Re: LG Flatron W2242S 'Dead in the Water'
Meanwhile, back at the T101, probing the high voltage primary. Bingo - 'the shakes' yield the spark I had been anticipating these past days. The Vcc voltage of 10.74V - derived from the 1 mA supplied via the 47K resistor attached to the 315VDC - is obliterated and leaves a residual 120 mV DC.
Obviously, the IC had been destroyed, as had the 33uF capacitor, and the 1N4007 which serves to rectify the Vcc supply from it's dedicated winding. YUK! I'm concerned about the potential lateral damage. Photo-coupler! Low wattage resistors...
GERIATRICDAI
Member
Last Activity: 01-10-2020, 12:37 PM
Joined: 07-20-2014
Location: Bournemouth, Dorset, England
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Re: LG Flatron W2242S 'Dead in the Water'
Initially, I will ask if your T101 transformer is for sale?
As mentioned previously, I did insert a +5v & +22v supply refenced to chassis. This resulted in the Blue LED illuminating and the 22v circuit attempting to drive the invertor circuit when the On/Off button was pressed. ( totally disconnected from the mains - of course!) Unfortunately, my ancient Farnell variable supply is current limited to 500mA and you could observe the supply voltage collapsing to 15v as the inverter attempted to start ( with...Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
It disturbs me to know I have to package the whole contraption, without knowing if the fundamental SMP supply is serviceable. What I mean is this. Without the interface to my original PC, there is the possiblity that the PSU in question, may be inhibited. You can guess where I'm coming from! Time spent in re-configuring the system, only to be 'kicked-in-the-face' if all is dead!
Right back at the start, I was bleating about the absence of either an 'Amber' or 'Blue' indicator lamp. Is it likely that either or both of these...Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
Good Man, I will study the chips behaviour under 'start-up' conditions.
Meanwhile, despite all the squeels of objection. Just pretend I wanted a multiple 5V and 22v dc supply, isolated from the mains, with a modest current capability. Let's say 1 amp at 5v and 500mA at 22v. The opto coupler has a part to play, normally. associate with failures.
Is this too much to ask?
P.S. The copper tracks are really ' one use only' unless you have your wits about you. This is 'one-shot' engineering...Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
I do understand where you are coming from. Nevertheless, had you this board in front of you, to check it's functionality, what would you require to test it?...Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
You really have provided me with some excellent material. Right now, I do possess a full set of genuine Panasonic elecrolytics. Would you like to suggest the first I should replace - rather than a blanket replacement? I must admit to being nervous on seeing 313VDC appearing at pin 1. As for re-soldering the IC pins? My Weller Soldering Staion PS3 has started to behave like a pig - either roasting, or cooling . However, I can still manage to de-solder and re-instate without destroying the beast. Damned if I can do with a soldering...Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
An excellent suggestion and probably capable of saving many a scuppered vessel due to nothing but 'the shakes'. Have you noticed how probe technology still believes we are clamping our probes onto 50W wire wound resistors! However, in this instance, I did wish the power supply board to be completely separated from those that normally feed from it. A crude attempt to provide the nominal loadings for both the 5v and 22v circuits, using incandescent lamp bulbs, was a 'no brainer' - the filament cold resistances were practically...Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
By the way, the replacement chip, is exactly as you specified. I had no alternative, other than, to believe the blurb. I'm pretty sure all is well regarding the specifications.Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
You are a most welcome contributor. I will try to understand those early microsecond activities. Thanks for the contribution....Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
The measurements I make, are always at the storage capacitors. Too often, a slip of the probe generates a 'court case - citing negligence for blowing up a perfectly good piece of equipment'. As you get older, try to avoid the shaking hand, trying to target a pin - 50 thou removed from it's neighbour. By all means, have a specially made up test connector, for the equipment under test. Time consuming and not really practical - although a delightful theoretical asset!
In this instance, we had the 'one hand in...Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
U101 - why change? Cheap and cheerful - easy to remove, and replace, with a modicum of care. Past experience with folk finding their bedroom LCD TV kaput, usually associated with leaving the damn thing on 'standby' all night. That's one of the problems with the UK's 230VAC supply - we are so easily subjected to overvoltage transients that exceed the upper limits of the equipment. 20 milli-seconds is forever to a Switch Mode Suppy.
I can cite a number of chip replacements that cost less than a pound and restored...Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
Testing took place with the monitor 'stand-alone'. Is it just possible that an initial power-up would have illuminated the blue LED and displayed the LG Logo? Surely, any subsequent attempt to switch the monitor on, would result in the same sequence.
Now, let me try and attach some of the photographs requested....Leave a comment:
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Re: LG Flatron W2242S 'Dead in the Water'
Hi,
Good of you to take an interest.
U101 is a LAF0001 which I replaced with replacements from China, and had the pleasure of seeing that blue light illuminate, followed by the LG Logo and lasting all of 10 seconds - then, back to being an inert lump!
I must admit, without the means of viewing things dynamically, it's a bit like 'throwing snowballs at the Moon.' This is where I have to rely heavily on those folk with experience.Leave a comment:
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LG Flatron W2242S 'Dead in the Water'
Hi Afficionados,
I have followed some of your excellent efforts and advice whilst exploring my options with the faulty power supply. For the record, the inverter transformer secondary readings were within .1% of each other ( 964 ohms on my Fluke MM). Please be advised, I have long been without my sophisticated electronics gear. Now down to an AVO 8 and my intermittent Fluke!!
Meanwhile, let me advise, China sent me two replacement SW chips, I replaced the original, and had the benefit of seeing 'LG' appear on the screen - shortly afterwards, when selecting the 'Menu... -
Re: New Members - please post your introductions here
My name is GERIATRICDAI - for no other reason than it is true!
It was so nice finding a Forum crammed full with helpful folk and not be conned into parting with money.
My origin did involve 'cats whiskers', 90v HT batteries, Accumulators, enourmously long aerials, thumping solid earth terminals - I was 10 years old then. 'Fast Forward' six years and you may observe a young RAF Apprentice. Looking back, I can honestly say I enjoyed every day of my varied working life, and, never dreaded the thought of...Leave a comment:
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Re: New Members - please post your introductions here
How on earth did you manage to post an 'intro!'...Leave a comment:
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