Fuse size in IBM ThinkPad T22 wallwart power supply

It'll be a switcher. If it got wet, and the input fuse is blown, and the board is blackened, it can probably be pretty much considered to be beyond resurrection ...

I'd feel inclined to clean up the blackened bit as best you can, and then hang a 1 amp fuse across the original. If that immediately blows, it's not going to be worth wasting more time on.

Arfa

Attach a 55 watt incandescent lamp across the open fuse and use that as the test fuse.

And if you don't understand how that would work for you, you shouldn't be doing none of this, at all.

Jamie

You can get new power supply on Ebay for $8.

I don't think there's a fuse inside. Dry it out as best you can. Give it about a week or two in a warm area. Then, try it again. Otherwise, just buy another power supply on eBay.

dn't

Forgot about using a lamp as a fuse replacement to limit the current. Or heater for higher current

Didn't know they made 55W bulbs, found 60W and 40W and one that switches 50-100-150, but no 55W

Hmmm....that's about 260 ohm HOT, when cold more like 26 ohms. so the current will go somewhere between 5A down to 0.5A

still safer than putting in a 'penny'

thank you for the URL. Any experience with any of these suppliers?

thank you for the URL, I'm not familiar with using eBay, especially since I avoid eBay like the plague.

but this time, ....any experiences with any of these suppliers?

Yes, there is a pigtail fuse inside. just can't read the value on the UNDERSIDE!

Don't even want to start taking it apart if the rest is dead.

I've bought about a dozen laptop power supplies on Ebay, but can't remember the vendors names. They work well on the computers I bought them for.

Thank you, that's the FIRST time I've bought on eBay.

Cost 8.95 total cost, very prompt arrival with their expenditure for shipping 3.28 !! labeled made in China, does NOT have the AC plugged in LED, but at these prices, I can live without it.

Seems to work, the laptop display is still defunct.

I buy from eBay all the time. I often find that components that I can't source from my regular mainstream suppliers, are readily available from eBay shops. Sometimes, you wait a few days when the 'shop' is in China or Singapore or wherever, but it's worth living with that to be able to get the bits. I can honestly say that I've never had a problem with any item that I've bought. A couple of weeks back, my HP printer was showing that the yellow ink had run out - again - and was refusing to print in colour as a result. The cartridges are about 7 UKP a pop, and there are six of the buggers. The 'high capacity' black, which still contains pitifully little ink, is even more expensive. A few months back, I needed a couple of colours, and the local store had run out of them both, so I did what I have never dared do before, and bought a couple of no-brand compatibles from a printer ink shop in the town. They weren't actually very much cheaper than the real thing, but I have to say that they did work ok.

So when the yellow ran out again last week, I decided to have a look on eBay. I found a UK shop located up in the northeast, selling a kit of 12 - yes that's twelve! - cartridges, for 7.99 UKP total (!!) with free postage !! I had to read it several times. Not only is this two complete sets, the colour ones are 18 ml content, and the black is a 45 ml. The blurb says that they are guaranteed for 12 months, and are fitted with the 'high capacity' identifier chip.

I ordered them at 2am. By 8am, they were showing as 'shipped', and they arrived in the post first thing the next morning. Each cartridge is individually vacuum wrapped. For sure, there is a lot of Chinese writing on the packets, so I guess that's where they come from, but hey, who cares ? Not me, that's for sure. Anyway, I put the yellow in, and the machine accepted it without question, and has indeed registered it correctly as a high capacity cartridge. So far, it has performed faultlessly. The dark magenta started to issue warnings that it was getting low today, so I guess that will be the next one to go in.

I think that as long as you are sensible with eBay dealings, and take note of the feedback that's been given to a seller by his customers, there's no need to fear using it, at all.

Arfa

Plug in an external monitor into the "VGA" connector.

Sigh. When the laptop recovers from the baptism, turn it on, and shine a flashlight on the screen. Can you see the image of whatever it's booting? You may need to move the flashlight around to see the image. If it's visible, it's probably the inverter. However, if it comes on with an orange glow, it's the CCFL lamps in the LCD panel.

Yep. Google for "Thinkpad T22 LCD Inverter".

About $6.00

Yep. If you short it out with salt water and it can blow up. High voltage does funny things to sensitive electronics.

The screw covers are made from sheet plastic and held in with rubber cement. Pound a very small flat screwdriver between the screw cover and the plastic frame, and pry upward.

Find an AC voltmeter and measure the output voltage. For laptops, my guess(tm) is about 500-800 VAC. Please remember that you have but one life to give for your laptop.

