Tascam M520 Story...

[sweetbeats]

I Need Help With Selecting Wire Guage For The Power Umbilical

So when I originally talked to Tascam about what to use for the multicore power umbilical wire Jimmy said "Uh...probably 20 gauge. It would have been unshielded." But based on these current specs:

+- 15 are fused at 4 amps each

+ 48 at 2A

+6 at 4 amp and it is shared with the 11VAC

+-18 are fused at 2A

20 gauge isn't going to cut it.

Can somebody help me figure out what guage wire I need to make this cable???

 

[Herm]

Remember you are only going 15, 20 feet with the cable. And the fused amps is higher than the draw of the mixer. I am no expert but 20 to me looks to be plenty.
Heck house wiring 14 gauge is safe rate at 15 amps for 100 feet!

 

[sweetbeats]

Herm,

Remember you are only going 15, 20 feet with the cable. And the fused amps is higher than the draw of the mixer. I am no expert but 20 to me looks to be plenty.
Heck house wiring 14 gauge is safe rate at 15 amps for 100 feet!

Yeah, that's kind of what's driving my question. In fact, the factory cable is only 6 feet, which is probably the length I'm going to use for the one I build. I'm trying to keep in mind though that even though the PS is fused at those ratings, which are higher than the nominal draw, the cable needs to be able to handle at least the maximum current that may be placed on the cable, and therefore the cable needs to be able to carry more than the fused current ratings. Same as in a house...you can't (or shouldn't) put 14 gauge wire on a 20 amp circuit...the wire may burn before the breaker trips.

What would be great is if I could reliably get away with 22 gauge, because my local electronics supplier has 20-conductor unshielded 22 gauge stranded cable...it would be perfect, but I want to make sure that I wouldn't be under-spec'ing the cable at 22 gauge...I have a feeling that might be pushing it...

Its just hard to tell because I haven't found a chart that relates current, cable type and distance. I've found a couple that relate current to cable type, and those (like the one at my local electronics supplier) state that 20 gauge is only good for 1.4 amps.

HELP!

 

[evm1024]

http://www.powerstream.com/Wire_Size.htm

This link takes you to a table to has both the hookup and power capacities of standard wire sizes.

Hookup is the few inches to feet in a chassis, power if for , er, well, power. You will fall somewhere in between.

At the amperage we are talking we are not talking about flames but rather voltage drops.

Should be more or less a constant voltage drop but you would want to minimize it.

I'm thinking 16 gauge for ground and main power and perhaps 20 others.

-E

 

[sweetbeats]

Ethan...here it comes...get ready...

The neophyte-ist question(s):

Restating the pinout for the PS-520:

-15V (Pins 14, 15)
0V (C) (Pins 8, 9)
+15V (Pins 1, 2)
GND (Pins 12, 13, chassis)
+48V (Pin 16)
0V (D) (Pins 10, 11)
+6V (Pins 3, 4)
11V AC (Pin 17)
11V AC (Pin 18)
-18V (Pins 19, 20)
GND (same as above)
+18V (Pins 6, 7)

Two questions:

1. You refer to ground and main power to utilize 16ga. Would that be for pins 12 and 13 for the "ground", and then pins 1, 2, 14 and 15 for the "main power" (since, as you stated earlier that the +/-15VDC circuits power most of the opamps in the board)? I'm just trying to translate "ground" and "main power" to the pins on the multipin connector...

2. So you are suggesting 16ga. for those primary circuits, and 20ga. for all else...In looking at the chart on the site you linked, 16ga. presents an approximate 4ohm resistance over 1000 feet, and a 22amp current carrying potential...I don't know how to convert that 4ohm resistance per 1000 feet to the resistance experienced over 6 feet, but I figure it would be much lower over 6 feet and hence a minimal voltage drop...plus the 22amp current potential is way over the 4amp fuse rating. Even the 20ga. is just over 10ohms per 1000 feet with an 11amp potential. Are your wire guage suggestions simply taking into account standard over-engineering practices in wiring and/or is it your opinion that (if the original umbilical truly was 20-conductor 20-guage as Jimmy at Tascam suggested) the original cable was inadequately engineered? Ethan, please don't entertain that I am questioning your advice or judgement. You clearly have a much greater degree of knowledge, education and experience on these matters. My questions are my attempt to understand the data/ideology you are presenting.

