Tascam 48-OB Story...

[sweetbeats]

Well friends, whilst I wallow in indecision about what caps to purchase to recap the PSU in my invalid 58, I itched to do something, so I dove in and started refurbing the 48-OB that I got with my 58-OB a couple years ago...I figure with my skills at second-guessing myself with caps the 48 will be up and running before the 58...

Anyway, it is a very clean and straight low-hours 48...solenoid cushions are goo so I got two of the three solenoids cleaned up and cushions replaced last night. This 48 will also need a reel motor as I robbed one out of it for my 58 before I had a parts 48...and I can't recall from where but somehow I have two other reel motors as well now so I should be able to find a good one in there.

Overall I'm hoping the refurb process will go much faster with the 48 than it has gone with the 58 since the 58 has had to wait for all the learning and acquisition/fabrication of all the right tools to do the job, but now armed with said gear and some knowledge it should be much easier.

I know the 48 has also got a channel card that is not passing audio, but I have yet to see if it just needs to be reseated, and if it is more than that I do have the parts deck.

Here is a shot of the heads:


Of course it needs some cleaning up...

So next I'll get that third solenoid cleaned up, get a reel motor put togother and installed, clean it up and start checking/adjusting systems.

Here is a shot of the 58 and the 48 together right before I went to pick them up...

[cjacek]

Ahh.. another 'Tascam _ _ _ _ _ _ story'.. I LOVE THOSE!!

Very low use tape path you've got there.. Kinda reminds me of my own 48.

Cory, shhhh, between you and I, don't go overboard with the refurb job on this one.... I lova ya man but that '58-OB story', especially toward the end, brought a tear to my eye, not to mention an anxiety or two...

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[sweetbeats]

Cory, shhhh, between you and I, don't go overboard with the refurb job on this one.... I lova ya man but that '58-OB story', especially toward the end, brought a tear to my eye, not to mention an anxiety or two...

You and me both, pal...you and me both. Its been a learning process on several fronts.

If you've read the latest on the M-520 Story thread you might have picked up that I am starting to learn something...I finally decided to dash ideals, finish getting the board cosmetically clean and then get it into the control room and start using it; dealing with repairs updates as I go rather than not using it until its "all done"...it doesn't work that way.

The only upside to the catastrophe on the 58 is that (thanks to Ethan and others) I've learned a ton so far in the process of resurrection which will speed up other issues as I come across them in the future, but believe me, your words don't need to be hush-hush. I am openly over the top and get myself over my head. I will try to exercise good and careful judgement on when and when not to "go there" with the 48. I might be able to track to analog after all with that demo project that has been delayed...I've met with the client and we will be tracking scratch vocal and piano tracks to the DAW in the next couple weeks, and who knows? The 48 might be ready by then. I'm not going to push it though. If it works out it works out. Pushing takes all the fun out of the refurb.

[analogkid]

The word is 'Glutton' lol. But seriously, those heads look near perfect, get that baby going!


having said that, I look at my !#$#$!^#!@ Otari 4-track trying to decide what to do about the loose recording head (hence it works/doesn't work etc.) I have been SO tied up with my real life I just can't seem to find the energy to get my song demos recorded - I need a vacation followed by two more vacations to re-energize.



AK

[sweetbeats]

AK...What's the deal with the record head on your Otari???

Stripped mounting screw or something?

[sweetbeats]

So I got the third solenoid (pinch roller) cleaned up and the new cushion installed this eve, and found a good reel motor in my bunch. The lead is short, so that may get a little tricky getting it installed once its soldered to the Joint PCB, but I think it'll be okay.

Some observations on the 48...

I'd stated some time back in my 58-OB Story thread my preference for the 58 over the 48 for a number of reasons...

1. more robust tension arm design with roller bearings on the 58
2. 1/4" aluminum mounting plate for all transport mechanisms vs. the formed steel version on the 48
3. front access for channel cards and cal trimmers on the 58 vs. underside access on the 48 (which was an issue for me since the rack the 58 is in is fixed-position, but now that I have a CS-607 rack...)
4. and of course the capability for a full-function remote on the 58...
5. Cool EDIT scrub-wheel on the 58
6. triple-guide with scrape filter tape path vs. 2 guides and no scrape filter
7. nothing beats a really big head-gate either like on the 58...its just a cool looking deck IMO...

