paper under and in front of the tape deck, so that soon you will see the results flaked off from the tape as it lands.

Then fold a bounty towel in half, then multiple times until about 1" in width, and about 8 layers thick, place it between the two reels resting on the back of the head cover block. You might want to scotch tape it in place unless you want to hold it there for the next two hours. Wet the towel somewhat using 91% alcohol, mainly on both ends near the reels; then the threaded tape gets put on top of the towel, with the backcoated surface in contact with the towel.

Next, fast wind the tape in the forward direction. Then at the end, stop and fast wind in the reverse direction, slightly moving the towel, you should see an outline of black gunk removed from mainly along the edges of the tape, but possibly acroos the whole back of the tape during this first pass. Continue with a 2nd, 3rd, 4th, 5th, and 6th passes, just fast winding with the tape contacting only the two tension arms and the towel between the two reels.

You should see there will be hundreds of specks "whiskers" of black jetting off from these tension arms, and do clean the tension arms off after every 2nd winding pass. Brown oxide will be present on the surface of the tension arms, possibly also a white reside, which is binder residual gunk. Use Q-Tips to clean the tension arms of this material after each pass, or second pass depending how much accumulates.

Also change to a slightly moved new towel surface or refold onto a new towel surface after a few runs, if it gets too dirty. By now, if you placed the white paper in front of the set, you should see lots of oxide and backcoating whiskers flicked off onto there.

After six times through, you might try and thread through a single or even two stationary tape path guides, or even try using the whole normal tape path. Continue doing the fast winding four more times using the whole tape path, and cleaning off the heads and guides of gunk and wiskers. Clean the heads and tape guides after each pass using the full tape path. Using the Akai GX-266II, both erase heads are likely to be saturated with brown oxide.

After about an hour or so, and perhaps ten or twelve runs through, the tape should be able to travel with little impaired movement, and traverse the full reel at normal speed, not slowed or making noises or squeaks... If not, sorry, you will have to continue processing it until it gets better.

Note - some areas of tape might have accumulations of "clumps" of oxide, that "thrrrrp" when it passes over the heads, guides, or tension arms, and such clumps may need hand cleaning using a Q-tip and alcohol, gently as they may be on the oxide side of the tape.

Eventually this step by step method will cure the tape ( at least Sony Tapes ) of their problems. As far as I can tell this cure is semi-permanent, unlike tape baking which only works for a limited time.

Hope that helps,

--

-Steven L. Bender, Designer of Vintage Audio Equipment



Comment #31

MORE: Saving Sony Sticky-Shed Tapes!

Hi Steven. I emailed you recently complaining of an intermittent squealing noise during playback on my Akai 630D deck. You referred me to comments 28,29,30 on your comments page. I followed your instructions on cleaning tape, with a slightly different method.

I found it difficult to follow your exact instructions with my 630D, so I used a paper towel moistened with alcohol and cleaned the tape on fast-forward and reverse using the complete tape path. I just held the paper towel under the tape as it passed under the tape tension guide. After running the tape in each direction I tried playing the tape and it played flawlessly.

I have only tried it on new old stock tape so far. The tapes I have cleaned and played back without problems are: Ampex Grandmaster 456, and Maxell UD 35-180 (n). Perhaps this cleaning will have to be a requirement before each playing of the tapes I've had problems with. For the short amount of time it takes it will be well worth it. I hope this may help others with the same problem. Keep up the excellent work youv'e done with your web page and again thanks for your time.

Steve H.

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

Well I'm glad you got decent or usable results following a somewhat modified method on the GX-630D, which doesn't have a symmetrical tape path, like the GX-266II, or GX-635D. But I should caution you that tape slitting is an extremely precision process, which is lterally slit and trimmed off a few molecules at a time at the factory, and anything done here at home, can produce mediocre results at best.

As I mentioned, using the full tape path could very well cause a condition where tape will freeze up totally when in the tape path, and the result could be stretch and permanent BAD Damage. So using the GX-630D tape can be seriously stretched, as the semi-pro designed GX-630D for 10.5" reels uses reel motors that do pack a wallup of torque when engaged at their really Fast Winding speeds.

Problems of tape stretching or poor slitting do show up as bad variations in high frequency response, this can be tested for and becomes noticeable on a null test where phase differences between channels becomes especially gross at high frequencies on some tapes with uneven edge dimensions or poor slit.

These days people just don't know or care about slitting problems, as it mostly is awareness by professiomnal studio people who spend a whole day tweaking their high-end Studers and Ampexes, and a variation of a single dB makes them start to act crazy... :-).

