Crystal Oscillator leakage help!

Jackovarian

1: Can Crystal Oscillators leak? (small cylindrical kind. I've googled and googled and no use)

2: If one were to leak could they cause a dead circuit, it connects right at the RISC processor National PC97551 (runs at 20mhz.)

I have this dead motherboard, no lights nothing, except that it makes a ticking noise near the gfx area. So upon further investigation I found an oscillator, which seemed to have rusty brown dried in stuff around one side. (it was lying flat) It looked as if it may have a puncture in its side. So, thinking it could just be flux, I removed it from the board and cleaned it a bit. Whatever it was just brushed off.
It does seem like flux, but the only reason I'm doubting that is the fact that there are other oscillators like this around the board and they are very neatly soldered, and this machine was never serviced or opened by anyone but myself.

oh, the click noise was coming at least four inches from the oscillator. In an area where there are no components!

I tested using a sensitive microphone.


any help would be greatly appreciated.

(I know this motherboard is probably shot, but its not mine, its just a last ditch effort for a friend before they fork out for a new machine.)


machine is a fujitsu siemens amilo d7850

Power is running through the board fine to a point, only the - is reaching the battery. + gets up as far as a transistor, right beside the battery terminal, but its like there isnt enough power being let through by the tiny resistor before it to open the gate, so to speak.

Solitaire

No, but they can burn out due to abnormal surges or simple wear. Plus that board sounds a bit like its powerded in the residue of a blown cap sopmewhere. Unless you a) have 100% knowledge of what every trace and component on the board does and what levels should be present, b) have like-for-like replacement components and c) have experience with and ownership of a working SMD soldering rig then that mobo won't be pulling a Lazarus anytime soon. Your mate's gonna need a new comp...

x in the city

well a dead xtal would be a reason for it not to power up for sure.

careful with them, they have traces going through several layers of the pcb.

you can just get one from maplin at the right frequency and slap it on [very carefully]


the clicking noise is the cpu 'resetting' upon power up

it most likely cant find a clock signal due to fubared xtal

Jackovarian

Thanks lads. For the sake of the small expense I might aswel get one to try out. As for the layers of pcb, the contacts lay in a solder pool on the back of the board, which went through the board, I made sure of it before i removed it. So its a simple matter of laying them back down, rather than trying to push them into the hole, like a normal circuit.


Another thing i stumbled upon last night, but didnt think much of was the possibility that it could be the bios chip...

Now, its a removable chip, so I may just buy a replacement one aswell, just to try out at least.

But, is that reasonably possible? Even for a basic light to come on?


Oh and i forgot to say, this problem started slowly. over the course of a few weeks. I forget the symptoms during the time period. But My immediate thought (other than battery or ac adapter) was bad capacitance or power regualtion.

I read an article about ibm travelmates with dodgy power regulators, that would crack and pull away from the board, you'd have to turn the machine upside down, tap them, and they'd fall out, then you'd have to re-solder them. (I'm talking about the dark square metal ones, with the round solenoids in the centre, and four solder points, one on each corner, two high, two low)

Jackovarian

So, got a new crystal ,same frequency, put it on perfect.

same old story.

Ticks. There is heat coming off the board under the gfx heatsink. Its a small rectangular component. (f) 45 SS84, could be a power regulator. Might just be heating up due to whatever else is happening. Its the only component thats heating up. Its not making the noise.

Its a rectangular black box, about 8 mill long, 6 mill wide and 3 deep. Has two wide connections on each end. thats it. Can't figure out what it is. Theres still power running through it fine. All I can tell is that it has been included as part of the gfx cooling process.

any ideas?

Jackovarian

actually, I think its a surge suppressor.

Jackovarian

Ok, forget that component,


the ticking noise is the RISC processor and the timing crystal (NEW ONE)

Same as before.

Jackovarian

The RISC is obviously working, as is the timing crystal. So, my last port of call before I quit is the bios chip.

I've gone to the amibios site, where it says that a dead motherboard can be a sign of a dead bios chip.


any input would be appreciated!

blackgold>>

are the keyboard leds lighting up when you power it on?

Jackovarian

No lights at all. Just the noise.