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Amek TAC Series 350 Power Supply
Old 26th July 2005
  #1
Gear Nut
 

Amek TAC Series 350 Power Supply

Hello everyone . . . I have an opportunity to purchase an Amek TAC Series 350 Power supply . . . I have an Amek TAC Scorpion . . . there is nothing wrong with my current power supply . . . but I may be able to purchase this one real cheap and was wondering if it would be an improvement over the one I have (less ripple . . . more voltage) . . . would this be a worthwhile purchase?

Thanks,

Justin
Old 26th July 2005
  #2
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brianroth's Avatar
 

Sorry, unfamilar with the power supply model. I presume it provides the same voltages, and available currents, as your Scorpion supply, and has the same interface connector.

If so, then get it as a spare part.

Bri
Old 8th January 2006
  #3
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Hi
If memory serves me it will not be powerful enough to keep the Scorpion going for long. I think it will overheat otherwise it would just plug in as the 4 pin XLR is the same. The 350 is a big brother to a 250 supply (bigger transformer and extra transistors) but is still insufficient for a Scorpion. Scorp supplies were rated for about 7 amps, using a 5 amp and a bypass transistor. The 350 uses a 1.5 amp regulator with a bypass transistor making it about 2.5 amps. The 350 adds another transistor making it about 3.5 amps.
Matt S
Old 31st January 2006
  #4
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4 pin xlr for tac power supply??

i have recently aquired a tac scorpion mixing console with seperate power supply. can anyone tell me where to find the cord that connects the mixing console to the power supply. i havent had any luck locating one to purchase. thanks
Old 31st January 2006
  #6
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Hi
All the supplies 250/350/750 used on the smaller desks use a 4 pin XLR wired pin to pin 1=1, 2=2 etc using 0.75mm or 1.0mm per core cable.
Colin's price is not bad if you are not into soldering neatly, it is a bit of a squash in there!
Matt S
Old 22nd November 2007
  #7
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Hi, I have a TAC B2, the psu was stolen...and I was using a home made psu for the B2...after a wile the diy burn...where can I find a schematic of this psu??

thank for you time!!!
Old 22nd November 2007
  #8
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Hi
The circuit is in the back of the manual. It is a variant of the circuit shown on the data sheets for the LM317 and LM338. Apart from layout and some component changes several of the AMEK supplies are very similar, having a variable regulator plus an extra 'pass' transistor to boost the current capability to around 3 Amps and 10 Amps as appropriate.
Matt S
Old 23rd November 2007
  #9
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Hi, can you tell me about the voltajes? i lost the manual as well :(
Old 23rd November 2007
  #10
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Hi
The audio rails are plus and minus 17.5 Volts. Current depends on desk size. a 350 gives about 3 Amps, others are 5 or 10 Amps, although the consumption from the desk should be about half the rating of the supply.
Matt S
The Phantom is 48 Volts about 100mA using a LM783 usually.
Old 23rd November 2007
  #11
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Can you tell me where can I find a pdf manual for the B2???
Old 29th November 2007
  #12
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can i try something like this????

Audio Mixing Console - Part 3
Old 29th November 2007
  #13
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Hi
You could but as it says it is not current limited. Read the application notes for the LM317 / LM338 and you will see how it can be done. Google the part number and read the National Semiconductor notes.Having the regulator on the same heatssink as the 'pass' transistors helps protect them agains burnibng out if it all gets too how as the regulator has thermal protection inbuilt, a feature not seemingly appreciated by Rod (in the article).
Matt S
Old 30th November 2007
  #14
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thanks so much, I will do the seach...until now I can not find the schematic of the tac psu...none...any ideas???
Old 30th November 2007
  #15
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This is what I've found this far...