Anyway, a few days back, I took one of the Sony SLH Reels that had undergone my "several step process of a cure" and I compared the performance of this "cured" Sony SLH-550-7BL Reel, against a TDK LX-35-90B Reel that didn't need have any prior problems. Performance was compared using a "null test", at 7.5 ips and a at first, recording of a 400 Hz. tone. Basically the levels are matched using a "null adapter", which cancels the audio out signal, so a perfect performance is hearing nothing.

Once nulled in SOURCE, the deck is switched to TAPE. The resulting deviation was OK for both tapes at 400 Hz., a bit worse for the Sony. Then, switching the signal to 12.5Khz. the TDK LX Reel still performed admirably, but the Sony Reel was just all over the place, with variation of several dB visible on the meters, mostly dropping down in the left channel, which did indicate some tape stretch or significant slitting imperfections.

I stress that the progressive use of a single tension arm or two tension arms to remove edge-gunk along with an alcohol wash is a time consuming process, and much, much, much kinder to the edge of the tape than would be a more brute-force "full tape path run". While the latter still might work, it would have much more adverse and severe effects on the tape, in terms of tape stretch and tape edge damage.

I should also state that these Sony or other tapes brought back from the brink, in this manner, are probably at best, adequate for general recording of FM radio or something, but its performance was CLEARLY INFERIOR and much worse than I had expected. The performance wasn't the tape decks' problem, it was for sure the Sony tape.

-Steven L. Bender, Designer of Vintage Audio Equipment



Comment #32

Re: Pioneer RT-909 reel to reel Problem

Date: Sat, 13 Dec 2003 03:21:02 -0800 (PST)

>>>>>> Todd Jones wrote:

>>>>>> Hello.. I have one of these reel to reel decks. It Fast forwards and rewinds fine, but it doesnt play... I checked the belt.. and it's fine.. apparently the capstan (?) motor isnt running.. can someone help me fix this without having to resort to looking for a service manual? Any help will be apprieciated! Thanks in advance! Email me with the solution! No Spam please

>>>>>> Todd Jones

>>>>> Bob Toepfer wrote:

>>>>> The first thing to check is to see if the pulley on the capstan motor turns freely. If not, you will need a new motor. If it turns freely, you may have a bad end of tape switch on either the right or left tension arm. Both have to been enabled to get power to the capstan motor.

>>>>> Bob

>>>>> www.vintage-electronics.net

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

>>>> Yo - Bob -

>>>> If the set rewinds and does fast forward, that kind of action means that both end of tape switches on the tension arms are OK. C'nest pas ???

>>>> If the Capstan Servo Motor is not running, isn't it more likely that he has a blown Servo IC ?

>>>> -- >>>> Steven L. Bender, Designer of Vintage Audio Equipment

>>> Bob Toepfer wrote:

>>> Steve

>>> If you are going to be an Ass.....you should try to be a well informed ass. Check your schematic..you will see that if the left sensor is bad the fast forward and rewind will work but the capstan motor will not. The purpose of this forum is not to build your ego but to help others out with problems, repairs, or parts sources. If you are unable to do any of the three......then remain on the sidelines........

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

>> Oh yeah, right Bob, nice judgement ... call me an "Ass" in a public forum. I know the RT-909 schematic and circuit is about as convoluted as possible, but anyway..

>> The schematic was noted by Pioneer "actual circuit may vary due to improvement in desgn" reveals that the Left and Right EOT switches S2 and S3 are in fact in series, so if either switch is bad, none of the transport functions will operate... not Play, not Reverse Play, not Rewind, not fast-forward.

>> Switches S2 and S3 directly affect the 24 Volts coming off Q214 and Q245 into Q210-Q213 powering capstan motor operation. They also affect the tape functions and baseline solonoid operation controling tape function voltages via Q245 and Q214 and IC logic powering the four solonoids through Q219. So with power lines enabled and powered, both the Servo IC21, Q21, and Q22, as well as the capstan motor itself are powered as are the four transport solonoids.

>> So, if the transport functions do work, but not the capstan motor, either Servo IC21, Q21, or Q22 would appear to be faulty, or not getting juice. But then, I said that in a simpler way before. And as a part resource, I have replacement parts for S2, S3, IC21, and Q22 available.

>> -- >> Steven L. Bender, Designer of Vintage Audio Equipment

> Bob Toepfer wrote:

> Steve

> Just call them like I see them. Again, check your schematic. The reel motors tap off between the two switches and the second switch only effects the power to the capstan motor. Blanket replacement of parts is a poor substitute for troubleshooting. Why replace all of those parts if only the switch is bad?

> By the way, what is a Designer of Vintage Equipment? Unless you designed it when it was new, you can hardly design vintage equipment now....that would make it new and not vintage. Am I missing something?

