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LCD monitor power supply
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I have a bad news story. The 100-240 v input, 12v 4A output power brick
that sends power to my 19" LCD monitor apparently took a dump overnight. An LED on the brick does not light up properly, I can't measure anything on the output side. I've already looked in my spare parts piles, I do not have any power bricks or wallwarts that come close enough. I'm in the process of opening the plastic case, to see if anything is obviously wrong and can easily be fixed. It's glued (no screws) so it is slow going with a hobbyist slitting saw: <> On the chance that the brick is properly toasted and cannot be fixed, what are some other options for 12vdc @ 4a to power the monitor? Yes, I can Google for something, but I thought I'd ask here first. If something quick and easy makes for a good project build, why not do that instead of rushing of to purchase a turnkey item? Reese |
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2 years ago, same power supply gave suddenly his last breath just after a couple of months on my desk.
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Since then and after I repaired it, I let it breath fresh air by removing its plastic cover for good. In summer, I even keep it cool by a small fan. Sorry I can't help because I didn't repair it myself. I am not skilled in repairing other's circuits :( just what I design, for which all schematics are available to the last detail :) To me in the least, designing and repairing belong to different worlds though both are based on electronics. --- In Electronics_101@..., Reese <reeza@...> wrote:
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lists
In article <201101191636.p0JGaCm5021032@...>,
Reese <reeza@...> wrote: On the chance that the brick is properly toasted and cannot be fixed,Car battery ? :-) Maybe: . LM338 is an adjustable regulator output can be set at 12V. It is a 5A regulator so the external regulator transistor is not requiredThis design is a bit over-rated for your requirement. Transformer can be 15V at 85VA or you /might/ get away with a 12V transformer depending on your incoming mains. C1 capacity could be halved and voltage rating 25V upwards. Again, B1 could be downrated to 5A. Personaly i always put a fuse on the transformer seconary side and this should be 5A "Anti-surge" Note. I haven't fully worked through the design but it looks OK. -- Stuart Winsor Midland RISC OS show - Sat July 9th 2011 |
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At 12:14 19 01 11, Kerim F wrote:
2 years ago, same power supply gave suddenly his last breath just after a couple of months on my desk. I like that idea - opening it up so that it can breath. Meanwhile, I stumbled across a 12 vdc 3.5a power brick that had been acquired for a trickle/float charger project for motorcycle and car batteries. I plugged it into the monitor, after verifying output polarities. Something inside the monitor immediately began sizzling and some smoke came out. :( I'm watching a couple of items on eBay, and checking NewEgg, Amazon, etc. Reese |
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At 12:31 19 01 11, vaclav_sal wrote:
Before someone else saiz it - it is cheap, buy a new one!Me too. Because if you think it is that cheap, buy one for me. I'll be happy to provide an address privately, if anyone wants to send something. By all means - gut it out to see what part let the smoke out!See last post. Monitor looks smoked also. Money is tight so it's not like I can afford the new monitor and expedited shipping on short notice. Reese |
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At 12:36 19 01 11, lists wrote:
Potentially messy but yes, that's an option. Not viable with theOn the chance that the brick is properly toasted and cannot be fixed,Car battery ? :-) latest development re: the monitor itself though. :( Maybe: This is the sort of DIY solution I was looking for. Thank you. I might do this even after acquiring a new monitor. Nothing smelled of smoke when I entered the home office this morning. Power brick was dead, monitor was malfunctioning. Fit monitor with a new power brick, the monitor smokes. Very odd. I'm not sure I can tell which failed first, the monitor or the old power brick. Whether it was a cascading failure or not. Monitor was about 5 years old, btw. Reese |
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Stefan Trethan
You could easily find a replacement, this voltage and current rating
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is common, perhaps even a PC PSU will do. It'd be easy to fix too, I could probably give a hint with a good chance of success from a couple of photos. But now it seems you fried your monitor anyway, so no point. ST On Wed, Jan 19, 2011 at 5:27 PM, Reese <reeza@...> wrote:
I have a bad news story. The 100-240 v input, 12v 4A output power brick |
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Mark Tolleson
How interesting that this should come up.? I've been meaning to ask someone who knows (and what better place than this, to do that) about how forgiving appliances with these brick supplies are.? I have, on more than one occasion, run an item with a brick that exceeded its rated voltage by a good bit, and have never had a problem.? For instance, recently I ran a small ethernet hub rated for 7.5 volts with a 12 volt brick for several weeks with no apparent problem.? As I type I'm running an HP LCD monitor rated for 12 volts with a 19 volt brick.? Again with no problem (yet).? Am I just lucky or is there some big secret here?? Whenever I do this I make sure the current is sufficient to power the appliance.
