Otari MX-80 VU Meter Lamps

[miroslav]

[MENTION=94267]miroslav[/MENTION] all the Teac lamps are 8V powered by either 6V AC or 5V DC power. I think the correct amperage rating is 100mA...that’s what gives the correct illumination.

I'm just saying that the Otari spec is to use 6V lamps, and that's the voltage they are getting...so I would go with what the spec calls for.

Also...the point I'm making is that rasing/lowering of the voltage affects their brightness (because it directly affects the current)...so that's why I'm saying that switching the VU lamps to 8V while feeding them only 6V will make them dim down...but it may not be enough to be a problem.


Here's something I got of this website: BulbAmerica
"For example 120V and 130V bulbs are interchangeable and the pros in using a 130 Volt bulb are: cooler burning bulb, less energy use, longer life and better handling of voltage surges. The cons are lower lumens output (not as bright) and lower color temperature."


I agree that the 8V will still work...it's just a question of will they be bright enough.

 

[jpmorris]

What do you guys think of the Adams Smith Zeta Three box? I have seen that model pop up repeatedly in my searches on the topic?
Also, thanks so much for the suggestion on ceramic screwdrivers!! That makes total sense and I'm sure you just saved me from going through the same trouble as I doubt I would have thought of that!

I don't have any experience with the Zeta, I'm afraid. The setup I'm using has a TASCAM 8-track chasing the 24-track. I never figured out how to get the MX80 autolocator to do anything useful, but the TASCAM can do automatic punch-in. So things like vocals and bass which are going to take a lot of attempts and punch-ins to get right, I'll do those on the 8-track first and then copy them to the Otari afterwards. (TASCAM parts are cheaper and easier to find!) The backing tracks are usually sequenced and require less fussing around, so I record those direct on the MX80. Point being, because the TASCAM is happy to chase other decks, I haven't yet needed to try and lock the Otari to anything else. I have the computer chasing the MX80 using a Phil Rees MTC box, but because I'm doing MIDI sequencing with hardware synthesizers, jitter is not a problem for me.

Another thing about lining up the channel card input levels if you need to do that - an extender card makes this a lot easier since those trimmers are on the component side of the card, not the edge-mounted ones you can get at via the front panel. However, you can line up the input/output levels without one.
The trick I used before I obtained an extender was this: I removed card 24, and put card 1 in its place (while the machine is powered down, obviously). On the 24-track version, there is a gap to the right where the channels 25-32 would sit, so you can stick your hand and the (non-conductive) adjustment screwdriver inside the machine and alter the trimmers until you get the desired input or output level - depending on which trimmer you're adjusting. Then you power the machine down again, and put the #1 card back in the #1 slot, take card #2 out, put that in slot #24 and so on until you've finished, and which point you put #24 back in. From the sounds of it you have all 32 cards so you'd probably need to remove a few of those first to make space, especially if you're only ever going to run in 24-track mode anyway (keep the others somewhere as spares, the machine just ignores the missing cards).

 

[ecc83]

I'm just saying that the Otari spec is to use 6V lamps, and that's the voltage they are getting...so I would go with what the spec calls for.

Also...the point I'm making is that rasing/lowering of the voltage affects their brightness (because it directly affects the current)...so that's why I'm saying that switching the VU lamps to 8V while feeding them only 6V will make them dim down...but it may not be enough to be a problem.


Here's something I got of this website: BulbAmerica
"For example 120V and 130V bulbs are interchangeable and the pros in using a 130 Volt bulb are: cooler burning bulb, less energy use, longer life and better handling of voltage surges. The cons are lower lumens output (not as bright) and lower color temperature."


I agree that the 8V will still work...it's just a question of will they be bright enough.

Yes, running an 8V incandescent lamp at 6V will reduce the light output and make them a bit redder but it increases longevity massively!

My example of 6V lamps in guitar amps is given becuse they have a very hard time of it. Not only battered by vibration when the amp is running but subject to mains variations. We should get a nominal 230V but 240 is much more common and 250 by no means rare! The fact that valve filaments rarely fail, even in gitamps is precisely because they "underrun" and glow just above cherry red. Amps heater supplies can be closer to 7V as well.

Of course the tape machine lamps are not subject to 130dB sound attack but they ARE a PITA to change. Personally I would just fit leds. When was the last time you had one of those fail?

Dave.

 

[miroslav]

When was the last time you had one of those fail?

I got the deck back in 2012...mind you, I don't run it 24/7, but I was using it a lot for awhile, then a bit of low use, and now will be ramping use up again.
When I got it I replaced the dozen burned out ones. Since then, only one more of the original bulbs has gone out, and none of the new/replacement bulbs.
So I don't see it as a real critical point, especially since each VU has two bulbs, and if one goes out, the other is still lighting the VU to an "ok" visible degree.

