Tascam 58-OB Story...

[sweetbeats]

Yeah...

I do like the 58 better, but the differences are minor:

On the plus side for the 48 is the ceramic capstan shaft...wish the 58 had that.

Plusses for the 58:

• The tension arms. Much more robust mounting design and much easier to adjust roller height, and the larger ball-bearing rollers are nice.
• The 58 handles tape more gently...This is largely related to the lifter mechanism IMO.
• 3 tape guides and a scrape-filter on the 58 vs. 2 and none on the 48.
• For my mounting configuration the 58's front amp-card access panel is a joy for accessing the cards and for using the extender card whereas the 48's cards are accessed on the underside like the 38. The 48 does have all those access holes to get to the trimmers, but my rack is a fixed tilt at this point...love those heavy-duty zip ties to keep that thing locked. Without them my 58 would be upside-down. Plus on the 48 you have to remove a bit of the skin to remove the cards and the 58's are ready to pull if needed once you drop the VU meter panel.
• And the cards themselves...I've never tried to check but the layout is the same as the 38 and I wonder if they share the same cards while the 58 shares its cards with the MS-16, so a little different breed. Not sure what that means to the end-user though...Ethan noted a particular IC on the MS-16/58 amp card that has been used in some other nice places...maybe the same considerations have been made on the 48 cards? Who knows...
• The 58 has that solid thick aluminum plate to which all transport mechanisms attach, the 48 uses a stamped steel sheet (albeit relatively heavy guage stuff)
• full-function remote capability on the 58...

Blah, blah, blah. I'm splitting hairs. Both can sync. I actually like the tape routing on the 48 better. A bit easier to thread and appears more logical than the 58.

Oh, one more plus for the 48, I love how the capstan sounds when it spins up.

I'm not trying to knock the 48...I just prefer the 58, and overall they are indeed of like quality. That is for sure. My preferences are limited to design stuff really and some of that just particular to my installation. Both solid decks.

 

[sweetbeats]

Pulled the supply reel motor...

Doesn't look good, which is, in a way, good.

And another thing, All this tweaking and such is paying off. It took me about 20 minutes to pull the motor and have it opened up, and that includes removing all the paneling on the deck necesssary to do so.

Anyway, things look pretty yucky in this motor. Not sure what is going on, but its appearance does lead me to believe that its condition may be contributing to my tension issues.

Here is a closeup of one of the brushes. Scored and dirty...I must have reinserted this brush the wrong way though I never thought it mattered, but you can see two wear patterns on the face:

Here is a shot of the commutator...wow. The gaps between the sections are practically packed with debris. Looks bad:

Here is a shot of the rear end-cap of the motor...the brush housing...just showing the debris:

I know this motor was disassembled when I did the swap as I replaced the nose bearing...I would not have put this back together in this condition, so this has all happened in a relatively short amount of time...very few hours.

Ideas/suggestions?

 

[cjacek]

I'm glad you've narrowed it down, Cory. Will you be putting in a good motor from your parts 48 unit, so that you'll know right away if it was the motor?

With regard to the cards [and thanks for the comparison of the 48 / 58], I'm pretty sure the audio cards are not the same as on the 38 but is there a way to confirm? What are the part #'s for the 48 / 58?

BTW, great photos but I'm unfamiliar with it to comment on a tech level.

----

 

[analogkid]

looks a bit messy... is that black substance metallic? I know little about motors I am afraid.




AK

 

[sweetbeats]

AK, it is brush residue from the brushes being worn.

Daniel, I don't know the 38 amp card p/n...don't have access to that one. Otherwise I could compare with my 48. Anybody with a full 38 manual that can post the record/reproduce amp card assy. part number?

The 48 and 58 cards are completely different.

Not sure what I'm going to do about the motor issue yet. Been away this weekend. I'd clean this motor up and put it back in but soemthing is not right with the way the brushes are wearing...plus I think I am pretty much cold on my idea of putting in that quick-disconnect on the motor lead. What if there's a cold joint in there that is causing some resistance under load? Who knows, but it adds a point of failure, so I'm going to solder the next motor to the PCB.

 

[sweetbeats]

So...anybody have any suggestions with the motor?

I plan to take a toothpick and clean out the gaps between the commutator sections and clean with alcohol...blow out the end cap and wipe down the brushes. I'll pull a motor out of my parts 48 and open it up to see how it looks, but this time I'm going to make marks so the brushes go back in where they came out and to ensure that the orientation is the same...

 

[analogkid]

That sounds like a good idea (insuring the brushes go in the same way they came out), I wonder if the wear was caused because the brushes went in different and were rubbing excessively?