Well, after the fracas I've put myself through by partially cooking my 58 and getting really familiar with its innards whilst I slowly repair it, I can tell you something the 48 has over the 58 hands-down...The 48 PCB mounting design/frame is WAY better...what I'm talking about is the overal logic in how/where they mounted all the PCB's. For one thing, though it may be an inconvenience to have the channel cards accessible from the bottom, it is worth getting over because all the trimmers are accessible at the edge of the channel card vs. three layers on the 58 cards. Plus, all the other PCB's are so nicely accessible. On the 58 it is a major chore to access the PSU PCB and the interface PCB for example...removing the Mother PCB was a mother. All the 48 PCB's are all mounted horizantally on guides. Two screws and the PSU PCB slides out...likewise for the interface PCB. Just a much smarter, more serviceable efficient design. Other 48 positives are the slick ceramic capstan shaft (BTW, hope you never have to pull the capstan motor on a 58...I still haven't figured out how to get to the capstan PCB on the 58...the 48 capstan motor is right there), no achilles-heel RCA jacks on the 48, and all the PCB access is gained by removing the upper bonnet panel in the back and then tilting the I/O panel out. If I was a field tech back in the day I would bemoan a call on a 58. Even the mechanical layout on the 48 is more logical...solenoid linkages are more robust and direct. So while the 48 lacks some of the professional robustness and features of the 58, it makes up for it in refinement. It commanded my respect as I sat there and marveled at the construction revealed by the yawning I/O panel.

That's all for now.

[sweetbeats]

The reel motor I picked wasn't running so hot, and the wire lead was really short so I opened it up, cleaned the commutator gaps out with a hobby knife and soldered in a longer lead from a different motor. Tested it out sitting on top of the 48 and it is a sweet motor. Runs quiet and fast with lotsa torque. Hopefully install it tonight.

[cjacek]

Cory, thanks for an A / B on the 48 / 58. My thoughts exactly as I've owned both. I mean, I still have the 48 and one of the reasons I decided not to service the 58 [but rather sold it], was the horrific internal design / access. I always say that if TEAC married the positives of both units and removed the negatives, you'd have a perfect design, like going with the 58 robust, bomb proof, transport and making servicing / access more user friendly, like on the 48.... and yeah, throwing out that RCA design / mounting [on the 58]....

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[sweetbeats]

I wonder if there is a way to retro-fit the 58 head mounting plate to the 48....

I have a parts 58 on the way thanks to member Paul Warp...maybe I'll mess around with that between the two parts decks. Sick...wrong...I'm thinking that it will entirely not work now as I picture the two plates and the tape path in my mind...I have to look though and see if there are extra mounting holes in the 48 plate for another guide or the scrape filter...I've got the one removed from the parts 48 so I can hold it up to the 58 a get a real good visual comparison. I'm not going to pursue this one unless the simplicity of it jumps up and bites me.

The other thing I was wondering about is if I'm a bit too jaded about my opinions of the tension arms...a proper sleeve bearing like on the 48 tension arms may actually be quieter than the ball bearing rollers on the 58 depending on the age of the two. I also like the placement of the tension arms on the 48 better than the 58 from a statics point of view. I really noticed it when I was trying to resolve that tape path issue on the parts 48...do you remember that, Daniel? The tape was getting pulled toward the deck in REW? Anyway, I never resolved that issue, but that was the first time I had run tape on a 48 and the 48's tension-arm position seems to be able to handle transient load changes better than my 58. I think it is interesting that, since the 38 and the 58 came out at the same time, yet they differ so greatly in the tape path configuration, and the 48 that came out later follows the 38, but the MS-16/ATR60/ATR80 decks are like the 58...who knows...

And here would be a really hairy project...wire up a 48 to utilize the RC-51 full-function remote. Doable having the schematics of both and assuming that many of the circuitry conventions are likely the same. I'm not going to do it. Nope. Need to actually record something first. Yup....promise...I do...yup. But I have the basic 58 remote, the RC-50, and I don't want to buy an RC-71 too...wonder if I can make an ELCO to RC-71 style adapter and use the RC-50 on the 48...

Cory, thanks for an A / B on the 48 / 58. My thoughts exactly as I've owned both. I mean, I still have the 48 and one of the reasons I decided not to service the 58 [but rather sold it], was the horrific internal design / access.

