R51 motherboard swap attempt

[erik21]

I've swapped an R51e(?) motherboard into my ailing T40 after a failed reflow (on the T40 board). After putting it mostly back together (having mostly everything connected, including the LCD) I plugged it in and hoped for something on the display.

What I got: one beep, three beeps, three more beeps, and then another beep. This is supposed to mean faulty ram or ram socket. I moved the RAM in the back socket to the front socket, I tried removing the RAM in the back socket, and I tried re-seating the one in the front socket. No dice. Still the beeps.

What I'm wondering is...does this mean the board or socket is faulty for sure? Could it be because I didn't have everything screwed in tight? Could I have *fried* something - are any of the screws used as grounds?

Please reply(!),
erik

[Harryc]

R51e - 256MB std / 2GB max / PC2-4200 533MHz DDR2 / non-parity / CL4 / single channel /
two 200-pin SO-DIMM sockets / std memory in one socket / one socket available

T40 - 256MB std / 2GB max / PC2100 266MHz DDR1 (DDR-SDRAM) / non-parity / CL2.5 /two 200-pin SO-DIMM sockets / std memory in one socket / one socket available

http://www.lenovo.com/psref/pdf/ltwbook.pdf

[erik21]

R51e - 256MB std / 2GB max / PC2-4200 533MHz DDR2 / non-parity / CL4 / single channel /
two 200-pin SO-DIMM sockets / std memory in one socket / one socket available

T40 - 256MB std / 2GB max / PC2100 266MHz DDR1 (DDR-SDRAM) / non-parity / CL2.5 /two 200-pin SO-DIMM sockets / std memory in one socket / one socket available

http://www.lenovo.com/psref/pdf/ltwbook.pdf

Harryc, you rock! That must be it.

I made one more observation, which is that, upon swapping the new board in, there's not really a full battery bay. The "bay" on the board I swapped in was part of it's lower plastic shell. Could this be an issue? I'm a little afraid to attach the battery. (EDIT: looks like it's an R51, not an R51e. Seems that it'd make it PC2700. )

[RealBlackStuff]

When you come up with such questions, it would help us tremendously, if you would also post the 7-character TYPE/Model number(s) of the Thinkpad(s) involved.

PC2100 and PC2700 RAM modules are compatible and interchangeable.
They would not fit in a PC4200 slot, nor would it work the other way around.
Look at the groove between the gold-plated contacts, it should line up exactly with a small 'cam' in the RAM slot, and go in smoothly. If not, you try the wrong type of RAM.
The R51(e) is thicker than the T40, and therefore only looks like having a bigger battery bay.
Battery should fit without any issues.

[erik21]

Thanks, I'll keep that in mind in the future. I wasn't aware of the potential ambiguity.

The model numbers are 2373-72U and 2883-8QU. The RAM I'm using is PC2100. Are 2700 and 2100 always compatible and interchangable?

Thanks again,
Erik

[sjthinkpader]

For a T40, PC2100 is the default memory technology. PC2700 modules are normally compatible in T40 but run at PC2100 speeds.

The key in a PC2-4200 DDR2 socket is positioned differently than PC2100/PC2700 DDR sockets but you might be able to force a module in. If you lay them side by side, DDR2 key is a little more toward the center and the DDR key is a little more to the edge.

For T4x/R5x series, the DDR2 key is positioned on the opposite end than DDR key.

[erik21]

Okay, I'm going to try swapping a stick of PC2700 in. Is there a chance that a bad socket could fry the module I put in? Is the chance significant? (A friend told me this, but it sounds dubious, but I'm checking with you guys first; you seem to know what you're doing. :-])

Also, if it doesn't work, is it a for-sure that the socket is bad? Could anything else possibly be wrong?

Thanks,
erik

[Harryc]

Thanks, I'll keep that in mind in the future. I wasn't aware of the potential ambiguity.

The model numbers are 2373-72U and 2883-8QU. The RAM I'm using is PC2100. Are 2700 and 2100 always compatible and interchangable?

Thanks again,
Erik

2373-72U is a T40 board that uses PC2100 266MHz DDR-SDRAM / non-parity / CL2.5
2883-8QU is an R51 board that uses PC2700 333MHz DDR1 (DDR-SDRAM) / non-parity / CL2.5

You should be able to run PC2100 in a PC2700 machine, but that might not always be the case. I'd agree to try a stick of PC2700.