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Post by jeremy on Dec 14, 2016 13:17:45 GMT -5
Just to be clear MT, you want me to short Pins 1 and 2 on IC102 correct?
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Post by jeremy on Dec 14, 2016 13:30:49 GMT -5
MT, Here's a pic of the bottom of the PSU (where we're working), the schematic for this PSU is deplorable since it suggests PC102 is in 2 areas...? Maybe this photo will help  |
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Post by mastertech on Dec 14, 2016 17:17:20 GMT -5
The 2 pins on the right in your picture. Yes, short them out and try.
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Post by jeremy on Dec 14, 2016 20:28:41 GMT -5
MT, That worked (sort of),
The projector powered on and stayed on the first time I turned it on after shorting pins 1 & 2 out on IC102. I didn't have a lamp in it so I unplugged it and put a lamp in and tried it again, 2nd time it powered on for a bit, then went off again, and just pulses the standby light every second until I unplug it, which it is doing as a norm now.
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Post by mastertech on Dec 14, 2016 20:59:30 GMT -5
Well that circuit monitors all the voltages the PS produces. Since all the voltages appear to be there and be correct according to your earlier tests then the circuit itself is not operating properly if shorting those pins cause it to work. Shorting those pins would send a correct signal to the controlling ic, which it appears it did. So it is possible something in the circuit that turns on that pc102 may be bad. But I would feel more comfortable if the projector did function. But since it is not and assuming the output voltages are still all correct then it is possible that whatever is causing this problem is also causing another problem . You say it keeps pulsing the standby light. Is the PS pulsing the output voltages also? Or are they ON? or OFF?
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Post by jeremy on Dec 14, 2016 21:56:28 GMT -5
The voltages are on when the PS is pulsing, but the voltages do pulse a bit, for example: 5.3v drops to 5.1v every time it pulses, and its about the same difference for all the other voltages too, not a lot, but noticeable on the dmm by a few hundred millivolts
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Post by mastertech on Dec 14, 2016 21:59:14 GMT -5
Before soldering those pins did the PS shut off completely when it shut off or didn't you test?
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Post by jeremy on Dec 14, 2016 22:18:15 GMT -5
Before soldering the pins, when the PS would shut down, it would basically lose all power for about a second (no LEDs, nothing) then power back up into its standby sequence and then you could press power again and repeat the cycle.
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Post by mastertech on Dec 14, 2016 22:22:25 GMT -5
Well you could try removing that pc102 and see how it reacts empty.
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Post by jeremy on Dec 14, 2016 22:35:34 GMT -5
I'll do that and get back to you with how it behaves
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Post by jeremy on Dec 14, 2016 22:49:23 GMT -5
Removed PC102, it powered on, stays on, lamp lights up, and it displays as normal... PC102 bad? I have another PS with a couple photo couplers on it
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Post by mastertech on Dec 14, 2016 23:33:32 GMT -5
You can try just replacing it first but if that is not it there is not much to that circuit. I could give you a list of what to test if need be.
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Post by jeremy on Dec 14, 2016 23:44:54 GMT -5
That would help MT, the Photo coupler isn't the issue, put a different one in and it behaved as it did before removing and testing (pulsing LED). What should I check?
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Post by mastertech on Dec 15, 2016 13:27:20 GMT -5
I would start by testing for any shorted legs on ic202,Q201,Q202,Q203.
If they seem to test normal then put pc102 back in, verify the unit shuts down and then remove ic202 and try again if it shuts down.
This manual does not give part numbers so I do not know what ic202 is. See if it has any numbers before removing in case of damage.
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Post by jeremy on Dec 15, 2016 19:47:12 GMT -5
MT, Checked all those, they don't appear to be shorted at all. So I put PC102 back onto the board, tried it out, still shutdown after powering it on. Then I pulled IC202 off the board (got it off nice and clean even  ), and tried it out again without IC202 but having PC102 back in place, it also works this way, but there is a hissing sound coming from the PS (to be fair, there was the same sound when I pulled PC102 off the board and tried it) |
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), and tried it out again without IC202 but having PC102 back in place, it also works this way, but there is a hissing sound coming from the PS (to be fair, there was the same sound when I pulled PC102 off the board and tried it)