I'm not even sure if 6 strands of 16ga. wire and 14 of 20 wrapped in heat-shrink will fit through the opening in the HRS hoods...

 

[A Reel Person]

...

The original cable is quite thin, with the entire multicore and insulation fitting nicely through the hole provided in the hood. It's almost exactly the same size, so I'd say the individual wire gauge is quite thin.

 

[sweetbeats]

Dave...thank you sincerely for taking the time to look at your cable and post up about it.

This is asking too much, but that has never stopped me before!!

Would you be willing to pull the cover off of one of the hoods and tell me if all the wires look the same size, and to take a piece of known wire and compare so I could confirm the wire guage?

If not, I totally understand. I appreciate what you have done already.

 

[sweetbeats]

Aaaauuughghaughgh the agony!!!!



Got the call back from Tascam and the socket-end of the power umbilical is discontinued...to make matters worse the Hirose 1300-series hood I found the other day at local electronics shop boneyard is NOT the same size as the one for the M520...I think it must be for a 24 or 28-pin connector. It is so close in size. At least I can use the guts of the hood (the latch and all that) in the event I need spares of that in the future. I think all that stuff is the same, just the shell itself is a different size.

Crumb...

NOW what???

I will need to come up with a long-term solution. For now I'm going to proceed as I was by unmounting the socket-end from the PS-520 and taking advantage of the slack in the harness to direct-connect that to the back of the M520...that will work for now while the mixer is on the work table in my temporary room, but it is going to be so tight in my "studio" that there is no way the PS-520 can sit right behind the mixer back-to-back...it is going to have to be mounted in a remote rack.

ARG!!!!

At least I did get the male side of the connector. Its a start right?

 

[A Reel Person]

Ok, doorstop.

Naw, just kidding.

I've thought of redoing a point-to-point soldering to install a "common" DB-25 connector, then constructing a DB-25 cable, but that's overly ambitious of a DIY job, for me especially.

I've heard online that a person did a point-to point wiring of the board and supply, but that would prove unwieldy in installations and moving,... hence the originally detachable umbilical cable design.

One thing I'm certain of, is that if there's 20 conductors in that little cable, they're very thin wires, indeed. Unfortunately, the cable is only marked with the original manufacturer and date,... no standard wire gauge or info.

 

[sweetbeats]

Dave, your doorstop comment...my heart skipped a beat...I'm very fragile right now...

But can you pull the cover off one of the hoods? There are just two screws. It would not disturb the cable mounting or solder-joints at all...just two screws, lift off the half of the hood, look at the wires and try and find a same-size piece of wire of known guage...couldjacouldjacouldja????? YER NOT DOING ANYTHING ELSE RRRIGHT???????

I'D BE SO HAPPEEEEEEEEEE!!!!!!!!!!!

Seriously...couldja?

That is an idea about the DB25...or even a CN24 (cinch 24-pin...might be a bit better contact surface...) MAN I could do that...I built that crazy CN50 to ELCO 38 sync cable for the 58...I could DO that...If...if the CN24 connector lugs fit the hole spacing in the M520 and PS-520 chassis...oooooooooooooooooooooooo ...I think...I think I HAVE a CN24...wait! Its a cable mount for the MASTER I/F cable for the synchronizer... But wait again! The ES-50 has the chassis-mount connector...or I guess I could just find a spec sheet on the internet...

Okay. Is using a good quality cinch connector a bad idea for low-voltage power interconnect??

And DAVE...the wire guage...WHAT OF THE WIRE GUAGE MAN?!?

Too much coffee. Sorry...

 

[A Reel Person]

I was proofing a DP-02CF recording test, man.

I was hesitant to burst open the hood, lest the solder joints prove to be brittle. That's as yet TBD. I'm not much with a screwdriver around the house, anymore.

So, what's the deal on wire gauge? The bigger the number, the smaller the gauge? Wouldn't 22 be very thin? If I were to burst open the hood to have a looksee, I'd have no standard gauge wire around to compare it to, anyway.