Yeah...in all seriousness, when I go back and forth looking between the 48 and the 58 opened up, the 58 is sort of Wing-Ding Dilly-ish, for those of you that know the story...No disrespect meant to the engineers and design department, but in some ways it looks like somebody said "Okay, where are we gonna stick the PSU then?" and then somebody goes "We still got some room over here in the side...couldn't we just tuck it over there?", whereas the 48 looks like a group sat down and said "Okay people...We have this space here. How can we fit these components in to utilize the space efficiently and maximize access while minimizing wire runs?" That last point I forgot to mention too...the PCB's are ordered more or less from top down in logical order...the PSU is right under the transformer, and then the Control and interface PCBS on one level right below that and so on. Very logical.

Pictures of both for perspective:

[cjacek]

Originally Posted by sweetbeats

in some ways it looks like somebody said "Okay, where are we gonna stick the PSU then?" and then somebody goes "We still got some room over here in the side...couldn't we just tuck it over there?", whereas the 48 looks like a group sat down and said "Okay people...We have this space here. How can we fit these components in to utilize the space efficiently and maximize access while minimizing wire runs?"

Pictures of both for perspective:

Cory, were you listening when I pretty much said the same exact thing upon examining both machines? HA!

Yeah, it's like somebody threw everything but the kitchen sink into the innards of the 58, with little thought involved but the 48 looks like they really obsessed about it and it looks it. For people like myself, who are obsessed with order, cleanliness and such, the 48 is a God send.

Excellent pictorial perspective of both machines. Thanks!

BTW, I like your creative thought and passion that you have for the machines but lets not go crazy with the tinkering, OK?

EDIT: Were you not able to align the tension arms using the screws underneath?

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[sweetbeats]

Cory, were you listening when I pretty much said the same exact thing upon examining both machines? HA!

Yes. I was. Kreepy.

Were you not able to align the tension arms using the screws underneath?

The advice got tabled by other projects, and particularly when I decided to part the "parts" 48. I will be readdressing your posts and that section of the 48 manual here shortly though as I get my 48 up-to-snuff.

I'm really excited now. I had always regarded the 48 as sort of a lesser step-brother to the 58, but it is its own deck.

BTW, I like your creative thought and passion that you have for the machines but lets not go crazy with the tinkering, OK?

butbutbutbutbut...

Fish gotta swim...tinkerers gotta tinker, but I'll keep it moderated. Its more just a curiosity thing really. Above my interest in tinkering is a passion for order and for keeping things original and only upgrading where necessary/prudent, and "prudence" is becoming more conservative all the time.

[analogkid]

Personally I like the 40 series decks the best of that generation of Tascam Reels. I love my 42B - in fact looks like for the moment I will be using it alone to bounce tracks for some song demos, sine the Otari is flaking out again - that's another thread entirely though.

AK

[sweetbeats]

Got the replacement reel motor in. Works like a charm.

The 48 is a joy to work on. Like stated above averything is really accessible and logically laid out...I equate to the VW Scirocco I had many years ago. Great car but in many ways a total PITA to work on. I remember trying to change the air filter and the air filter housing is buried under the fuel distributor of the Bosch mechanical fuel injection. Scads of braided fuel hoses...even after you got the clips of the air filter released ( a knuckle busting chore) the top of the filter housing was so resistant to movement it was hard not to mash the new filter as you put it in. I remember saying out loud my first time doing the job "There has got to be a better way they could have put this together..." That is like the 58. I really liked my Scirocco, but it left some things to be desired. Enter my Subaru Legacy wagon...early 90's vintage. Changing the alternator is literally half to a third the struggle of the air filter change in my Scirocco. That's like the 48.

I removed switch caps and knob covers tonight as well as all the dres panels for cleaning. Its a really clean deck.

The pinch roller is going tacky. Should be no surprise since the solenoid cushions were goo.

Next up, continue cleaning and check which channel wasn't passing audio and try and resolve that (starting with reseating cards).

[cjacek]

Great stuff, Cory. I sure am looking forward to the updates.

[sweetbeats]

Awesome...thanks Daniel!

You know me...I'd be putting up a ton of pics via my ftp site, but it is still not working right...I'm about ready to use an interim alternate...anybody recommend a good hosting site?...Maybe Google has something...I have an account there...