Incidentally, the fan is often a problem on such Thinkpad laptops.

Jeff,

Thank you for the URL to eBay. The inverter PCB was identically labeled to the one I removed and only cost $5, however, upon re- assembly the screen is still dark.

Where it stands now:

The Laptop when connected to an external monitor, a C500 Multisync, came right up recognized the new monitor put in drivers and was displaying normally. Conclusion, the HD, the CPU works! so all is not lost.

The USB port did NOT work for a very long time but multiple insertions seem to have awakened that port. Hmmmm, wonder if it is still 'corroded' connectors to the buillt in display.

Anyway, I tried a flashlight near the LCD screen and could see nothing, no changings, like I expected something to be viewable. Maybe stronger light?. not sure the screen is being updated at all.

Culmination, so far is my first two experiences with eBay have been excellent. Prompt shipment, with tracking numbers, sadly, USPS screwed up badly and I did not receive the $5 Inverter PCB for almost a month! Plus, the shipping company had to resend at their expense! just not right.

Any suggestions for the next step?

(...)

How far did you get with:

--Winston

Measure the inverter output voltage as above.

Make sure you don't have the keyboard video switch set for external monitor only. On the T22 it's Fn-F7. Hold down the Fn button, and tap the F7 button *ONCE*. Anything on the screen? If not, tap the F7 button again.

Check the CMOS setup and make sure that the default display is the internal LCD display, and not the external.

I've received blown LCD inverters in the past. That's why I always buy two inverters. That's the risks of buying used parts extracted from allegedly working units.

Remove the keyboard and look for the video connector. It's a big fat cable coming from the left hinge and ending up on the motherboard. Make sure the connector is properly seated.

Check the backlighting display settings in the Thinkpad hardware manager application (I forgot what it's called). On some versions, it's possible to set the display brightness (also known as backlighting) to zero.

I have spare displays, but I don't think that's an option for you to try.

It's difficult to see. Humor me and start over. Shut off the laptop. Remove the AC power supply. Unplug the battery. Go away for about 15 minutes to make sure everything is reset. Do *NOT* attach the external monitor. Put everything back and turn on the machine. Do NOT play with Fn-F7. Now, try the flashlight trick.

I've had plenty of problems with USPS over the years. The other carriers are usually much better. Be sure to complain to the USPS and mention that they only have online delivery notification, not tracking, making it difficult to find lost packages.

Oops. Wrong description. It's a flat ribbon cable with the connector located about 1" from the rear center of the laptop on the motherboard.

FINALLY!! I verified that the LCD screen is validly changing pixels, all I need is the backlight.

Measure voltage. If the tube is OFF, is that the firing voltage? trying to get the tube to arc? sounds about right. 400 to 600 Vac firing voltage then goes down to the 20V 1A range.

Would you verify that there is NO polarity to the fluorescent tubes supply?

Ok. The panel is good. That leaves the LCD inverter and/or the CCFL backlighting tubes.

Could you please re-write that in English? It's not clear if you measured anything, what you measured, how you measured it, and what numbers were seen.

The CCFL lamp wires are not polarized.

However, the connector from the CCFL tubes is sometimes polarized. It is possible to plug in backwards. It will sorta fit, but not be seated correctly, resulting in no connection. My guess(tm) is is what you've done. Unplug the cable from the CCFL lamps and LOOK AT THEM carefully. Match it with the socket on the inverter. Hopefully, that will fix it.

Is there any possibility that the Lamp would work, the inverter would work, but some 'controller' is toast?

Looking at the corrosion pattern on the inverter PCB, it looked like the high voltage could have gained access back to the multi-pin connector, which [to me] translates to "any IC driver wired to that connector is likely to have been fired." Yet those same drivers are probably on the system board. which may, or may not, affect the system operation.

Oops, English is my native language, just doesn't often show.

Years ago, one of my clients made OCR electronics, my first design for them was to design reliable fluorescent tube power source *and* make certain the light pattern across a sheet of paper was uniform. To 'fire' the tube took any where from 400 to 600 Vac and once fired [the tube is now filled with conducting plasma] the operating voltage drops to 20-30 Vac at 1/2A, or so.

My [confusing] words were more of memories, than statements. I did not, have not, no real way to do so yet, measure any voltages around the Laptop.

Is the 'seating' of the connectors really that critical on the Laptop? I mean those connectors are cheap, low insertion force, miniaturized molex thingies that I find hard to believe provide reliable connection at all. But, are they really likely to be the problem, more than the likelihood of a non-operating component?

Regards, Robert