Infocus power supply isssue

[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

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.

[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

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

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

I'm probing around here checking some diodes and I found one here D106A in diode test it reads 0V both ways.. on the backside of it is a white 0.025 Ceramic resistor.

[subarub4]

Re: Infocus power supply isssue

looks like that shrinkwrapped cap near the transformer is bulged.
i would replace all.
and i suspect that once the 5v is there again a power on command from the logic will fire up the pfc and the unit will work.no pfc in standby.very common.

I wanted to know why are these shrinked wrapped in the first place? I took the shrinkwrap off and it's not bulging it's 220 uF 16V and one of the few caps I do have around that matches but only 85C rated but OK just to test.

I wont do that much more until all the caps are replaced and hopefully I will get that order placed today. Only comes to like $7 in all.

[subarub4]

Re: Infocus power supply isssue

what are the markings on q204 and q213?

q204 =241
q213 = 241

[kc8adu]

Re: Infocus power supply isssue

looks like that shrinkwrapped cap near the transformer is bulged.
i would replace all.
and i suspect that once the 5v is there again a power on command from the logic will fire up the pfc and the unit will work.no pfc in standby.very common.

[Khron]

Re: Infocus power supply isssue

What are the markings on Q204 and Q213?

[subarub4]

Re: Infocus power supply isssue

Q602 and the trace that runs down to C118 & R129 are connected which seem to go to Q204 & Q213 which ends up at those optoisolators.

Right now I'm temped to replace all the caps with Panasonic's but still curious where in the circuit the voltage just drops out at.

[subarub4]

Re: Infocus power supply isssue

I can try..

Q213 when I touch the two pins closest to each other I get continuity on the other hand for Q204 I get nothing

[Khron]

Re: Infocus power supply isssue

Any chance you could try to lift the schematic of that piece of circuit, then?

[subarub4]

Re: Infocus power supply isssue

Yep I have one of those meters

[Khron]

Re: Infocus power supply isssue

Hmmmmm... Judging by how Q204 and Q213 are arranged, i'm starting to get a hunch that maybe that FET is actually triggered by a signal from the secondary, through the left-most optocoupler (in this last photo)...

Do you have access to a multimeter (ideally one with a continuity-tester, aka "beeper")? It could help a lot in tracing this circuit, what with traces going under surface-mounted parts and all...

[subarub4]

Re: Infocus power supply isssue

I hope this helps I made lines to show where the TO-220 goes to.

[subarub4]

Re: Infocus power supply isssue

Found the datasheet for the (slightly more recent) A-version, R2A20113A.



Upon closer inspection of the photos, i reckon the voltage to that white 2-pin plug is actually turned on and off by the TO-220-packaged transistor right next to it (3-legged, no heatsink). Can't really make out where its control signal's coming from, though, but it might involve Q213.

Also, the PFC chip's Vcc supply line seems to be coming from the area around the main PWM chip; it's filtered by C117 and C117A (big ceramic caps right next to each other, on the bottom of the board). If you trace the circuit, you'll see that long PCB track ends up in the main PWM area - i can only keep track of it until near the small ceramic C118. Either way, you'll want to check if that's over 12v (PFC chip needs at least 12v to "wake up"; after that, it'll keep working until its supply drops under 9v).

The 3 legged TO-220 near the white plug is P1260ATF As for the PFC chip I'm not seeing voltage on it at all

[Khron]

Re: Infocus power supply isssue

Found the datasheet for the (slightly more recent) A-version, R2A20113A.



Upon closer inspection of the photos, i reckon the voltage to that white 2-pin plug is actually turned on and off by the TO-220-packaged transistor right next to it (3-legged, no heatsink). Can't really make out where its control signal's coming from, though, but it might involve Q213.

Also, the PFC chip's Vcc supply line seems to be coming from the area around the main PWM chip; it's filtered by C117 and C117A (big ceramic caps right next to each other, on the bottom of the board). If you trace the circuit, you'll see that long PCB track ends up in the main PWM area - i can only keep track of it until near the small ceramic C118. Either way, you'll want to check if that's over 12v (PFC chip needs at least 12v to "wake up"; after that, it'll keep working until its supply drops under 9v).

[subarub4]

Re: Infocus power supply isssue

SOIC8 = "Small Outline Integrated Circuit" with 8 pins/legs, and by that one i mean the small 8-legged chip on the back of the board, underneith the big heatsink, identified as IC101.

Oh ok I thought so..

Here it is

[Khron]

Re: Infocus power supply isssue

SOIC8 = "Small Outline Integrated Circuit" with 8 pins/legs, and by that one i mean the small 8-legged chip on the back of the board, underneith the big heatsink, identified as IC101.