no no no. dont scope a startup pulse.
there are 0.1uf 400v starter charge pump caps that need looked at, along with the coupling cap.
youll need an analog ESR meter to read these for opens. on a TENMA brand analog ESR meter, they will check somewhere around 20 ohms. if the needle barely moves, or doesnt move at all (assuming the meter is calibrated). then the cap is bad and should be replaced.
there are 0.1uf 400v starter charge pump caps that need looked at, along with the coupling cap.
youll need an analog ESR meter to read these for opens. on a TENMA brand analog ESR meter, they will check somewhere around 20 ohms. if the needle barely moves, or doesnt move at all (assuming the meter is calibrated). then the cap is bad and should be replaced.
Re: Power Supply - On the bench
SUCCESS! Replacing the output caps with high ESR allowed the supply to start and run just fine. They were difficult to find but the 105o parts were used to try to extend the power supply life.
ROOT CAUSE of FAILURE: There is really nothing wrong with the Magnetek power supply design. However, the InFocus system design has a serious flaw in the power supply cooling when the unit is in standby ( only whatever convection cooling is available). So the unit that sits in standby for a period of time bakes the caps and one day, the baked caps in the control loop are in such bad condition, the supply cannot start up if it ever loses power. If you have these projectors installed permanently, remove the power completely when not in use. The lightning bolts at InFocus should warn the user about the issue. Thanks again daGimp for the lead.
SUCCESS! Replacing the output caps with high ESR allowed the supply to start and run just fine. They were difficult to find but the 105o parts were used to try to extend the power supply life.
ROOT CAUSE of FAILURE: There is really nothing wrong with the Magnetek power supply design. However, the InFocus system design has a serious flaw in the power supply cooling when the unit is in standby ( only whatever convection cooling is available). So the unit that sits in standby for a period of time bakes the caps and one day, the baked caps in the control loop are in such bad condition, the supply cannot start up if it ever loses power. If you have these projectors installed permanently, remove the power completely when not in use. The lightning bolts at InFocus should warn the user about the issue. Thanks again daGimp for the lead.
mmclendon said:
You are correct to some extent, but your analysis is wrong.
there IS a design flaw to the infocus magnatek power supply.
If you look, the only cap that actually goes bad is the 100uf cap right behind the chopper controller output IC.
Why? if you look, for one, this chip has no heatsink, and 2, the capacitor is right behind it directly against it. this allows the heat to transfer from the chip streight into the capacitor, almost like they did this directly on purpose so it will fail soon.
remedy for that is to put the new capacitor in, but only push it in a little bit, soldering it in. which will have super long leads. then bend the capacitor over, away from the heat of the IC.
problem solved.
there IS a design flaw to the infocus magnatek power supply.
If you look, the only cap that actually goes bad is the 100uf cap right behind the chopper controller output IC.
Why? if you look, for one, this chip has no heatsink, and 2, the capacitor is right behind it directly against it. this allows the heat to transfer from the chip streight into the capacitor, almost like they did this directly on purpose so it will fail soon.
remedy for that is to put the new capacitor in, but only push it in a little bit, soldering it in. which will have super long leads. then bend the capacitor over, away from the heat of the IC.
problem solved.
This projector is kicking my butt.. Same problem, worked fine, power went out no lights.. Managed to get it going a few months ago was fine until power outage then back to same problem.
Where do I get these caps? I have a kids party in a few weeks and would like to give it a shot before I pull the trigger on a new one..
Or of anyone out there does a repair at a reasonable rate??
Thanks,
Chuck
Where do I get these caps? I have a kids party in a few weeks and would like to give it a shot before I pull the trigger on a new one..
Or of anyone out there does a repair at a reasonable rate??
Thanks,
Chuck
Will these work?
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=020-1704
And I know this isnt' the high temp one but will it at least fix the problem?
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=020-1138
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=020-1704
And I know this isnt' the high temp one but will it at least fix the problem?
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=020-1138
Gentlemen, after many hours of searching I think you are going to be my saviours!
I have an Infocus Screenplay 5700 which has a failing power supply. Essentially it won't power up, the fans just idle. If (as advised by a TV repair engineer I know) I apply a hot hair dryer through the side of the PJ aimed at the PSU - after 30 seconds or so, it fires up and works perfectly. He told me that this is common in old TVs where CAPs need to be warmed up to function as they are old.
So.... (I'm not in touch with the engineer - I'm in another country now) - I took the PJ apart today to try and isolate which cap or caps to replace. Thing is, they all look fine
- I used a basic DMM to test rising resistance, which they all passed, but to be honest the figures didn't mean anything to me. All I could see is that the resistence would climb , at varying speeds for each cap, then fall if I reversed polarity of my meter.
