Infocus power supply isssue

[Khron]

Re: Infocus power supply isssue

Wait, where's that 0.025(ohm?) resistor? And for certainty, that diode would best be measured out-of-circuit...

EDIT: Nevermind, found it

See if you can unsolder / extract that resistor, and THEN measure that diode again. But that shouldn't be very essential - it looks only like a reverse-protection for the current-sense circuitry (the white resistor is the shunt, between the - terminal of the main filter cap ("primary ground", for all intents and purposes) and the - terminal of the rectifier bridge)

[subarub4]

Re: Infocus power supply isssue

Wait, where's that 0.025(ohm?) resistor? And for certainty, that diode would best be measured out-of-circuit...

yep I had to lift it out of circuit and it's reading normal now.

That resistor is between the Bridge rectifier and FET in the front

Edit: My Panasonic caps shipped

Also if it's just a shunt then it's pretty much pointless to have me pull it out and check then?

Also for Q204,Q213, Q602 & Q603 which way should I be measuring? and the two optoiolators are IC203 & IC204?

The optoisolator are FOD817BW I get reading on one side but nothing on the other side.. and On the other one I get no reading at all.

Ic204 I get 2.8V on pins 3 & 4

[Khron]

Re: Infocus power supply isssue

I meant you couldn't be sure about the diode readings, with that shunt in parallel with it

And regarding the transistors... Q204 and Q213, you said, say "241" on them. Now, on my go-to SMD code database, there's five possibilities for "241", and none of them are transistors (or at least not in the correct package).

In the "24" group though (if the "1" is some fab code or something else), the most likely suspects are one of the several variants of DTC114, that's a "digital" transistor (with a built-in base resistor), which WOULD sort of make sense in this context. They *are* basically employed as switches here, as far as i can figure.

http://chip.tomsk.ru/chip/ChipDoc.ns...1501&count=500
(Note: the "24" section is between "249xx" and "24A")

If i can get around to it, i'll try to re-draw a schematic of the primary, as far as i can figure.

What're the markings on Q602 & 603?

[subarub4]

Re: Infocus power supply isssue

I meant you couldn't be sure about the diode readings, with that shunt in parallel with it

And regarding the transistors... Q204 and Q213, you said, say "241" on them. Now, on my go-to SMD code database, there's five possibilities for "241", and none of them are transistors (or at least not in the correct package).

In the "24" group though (if the "1" is some fab code or something else), the most likely suspects are one of the several variants of DTC114, that's a "digital" transistor (with a built-in base resistor), which WOULD sort of make sense in this context. They *are* basically employed as switches here, as far as i can figure.

http://chip.tomsk.ru/chip/ChipDoc.ns...1501&count=500
(Note: the "24" section is between "249xx" and "24A")

If i can get around to it, i'll try to re-draw a schematic of the primary, as far as i can figure.

What're the markings on Q602 & 603?

Q602 = M4A
Q603 - M3A

What I'm still trying to figure out is where the voltage stops and drops off

EDIT:

I think I found a decent SMD codebook, the above seem to be transistors I got the pinouts they seem to be Motorola Diodes? I just want to make sure this is right.

And for Q204 and Q213 it does indeed say 241 on it My pdf I have is showing it as a 24V 300mW Zener but not sure if thats right.

[budm]

Re: Infocus power supply isssue

So are you getting any DC voltage on the wire harness to the main board? Is this projector? If it is, there should be lock-out safety switch that will not let the unit to turn on if the covers are removed or open, you may want to look for micro switches.

[subarub4]

Re: Infocus power supply isssue

So are you getting any DC voltage on the wire harness to the main board? Is this projector? If it is, there should be lock-out safety switch that will not let the unit to turn on if the covers are removed or open, you may want to look for micro switches.

The switch is fine it's not the issue it wont power up at all because no stand by voltage on the low voltage wires if the IC would turn on I would suspect it would get power..

however I was looking at it today and the transformer which I assume is the SMPS one I have like 164VDC on the primary side but nothing on the secondary side.