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Thanks, Mark --- On Wed, 1/19/11, Stefan Trethan <stefan_trethan@...> wrote:
From: Stefan Trethan <stefan_trethan@...> Subject: Re: [Electronics_101] LCD monitor power supply To: Electronics_101@... Date: Wednesday, January 19, 2011, 1:03 PM ? You could easily find a replacement, this voltage and current rating is common, perhaps even a PC PSU will do. It'd be easy to fix too, I could probably give a hint with a good chance of success from a couple of photos. But now it seems you fried your monitor anyway, so no point. ST On Wed, Jan 19, 2011 at 5:27 PM, Reese <reeza@...> wrote: I have a bad news story. The 100-240 v input, 12v 4A output power brick that sends power to my 19" LCD monitor apparently took a dump overnight. An LED on the brick does not light up properly, I can't measure anything on the output side. I've already looked in my spare parts piles, I do not have any power bricks or wallwarts that come close enough. I'm in the process of opening the plastic case, to see if anything is obviously wrong and can easily be fixed. It's glued (no screws) so it is slow going with a hobbyist slitting saw: <> On the chance that the brick is properly toasted and cannot be fixed, what are some other options for 12vdc @ 4a to power the monitor? Yes, I can Google for something, but I thought I'd ask here first. If something quick and easy makes for a good project build, why not do that instead of rushing of to purchase a turnkey item? Reese ------------------------------------ Please trim excess when replyingYahoo! Groups Links |
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At 13:03 19 01 11, Stefan Trethan wrote:
You could easily find a replacement, this voltage and current ratingA nit: The monitor was suspect and there is no reason to believe it was not already fried. I'm still curious about the original power brick, for a learning exercise if nothing else. I have the plastic case off, 1st piece of EM shielding removed. Some photos have been taken, as well as photos of the VGA/power board from the monitor. I will be posting them (links to them) later today or this evening. Reese On Wed, Jan 19, 2011 at 5:27 PM, Reese <reeza@...> wrote:I have a bad news story. The 100-240 v input, 12v 4A output power brick<> |
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Stefan Trethan
You are just lucky.
The typical specification on that type of crappy power supply is 5% voltage tolerance. So that the load will survive much more thann 10% overvoltage can not be assumed, but is not uncommon either. I usually don't go outside one or two volts of the specification, and rather under supply than over. ST On Wed, Jan 19, 2011 at 8:10 PM, Mark Tolleson <mark1200sportyrider@...> wrote: How interesting that this should come up.? I've been meaning to ask someone who knows (and what better place than this, to do that) about how forgiving appliances with these brick supplies are.? I have, on more than one occasion, run an item with a brick that exceeded its rated voltage by a good bit, and have never had a problem.? For instance, recently I ran a small ethernet hub rated for 7.5 volts with a 12 volt brick for several weeks with no apparent problem.? As I type I'm running an HP LCD monitor rated for 12 volts with a 19 volt brick.? Again with no problem (yet).? Am I just lucky or is there some big secret here?? Whenever I do this I make sure the current is sufficient to power the appliance. |
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Mark Tolleson
Thanks, I guess.? This whole power adapter thing just irritates me.? Who started this and why?? I remember a time when they just didn't exist (that I knew of).? I have a box full of these things and I despair of ever putting them to good use (or getting them to someone who could).? As sure as the tectonic plates will someday sink due to the National Geographic Syndrome? (stacks and stacks of old NG magazines) we will find ourselves knee-deep in old power supplies.