AK

 

[cjacek]

Daniel, I don't know the 38 amp card p/n...don't have access to that one. Otherwise I could compare with my 48. Anybody with a full 38 manual that can post the record/reproduce amp card assy. part number?

The 48 and 58 cards are completely different.

I already posted a question about this. Hopefully this'll get cleared up soon.

Cory, if you have a minute, could you please tell me what the part # of the 48 audio card is? My manual is all packed up so I don't have access to it.

Not sure what I'm going to do about the motor issue yet.

Cory, did I understand correct, from your previous posts, that the motor in question, that you ordered, wasn't as advertised and it might have been opened? Personally, I'd put a known to be good motor in there [from your 48] and see if the 58 behaves as it should. If it does then it was the motor.

--

 

[sweetbeats]

Daniel,

Tascam 48 rec/rep amp card p/n 5200110520.

The motor that is yucky inside is an original from my good 48, but I think I was not careful to reinstall the brushes as they were before I pulled them (the motor had a noisy nose bearing).

 

[cjacek]

Got it, thanks Cory.

--

 

[sweetbeats]

Motoring ahead

Spent some time last night partially disassembling my parts 48 to get another reel motor out of it.

As I've said in the past it was a hard decision to part out a basically functional machine, but as I get into it my decision is becoming more comfortable to me...

• The XLR connectors are visibly oxidized.
• It is very dirty inside. This machine was not lovingly cared for...dust bunnies, considerable layer of dust on everything (except the amp and bias cards since they live in their own sheltered bay at the bottom of the deck). When I pulled the "bonnett" off (the cover panel that goes over the sides and top), as I pulled the bottom of the sides out a small pile of dirt literally dropped onto the table on each side.
• Stripped out and missing screws everywhere.
• Kinked supply-side brake band.
• I took the reel tables off to get a better idea of each motor's performance...the takeup motor is noisy and runs slow...might be salvageable but it is not healthy. Supply motor seems healthy but at some point a previous owner, in order to keep the reel tables from slipping on the motor shafts (because they stripped out the threads in one of two lock screw holes in each reel table ) drilled shallow holes on the end of each motor shaft!! Fortunately the shafts aren't bent or damaged from this beyond use...Picture of the supply motor shaft below which only has one hole. The takeup motor shaft has two...
• Pulled the headstack off...dirty, dirty, dirty. Yuck! The tape path has clearly not been adjusted right for a long time. Both guides show asymetrical wear. The erase head looks fine, as does the repro head (some wear but looks symetrical), but the sync head has a trapezoidal wear pattern...my uneducated guess is that they could be relapped, but it is a little disappointing to discover this, mainly because it is the result of negligent use. The lifters have been rotated...that must have been fun...
• Just general bits and pieces missing everywhere...

Anyway, I got the motor out and maybe in the next couple days I'll install it in the 58 and see if it changes things at all, and before that I'll probably open the motor up and see how it looks in there...making sure to put the brushes back in the way they came out!

 

[sweetbeats]

Opened up that motor out of the parts 48...

I was surprised to find that the motor I pulled from my parts 48 last night actually looks somewhat high-mileage. But it ran really smooth, and the wear inside looks vastly different from the yucky supply motor I pulled out of the 58. Fine dust from brush wear rather than bits and pieces and scoring. So anyway, the bearings are in good shape, and there's life left in the brushes...I cleaned it up as good as I could.

Took this picture to show the difference between clean commutator sections and the dirty ones pictures a few posts ago.

Prior to cleaning this motor there was some buildup in between the commutator sections, but nothing like the motor I pulled out of the 58. To clean it I used an air duster, toothbrush, and a little iso alcohol on a swab to wipe the faces of the sections when I was done. Took 60 seconds. You can see the trough being worn on the commutator by the brushes. I'm assuming this is normal, and this motor looks to have many miles left in it. The questions is whether or not it will perform differently in the 58 than the one I pulled.

To be continued...

 

[sweetbeats]

A little bit of everything...

So I got the motor back in...I don't remember it being that noisy in the 48...it is a sad sounding motor...I think maybe one of the bearings is actually going bad, but I'd cleaned it, it was soldered in so I figured I may as well test it out.

Got it installed, loaded tape and ran some basic tension adjustments/tests and y'know what? Its better! Not up to spec, but better.

I want to do some fine-tuning, but the two sides are running pretty close, and the differences could be related to the fine-tuning that I believe is needed, and/or the fact that the replacement motor sounds and maybe is tired (though it spins crazy fast).

