UC2525ADW Hell in Artesyn 73-551-0048 210W 48V DC O/P Module!!!

[Chris56000]

Hi!

I wonder if anyone can help me with getting a UC2525ADW going in a dead Artesyn 73-551-0048 48V O/P Module at work please?

First of all the UC2525 datasheet is useless as a guide as there's no application circuits of any sort - let alone anything that resembles the convoluted strange nonense Artesyn have used in this module!

The module is one of three used in an Artesyn MP1 Power Supply chassis, the other two are a twin 5V module which is awaiting parts and a twin 15V module which is repaired and in perfect working order! (I've had the MP1 and the dual 15V Module on soak several days continuously)

The MP1 chassis is basically an active PFC pre-regulator stage that provides 380V H.T. along with an 18V Housekeeping LT Supply,
plus "DC Power OK" and "DC Power Return" and "Sync" signals on a smaller 5 pin connector, one for each module. The 380V HT and the 18V LT supplies are working perfectly - as I explained I've had the main chassis running several days!

The problem I have is the control PCB for the 48V module - I'd to remove the UC2525ADW chip because the original appeared to be dead, and in doing so the pads for pins 1, 2, 3 and 4 all disappeared off the PCB!

I can't find any obvious traces of where pins 1, 3 and 4 are supposed to connect to, pins 3 (Sync) and Pin 4 (Osc Out) could possibly be N.C., I found a pad from Pin 2 (+In) with a resistor pad that goes to a 0805 1k00 1% resistor whose other end disappears into the undergrowth amongst the timing/discharge components associated with pins 5, 6, 7 and 8 but I've not been able to sketch anything that looks sensible!

What really is daft, tho' is pin 5 (CT) goes via an 8k20 1% 0805 straight down to chassis-earth and pin 6 (RT) goes to an 0805 SMD capacitor! - that can't be right surely?! - I know I didn't simply miscount the pins!

Can anyone offer me any help or guidance with this before I get another bollocking at work from my Fat Controller of a manager please? (He's totally non-technical!)

As I said at the beginning, the datasheet is useless for trying to sort out this incomprehensible mess Artesyn designed!

If anyone reading this has, or can get access to, one of these 73-551-0048 Artesyn Modules and can post a really good photo of the tracks and the SMD all round the UC2525ADW even that would be a great help!

Artesyn's documents on their website refer to a "UL Labs Design Report" that contains a schematic and BOM for each module but needless to say I can't find this document - can anyone suggest where I might get a copy of this from?

Sorry for the long post - I'm really, really stuck with this one!

Chris Williams

[coromonadalix]

have you checked this link :

 http://www.ti.com/lit/ds/symlink/uc3825a.pdf

[Chris56000]

Hi!

Not whilst I was at work I must admit!

I couldn't make out the number of the one I took out as it was covered in yakky stuff, but if I'd put the wrong device in there I certainly would get stuck with a dead unit!

The '2825 matches the resistor and.capacitor I found on the PCB, so I'll try a '2825ADW in it – the other two modules are definitely '2525s, one is working and the chip on the other hasn't been disturbed – the '2525 and '2825 have the same o/p, power, ref and earth pins so I could easily have erroneously thought that it was a '2525 I was dealing with!

What's bothering me tho'., is I can't find anything other than what looked like an unconnected pad on pin 1 – it it possible that 1 might have gone to 3 or 4 as a unity–gain follower with control on pin 2 – pin 2 has a 1k00 ±1% 0805 resistor disappearing into the undergrowth?

Chris Williams

PS!

The pin designations I'd used in my first post referred to the '2525 which I'd erroneously thought was the device that had been originally used by Artesyn – the external components I found on the PCB certainly would NOT make sense with a '2525 but they do with the '2825!