[Repaired] SMPS Repair: Name the Controller IC with the blown top!

[Towger]

I was presented with dead a LED PAR from one of the better Disco Dave manufactures of such equipment.
However, unlike the the big boys in the world of entertainment lighting they don't (or won't to me), supply schematics.
They will sell me a new power supply for $140++, except they will not have stock for another 2 months. Must be a common fault...

Anyway the patent is a  '24V 4.16A 100W' very basic looking SMPS, of a small non standard size.
It presents the following symptoms:

Main fuse and PCB fuse were intact.
Q1 - Mosfet 26NM60N - Shorted
RS1 - 0.22Ohm 1% - Open (1MOhm)
D2 - (Cooked cannot read) - Shorted
C4 - 3A332J Capacitor - Cooked by D2 (.96uf!)
R4 - 10 Ohm (?? Print missing from mid digit) - Open
U1 - SO8 - Top vaporized

I tested the unit on my bench supply and it appears to work fine, drawing 2.8A at 24V on full white.
The main cap appears to charge when plugged into the mains.
I fed 24V back into the output and the resistance across the optocoupler dropped at around 24.3V, so I assume that part of the supply is OK.

My main problem is the SMPS Controller IC has blown it's top, and I cannot find the remains! So I know know what to replace it with.  So I will open that question up to the combined knowledge of the EEVBlog.

Below are the front and back of board, there is also a heatsink which wraps around the top of the PCB:

[rastro]

Some thoughts:

1. Since the top is blown off, is there any way to view the die under a microscope to see any if there is any manufacture/model markings.
2. Identifying which pins are the IC's power and ground would probably be helpful - at least eliminating some 8-pin-DIP candidates.
3. It may be good idea to include the manufacture/model of the unit - you never know someone may have it and can look inside.

Looks like pin-1 of the IC is top Right (not left). 

[Towger]

Hi Rastro,

Thanks for your reply.
I don't process to such equipment!
The make and model: http://www.chauvetlighting.com/products/spec/SlimPAR_Quad_12_IRC_UM_Rev2_WO.pdf

Pins
1 - Mains - and optocoupler (817).
2 - Other side of optocoupler.
3 - Mains + via two 560K resistors in series.
4 - This is tied to mains - via a 24k resistor.
5 - Not connected
6 - Goes to the mosfet source leg via a R4 10K.
7 - Two 10uF 50v low ESR caps and a diode - I assume this is power for the Controller IC.
8 -  Drives the gate of the mosfet through a resistor and diode in paralle.

I have looked at datasets and can't find any which drive with pin 8. But I am no expert...

[T3sl4co1l]

$140?  Lucky you...  That thing's not worth $30, and doesn't even have the most basic of EMI filtering!!

Looks like U1 is pinned...

(Counter-clockwise from top right)
1. GND
2. FB / COMP / ISET (internal pull-up; use phototransistor sinking to GND)
3. VCC / startup current (input)
4. Timing resistor (to GND)?
5. NC?
6. ISENSE (probably 1Vpk or so)
7. VCC / AUX power (input)
8. OUT / GATE (drive; possibly 1A peak capacity; bipolar?)

Peak current mode controller, like UC3842, but the pinout and usage isn't right.  Don't know offhand what things would fit.  Could be TI, ST, or some no-name Chinese ASIC (yes, they make their own sometimes).

FWIW, D2 is probably pointing the other way (as I guess you weren't sure about).

Can't quite make out the feedback resistors, but it seems to use a TL[V]431 or equivalent regulator (the SOT-23 on the output side).  The resistors, and the internal reference voltage, set output; I'd guess 12 or 24V offhand.

It's also a single output supply.

Surely you can fine a compatible (at least electrically, if not form fitting -- but smaller) unit elsewhere?  Meanwell comes to mind.

Tim

[Towger]

Thanks Tim,
I have bookmarked an expensive medical grade supply, which is slightly smaller than the original.
Most of the others are slightly longer or wider.
The other option is a cheap external power brick, they tend to be smaller and i might be able to bucher one to fit.
It is possible to buy 3 chinese 70w Pars for the price of a new SMPS for this 'quality' fixture.

[Kibi]

I have a Chauvet COLORdash Batten Tri in front of me. My thinking is that Chauvet continue to use the same PSU manufacturer / supplier throughout their range.
It has a power supply manufactured by Yaonen. It has a number on it YN111011458.
It's a very different model power supply to yours, it uses a 7 pin DIP on it which is a NCP1230 made by ONsemi (also available in a SOIC-8). Unfortunately, looking at your PCB layout, this does not match the datasheet.
This is probably not a lot of help apart from the name of power supply manufacturer if you did not know that already.

[Towger]

Thanks Kibi,

Chances are they are designed by the came company, so I have started to look at ONSemi Datasheets etc  Their NCP1654 (Power Factor Controller?) http://www.onsemi.com/pub_link/Collateral/NCP1654-D.PDF looks close, Pin 5 is used for VControl, but is not connected on my PCB. 

5 Vcontrol Control Voltage /
Soft?Start
The voltage of this pin Vcontrol directly controls the input impedance. This pin is connected to
external type?2 compensation components to limit the Vcontrol bandwidth typically below 20 Hz
to achieve near unity power factor.
The device provides no output

Maybe someone better than my self can cast their eye over it.

[wraper]

PFC is completely different stuff.

[wraper]

AP3101 seem to have the same pinout http://www.diodes.com/datasheets/AP3101.pdf

[wraper]

I would even say it's almost reference circuit. Probably this is not particularly AP3101 but some compatible clone, but likely should work as replacement.

[wraper]

SG5841, SG6841, OB2268, OB2269 seem to be pin compatible too.

[Towger]

Thanks Wrapper,

I spent the early hours of morning in bed looking at their datasheets on my phone....

AP3101 : Pin 5 is ADJ Adjust the level of skip cycle -0.3 to 7 V - Pin 5 is not connected on the PCB...

SG5841, SG6841:
Pin 5 RT Temperature
Protection
For over-temperature protection. An external NTC thermistor is connected from this pin
to ground. The impedance of the NTC will decrease under high temperature. Once the
voltage on RT pin drops below a fixed limit, the PWM output will be disabled.

Looks like like Pin 5 could be left swimming in the breeze, no need for thermal cutout on a 70W convection cooled PAR can!!

Looks like we are on to a winner. Have to go now and bring the kids to all their Saturday activities.

 

[Towger]

http://www.leadtrend.com.tw/pdf/LD7552-DS-00.pdf
uf4007

[Towger]

Two months to the day: She lives again, with any luck it will not blowup after a few hours! Went with a OB2268 in the end.  Many thanks to all who helped along the way.