Chips for Compal EAL50

my laptop's main board model is EAL50 and a local repairer confirms the fault is the voltage regulator with part number 4407-BESK4H but that part is not listed anywhere so I can't get a replacement or any details to help work out what would be a valid alternative.

No replacement main board is available either so i need to fix this one.

Where do I look to find what part I need?

Pic1 shows the main board with the parts' location boxed (top left of image).
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Pic 2 is as close and clear as my camera gets, but the stamp is still not visible.
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The parts are DIL 8 pin chips about 6mm long and 5mm wide. There are 2 of them (I didn't realise there are 2 and don't know which is faulty so I guess I'll be replacing both

There is not much room for numbers. There is a logo (see pic 3) and 4407 on the top line then BESK4H on the line below. These 2 lines of print fill the top surface of the chip.
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So, anyone know what these chips are and what I can replace them with?

Hi Welcome to the WTT forums

I see that you have been trying to solve this problem for a month or two now:
http://www.fixya.com/support/t541757-compa…ded_4407_besk4h

From a workshop perspective this is likely to be an uneconomic repair, and most shops would point you in the direction of ebay for a replacement or at least a replacement mobo….However if your service tech has been able to identify correctly the unservicable chips and the part number, then can you get him/her to either replace them for you or supply them to you.?

I have checked my data sheets and the part numbers you quote do not appear on any of the likely sources….for quickness I would suggest you consider resourcing a replacement mobo either ebay or other auction facility of your local computer breaker……if you had the values/descriptors of the parts concerned I would try either Maplins or Radio Spares
http://www.maplin.co.uk/?DOY=search&C=SO&U=strat15
or http://uk.rs-online.com/web/
Good luck with your search
Regards
paws

You're right. This has been on a back burner for months. I'm being pressed to "tidy up that pile of junk" so I thought I'd try posting in a fresh forum. Thanks for the suggestion but I've been down that track. The local repairer took the thing apart and diagnosed the fault and determined that these chips were to blame but, as you have also discovered, they're not in any catalogue (at least under this part number) so can't be ordered in or sourced from Maplin or elsewhere. I also looked at replacing the main board but can't get one - even though they're still appearing in new notebooks (as revealed by a web search - there's at least 1 Scandinavian outlet offering new notebooks based on the EAL50 main board, but not spares) there are no suppliers of main boards. I even contacted Compal's UK service department but their answer was that there are none in stock. When I pressed for info regarding when stock might be available I got a simple repeat of "as we said before there are none in stock". So, unable to replace the main board en bloc, and unable to find the actual parts by number, I figured the next step would be to try a generic voltage regulator that would fit the 8 pin DIL holes and match the chips' characteristics as closely as possible. I was hoping that this forum would help me identify what chips I need to get from Maplins. You mention computer breakers, but I've never seen anything on those lines. None of the repair shops locally will deal with "scrap" and I hate the idea of dumping what amounts to a complete notebook with a a few cent's worth of dead parts into landfill. I hope it doesn't come to that, but it's looking likely.

Hi Brian and

As odd as it sounds, Compal, the world's 2nd largest laptop maker, is not well known in the US. Compal is a huge OEM/ODM provider for many laptop brands - Compal designs and makes the barebones laptops and ships them off to Dell, HP/Compaq, Acer and Toshiba, among others, where they are branded then populated with RAM, drives, CPUs, monitors (all made by some other OEM company), and some "proprietary" stuff, then sold as their own products.

I doubt that mainboard is rare and yet, as noted, a search on EAL50 yields little more than your own inquiries. So it would seem information about that mainboard is being controlled - probably through NDAs with the resellers. If this laptop has been re-branded, you might send a note to the reseller's technical support.

What is the make and model of the laptop? How old is it? Can you see the BIOS make and number?

generic voltage regulator that would fit the 8 pin DIL

Ummm, no. There is no "generic" voltage regulator. What voltage would you have it regulate? Motherboards use several. The problem we have now, from a repair standpoint - assuming your repair guy is right and it's the regulator (and only the regulator) you indicated - since the part numbers don't seem to match, we don't even know what that regulator chip really does - we at least need the schematics (electronics road map or blueprint) to determine its designed specification, the voltage or voltages it is supposed to regulate. Also, since regulators, by design, are pretty rugged, I would wonder why it failed? Heat is the bane of all electronics. Unless you hit it with a hammer, heat did it - slow roasted, or in a flash. Was it a faulty component that just failed on it's own? Or did something else in the circuit fail and the regulator took the brunt of the excess current? We don't know. I would be concerned something in the power supply and charging circuits failed, then took out the regulator - that is not uncommon. It would be sad to go to great effort to identify, purchase, and replace the regulator only to watch it go up in smoke the first time you powered up.

I agree with paws, unless you have the tools and are skilled at soldering heat sensitive devices to multi-layered printed circuit boards, in other words, you can do all the labor yourself, the cost of repair outweighs the returns - unless the returns are simply the successful accomplishment of a personal restoration project!

I hate to send you away after your first post, but your best bet might be to talk to others that might be having similar problems. If me, I would post this question in the "unofficial" Compal Forum at NotebookReview.com. They may know how you can get a replacement board, or cannibalized parts, or at least point you in the right direction.

Whatever you decide, good luck and keep us posted. I am curious to see how this turns out.

Thanks for this. I had taken my local repairer's diagnosis as absolute, and have been blindly seeking out some way to replace the chips or main board. With what I have learned about this board, and specifically the lack of detailed information about it, I'm now wondering just how the repairer managed to pin down that it was the voltage regulator (or indeed if if these chips are supposed to regulate voltage at all) without the benefit of schematics or spec sheets. I think I am able to swap out the chips without damaging the rest of the board or near components, but in light of what you say, I could go through all that and still have a dead notebook. If my fix doesn't work I won't know if the original problem was these chips but I'd killed something else, or if the original problem wasn't these chips in the first place. Heck - I might even end up with the original unfixed problem plus new damage caused by my replacing good chips with incompatible ones. Sheesh! - I'm hereby abandoning my quest to replace the chips. I'll concentrate on finding a replacement main board. Thanks for the link to the unofficial Compal forum.

If my fix doesn't work I won't know if the original problem was these chips but I'd killed something else, or if the original problem wasn't these chips in the first place. Heck - I might even end up with the original unfixed problem plus new damage caused by my replacing good chips with incompatible ones.

Catch-22. You can't really tell if something else destroyed the parts without the risk of destroying the new parts you just replaced. Preventing further damage is always the problem when troubleshooting electronics, attempting to isolate the fault.

Ideally, you would want a mock-up - a special test set that you connect the board to and the test equipment basically tells you what's wrong. Of course those are expensive - Compal probably has them on their QC end of the production lines, but it's not something your normal electronics repair guy would have on hand. Without that, you need some sort of technical manual or schematic, and know how to read them, necessary tools and skills, and/or lots of spare parts to swap in and try, a bit of luck, and a good ground.

In your repair guy's defense, since these were popular boards he may have seen this problem many times before, and already gone through the routine of trying to replace the parts.

If you do locate the regulators and you want to try your hand at replacing them, I recommend you go down to your local Radio Shack or electronics hobby story and buy a cheap printed circuit board and a bag of chips and practice your soldering techniques first. Again, heat is the bane of all electronics - and too much heat from a soldering iron can destroy a component just as easily as heat from too much current. And yet not enough heat will cause a bad or cold solder joint. It takes practice to get it right consistently.

the ic is made by alpha and omega type AO4407 into google for data sheet