I've also heard a while back of someone detaching the connectors and just mating them, as you're proposing, with the P/S unit located just behind the board. It may not get any better than that!

 

[A Reel Person]

Double post!

Double frickin post!

 

[sweetbeats]

Dave, that's cool...22 would be pretty thin yeah. Telephone wire is, like 28 guage. The bigger the number the smaller the wire. Snake cable or mic cable conductors are typically 22-24 guage to put it into perspective. I don't think you'd disturb any solder joints if you opened at as the cable jacket is fixed to one half of the shell, and the connector itself is screwed to the same half, so you can actually remove one half of the shell without disturbing the joints/cable at all.

No prob if you're not into it, it would just be really cool to have a definitive word from an owner of the real deal...I might be able to tell from even a picture of the opened hood, and/or a measurement of the diameter of the outer jacket.

Can you help me?

I respect you...if I need to just go take a nap just say so.

Thanks for whatever you can do.

 

[kimo]

Yo Beats,
My friend is building that cable for me right now. I have a call out to him to ask him what types of wires he is using. You'll be the first one to hear about it when he gets back to me. Any specific questions you want me to ask him?

 

[sweetbeats]

Yes!!

What guage cable is he using, and where did he get the connectors???

 

[evm1024]

Those are sumicon 1600 connectors (Corrrect me if I'm wrong). You might (have already) gotten the part numbers and sent an email off to Hirose USA to see if they could help you.

Digi Key has the 34 pin connectors but not the 20 that I could see.


Also the pdf for the connector specs the pins at 3 amps which means that they are for 24 gauge or so.

Regards, Ethan


PS I'll still give you $100 for it!

 

[sweetbeats]

Those are sumicon 1600 connectors (Corrrect me if I'm wrong). You might (have already) gotten the part numbers and sent an email off to Hirose USA to see if they could help you.

Yeah, yeah!! I just discovered the Sumicon 1600 reference this afternoon and sent a message to Hirose to try and confirm the pin pattern!

Next will be the challenge of finding a place to sell it to me...

Digi Key has the 34 pin connectors but not the 20 that I could see.

Hmm...Thank you for that...very much...maybe I'll contact them tomorrow to see if they can get the 20's.

Also the pdf for the connector specs the pins at 3 amps which means that they are for 24 gauge or so.

The plot thickens...How can they (Tascam) fuse a circuit with a 4 amp slo-blo fuse and then spec a hookup path that is rated for only 3 amps??? I don't get it. But it would be great in a way because then I could just use the 22ga. 20-conductor unshielded cable I found locally right?? Or will that choke the mixer? What to do??

PS I'll still give you $100 for it!

Ethan, my friend, this may shock you, but I do believe we are getting further and further from the possibility of a transaction...

BUT...When I get the 48 put together and get it placed with the M520 and the 58 I'll have you over and we'll have a beer together and look at those 28 glowing VU's

 

[sweetbeats]

Its alive...ALIIIIVE!!!

There is also a video I took of the momentous occasion:

YouTube

So Those 4 VU meters don't light...not sure where to start with that, and there are a number of LED's that flicker...mainly the eq ON indicators. I'm guessing it would be good to:

1. dribble a little deoxit into every pot and exercise it using the shoelace technique
2. dribble a little deoxit into every switch and exercise it
3. tip the modules up and disconnect each connector, apply deoxit to the contacts and connect and reconnect the connector a couple times

and see if that takes care of the little niggling things. Then anything else that remains I can dig into deeper.

I did plug in the headphones a do a quick test on a couple things just using the SOLO buss and there is nothing out of the ordinary so far there which is good. I can tell you that I can hear the hispanic radio station really well though if I position the SOLO pot to the right position......the transmitter is 3 blocks away.

The oscillator works too.

 

[analogkid]

Beautiful!



AK

 

[kimo]

Right on, Man!
You got me all excited about firin' mine up!
I think the video may be corrupt though. I could watch your intro, but right before you press the button, the video stops itself. I tried it on a couple of different players, mac and pc, but no luck.

All the same, Congrats brotha!!