R52 doesn't power on. Where to start?

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#1 Post by **RealBlackStuff** » Thu Sep 18, 2008 3:38 pm

I have an R52 (1858-W14) with the 400MHz 39T5647 mobo (910GM chipset).
No lights come on and the battery seems dead as well. Doesn't measure any current).
No fan spinning up, no beeps.
Tried with LCD, and without LCD but with external monitor. No luck.
Checked out all the fuses I could find.
Checked for cold solder joints.
Nothing found so far.
The wifi- and modem-cards have been removed.
Tried one stick of RAM in both slots, as well as a stick in each slot.

The mobo is currently out of it's case, but still no luck.

From your experience, what are possible suspects?

spuddog · #2 Post by **spuddog** » Thu Sep 18, 2008 3:45 pm

If no lights at all come on at all-at-all and the battery is dead, maybe power jack or power supply?

Scott

mgo · #3 Post by **mgo** » Thu Sep 18, 2008 4:15 pm

RealBlackStuff wrote:I have an R52 (1858-W14) with the 400MHz 39T5647 mobo (910GM chipset).
No lights come on and the battery seems dead as well. Doesn't measure any current).
No fan spinning up, no beeps.
Tried with LCD, and without LCD but with external monitor. No luck.
Checked out all the fuses I could find.
Checked for cold solder joints.
Nothing found so far.
The wifi- and modem-cards have been removed.
Tried one stick of RAM in both slots, as well as a stick in each slot.

The mobo is currently out of it's case, but still no luck.

From your experience, what are possible suspects?

I had a R51 that acted in a similar way. I stumbled on a solution. By pulling the battery out (with the machine off, of course) and pushing the battery back in, the machine returned to life when powered on. Perhaps it was dirty contacts on the battery plug on the chassis.

#4 Post by **RealBlackStuff** » Thu Sep 18, 2008 4:40 pm

I have plenty adapters that all work.
The DC jack is OK, and the white plug attached to it and the mobo shows 16V.

Should there be a current between the + and - contacts of the battery? Nothing there on mine.

mgo · #5 Post by **mgo** » Thu Sep 18, 2008 6:13 pm

RealBlackStuff wrote:I have plenty adapters that all work.
The DC jack is OK, and the white plug attached to it and the mobo shows 16V.

Should there be a current between the + and - contacts of the battery? Nothing there on mine.

I've never done any measurements in that area, so cannot say. It's also possible that one of the mobo leads has separated. Just a wild guess there.

sjthinkpader · #6 Post by **sjthinkpader** » Fri Sep 19, 2008 12:30 am

Are you sure this is 400Mhz MB? My R52s are 533Mhz. You have DDR2 RAM in the slot and 730/740/750 CPU?

kebomix · #7 Post by **kebomix** » Fri Sep 19, 2008 6:52 am

try to work it on power , i have R52 (1858 - 69G)

#8 Post by **RealBlackStuff** » Fri Sep 19, 2008 10:04 am

The current CPU is a Celeron M 360, 1.4GHz, 400MHz FB, 1MB L2 cache.
To be replaced with a Pentium M 745, 1.8GHz, 400MHz FB, 2MB L2 Dothan, if/when I get it going.
Just in case, my mobo will not take 533MHz CPUs.

FYI, I have repaired lots of T23s and T30s, but this R52 so far eludes me.

Are there specific problems on an R50/51/52 that keep recurring?
I'm sure one of you has THE solution.

spuddog · #9 Post by **spuddog** » Fri Sep 19, 2008 11:52 am

It really doesn't help your situation, but on the Lenovo support page it lists the processors for a 1858-w14 as:

Intel Mobile Pentium M 730(1.6GHz), 740(1.7GHz), 750(1.8GHz), 760(2.0GHz), 770(2.13GHz)
Intel Celeron M 350(1.3GHz), 360(1.4GHz), 370(1.5GHz)

So although you have a 400mz processor in the machine now, it does seem to support 533mz cpu's.

Now back to the power on problem, have you tries taking the battery out, then trying to power up with the adapter only. maybe there is a short in the battery.

Scott

#10 Post by **RealBlackStuff** » Fri Sep 19, 2008 12:21 pm

If you read my first post again, it says there I have a dead battery.
I've tried it with battery attached as well (inspite of it being dead), on the off-chance it would trigger something.

I'm looking for specific items to check, such as a specific inductor, condenser, resistor or whatever, that has gone south on similar mobos.
Or are these mobos so stable, that nobody has had a problem with them?
Hard to believe

#11 Post by **rkawakami** » Fri Sep 19, 2008 1:30 pm

Not R52 specific, but this might apply.... I have three T41 motherboards which didn't respond to all of the power sources I've tried - AC adapter, main battery and docking port (don't have an Ultrabay battery). I too have checked the DC jack, the plug at the motherboard, all of the fuses that I can find and they all check out working but there's no life at all. A couple of the boards have what appears to be corrosion around various components; almost as if something was spilled on it. There were are also a couple of parts which appeared to be damaged so I put the boards away for another day. (Can't recall off-hand exactly what kinds of parts they were but it wasn't anything obvious like loose inductors or light-emitting transistors; more like chip resistors or capacitors.)

With a totally dead system, I'd start looking at all of the power MOSFETs and power controller ICs on the board, pulling datasheets on them to see where to stick a voltmeter or oscilloscope. While I don't actively look for R5x systems on eBay, I have noticed plenty of T4x systems which are described as "dead". This leads me to believe that there's something relatively common which occurs that takes out the entire motherboard (video issues aside).

spuddog · #12 Post by **spuddog** » Fri Sep 19, 2008 4:37 pm

Re-reading your first post, you ask for ideas on what to do. I'm sure the people who responded, did not know you were interested in Specific Items to check. Sorry to waste your time.

Scott

vlyne · #13 Post by **vlyne** » Fri Sep 19, 2008 9:11 pm

Good to know I’m not alone! I’ve had two boards with the same symptoms (or lack of symptoms!). In both cases (one an R51 I think, and another an R50, plus another unrelated case of a Celeron R50e), a capacitor under the motherboard, left of the S-Video port (where there is one) and south of the parallel port was blown. On the non-Celerons it’s between and just north of two chips marked “Pulse” or “Midoc”. Repairing this with an SMD 5 microfarad capacitor (if anyone knows what it should be please let me know) fixed one board but the other is still dead (the dead one apparently had a liquid spill so I'm not surprised it's still dead). Whatever blew the capacitor probably took out some other part so I’ll have another search later on when time permits. I also noticed that the curiously located lid switch on the LCD connector can get stuck and give symptoms of starting but not booting. Hope you find the culprit!
Cheers

R52 doesn't power on. Where to start?

R52 doesn't power on. Where to start?

Re: R52 doesn't power on. Where to start?

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