Otari MX5050 newbie questions

[squasher]

I purchased an Otari MX5050 B2HD a week ago in the hopes of getting involved with the Tape Project. I am a complete newbie with regards to RTR, however, and have a few questions. Please bear with me.

1) My machine came without hubs of any kind. Correct me if I'm wrong, but I assume I need a pair before I can use the machine. I'm confused because all the Otari hubs I see (on ebay) are listed as '10" NAB hubs'. My initial assumption was that I wouldn't need the hubs if I were playing 7" tapes.

2) Should the guide roller (is this the impedance roller?) have a rubber surface similar to the pinch roller? My B2HD's guide roller is metal. Given that the aftermarket Athan impedance roller is made of a compliant material (polyurethane), doesn't that imply that my stock guide roller should be rubber as well?

3) How can I tell whether tapes are "tails in" or "tails out"? Or, in other words, how can I tell which side of the tape has the oxide on it? I've acquired a few commercial 7 1/2 ips recordings and can't tell how they've been wound on the reel (or which side to play).

Thanks in advance,
Chris

[ironbut]

Hey Chris, welcome to the forum.

The NAB hubs are for 10.5" aluminum reels (there are also larger ones but they won't fit on your machine and are scarce as hen's teeth anyway).
The 7" reels (both plastic and aluminum) and most plastic 10.5" reels don't need them. The prerecorded tapes that you can find on eBay are quite often on 7" reels with a larger hubs. These are often referred to as "low torque" reels. There are a couple of different Otari NAB hub adapters but I'll leave which are better to others who may have tried both.

Many of the after market parts that you'll find are different from the stock items. Just because the Athan roller is covered, it certainly doesn't mean that you have to have one that is. It may well be that the Athan part is ultimately better, but this would be considered to be more of a tweak.
In general, most used machines need a little work to get them to do their basic job of moving tape gently and consistently across the heads up to spec. I'd concentrate on that before any tweaking.

Tails out refers to how a tape is wound on a reel. This term is used on 1/2 track stereo tapes ( left channel is the top half of the width and the right channel is the bottom half of the tape width) and full track mono tapes. When a tape is stored tails out, you must first rewind the tape from the take up reel side (right side) onto an empty reel on the supply side (left side) to play it correctly. If you were to play a "tails out" tape without rewinding it, the sound would be in reverse.

It used to be that the outside of all tape was the shiny side and the oxide/inside that makes contact with the heads was dull. Things started to change with something called back-coating. All current tapes are back coated and the outside is no longer shiny but a dull black (lamp black is used for back-coating). And many of the currently produced tapes are now polished on the inside/oxide which gives it a shiny appearance. So, if you were to consider the level of gloss, the tables have totally turned from what they used to be a few decades ago. Suffice it to say, all currently produced tapes are black on the outside and brown on the inside.

If you wish to learn more, I recommend that you download a manual for your machine;

http://www.analogrules.com/

Not the easiest site to navigate but the price is right.

To supplement the manual, check out the " Beginners Guide,.." which is located in a sticky above the General Forum. There's also a list of reel to reel links with all kinds of good stuff pertaining to magnetic tape and reel to reel.

Hope this helps.
The terms "supply reel" and "take up reel" are both related to how the tapes are configured when in "play" or "record" (always left to right).

[steveidosound]

Welcome!
Pretty standard newbie questions that I will attempt a first answer of below each question. Others may want to chime in and honestly the answers are all on here in a number of places. I would also suggest reading Beginners Guide to Tape Recorder Basics under general discussion.

I purchased an Otari MX5050 B2HD a week ago in the hopes of getting involved with the Tape Project. I am a complete newbie with regards to RTR, however, and have a few questions. Please bear with me.

1) My machine came without hubs of any kind. Correct me if I'm wrong, but I assume I need a pair before I can use the machine. I'm confused because all the Otari hubs I see (on ebay) are listed as '10" NAB hubs'. My initial assumption was that I wouldn't need the hubs if I were playing 7" tapes.

A. You do need hub adapters and probably spacers to go behind them to use 10.5" NAB hub metal reels such as the Tape Project tapes. You don't need them for 7" reel tapes. I am presuming you have the normal small spindles on your reel turntables with reel locks.

2) Should the guide roller (is this the impedance roller?) have a rubber surface similar to the pinch roller? My B2HD's guide roller is metal. Given that the aftermarket Athan impedance roller is made of a compliant material (polyurethane), doesn't that imply that my stock guide roller should be rubber as well?

A. I am going to take a semi-pass on this one. My older Otari is also rubber on the left wheel. I have seen metal on plenty of other machines though.