Anyway, got the front dress panels all cleaned up and some of the rollers...have the impedance and tach rollers to do yet...fortunately the tach roller rubber is good, and the pinch roller from my parts 48 is in good shape, just needs cleaning up. I'll probably get a spare from Tascam or spring the extra for a better-than-new one from Terry's Rubber Rollers.

The reel platter and hub design is better on the 48 than the 58...more positive mating between the two which will avoid eccentricities I had to deal with on the 58.

[cjacek]

Cory, http://www.photolava.com/ is cool. I've been using it and am quite pleased. Try it out for a photo or two and see if you like it.

Your thread reminds me to get a few spares for my own 48. I need one plastic hub, as it's beginning to show a tiny crack [I'll probably order 2]. Another few things are tension arms [as I may opt to replace the one I needed to straighten out - remember that Cory?]. Here's that original thread.


Then there's the re-rubbering of the counter roller. I already have a new pinch roller from TEAC so I'm good there but they don't stock any tach rollers. Will need to opt for TERRY some day soon.

As for the tension arms, I will first need to open her up to see which part actually is the weak link and order the appropriate part.

Anyway, thanks for this [and other threads] Cory.

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[sweetbeats]

...as I may opt to replace the one I needed to straighten out - remember that Cory?

I do, Daniel! I haven't really checked mine closely yet to see if they are square...I remember checking when we were dialoguing about that issue, but I can't rememeber what I found and I'm too lazy to go looking..., but I have to say that even though the arms are not as formidable as the 58, I do like the design better overall...I started getting the tape path adjusted last night and now I understand how the tension arm height is adjusted...its really easy and can be done on the fly easier than the 58...overall the tape path setup on the 48 is much more user friendly. At first I thought the 48 was really lacking compared to the 58, but to be honest it feels much more refined now that I've started working on it...my 48 is really growing on me...you were right that that problem with my parts 48 where the tape was getting pulled out on the impedance roller when switching the transport from FWD or PLAY to REW was a simple tension arm height adjustment. It is really easy to get the tape path setup.

Here is a pic of the 48 all dusted out and cleaned up inside, ready for all the bits to go back on...



Here's the back...woohoo.



Here's the back with the I/O panel dropped down...you can get a good view of the component layout...everything is really easy to access and I love how the power supply and interface/control PCB assemblies slide out (those are the two horizontal PCB assemblies just below the transformer and the reel motors).



Contrast the last picture with this one of the back of my 58 and you can really see what I mean...layers of vertically effaced PCB's greet you when you open up the back...if you need to access anything but the control PCB (the one to the right of the fuses) its a struggle...the power supply is to the left of the capstan motor...yes...wedged against the side, and you have to remove the capstan motor and keyboard PCB's in order to carefully manipulate the power supply PCB out of the deck to work on it (since you fried part of it doing something really dumb ). Oh and did I mention that the keyboard PCB (mounted on the front face of the deck of course) wiring is soldered and not on a connector? Which means you have to carefully manipulate that through the deck from front to back (which means you have to remove the arming panel) so that it is clear of the power supply in order to get that out. Hopefully you can understand why I'm so tickled with the 48...The 58 is really a great deck, but it is helping me appreciate the 48.



Later that same evening...

I got some of the "the bits" reinstalled, at least enough to start doing the mechanical alignment...





I really like the tape path configuration...I think it is easier on the tape and on the path. When I run the 48 it really seems, as I said above, more refined than the 58 (which makes sense as it came a couple years later). I've made it clear that I lament about the 48 lacking a third guide and th scrape filter of the 58, but you know what? Tape path alignment is so easy on the 48, and it pulls tape really nice. It is quiet going through the path. So far the tape packs aren't nearly as nice as what I was getting on the 58, and that may be the way it is or it may imporve with continued mecahnical alignment. I wish it had the full-function remote capability...can't have it all, but I am really appreciating the 48 more and more.

I also thoroughly cleaned and demagged the tape path.

Next up:

• Finish the mechanical alignment including checking the pinch roller, brake and tape tensions.
• Mount it in my refurbished CS-607 rack (which will be nice for tilting it and accessing the trimmers/channel cards)
• Align/calibrate the electronics

And with that...