Anyway, best note I've ended on in a bit, so I'm going to stop while I'm ahead for now.

Oh, tape packs look nice too. REW is much better, and FWD still looks great.

 

[analogkid]

Glad things are improving! Interesting that the motor seems louder once in the 58... wonder if there is something else going on? I will keep my eyes peeled for a motor, if the 48 motor works what is that part number? There is a tiny chance I may end up with anothe 42 for parts.



AK

 

[sweetbeats]

Hm...THAT might not be helping...

Well, AK, you're right. There is something else going on...I forgot about the thin thrust washer that goes between the tail bearing and the end cap...I was blowing the end cap out outside in the dark. Launched the washer and I altogether forgot it existed...found it this morning in the yard...

I'll have to pull the motor again, but I won't have to desolder it from the PCB, and fortunately all the skin is still off the deck so it should go pretty quick...

Silly...

 

[analogkid]

Found it in the yard? ROFL! Don't worry I am laughing with you, not at you... my shop floor at work is likely hiding thousands of washers and springs!



AK

 

[sweetbeats]

Thrust washers are gooooood

Pulled the replacement supply reel motor out to put the thrust washer in.

Made all the difference in the world. The motor is smooth and quiet now.

Hey AK, thanks for the sentiment on the reel motor (i.e. keeping you eyes peeled). I really appreciate it. Turns out I have motors everywhere! I forgot I had purchased a good motor on eBay some time ago to replace the motor I pulled from my good 48...So I've got the motor I pulled from the 58 (that originally came from the good 48, the one with all the crud on the commutator), the motor that originally came out of the 58 with the bent shaft (but there are good parts there), and now the parts 48 motors... Motors, motors, motors.

 

[sweetbeats]

More more more tweaking...

So when I was putting the thrust washer in the supply reel motor I noticed that the takeup reel motor was rubbing on the brake band...eccentrically. So I replaced the hub and adjusted the brakes a bit...better.

Then when I pressed play, nothing happened...pinch roller not engaging...little locking collar came loose...okay...readjust pinch roller pressure.

Pulled the lower dress panel off and reset tensions. When all is said and done it is not up to spec, but it'll and it is a little better than it was before and I don't have to have the supply tension arm spring totally maxed...packs look good.

While I wait for spooling to check tape packs I decide to start hooking things into the patch panel...then I start thinking I could just improvise and record something...ANYTHING...so I start patching in the compressor and my digital mixer (for playback monitoring...right...I don't have gear in service right now to hear the material without it taking a totally unnecessary A/D/A trip...seems there's a half naked M-520 that is quickly becoming more valuable to me...!

So...how DOES it sound???

 

[sweetbeats]

It was such an education to record some instrumental material into the 58 tonight. I recorded about a 75 second improvisation over 8 tracks using only electric bass. Tried to capture different types of sounds...plucked low range, plucked high range and harmonics, some percussive muted string slaps...random thoughts:

*Here's the thing...all my input path gear is centered around a DAW...no analog mixer. With digital it is easy to avoid needing to boost a signal past where it is at after the head amp stage since it needs to stay under 0dB's right? Not so with analog...I patched my bass right into a compressor that has a hi-z input, and took the output from that compressor channel to the patch panel and on to the 58...about the best I could do using the output level adjust on the compressor was to get average peaks on the 58 of about -10 before the output stage on the compressor would clip...not using any n/r yet so the hiss was really loud...I think I understand the value of an analog mixer for certain now...I had this logical understanding and then that deal on the M-520 came up...now I have a practical understanding, and I'm glad I have that mixer.
*Track 5 has this really annoying rythmic clickety static that is printing to tape that can be heard when monitoring the sync head...its weird. Never heard it before though tonight is the first time I've actually used all the cabling I made and the first time I've recorded anything through the n/r units (in bypass mode). I'll have do some experimenting to see if I can isolate the source, though I have a bad feeling it is an internal issue with the 58...maybe I'll swap channel cards...the noise is pretty much not there when monitoring with the repro head but really there in the sync head.
*I've been doing my bias experiments with channel 8, and I now know what a tape recorded without the right level of bias sounds like...fuhhhhhzzzeeeee. *Outside of track 5 clickitiness, and track 8 fuzziness, and undesirable hiss all around, it sounds pretty good, although it is still passing from analog to digital and then back to analog before it hits my ears. That is frustrating me...

So it records and reproduces albeit with some caviats...more work to do.

 

[analogkid]

Do you have/did you use a direct box? Hard to get a goodbass sound otherwise, unless you go to the trouble of miking a good amp.


AK