The new 6V bulbs are better and a bit brighter...so I would love if they all were the new bulbs, but I saw no reason to remove working original bulbs just for that.
My real point is that if the 8V bulbs are too dim, all you'll get is this sorta glow (kinda like my one meter with the single working bulb)...but from any bit of distance, there is not enough crisp brightness to really see the needle action.
That may not be an issue for some folks who have a different setup in the studio, or for someone who is purely engineering and is near the deck most of the time...but for me, when I step across the room to play an instrument or do a vocal, and I'm the only one there, being able to see what the meters are doing from a distance is important so I can properly set levels without having to go back-n-forth and all that.

My old TASCAM 3500 console was great for its bar graph meters, which were multi-colored and very bright and easy to see from a great distance...and since I would use the console for cue monitoring when tracking to the deck...if I couldn't quite make out the VU reading on the deck, I could glance over to the console.
Now the deck VU visibility is even more important because my current Trident console also has VU meters, and they are a bit smaller with no Peak indicator (like the deck has)...plus with the position of the console, its VUs are off to the side, and hard to see from many angles....while the old TASCAM bar graph meters you could see clearly from most any angle. Still...I'm happier with the Trident...but now I do depend on those VU meters on the Otari that much more...and TBH, I've thought of changing out the one bulb, 'cuz the one VU meter looks like it has a black eye......which I can actually do pretty easily by simply swapping out the whole VU with one of my spares, which is not as involved.

Anyway...the 8V bulbs may be OK...it's hard to know how much different the brightness is until you have both 6V and 8V bulbs installed in two VU meters, side-by-side...but I would still go for spec and brightness rather than worry about longevity, and like I said, the LED option doesn't appeal to me.

 

[sweetbeats]

If Otari spec’ed the 6V bulbs then that’s the place to start. I only brought up the 8V lamps because that’s all I’ve ever dealt with as far as the Tascam stuff.

 

[miroslav]

So I was checking out the link posted earlier to those bulbs...and saw there was a Spec sheet for the bulbs:
https://www.jkllamps.com/pdfs/AXIAL_SPECIAL_T-1_1_4.pdf

Considering the discussion about the 8V lasting longer...I noticed in the sheet that they are rated for 5,000 hours while the 6.3V for 10,000.
Granted, running the 8V bulbs at 6 volts may help them go longer...but I doubt it would be as long as 10k hours or beyond.
So there wasn't much to be gained by using the 8V bulbs in the Otari...and they may not even last as long as the 6V spec bulbs.

Either way...5k hours or 10k hours is a pretty long time for the home/project users.

The other less favorable thing I saw about the 8V bulbs is that they are over 2cm...which I think is going to be too long and/or will require some wiggling with the leads to get the bulbs in....it's going to be real tight. The 6.3 bulbs are shorter and would fit easier.
The OEM Otari bulbs are about 15mm...and the ones I bought were about the same.

 

[jpmorris]

The other less favorable thing I saw about the 8V bulbs is that they are over 2cm...which I think is going to be too long and/or will require some wiggling with the leads to get the bulbs in....it's going to be real tight. The 6.3 bulbs are shorter and would fit easier.
The OEM Otari bulbs are about 15mm...and the ones I bought were about the same.

Something which is critically important to note is that the edges of the meter are grounded! If you use a too-long bulb or LED/resistor combo that sticks out the side and contacts the silver tape around the edge of the meter faceplate, you will end up with strange failures which may include the lighting for the meter going dead, popping the 6V breaker at the bottom of the machine, or 6V AC from the lighting leaking into the meter input and making the needle(s) go wild. Check that there's no continuity between the two circuits after you've put the faceplate back on the meter.

 

[miroslav]

Something which is critically important to note is that the edges of the meter are grounded! If you use a too-long bulb or LED/resistor combo that sticks out the side and contacts the silver tape around the edge of the meter faceplate, you will end up with strange failures which may include the lighting for the meter going dead, popping the 6V breaker at the bottom of the machine, or 6V AC from the lighting leaking into the meter input and making the needle(s) go wild. Check that there's no continuity between the two circuits after you've put the faceplate back on the meter.

Yup.

That's why I said it will take some wiggling with the leads. There's only so much room in there, and you have to kinda fold them back and behind...etc.
I guess one way to avoid the contact would be to add some heat-shrink tubing to the bare leads, but again, there's not a lot of room there, so a smaller bulb, even by 4-5mm makes a difference with the ease of getting them in there.