3) How can I tell whether tapes are "tails in" or "tails out"? Or, in other words, how can I tell which side of the tape has the oxide on it? I've acquired a few commercial 7 1/2 ips recordings and can't tell how they've been wound on the reel (or which side to play).

A. Tails in or out refers not to which side of the tape faces the center of the reel, but to which end of the tape is on the outside of the reel. Generally 2 track tapes (again, like Tape Project tapes) with signals recorded only in one direction, are stored tails out, and the term is meaningless for 4 track tapes such as commercial prerecorded ones from the 60s and 70s with an A and B side. When it is all on one reel you are at the head of either the A or the B side. As to which side faces the outside of the reel, on older tapes with no back coating the shiny side with no oxide faces out and the dull side with oxide faces in and contacts the tape heads. Newer back coated tapes have a darker color coating on the part that faces out - the "BACK" coating.
Furthermore, on all machines made since the late 50s the full reel is loaded on the left so the tape pulls off the bottom outside edge and the reel rotates counterclockwise. It is threaded through the machine left to right onto the take-up reel so that will also rotate counterclockwise during play. This will play the A side of a 4 track stereo tape and the only side of a 2 track stereo tape that is tails in (head of the program out). (You have to put the full reel on the right and first rewind tails out to play)

Enough info. for now. Thread up a 7 1/2 inch per second quarter track commercial tape, set the reel size to small and the heads to 4 track and the speed to 7 1/2. Hook up a stereo output cable from the line outputs to an aux or tape input of your stereo and enjoy.
You do however, want to make sure there are no gross problems and the machine is operating more or less normally before putting on any important or expensive tape.

[steveidosound]

You can type faster than I can Steve :)

[squasher]

Thanks for the helpful responses. Sorry to be so dense but I'm still unsure how to mount 7" tapes to my machine's spindles (without falling off).

I can fit the 7" reels onto the spindles but was expecting to have some mechanism for securing/locking them to the spindles. The spindles on my machine are smooth and straight with no apparent locking mechanism. There's no mention of reel locks in the manual so I don't know what they should look like. Shouldn't there be some kind of hub (or other) that goes over the tape reel, engages the spindle, and prevents the tapes from sliding off?

I've already gone through the links and resources mentioned (analogrules.com, etc.) and didn't find this answer. I had already downloaded the B2HD manual and that, too, couldn't help.

Chris

p.s. I've attached a pic of the spindles on my machine if that helps in anyway.

[steveidosound]

Ah yes, your machine has no reel locks. There are rubber reel hold down clamps that work for smaller machines with shorter spindles.You could try and find a pair and punch the hole through so the spindle protrudes through the clamp. People have used tight fitting rubber grommets for this purpose. My old Magnecord had a set of collet type clamps for 7" reels as well as the NAB hub adapters for the 10.5" NAB hub metal reels. I am not sure what Otari's original solution was for 7" reels. Probably a variation on one of the above ideas.
To state the obvious it is only an issue with the deck vertical. On it's back or tilted back at an angle it would not be an issue.

[Ki Choi]

The BIII has the spring loaded three prong spindles that you can pull out and twist to hold the 7" reels but for BIIs....  In order to load the 7" reel on to the BII, you must unscrew the center section of the BII hub and remove it completely.  Load the 7" reel onto the reel turntable to line up to the three wings on the spindle. Then place the BII hub on top of the 7" reel.  As you press down the BII hub against the 7" reel, you would turn and screw in the center section of the hub to make it stable.

See the picture below...

[squasher]

Thanks again for the help.

The obvious conclusion is that my MX5050 version (B2HD) requires the Hub adapters.

Chris

p.s. I anticipated this answer last night and have already ordered a pair (from ebay). I'll just have to wait for them to arrive before I can test out my machine further.

[Ki Choi]

We have many hardware and software R2R experts on this forum who are very nice (most of them ;-)).  For other newbies who are considering taking the R2R plunge, pre-purchase questions asked here would be beneficial to you and will be answered promptly (in most cases).

[jeri]

Chris,

All the impedance rollers an all my Otari machines are rubber-coated.  I vaguely remember buying a used machine once that had a roller with most (but not quite all) of the rubber missing.  So it could be that the rubber can get hard and lose adhesion with age.  That may be the case with your machine.  I checked with my tech this morning, and he confirmed that all Otaris use rubber-coated impedance rollers.  Since this roller drives the timing circuits, I urge you to have it checked before risking any valuable tapes.