Anyhow - with these pics - could you possibly identify the "area" of capacitors I should replace with new 105 degree ones. I could buy all 11 electrolytics that I can see but then I'd be throwing away a fair amount of money, and any extra soldering increases my risk of messing it up.
The 1st pic below is an overview of the PSU
Next, Below, close up of main bank of caps: - From what I can read there are 6 x 16v 680uf caps and 1 x 100uf 16v
Next, Below, Huge 450v 270uf 85 degree cap on PSU
Next, below, if I'm not mistaken, is the balast, which is fine I guess, as the PJ works once given the hairdryer-start!
Finally, close up of, what I think is the balast, cap - 450v 47uf
I'm making the assumption based on all the other posts on here that I'm looking in the right place? I'm perfectly capable of replacing caps. Just really looking to make sure I'm on the right path....
I have an Infocus Screenplay 5700 which has a failing power supply. Essentially it won't power up, the fans just idle. If (as advised by a TV repair engineer I know) I apply a hot hair dryer through the side of the PJ aimed at the PSU - after 30 seconds or so, it fires up and works perfectly. He told me that this is common in old TVs where CAPs need to be warmed up to function as they are old.
So.... (I'm not in touch with the engineer - I'm in another country now) - I took the PJ apart today to try and isolate which cap or caps to replace. Thing is, they all look fine
- I used a basic DMM to test rising resistance, which they all passed, but to be honest the figures didn't mean anything to me. All I could see is that the resistence would climb , at varying speeds for each cap, then fall if I reversed polarity of my meter.Anyhow - with these pics - could you possibly identify the "area" of capacitors I should replace with new 105 degree ones. I could buy all 11 electrolytics that I can see but then I'd be throwing away a fair amount of money, and any extra soldering increases my risk of messing it up.
The 1st pic below is an overview of the PSU
An externally hosted image should be here but it was not working when we last tested it.
Next, Below, close up of main bank of caps: - From what I can read there are 6 x 16v 680uf caps and 1 x 100uf 16v
An externally hosted image should be here but it was not working when we last tested it.
Next, Below, Huge 450v 270uf 85 degree cap on PSU
An externally hosted image should be here but it was not working when we last tested it.
Next, below, if I'm not mistaken, is the balast, which is fine I guess, as the PJ works once given the hairdryer-start!
An externally hosted image should be here but it was not working when we last tested it.
Finally, close up of, what I think is the balast, cap - 450v 47uf
An externally hosted image should be here but it was not working when we last tested it.
I'm making the assumption based on all the other posts on here that I'm looking in the right place? I'm perfectly capable of replacing caps. Just really looking to make sure I'm on the right path....
Small update - I metered the 100uf 16v cap and it only climbed a little in resistance - though it was on the board. I removed it and it metered fine. I put another in anyhow as I had one lying around (25v 100uf).
I changed that one as it seemes a popular one to fail.
So still have the problem. I did notice that I have small a blue quare cap right by one of the FET/transistors - maybe that little fellow is getting hot? It meters fine as far as I can tell though - in situ.
Perhaps I should just buy loads of the smallish caps and replace the lot? Don't fancy stripping the PJ down too many times - and I can't test until it is all back together each time as the fan power for the lamp comes from contacts on the case lid. That and the PCB gets in the way.
I changed that one as it seemes a popular one to fail.
So still have the problem. I did notice that I have small a blue quare cap right by one of the FET/transistors - maybe that little fellow is getting hot? It meters fine as far as I can tell though - in situ.
Perhaps I should just buy loads of the smallish caps and replace the lot? Don't fancy stripping the PJ down too many times - and I can't test until it is all back together each time as the fan power for the lamp comes from contacts on the case lid. That and the PCB gets in the way.
OK guys - I've kind of realised that this is a DIY PJ building forum section, and not a free for all tech support
Could I just ask for a little advice. I've done some more reading and as I have to use a hair dryer to get my PSU going, it looks like my startup capacitor is the guilty item. Thing is - what am I looking for to find the startup capacitor? Would it most likely be the massive 450v one?
As I can start the PJ with the application of externl heat, I really don't want to destroy it any further - a hard to start PJ is better than a dead one
This forum is the only place I've found where people know what they are talking about. Any help in teh right direction would be most appreciated.
Apologies in advance if everyone happens to be on holiday at the moment..
Could I just ask for a little advice. I've done some more reading and as I have to use a hair dryer to get my PSU going, it looks like my startup capacitor is the guilty item. Thing is - what am I looking for to find the startup capacitor? Would it most likely be the massive 450v one?
As I can start the PJ with the application of externl heat, I really don't want to destroy it any further - a hard to start PJ is better than a dead one
This forum is the only place I've found where people know what they are talking about. Any help in teh right direction would be most appreciated.
Apologies in advance if everyone happens to be on holiday at the moment..
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