[cjacek]

You rock Cory!!

This is absolutely great. Thanks for the hard work you've done with the info and photos. You're really doing awesome things on this board. Wow!!

Question: What do you think is the weak link in the tension arm assembly where it becomes bent overtime?

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[sweetbeats]

Daniel, thanks as always for the encouragement. None of these projects would have moved without this forum...none of them, so that's a testament to the value of it. My M-520 would have likely become a parts board to somebody, but it is clean, complete, functioning and soon will be contributing to the analog legacy and it would not have happened without the Analog Only forum.

Same with the 48 that is the subject of this thread. What I have done with it so far has gone so quickly because of the knowledge and experience gained with my 58 struggles, and I've worked through so much on the 58 sinch April with support coming nearly exclusively from this forum, and now its making for a quick turnaround on a basic refurb for the 48.

Way cool.

I have been meaning to look closer at the tension arm design on the 48. I may do that tonight or the next night and I'll take pictures and such and offer up an opinion on where the weak link is.

[cjacek]

No sweat on the arm tension design, weakness, issue... Whenever you get a lookie is fine.. Thanks in advance!

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[sweetbeats]

Okay...so my "next steps" were:

• Finish the mechanical alignment including checking the pinch roller, brake and tape tensions.
• Mount it in my refurbished CS-607 rack (which will be nice for tilting it and accessing the trimmers/channel cards)
• Align/calibrate the electronics

Last night I did a number of things related to that first bulleted item:

• Adjusted the brake linkages according to the manual. They were quite a bit off and the brake tensions were maladjusted to compensate.
• Adjusted the brake tensions and in doing so noticed a kinked brake band, but it was due to a tweaked hanger...needle-nose pliers fixed that. The brake tensions were really high.
• Adjusted the pinch roller tension...same thing...it was really high. BTW, I use a set of homemade spring guages to do the above, and there are several places in the manual for the above adjustments were things have to be adjusted to specific gaps (i.e. 1mm, 3mm). Get a set of metric automotive feeler guages for this. Works well.
• I got into checking the tension arm alignment too...mind you this is not in the manual. They are fixed and there are no adjustments, but a minor knock can tweak them as has been discussed in the past by cjacek. I have a basic aluminum carpenters square to check them. I'll try and put up a short video of how I do it, but based on what I saw of the design last night when I took a closer look, the arm itself is sturdy enough, but the spindle that the arm mounts on is small in diameter. This is where the weak point is IMO. Look at the picture below. Part #20 is the tension arm, part #19 is the post or spindle on which it mounts. Fine for the rigors of guiding tape, but in a scenario where the deck is being moved and the tension arm becomes gets in between a solid object and the momentum of that 90lb. chunk and its going to be tweaked. So I checked each tension arm on two axis, and held the roller and tweaked by hand in a way that recognized what needed to give...the spindle. Again, I'll try to put something up later. The supply-side was fine, but the takeup side was pointing downhill significantly, and slightly toward the headstack. The downhill orientation explains why I had to adjust the takeup reel table height way out. Both tension arms are now square.
• Did some more adjusting of the tape path since I read up on that section in the manual. Its been awhile...plus the straightening of the takeup tension arm changed things.

Next up is the tape tension...this is nerve-wracking for me after what I went through with my 58 for those of you that have read that. Never could get the tensions right, so I'm hoping this time will be different with the 48. I'll be double-checking what I did last night first, but then its on to the tensions and then after that the tape-to-head contact...then azimuth. Its so refreshing approaching these tasks without having the multitude of questions. Granted it was a 2+ year process to get to this point of not having a slew of questions every step of the way, but this is the reward.

[cjacek]

Ah, thanks for that Cory.

So you don't think it's the shaft which sticks out from tension arm but rather the part indicated by #19?

Which parts do you think I should be looking at then, as replacement, to cover all possibilities? Do I get both #'s 19 & 20, as indicated in the diagram?

It's actually interesting that you've found one of the tension arms slightly off, on your deck [was it the left side]? Mine was way off on the left so I just pulled it back to even it out. Several other users of the 48-OB model reported this type of issue, bent tension arms.

I wonder if someone can machine this same part but more rigid. If it is #19, that which is the weak link, it shouldn't be that difficult, I suppose.