[squasher]

Well, my impedance roller does not have a rubber roller and, frankly, doesn't appear to have ever had one (i.e. there's no left-over adhesive residue where a rubber roller might have existed). My version is a B2HD so I'd be interested in hearing from others with the same model.

As an aside, I just received a set of hubs and, finally, hooked it up to my system for the first time (a few minutes ago, literally). Unfortunately, I couldn't get it to play any music to speak of. I can hear the internally generated 1kHz Oscillator test tone (out of my speakers) but nothing when playing a tape. It looks to me like the tape is making good contact with the playback heads.

Disappointed but not daunted.

Chris

[ironbut]

Hi Chris,

Have your tried to listen through the headphone jack? Also, are the VU meters moving when you listen.
Check to be sure the selector is set to tape and not source (source is when you're monitoring the input for recording. It allows you to compare the sound of the original to the sound on the tape).
If you're getting sound through the headphone jack, review your manual to be sure you have it connected properly and that all the switches are set in the correct spot.

Past that, it's very common for machines that have sat for a long time without use for contacts to become oxidized or have crud built up on them. All the switches and pots that you would've checked are ones in which the signal passes through. Try listening on your headphones while you switch them back and forth. Don't be too vigorous since sometimes things can be so built up that pot especially can get jammed up and stuck on a hill of crap (nice visual huh?). So, don't force it. Long before that happens, you should be getting some signal through it. A good contact cleaner is a good idea (I use Deoxit D5). Just be sure not to flood it. A quick spritz will do.
If your machine has a switch for 1/2 track and 1/4 track playback heads, that's a real favorite hang out for tape gremlins. Be sure and work that sucker (but if you shoot it with cleaner, be sure not to get any on your tape path.

If you have any background info on the machine, that can be a big help.

[squasher]

Thanks for the help Steve.

Your suggestion to try out the Monitor switches was the correct one (although it highlighted another problem). The fact that I was able to hear the 1kHz was an indication that I had the Source Selected (and not Tape).

Unfortunately, the left channel doesn't appear to be working (no sound, no movement on the VU meter). The right channel is working (but sounds awful).

I've got more work to do to figure out the source of the problem. Given that I intend to bypass the output electronics and connect to the repro heads directly, I'm not too concerned about the left channel issues (yet) and won't spend too much effort isolating the problem.

BTW, assuming that I will connect the repro heads to an external preamp (Erose?), is there any benefit to keeping the connection to the internal MX5050 amps intact? (i.e. for the VU meters, headphone jack, etc.). I've got to believe that by hardwiring to the tapeheads, some of the basic functionality goes away   (source/tape monitor).

Chris

p.s. My deck was apparently used at a radio station at Michigan State University and has a serial # indicating it was built in 1982. Other than that, I have no other historical info.

[ironbut]

The tape head (1/2 track/1/4 track) is the usual suspect for that problem.
Also, it could be the tape/source switch(s). Work those and all the rest of the switches/pots. Don't forget the back panel switches.

It could also be the tape. Try recording something and switch between source and tape while it's running.

It's always a good idea to go through the tape path and give it a good cleaning. I worked at a college radio station and there could easily be a hunk of pizza stuck in there (or considering it was at MSU, may one of Magic Johnson's toe nails? Could be worth something!). The tape path includes the heads, all the guides, lifters holds the tape above the heads on rewind/fast forward). Use a good light, a magnifying device of some sort, and some alcohol (higher % the better) and some Q-tips. Pay close attention to the corners of the guides and the outside edge of the heads since that part's usually obscured by the head shields.

So, give it a good cleaning and take your time to address all the switches and pots.

It could also be a loose circuit board/module or multipin connector. It's worth taking the time to disconnect everything in there and reconnect it a couple of times (with the power off of course).

[squasher]

More questions to add to my newbie list:

1) Is it a bad idea to use a "dry erase" marker to identify the path that the tape makes over the heads? I recall reading this was a helpful debugging technique for head alignment somewhere on one of the R2R guides. I can't seem to find anyone else using this approach in any of the forums, however.

2) Is the Otari's 2-Track/4-Track switch's output contained within the head block? I am assuming that I don't need to worry about the output of each individual repro head if/when I directly wire to an external preamp. I find it strange that the 2T/4T switch doesn't appear anywhere in the MX5050 schematics (I haven't found it yet)....


Prior to testing out my deck, I had done a thorough cleaning (with CL-100 cleaner).  I will clean the pots and switches with contact cleaner later tonight.

Chris

p.s. I did happen to find a toe nail stuck in one of the shielded repro heads. It might be Magic Johnson's but the burnt-in wear pattern looks more like the image of the Virgin Mary. Do you want me to send it to you? ;-)