Finer details of the 340 and 345 series

[solidpro]

HI Everyone

I'm going to do a write up this week but I've been gradually going through and restoring a pile of 340 machines, along with one 345.

I can't find a simple breakdown of the differences between the models - does anyone know? Rather than having to scour hardware manuals.

I *think* all of the 340s are monochrome TFT, whereas the 345 I have is a colour TFT.
The 345 has the CPU on a baby expension card attached to a metal heatsink, so I guess it's a bit faster. Other than that, exactly the same.

Anyway, there is a funamental problem with all the DC power sockets on them - affecting nearly all of the ones I've seen in the exact same way. Luckily they're really simple and nice to disassemble and repair, so I'll do a write up sometime soon with photos.

The power button is a bit different to most other models - especially the 750 and the 360 which were pretty close relatives to this machine. I wondered for a short while if it wasn't built by thinkpad, but I believe it is - I guess they were just trying a different type of power switch.

Cheers!

[ThinkDan]

thinkwiki.de is a good source of this sort of info, they frequently list differences between similar iterations / models. For the 345:

• faster CPU

• larger HDD

• colour screens only

[solidpro]

Yes, that's essentially the conclusion I came to. Some of which after wasting 30 minutes about to swap something better from a 340 with something worse on the single 345 I have.

I've a feeling perhaps 345 machines had a very limited release.

faster CPU - yes and it was mounted via a heatsink screwed to the RF shielding on a little two-connector daughterboard.
larger HDD - probably, possibly, but all dying soon!
colour screens only - both colour and larger. The 340 machines I had with colour screens all had DSTN and what looked like >10" The 345 was colour, DTSN and was larger than 10"

[ThinkDan]

This online HMM gives an apparent combined listing of 340 & 345 parts, noting screen sizes only for the 340 (DSTN) but offering either DSTN or TFT for the 345.

[solidpro]

Hmmm, I think I got unlucky then.

The 345 I have exhibits a behaviour I've seen develop lots and lots of times and suspect it's age related wear to the ribbon assembly. You know when you adjust the contrast you can see on these really old screens it kind of handles the top and bottom of the LCD display seperately - sometimes when adjusting you can see a line across the middle? Well lots of these old thinkpads develop a minor vertical screen glitch pattern repeated all across the screen but usually worse on the bottom half. You can still use it, but it's like someone has put up some net curtains.

What do you think that is?

[astral]

generally, artifacting and "ghost lines" are expected behavior on passive matrix behavior. a picture would help me to tell whether or not what's going on for you is normal or not.
bad capacitors can cause these artifacts to grow worse/severe though. some displays are better in this regard than others. my PS/Note 425 screen looks god-awful and it's been recapped.

[ThinkDan]

It may be an artefact of how dualscan displays work, and may point to progressive hardware failure up around the panel itself. DSTN screens are treated as two halves (upper and lower) and each half is refreshed simultaneously to improve on the image clarity of passive matrix screens.

For many ThinkPads where DSTN and TFT were options, the same video chipset drives either display. I strongly suspect the failures you are seeing come in at the panel driver where the VGA output is presented to the panel. The DSTN panel would have a dedicated panel driver board that is doing this split'n'refresh trick, and would be very different from an equivalent TFT panel driver board. I think this is partly why the various screen types and sizes were only listed (and replaced) as complete upper lid assemblies in the HMM - too many parts that don't interchange physically or electrically.

If you can see distinct upper and lower screen halves behaving differently I would concentrate on the driver board by the panel and any onwards connection/cabling to the panel itself. If the VGA chipset were giving a duff signal, or the ribbon from the VGA to the panel driver was faulty, then I would expect this to give consistent faults across the whole screen, irrespective of the DSTN halving.

[solidpro]

That's really useful. Although I'm going to have to re-read it 3 more times to totally get a grip on how to tackle it.

This would be the 143rd reason to avoid thinkpads with DSTN screens.

[ThinkDan]

My terminology of 'panel driver board' may be incorrect, but it's the electronics receiving the video cable signal and interfacing directly with the panel, not any inverter associated with CCFL backlighting...

DSTN put colour screens into so many hands whilst shaving thousands and then hundreds off the cost of TFT colour. I wouldn't entertain it now, and I pity those who buy DSTN laptops now for retro gaming, but at the time it was a means to an end.

[ThinkDan]

Pulled a DSTN screen assembly out of stock for some photos:



It's the 9.4" DSTN for the 750 and later 360 models, probably others, but a good example of the time. The 'panel driver board' is clearly seen attached to the back of the panel, the inverter board (which also has the brightness and contrast controls) is separate. The latter has a small connection to the display ribbon, probably to communicate the contrast setting, brightness being done by the CCFL supply.

So I think the generic problem is at the panel. I see capacitors, lots of capacitors...