Hypex SMPS400A180

[DanielIt]

Hi. I have one monitor speaker that have 2 bridged UcD180 modules on 8ohm load for bass and 1 of same module on tweeter duty with this power supply.After 2 years of working ,last week on power up it wont work.As an electrical engineer myself i found that on power up 2 transistor of the supply board poppd up.The 2 in question are T7 and T14. The first is an smd part and i cant read it what it was,with some intuition and a little schematic i draw i think is an high voltage pnp part.The T14 is an npn KSP44.I already emailed hypex to ask what part number it is so i can change it myself and no answer for now.I must mention that the fast 5A fuse is working,the bridge rectifier too and the caps are good.Is only missing the low voltage startup part.
I ask is anyone have a module at hand if can make an macro picture of the tiny transistor to see the number printed.
Thank you in advance.
Daniel

 

[JonSnell Electronic]

Normally the SMD tuning capacitors crack on the board and then it overheats and dies. Hypex will not supply any information.
T7 has 1Bt printed on it. Have you checked U1 with a power supply to see if it oscillates? The two transistors feed U1.

 

[DanielIt]

U1 is not alimented.in hes path is T10 marked BCP56 that is another NPN transistor and it seems measured still good.I am gonna remove another transistor 1Bt from the board to see what type is and try to change it accordingly.Thank you for your big effort,will let you know how it goes when the KSP arrive in a few days.
Daniel.

 

[DanielIt]

Measuring another transistor marked 1Bt on the board is seems to pe an PNP device,as i was suspecting according to the schematic used.I do not have an osciloscope to see if U1 is swinging.

 

[DanielIt]

By measuring another 1Bt transistor on the board it looks like an PNP device.I could supply the U1 with 12V to see if it oscilates but i dont have a scope to see it.Any other way to aknowledge if it oscilates?

 

[JonSnell Electronic]

It oscillates at anything from 45kHZ to 300kHZ depending upon load. A scope is required.
Do you have a schematic you could email me please?

 

[DanielIt]

i only have drawn the 3 transistors i could reverse engineer from the board.From the hypex website i could get that the board is switching at 100khz.I will try to draw it in eagle to see if i can.

 

[DanielIt]

I made a quick drawing in eagle of the primary circuit.The diodes are only simbolic,there is a bridge rectifier and filter,and are all good.There are too many smd components on the board,that for reversing and making a full schematic would mean to desolder them all and throw away the board in the end.My scope is to try and repair it as it is with the only 2 transistors,otherwise will buy a new one hopping it will be exactly the same and will work in my powered speaker.

 

[DanielIt]

Back on the right track today.Even if it was more than 3 weeks ago i had a very pleasant surprise today when i received an email from Hypex customer service.I had brough a new supply from then 3 week ago and was very happy that i received it within 2 working days and my cab was working again.Now i have the part list of the transistors i need to repair my old one and keep it as spare.The 2 transistor are
T7 - BC846BW and T14- KSP44.
Hope this will be usefull for anyone with same problem.

 

[arnoldsq]

I know this is resurrecting a really old thread, but you wouldn't happen to have T37's part number would you?

 

[drMordor]

What I have

 

[arnoldsq]

Thank you for the drawings. I did get a parts list for all the components for the board from the company now also.

 

[ferino]

I need the resistor value of R55 on the SMPS400A180 thank you very much

 

[eriklhayes]

Repair Fix?

Did replacing the two components work in repairing/fixing the power supply.? I just found that mine has those two components cracked/burned.