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Mark --- On Wed, 1/19/11, Stefan Trethan <stefan_trethan@...> wrote:
From: Stefan Trethan <stefan_trethan@...> Subject: Re: [Electronics_101] LCD monitor power supply To: Electronics_101@... Date: Wednesday, January 19, 2011, 2:51 PM ? You are just lucky. The typical specification on that type of crappy power supply is 5% voltage tolerance. So that the load will survive much more thann 10% overvoltage can not be assumed, but is not uncommon either. I usually don't go outside one or two volts of the specification, and rather under supply than over. ST On Wed, Jan 19, 2011 at 8:10 PM, Mark Tolleson <mark1200sportyrider@...> wrote: How interesting that this should come up.? I've been meaning to ask someone who knows (and what better place than this, to do that) about how forgiving appliances with these brick supplies are.? I have, on more than one occasion, run an item with a brick that exceeded its rated voltage by a good bit, and have never had a problem.? For instance, recently I ran a small ethernet hub rated for 7.5 volts with a 12 volt brick for several weeks with no apparent problem.? As I type I'm running an HP LCD monitor rated for 12 volts with a 19 volt brick.? Again with no problem (yet).? Am I just lucky or is there some big secret here?? Whenever I do this I make sure the current is sufficient to power the appliance. Thanks, Mark [Non-text portions of this message have been removed] |
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lists
In article <88042.83861.qm@...>,
Mark Tolleson <mark1200sportyrider@...> wrote: Thanks, I guess. This whole power adapter thing just irritates me. WhoIt saves manufacturers a lot of money. Any new piece of equipment that is connected to mains power has to be submitted for tests and approvals before it can be sold. This is expensive. If it is DC or ultra low voltage AC powered it doesn't. So, the manufacturer just buys in a standard "off the shelf" power adapter which has already been approved and he's done. If he makes design changes or upgrades which would otherwise require a new set of tests he doesn't have to worry because he can carry on using the same adapter. Power supply manufacturer puts a standard unit, say 12V 1A, through the approvals process and then sells them by the million to numerous different equipment manufacturers and the cost per unit of the approvals process becomes negligible. -- Stuart Winsor Midland RISC OS show - Sat July 9th 2011 |
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Mark Tolleson
Well there it is then.? Sounds reasonable.? Now if every specification (voltage/amperage/wattage) got a standardized size barrel connector, then I'd quit whining.
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Mark --- On Wed, 1/19/11, lists <Stuartlists@...> wrote:
From: lists <Stuartlists@...> Subject: Re: [Electronics_101] LCD monitor power supply To: Electronics_101@... Date: Wednesday, January 19, 2011, 6:27 PM ? In article <88042.83861.qm@...>, Mark Tolleson <mark1200sportyrider@...> wrote: Thanks, I guess. This whole power adapter thing just irritates me. Who started this and why? It saves manufacturers a lot of money. Any new piece of equipment that is connected to mains power has to be submitted for tests and approvals before it can be sold. This is expensive. If it is DC or ultra low voltage AC powered it doesn't. So, the manufacturer just buys in a standard "off the shelf" power adapter which has already been approved and he's done. If he makes design changes or upgrades which would otherwise require a new set of tests he doesn't have to worry because he can carry on using the same adapter. Power supply manufacturer puts a standard unit, say 12V 1A, through the approvals process and then sells them by the million to numerous different equipment manufacturers and the cost per unit of the approvals process becomes negligible. -- Stuart Winsor Midland RISC OS show - Sat July 9th 2011 |
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lists
In article <710724.91605.qm@...>,
Mark Tolleson <mark1200sportyrider@...> wrote: Well there it is then. Sounds reasonable. Now if every specificationWouldn't we all, well, apart from the fact that sometimes they fit awkwardly on a distribution block. I understand that mobile phone manufacturers are moving towards standardising on a USB connection for charging their phones which will make life easier. -- Stuart Winsor Midland RISC OS show - Sat July 9th 2011 |
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I've actually had this exact same problem ( 19" LCD with a 12V/4A power
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brick that burnt out ), and since I had a pair of 12V/2A wall-warts laying around, I ganged them together in parallel. Seems to work great. Barring that, my standard approach to these problems would just be to hook up a spare ATX power supply - you can usually find them for free in old PCs that people throw away because they're underpowered they don't know how to clean up their virus collection. -Andrew On Wed, Jan 19, 2011 at 11:27 AM, Reese <reeza@...> wrote:
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I've said this many times - discussions of general PC software help are off-topic here.