Unless I looked at the wrong pins.

it has 4 pins on one side and 6 on the other.

[budm]

Re: Infocus power supply isssue

That standby power supply (the transformer on the right edge of the board) is always on, so unless it has shorted load, it may not start up. You can power sup the board without that wire harness connected and see if you will get the standby voltages on the connector. There is an Device (TO-220 SMPS IC) mounted on the small heat sink which is the one that drives the STBY transformer, do you have the number printed on the body?

[subarub4]

Re: Infocus power supply isssue

That standby power supply (the transformer on the right edge of the board) is always on, so unless it has shorted load, it may not start up. You can power sup the board without that wire harness connected and see if you will get the standby voltages on the connector. There is an Device (TO-220 SMPS IC) mounted on the small heat sink which is the one that drives the STBY transformer, do you have the number printed on the body?

Ha perfect timing, I was going to upload the video to that but it's a MR4010 and when plugged in (the power board alone) I'm seeing temps of 115F on it... does that seem pretty high to you? I thought something like that only gets warm when a load is on it?

http://www.shindengen.co.jp/product_...duct_id=MR4010

http://www.youtube.com/watch?v=uVD_T...ature=youtu.be

[budm]

Re: Infocus power supply isssue

That is not normal when you do not have anything else connected to the board.
1) It may be trying to run but the rectifiers in the secondary side is shorted so it is in the start/shutdown loop. Do you hear ticking sound from the transformer?
2) The internal MOSFET has leakage resistance so it is drawing the current all the time. Does it take long for the temp rise.
So you have to check the internal MOSFET Source (pin5) and Drain (pin9) to see what kind of the resistance you are getting, just make sure that the main filter cap is fully discharged first.

[subarub4]

Re: Infocus power supply isssue

That is not normal when you do not have anything else connected to the board.
1) It may be trying to run but the rectifiers in the secondary side is shorted so it is in the start/shutdown loop. Do you hear ticking sound from the transformer?
2) The internal MOSFET has leakage resistance so it is drawing the current all the time. Does it take long for the temp rise.
So you have to check the internal MOSFET Source (pin5) and Drain (pin9) to see what kind of the resistance you are getting, just make sure that the main filter cap is fully discharged first.

You know having been around a few SMPS now that's one of the first thing I checked for was to see if I heard any sounds and I did not.

And it does not take long at all to heat up.. I want to say within 2-3 min it's already over 100F.. you know what I'm going to go check now with a Temp probe.

I will check those pins

[budm]

Re: Infocus power supply isssue

I would say then the MOSFET is ON or it has low resistance between Source and Drain.

[subarub4]

Re: Infocus power supply isssue

I would say then the MOSFET is ON or it has low resistance between Source and Drain.

This is going to sound dumb but how do I find which pins are 5 & 9?

http://www.youtube.com/watch?v=5SMCC...ature=youtu.be

[budm]

Re: Infocus power supply isssue

If you look at the spec sheet, pin 1 start at the first left pin, pin6 and 8 are not present but you will still count them, so last pin on the right is pin 9.

[subarub4]

Re: Infocus power supply isssue

I see 36.44k

[budm]

Re: Infocus power supply isssue

So then the internal circuit that drive the Gate may be stuck high instead of turn the MOSFET on/off real fast like it should. At this point I would try new IC.

[subarub4]

Re: Infocus power supply isssue

So then the internal circuit that drive the Gate may be stuck high instead of turn the MOSFET on/off real fast like it should. At this point I would try new IC.

And that's going to take awhile since the only place I can find them is from China, when it does arrive I will have to see what the replacement one measures out to.

[budm]

Re: Infocus power supply isssue

I would like you to check the Snubber Diode D202 to see if it is bad.

[subarub4]

Re: Infocus power supply isssue

I would like you to check the Snubber Diode D202 to see if it is bad.

seems fine

[budm]

Re: Infocus power supply isssue

Ok.

[subarub4]

Re: Infocus power supply isssue

What would cause something like this to happen?