TAC PSU ONE custom

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kante1603

Well-known member
Joined
Dec 2, 2009
Messages
1,961
Location
Munich,Germany
Hello everybody,


I hope this is the right place to post.If not please moderators move it to a place where it fits better.


So I have three racks containing a bunch of preamps and eqs from TAC.
I was looking for a beefy psu to drive them with the option to even drive a bit more.
Asking Cemal (member sahib) over at TAC he offered me to a custom version of his new PSU ONE.
It is a fantastic psu I must say.Although I often thought about a smaller form factor I never found a transformer that fitted in a case less than 2ru.
This psu is 1ru only,but beefy enough to drive my racks with ease,it only gets hand warm,not more.
Cemal has custom made transformers that do fit in very well.
He offers different types of them,in my case it was two transformers at 150VA each.
A single one has two primaries (2 x 115VAC) and five secondaries (2 x 16VAC,2 x 24VAC and 1 x 48VAC for phantom power).
The whole design is layed out in a way that you can easily set up the psu as you like it,great!
I needed a +/- 16VDC and +48VDC only,but the main rails delivering a good amount of current,so you can double up the 16v secondaries from each transformer to get more "juice".
The heatsinks are done in a way I have not seen before:They have holes where you can sink in the regulators! This helps definitely to keep the form factor on a low height.Cemal told me the heatsinks are custom too.
The rack itself is made from steel (except of the fp),having threads for countersunk screws and is built like a tank.It even has some threads inside where you can mount a pcb e.g. to make a distribution board for your dc wires.I did it that way.
On my build I have three dc wire cables going off,having 9 pole EPIC connectors for my TAC racks.
Cemal was so kind to get a custom laser cut facia made for me,what a great service!


I want to show some pictures here,


have fun,


Udo.


Edited typo.
 
Mrosso said:
@sahib and @kante, I'm trying to find the TAC 1U  PSU schematic. I have the schematic with the main PSU PCB, but nothing with how to hook up the two toroidal transformers.
Thanks
Hi Mrosso,


if  you have a psu kit already then I'm sure Cemal (sahib) will help you with them.Just drop him a mail and ask for  it,he has very nice drawings of the complete setup.
It depends on what type of psu you're about to build,so wether you go for 51x or VPR (500 series) or anything else.As said it is totally flexible.Basically it is about collecting the correct wires to add up currents.These should be in phase of course.Then putting them to the screw terminals.Also the mains wiring to and from the input voltage selector must be done carefully,but,it is all on the silkscreen.
As soon as you have contacted Cemal it will be very clear to you,it's easy.


Hope to have helped,


best regards,


Udo.
 
I am in the midst of building this now and have a couple of questions:

1) I only need the +/- 16 volt and +48 volt supply. Am I able to wire the second toroidal transformer to the 24volt connections, using the 16 volt outputs of the transformer, and use it to power a second rack?

2) If yes, must I change the value of the resistor at the led indicator so it will work when passing +/- 16 volts?

3) Or, will the single toroidal transformer power two racks? If so, I suppose I am better off wiring the entire supply as designed so as to have the +/- 24 volts available in future?
 
Spiritworks said:
I am in the midst of building this now and have a couple of questions:

1) I only need the +/- 16 volt and +48 volt supply. Am I able to wire the second toroidal transformer to the 24volt connections, using the 16 volt outputs of the transformer, and use it to power a second rack?
[font=verdana, arial, helvetica, sans-serif]If you have the same two torroids then yes,basically it is a "mirrored" psu,so you can use the 24v rails as 16v rails.The only difference is that there is just one 48v rail.Please have a look at the pics in my first post here.Does it look the same (torroids,wire colours etc.)?[/font]
[font=verdana, arial, helvetica, sans-serif]If so you just need to change R7 and R8 to 2k4 instead of 3k9,the same as you have in the 16v rails (R9 and R10).These set the correct voltage range in addition with the trim pots on the regulators,in this case from 24v to 16v.[/font]
[font=verdana, arial, helvetica, sans-serif]Then just use the correct (16vac) wires from the second torroid and wire them to the "former 24v" connectors.
[/font]



Spiritworks said:
2) If yes, must I change the value of the resistor at the led indicator so it will work when passing +/- 16 volts?
Yes,change the preresistors to the same value as your "original 16v" led indicators to 1k5 ohms.




Spiritworks said:
3) Or, will the single toroidal transformer power two racks? If so, I suppose I am better off wiring the entire supply as designed so as to have the +/- 24 volts available in future?
If you want to drive two racks as 51x then use the 16vac wires from one,the 24vac wires from the other torroid.
This way you can draw the max. current from both transformers,it will drive two racks easily.
In my case I used the 16vac wires from both transformers and modded the 24v rails to 16v,same as you wanted in your first question.My psu "eats" three racks at 16vdc and even doesn't burp,and I'm sure it can drive more


Do you have the drawings,silkscreen and schematics from Cemal?
These clear everything up easily!


Hope to have helped,


best regards,


Udo.
 
I decided to build this as designed, using one transformer for the +-16 volts and the second transformer for the +-24volts.
I wired the 16volt one first, powered up and checked things out. Everything worked fine, and the output voltages were almost perfect, even without adjusting the variable resistors. 48volts was spot on, +16 showed 17volts and -16 showed 15volts. All indicator LEDs shone properly. Very good testament to the design of this supply.
I then installed the second transformer for the 24volt side and, when powered on, blew the main fuse. However, LED indicators for the +-24 volts lit up and faded away as the capacitors emptied.
I re-checked all connections and  solder joints, etc., and everything seems in order. Where should I check? What size should the main fuse be? The one supplied is only 1amp @ 250volts - is it big enough for the current draw of the two transformers?  Is it possible a bad transformer?


 

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Hi,


from what I know my transformers are specified at 150VA.......each!,and I'm in a 230vac land.
Meaning around 300VA in complete,so roughly 300 w /230 v= 1,3 Amperes if "calculated" this way.
Yours look like switched to 115vac,so you might want to go even higher.
Also there will be a certain inrush current that should not be underestimated.
So for me it looks like you're on the very low side with just 1A (slow blow?).
I'd put in a way higher one for let's say a second or so with your hand on a mains switch.
Maybe some trial and error,but should work o.k..
I remember my fuse blew too.......


If you want to go the safe way then just compare the dc resistances on all windings from both transformers.
Under no circumstance should there be a short,neither over a single winding nor between them.
You'll have to lift the wires from the circuit board of course.Also measure the primaries.
This way you can sort out if a transformer is damaged or not.


Hope to have helped,


best regards,


Udo.
 
I am only an e-mail away but thanks to my good friend Udo.

One has to really work hard to damage the transformer. So, I would not worry about that.

 
I put in a 5Amp fuse and everything holds and is working correctly. Thanks to Cemal for a beautiful piece of equipment. I will finally put this into service this week.
 
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