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Add to that, you are hijacking a thread. Steve Greenfield AE7HD Your grumpy neighborhood moderator --- In Electronics_101@..., John Eh <jwoolsey@...> wrote:
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Mark Tolleson
My 12v LCD is still working fine with a 19v supply.? Am I slowly burning it up?? Do DC appliances have built-in voltage regulators to protect them from lazy cheapskates like me?? Couldn't I change out a couple of components in the supply to change it to 12V?? Maybe I am lucky but I've never had trouble cheating this way.
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Mark --- On Sun, 1/23/11, Andrew Villeneuve <andrewmv@...> wrote:
From: Andrew Villeneuve <andrewmv@...> Subject: Re: [Electronics_101] LCD monitor power supply To: Electronics_101@... Date: Sunday, January 23, 2011, 10:48 PM ? I've actually had this exact same problem ( 19" LCD with a 12V/4A power brick that burnt out ), and since I had a pair of 12V/2A wall-warts laying around, I ganged them together in parallel. Seems to work great. Barring that, my standard approach to these problems would just be to hook up a spare ATX power supply - you can usually find them for free in old PCs that people throw away because they're underpowered they don't know how to clean up their virus collection. -Andrew On Wed, Jan 19, 2011 at 11:27 AM, Reese <reeza@...> wrote: I have a bad news story. The 100-240 v input, 12v 4A output power brick that sends power to my 19" LCD monitor apparently took a dump overnight. An LED on the brick does not light up properly, I can't measure anything on the output side. I've already looked in my spare parts piles, I do not have any power bricks or wallwarts that come close enough. I'm in the process of opening the plastic case, to see if anything is obviously wrong and can easily be fixed. It's glued (no screws) so it is slow going with a hobbyist slitting saw: < On the chance that the brick is properly toasted and cannot be fixed, what are some other options for 12vdc @ 4a to power the monitor? Yes, I can Google for something, but I thought I'd ask here first. If something quick and easy makes for a good project build, why not do that instead of rushing of to purchase a turnkey item? Reese [Non-text portions of this message have been removed] |
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An excelllent source for a variety of power supplies is Marlin P. Jones
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Associates, Inc., located in Lake Park, Florida (www. mpja.com). Prices are very reasonable, and a wide variety of linear and switch-mode power supplies are available. MPJ is always my first choice when I need a power supply. Another thought: "Wall Warts" are not (generally) NOT regulated. A "nominal" voltage is usually specified on the unit, but since they are not regulated, the actual voltage delivered to the device being powered can vary a great deal, proportionate to the V/I demand of the device being powered. Switch-mode power supplies are almost always regulated, and these are they types of supplies that are used with computer monitors, etc. IMHO, using an unregulated "wall wart" to powrer some devices can lead to drastic disaster at worst, and poor and erratic operation at best. MPJ usually has in stock, a variety of switch-mode, regulated "bricks" that are reasonably priced. I never attempt to repair a failed switch-mode brick..............it just not economically worth the effort........that is.........if you can ever actually repair the blasted thing and get back to spec. For example: MPJ shows several 12VDC bricks with 1 Amp, up to 4 Amp capability at prices around 10 to 15 bucks. Can't beat MJP's prices, variety, and fast shipment. Spend your time designing something that's fun and useful. Roland F. Harriston, P.D. **** Roland F. Harriston Andrew Villeneuve wrote:
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Peter Morris
The reason that you can often get away with using the wrong "brick" is
