Re: Emerson LF501EM4 Intermittant Power On
Thank you for looking at this - I've been working on this off and on for over a week and it's driving nuts... Looking at the block diagram, it gives me the impression that the logic board needs to see protect3 voltage from the power board before it will send backlight-sw voltage back to the led drivers - is that correct or am I thinking about this backwards?
Version 7
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Last Activity: 08-21-2018, 12:00 PM
Joined: 11-10-2012
Location: Spokane Washington
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Re: Emerson LF501EM4 Intermittant Power On
Anyone up to helping me out on this one?Leave a comment:
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Emerson LF501EM4 Intermittant Power On
Only after unplugging the set for an hour or so, then plugging back in, will the television power on. Once on, it will run for at least an hour (that's all I tested for). You can tell when it will power on because you will hear the power plug arch a bit when plugging it in.
The problem appears to be in the backlight circuit; protect3 (.45v), backlight-sw (.21v) and backlight-adj (.18v). Reset, P-on-h2, al+3.3v, amp+13v and p-on+21v are all the correct voltage.
I flipped the power board and I have proper voltages to #1 OVP, #2 UVLO and #14 VCC of each of the led drivers....Last edited by Version 7; 10-25-2016, 06:35 PM. -
FIXED - Sceptre X32 Power Supply Diagnosis
Thank You budm for your advice - replaced startup caps and this set has been up and running for a few weeks now!Leave a comment:
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Re: Sceptre X32 Power Supply Diagnosis
ok I'll give it a try - will have to order, so be back in a few days..Leave a comment:
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Re: Polaroid FLM-3732 Power On/Off
Hey Troy
I'm pretty new to this but one of the things I've read alot on here was the importance of matching your capacitors with the correct type. From what I understand, these power supplies require low esr / low impediance capacitors on the output side (possibly throughout) of the power supply.
The Chemicon LXY is low impedance and recommended for power supply output but the KMG is just a general purpose cap.
Here is a link to their capacitor group chart:
The Illinoise CHKM cap...Leave a comment:
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Re: Sceptre X32 Power Supply Diagnosis
The grey and purple 5v do drop off as well, but differently than the other voltages. When the unit is first plugged in, they are both 5v but after about 4 seconds, they drop down to 2.1 volts then very slowly (minute or more) discharge to 0v while the 12v and 24v circuits drop to 0v within a few seconds. After the unit is powered on and about 4 seconds after the logo appears, all voltages drop to 0v within a few seconds.
For the feed from the power supply to the control board they used a 12 pin connector at the power supply and...Leave a comment:
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Re: Sceptre X32 Power Supply Diagnosis
Connector "B" is well marked but connector "A" not so well. The right side shows the one ground at the top then the two 5v and two grounds at the bottom. The left side of the connector is actually marked "24v Audio" - I don't think that is right...
Here are the voltage readings I took on connector "A", from top to bottom.
Black ground
Brown 5v
EMPTY
Red 3.5v
Orange 12v
Yellow 12v
Green 24v
Blue 24v
Purple 5v
Gray...Last edited by Version 7; 11-15-2012, 01:21 AM.Leave a comment:
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Re: Sceptre X32 Power Supply Diagnosis
I do not. No clicking, buzzing, etc..Leave a comment:
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Sceptre X32 Power Supply Diagnosis
I attempted my first TV repair and got close, but no cigar... and I'm not sure where to go next.
The unit is a Sceptre X32 LCD TV and originally would not power up at all. It had 4 CapXon capacitors, two leaking/bulged, so I replaced all 4 with nichicon HE equivalents. The rest of the capacitors look OK, but I do question the large blue capacitor (filter cap?) as it feels like it could be slightly bulged, but I'm unsure and I don't have a capacitance meter.
After the repair, the unit does power up and displays the logo, but after about 4 seconds, the unit powers downs...
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