> Bob

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

Well my RT-909 schematic shows two wires crossing at 90 degree angles between the two S2 & S3 switches, but no connection there. Get out your 4x or 10x loup, and have a closer look, your schematic may be a fuzzy/bad print...

Since you asked... A "Designer of Vintage Audio Equipment" as I define it... I design new "Rebuild Kits" for older vintage amplifiers. Brings them forward some 30 years or so, to Millenium Class or Class 1 Level Audiophile sonics using special Ultralinear Transistor ( ULT's ) output devices that I helped design and implement. I also recently, I've been making Rebuild Kits to upgrade certain Reel to Reel tape decks that have very well known failure-prone parts.

-Steven L. Bender



Comment #33

Re: I need blank 4 track recording tapes

Date: Sat, 20 Dec 2003 09:06:48 -0800 (PST)

Matthew Roha wrote:

Does anyone out there know of a place where i could possibly purchase some blank 4 track recording tapes? I really need them! I'm in a band, and we want to record, but suprise suprise! no tapes! so long story short, we need tapes, please help!!!

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

Quantegy still sells tape, and some BASF/Emtec is probably still around many other types are available on the used market. Back in the 1970's, 80, and 90's millions of reels were made by Maxell, TDK, Scotch, Sony, Fuji, Denon, and others. Dozens of lines were produced, from basic Scotch 111 and 150 types to low noise, high output, and low print types, high end high bias backcoated reels and extra high bias, high coercivity type "EE" type.

Also reel sizes ran from 3" for tiny sets, 5" for medium size Uhers and Nagra's; 7" reels for most home decks and recorders, and 10.5" reels for Semi-Pro and larger home sets, as well as 12" and 14" reels for studio machines and duplicators.

So, best to specify what machine you have and type of tape you need as the variety is almost endless.

-Steven L. Bender, Designer of Vintage Audio Equipment



Comment #34

H.Roelofs wrote on:

Date: Thu, 25 Dec 2003 13:01:15 -0800 (PST)

Does anybody know how often you can erase a good tape like the Emtec SM 911 or Quantegy 407 and record it again before the sound quality gets less?

Happy Holidays,

H.Roelofs

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

I'd say the act of playing, erasing or recording tapes is all about equal on the tape, and while the erase head in most machines is "adequate" if properly aligned, bulk erasing on that 40lb. relic bulk eraser will be the only way to bring back the virgin low noise level of the tape and too be free from some artifacts.

There is a low-level noise phenomenon called "rocks" which is above the hiss level of bulk erased tape, which sounds kind of like going over a cobble-stone rocky road which can be head on erased tape, or even bulk erased tape, which may be a product of the erase head surface; record head surface, and even the Play head may influence this effect.

It seems to get noticeably worse closer to the beginning and end areas of any given reel of tape and may in fact be a slight scoring of areas of the tape surface at a microscopic level. When tape is reused hundreds and hundreds of times this effect may become quite audible, otherwise one tends to believe that minimal changes occur to tape within hundreds and hundreds of uses.

However, since the tape itself is like a very fine sandpaper, it will eventually wear down the surface on the head, so heads are more likely to be a source of problems than the tape will be. And now 30 years later replacement heads are rare and difficult to find, even used ones!

Although, certain heads like Sony F&F Ferrite, and the Akai GX Glass Crystal covered Ferrite heads, do last much longer, these too will eventually start to show wear, surface abrasions, and on Ferrite - gap scatter which can affect performance. So while soft [permalloy] heads as on the Pioneer RT-707 or RT-909 were good for maybe 1,500 hours due to the high tape tension those sets place upon the tape to contacting the heads.

Other permalloy heads like those in the higher-end 3 motor Tandberg sets may be good for 2,000 to 2,500 hours or so, before any serious wear sets in. Then, the Ferrite and GX Crystal Ferrite Record and Play heads in certain Teac, Sony, and Akai sets may make it to 20,000 or 25,000 hours, or more, I do have serious doubts about the early claims of 150,000 hours for the Akai GX heads.

I just see too many with noticeable abrasion to the surface and center gap areas to think that 150,000 hours is really an accurate number. However, GX heads were different from early ones to later ones, maybe the thickness of the glass differed with the model of head and some were covered in thicker glass than were others. I have no idea of which or how to find out.

Still, over the last 20, 25, 30 years, many Reel to Reel sets have had little use, while others were used continually, so some sets heads may indeed be in great condition, and others will be almost a total loss. The only way to find out is to examine the heads using a 10x loupe or maybe a 50x or 100x stylus microscope.

--

Steven L. Bender, Designer of Vintage Audio Equipment



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Last Update - February 5th, 2004 9:00 PAM.


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