http://mixguides.com/microphones/tip...MEKTAC.WEB.jpg

but it sais "negative regulator"...they use the lm 338 for both supplys??? conecting the + pin to 0V to produce the negative output?
Old 30th November 2007
  #16
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Hi
Use 2 times the circuit you linked to and you are almost there.
Yes the Positive of the second regulated output joins the Negative of the first output, this junction being the 'O Volts' ground connection.
The power transformer needs to be about 20 or 22 Volts AC and current should be 1.6 times the required DC current, so for a 5 Amp DC supply the AC current is around 8 Amps.
The regulators need BIG heatsinks unless you are using a fan. When running the desk you want the heatsink temperature to be only a little over the max your hand can tolerate, preferably lower. You should be thinking of 0.5 degree Centigrade heatsinks for EACH regulator to achieve this kind of temperature. These must be mounted properly in FREE air (not inside a box) unless you use a fan. Use thermal compound / thermal washers and bolt the regulator up tight.
I would use the LM338K (steel) regulator not the plastic TO220 version because you can get the heat out of it more efficiently, which translates into longer term reliability.
Small heatsinks and 'skimping' could cost you dear if one fails and it passes the unregulated supply into the desk.
Matt S
Old 30th November 2007
  #17
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thanks so much, I just find somewere else a schematic of the PSU...but i don't know if this si the correct choise for a amek/tac B2...the +V rail is current boosted, but the -V no....what about this???
Attached Thumbnails
Amek TAC Series 350 Power Supply-original-power-supply.jpg  
Old 1st December 2007
  #18
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Hi
Yes this the schematic for the AMEK / TAC power supply used on many desks and is suitable for the B2.
The boosted rail was mostly necessary for desks with a significant number of LED lightmeters as they draw significant power from the Positive only.
Having the schematic is only part of the story. Unless you do what I said above about BIG heatsinks it will burn out.
Matt S
Old 1st December 2007
  #19
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what about the phantom?...the schematic shows a LM317, what about the 783???, I had trouble finding the 783 data sheet.
Old 1st December 2007
  #20
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Come come now!
I just googled TL783 and it took me to the Ti website with the PDF datasheet.
You are not trying!
An 'ordinary LM317 should not be used as it is beyond the voltage rating unless it is the HVK version.
Matt S
Old 1st December 2007
  #21
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Hi again...here are some pictures of the B2, and a burn out home made PSU...I was wondering if is really necesary to build the boosted +V rail, so you said this was designed to feed led meters and stuf like that...as you can see, the B2 is a rather small (and old, but good sounding) mixing desk...Can i build to of the non boosted rails + the phantom?...keeping in mind the disipation issues you pointed early. take a look of the PSU picture...what you think?
Attached Thumbnails
Amek TAC Series 350 Power Supply-ssa44110-small-.jpg   Amek TAC Series 350 Power Supply-ssa44115-small-.jpg  
Old 1st December 2007
  #22
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sorry about the 783 thing, I'm in chile, so there's no much electronics market here in the end of south america...but the question remains...the schematic shows a 317...as you said the HV type.

Thanks very much!!!
Old 1st December 2007
  #23
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Hi
I can see why the original burned out, the heatsink is FAR too small, even with a fan.
The LM317 HVK is not so common so the TL part would be better, also because it is rated for 120 Volts and is essentially the same as the LM317. The HVK version is only rated to 60 Volts which is actually a bit close as the DC before regulation is around 55 volts or more.
The rectifiers should be 35 Amp types (not a lot more than 'small' ones).
The desk you show would be fine with unboosted circuits as there are no meters.
Do not let hot air from the regulators go over the capacitors, it will age them prematurely.
If using a fan, blow it over the caps, then transformer then regulators. The rectifiers need heatsinks and could be on the bracket as the regulators.
Don't use preset resistors but adjust the values of the resistors to get it set to 17.5 Volts (do this with the desk unconnected but put a load resistor on it while testing. 10 Ohm 'gold block' type 25 Watts on heatsink would be sufficient.
Matt S
Old 4th December 2007
  #24
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Hi, about the transformers....de burned out psu has one trnsaformer with both rail recifiers conencted in paralell and a diferent winding for the phantom...I need to buy a new transformer...what you sugest, until now I havent found the power specs of the B2....the transformes need to have 2 20V windins and 1 40V winding??? for the 20V, 1A, 2A, 3A???

(I guess that 1.5A for each rail woud be enough)

Thanks!!!
Old 5th December 2007
  #25
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Hi
You want 2 windings of about 20 Volts at 3 Amps minimum. (possibly 2.5 amps if your desk is small).You also need 40 volts at about 150mA. The original transformers were custom made so you will probably use 2 transformers as dual 20 volt windings are 'standard'.
The rectifiers are definately NOT wired in parallel!!
Matt S
Old 5th December 2007
  #26
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Hi, the B2 is 16 channles only...so 2.5A may be fine
Old 6th December 2007
  #27
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Hi
Probably. Build it and try it but leave space in the box for a more powerful transformer just in case.
Don't forget, NO components should run hotter than comfortable hand touch if you want it to be reliable.
Matt S
Old 7th December 2007
  #28
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thanks si much for your help, please forgive me for my english, I'm from Chile, south america...Here we have a small electronics market, and a smaller electronics tecnicians market (sound especialists at least)...

once again, thanks very much.

By!!!!
Old 7th December 2007
  #29
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Another question about AMEK power supplies

I am trying to keep a TAC Bullet 20x4x2 mixer that had it's power supply pitched out of a landfill and am wondering how much of the previous info applies to constructing a replacement?

[email protected]
Old 7th December 2007
  #30
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Hi
Basically all of it.
A 24 channel desk probably wants between 2.5 and 3 Amps so a 5 Amp supply would be suitable, use a pair of LM338K (steel) regulators, 20Volt 7 or 8 Amps AC per winding, BIG heatsinks or medium heatsinks plus fan.
Matt S
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