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[sweetbeats]

So you don't think it's the shaft which sticks out from tension arm but rather the part indicated by #19?

I don't really know for sure, but that is my intuition at this point, especially with deflection toward the top or bottom of the deck.

I spent some time just gently pushing on one of the tension arms and watching the behavior, and the union at the tension arm spindle where it pivots just seems relatively flimsy, whereas the post to which the actual roller mounts is much thicker at the base, and the guage of steel that was used for the tension arm and it being a "U" channel with diagonal bracing makes for a pretty rigid piece. Plus, the tension arm actually floats on the pivot spindle. It rides on a coil compression spring and the floating helps to facilitate better tape handling in spite of minor descepancies in the tape path adjustment (i.e. it won't fight with the tape if it is not spot-on adjustment-wise), but that means it has play in it and the post is held to the tension arm backing plate with a relatively small diameter screw...that's it, and the arm is held to that with the adjustment screw which is a 3mm screw...so that's why I'm banking on that being the weak link at this point. I plan on completely dismantling a tension arm on my parts 48 this weekend and really getting to the bottom of it.

Which parts do you think I should be looking at then, as replacement, to cover all possibilities? Do I get both #'s 19 & 20, as indicated in the diagram?

#20 is actually a well-engineered piece IMHO. Not as impressive as the likes of the 58, but well up to task. #19 and its associated bits is where I'd be looking at modding/retrofitting/reinforcing, but why?

Like I said, I'm going to open one up all the way and have a look, but AFAIK mine are now square, and I'm certain that my takeup-side arm got tweaked as a result of some trauma. I think the reel table on that side of the deck was shoved in when I got it and the reel adapter was busted. With proper care and attention I don't imagine its going to go out again y'know? Unless I open it up and go "my goodness but that would be an easy/simple upgrade!", I'm not planning on changing anything that's there.

It's actually interesting that you've found one of the tension arms slightly off, on your deck [was it the left side]?

No, it was the right side.

I wonder if someone can machine this same part but more rigid. If it is #19, that which is the weak link, it shouldn't be that difficult, I suppose.

I think to really do it right you'd need to oversize the hole in the tension arm so that the spindle can be oversized and mount to the backing plate with a bigger screw.

I'll update after I've torn one apart and had a thorough look, and I'll also put up that video of how I manhandled mine to straighten it out and my methodology to check its alignment.

[cjacek]

Cory, after this whole thing, your journey over the last 2 years, you're going to not only own a nice, analogue based studio but also will be able to service just about any tape recorder / mixer out-there!! I admire you for sticking it out, as I know how difficult it has been.. but I, for one, have seen, first hand, how immensely beneficial all of this has been, not only for you but for the potential hundreds if not thousands who read your most invaluable posts.

Keep it coming, man but for goodness sake, don't burn yourself out. It's OK to say 'NO' once in a while, ya know....

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[sweetbeats]

Aw, Daniel, I can't help it...like the tension arm thing...it is an issue y'know? At least until we know its not...I want to be assured myself that it is a non-issue or how to resolve it if it is an issue. I know there are others out there that can benefit, plus its pretty easy to check it out when you've got a parts deck accessible...its already opened up, and mechanical stuff is in my comfort-zone anyway.

Its been a ride, but the "ride" has taken me to this place that I had barely even dreamed of and there is music that needs to be shared.

Here is a song performed by a very good friend. It was a spontaneous 1-take tracking session wrought with glitches of humble reality (including the moths that kept trying to get through the visqueen ). He was over sharing his latest and I convinced him to come out to the "studio". It was tracked digitally, but even with careful application of my gear and the mastering process I can still hear the converters squaring off the edge of his vocal chords...hard to explain but I've experimented with this and it is one of those digitalisms that jumps out to my ears and it is not the conversion to the 128kbit mp3 either...I can hear it on the 24bit 88.2kHz raw tracks as well...my analog experiments totally avoid this and I can't wait to capture audio to analog in the future.

Those Sergeant Pepper multitrack files...They've been digitized, compressed, packetized, reassembled, and decoded by the time I'm playing back on my computer, and yes I know they were tracked on 1" 4-track right? But they still sounds unbelievable. I like the Beatles, but I'm not a devoted fan or anything. I respect their place in shaping music history. Tremendous influence and for good reason, but those tracks sound just incredible. Analog, baby!