because most of the monitor's internal circuitry requires voltages other that 12 (usually 5 and 3.3 among others). The monitor has DC-DC converters inside which will maintain a constant output voltage over a wide range of input voltages. When using DC-Dc converters, the higher the input voltage, the less current will be drawn from the supply. I'd be careful going too high though, as there will be some devices requiring 12V (audio op-amps spring to mind). Also, there are probably some electrolytic capacitors across the 12V rail rated at either 16V, 25V, or 35V. If 16V - 19V "brick" will kill them. With 25V - 19V will be close, but probably ok. If the caps are 35V rated, then 19V won't harm them. When choosing a replacement PSU (brick), the voltage is usually the most important point of specification. If the original was 12V 4A, then the replacement should be 12V (or close, eg. 11-14ish) and at least 4A. If the monitor requires 4 amps, a 2 amp PSU won't be able to cope. A 12V 10A PSU will work fine. A 20V 4A supply is not recommended. As for repairing the old "brick", in my experience, the most common cause of failure of switch-mode PSUs is electrolytic capacitors 'drying out'. This is often because the PSUs are built to a pathetic budget, meaning the cheapest parts are used, not the most appropriate. Switch-mode PSUs operate at high frequencies (usually in the region of 100KHz). With current flowing in and out of the bulk electrolytic capacitors at these rates, ESR of the capacitors becomes crucial in order to keep ripple on the output (and instability as a result) low. When capacitors with high ESR are used, the result is that the capacitors heat up while in use. This often causes the top of the can to bulge until the weak point in the middle breaks. At this point, the electrolyte will evaporate. As this happens, the effective capacitance of the capacitor reduces to almost nothing. The ripple of the PSU will increase and eventually, the PSU will no longer even start. In short, when I am presented with a faulty piece of equipment which I suspect may be the SMPS, I immediately visually inspect the electrolytic for signs of bulging. If there are any with even the slightest of bulges, I replace them without question. 9 times out of 10, this has worked. Just last week, I repaired a PC which would power on and then power down straight away. I took the cover off and there were 7 caps on the MoBo with bulging tops. I replaced them and the PC now works fine. Hope this is insightful for some of you. Please tell me if you think I missed the point, or have just wasted a lot of your time reading this. Thanks Pipester From: Electronics_101@... [mailto:Electronics_101@...] On Behalf Of Roland F. Harriston Sent: 24 January 2011 15:41 To: Electronics_101@... Subject: Re: [Electronics_101] LCD monitor power supply An excelllent source for a variety of power supplies is Marlin P. Jones Associates, Inc., located in Lake Park, Florida (www. mpja.com). Prices are very reasonable, and a wide variety of linear and switch-mode power supplies are available. MPJ is always my first choice when I need a power supply. Another thought: "Wall Warts" are not (generally) NOT regulated. A "nominal" voltage is usually specified on the unit, but since they are not regulated, the actual voltage delivered to the device being powered can vary a great deal, proportionate to the V/I demand of the device being powered. Switch-mode power supplies are almost always regulated, and these are they types of supplies that are used with computer monitors, etc. IMHO, using an unregulated "wall wart" to powrer some devices can lead to drastic disaster at worst, and poor and erratic operation at best. MPJ usually has in stock, a variety of switch-mode, regulated "bricks" that are reasonably priced. I never attempt to repair a failed switch-mode brick..............it just not economically worth the effort........that is.........if you can ever actually repair the blasted thing and get back to spec. For example: MPJ shows several 12VDC bricks with 1 Amp, up to 4 Amp capability at prices around 10 to 15 bucks. Can't beat MJP's prices, variety, and fast shipment. Spend your time designing something that's fun and useful. Roland F. Harriston, P.D. **** Roland F. Harriston Andrew Villeneuve wrote: <mailto:reeza%40reeza.com> <mailto:reeza%40reeza.com>> wrote: 600-h/413S586EGEL__SL500_AA280_.jpg On the chance that the brick is properly toasted and cannot be fixed, |
Steven AE7HD
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