760L seems to try to power on successfully but does not. PIC

[Krysti]

Ok, I just got this thing today which the seller claimed it worked fine.. well it does not.

Here's the situation.

I do have the official thinkpad AC adapter, the machine is in fairly decent cosmetic shape over than a crack in the lower portion of the case, not near anything important by the CD tray which seems operational.

The battery is presumably dead, which was expected.. does not power up without AC adapter.

When I power it on I get no battery/power LEDs indicating anything at all however I feel the disk spin up, I see the LCD briefly blink VERY slightly, I see the CD-ROM blink it's LED on the door panel, no system beep. Nothing from VGA out.

No VGA out is indicating to me that the display isn't part of this current problem, presumably it would display VGA out if it were just an laptop display issue, bringing it to the system below.
I removed all the CD-ROM, Battery, HDD, spray contacts down, nothing.
I removed battery all together and attempted to power it on without it, nothing.
Reseated the RAM module, nothing.
No visible internal damage from what I see, however Im not totally sure how to get into the entire machine beyond the RAM bay, and removing battery, HDD and CD-ROM. I'm not 100% how many of these screws lead to serviceable parts as I'm not totally familiar with Thinkpads and where I should poke and prod for potential issues given the symptoms. I'm not even sure where the backup battery is as the manual made it a little confusing and IF the battery is dead, I'm not sure it would lead to solving any of these symptoms.

The Audio indicator on the mini LCD screen below on the actual machine is blinking when I power it on, and after it presumably fails. The cylindrical icon turns on, then eventually turns off. ONCE I seen a floppy disk looking icon but that has yet to return. The power switch does not power down the laptop, must be unplugged/powered off at strip.

What bothers me, is I do not get a single error number out of the LCD (and not sure if it's even capable) and it just sits there blinking the audio icon, no other behaviour from the laptop happens as long as I leave it on.

Any advice would be great. This is my first Thinkpad, I just wanted a lil laptop for DOS. I picked it up for it's notorious reputation of being a rather tough machine, and hoping I can get this thing turned around.



Admin note: Added PIC warning. Please read Rules of the Road. Photos should be <50KB (which yours is) but also should be around 800x600.

MOD note: Picture is 163KB, WAY too big...

Admin mea culpa: Did I read the image size wrong? I thought I saw ~60KB, not 160KB.

[rkawakami]

Welcome to thinkpads.com!

- Before continuing on, realize that some of the things I'm suggesting here will probably violate any "warranty" you have with the seller.
- Download a copy of the Hardware Maintenance Manual from here: http://www.thinkpads.com/support/hmm/hm ... ol4hmm.pdf It has useful information on troubleshooting problems with the system and contains fairly detailed instructions on how to take the system apart.
- Double check the voltage from the AC adapter (see Power Systems Checkout). If it registers the proper voltages, then continue on.
- Given the age of the system, it might be a good idea to check/replace the CMOS (backup) battery. Check the voltage and see if it's less than 3V. The Standby battery is probably less important but since you have the system apart, check that one too. Complete instructions are also in the HMM (again, Power Systems Checkout section).
- Remove all hardware from the system that's plugged into sockets/connectors. This includes memory, hard drive, Ultrabay (optical) drive, PCMCIA, MiniPCI, communications daughter cards, etc. Do not remove the CPU. Then attempt to power up. You should get at least some beeps. Note the sequence and length of beeps (short vs. long). Look up the beep code in the HMM (Symptom-to-FRU Index). If the system remains silent, that's generally not a good sign and I'd suspect the DC-DC card or the motherboard. Assuming that the system becomes partially alive, continue on.
- Assuming that the batteries are good, and you received a beep code that indicates bad/missing memory or a problem with the motherboard AND the system seems to be partially alive again, plug one memory module into the system and repeat attempt at powering up/booting. Keep powering off, re-installing another device and re-booting. What you are looking for is a return to the "dead" system status. If that happens, the last thing you plugged back into the system is suspect.

[Krysti]

AC adapter operates proper @ 16v w/ 2 grounds and 1 positive as indicated on the back of the power brick.

CMOS battery tests ok. Standby battery tests about 2.6v of it's 3.5v or whatever it was. I have my doubts this would cause any of these symptoms but perhaps just hurt my standby ability.

Speakers appeared to be connected, so a lack of a beep when I removed all the hardware was a bummer. In fact, that darn audio icon on the status LCD panel on the machine is STILL blinking. I see NOTHING in the service manual about what this icon means when it's doing that, or why it should even matter. I resoldered the leads to the audio in case someone had worked on it and they were crapped up.

I disconnected and reconnected all the ribbons connected to the front board under the keyboard.

I booted this thing nearly empty, no beeps.. I haven't tested the speakers to an external device, I may do that tomorrow to see if they output at all.



For anyone else bumping into this topic, this is the proper service manual. http://download.lenovo.com/ibmdl/pub/pc ... tpvol3.pdf .. It's not really explained in great detail as to what you're going for when you unscrew the bottom front of the keyboard, but just flip it back around and remove the panel, speaker/mouse buttons side. All set.

If anybody else has any more suggestions, I'd be most grateful. I feel like I've reached the end of my rope with this thing because I'm not getting much output other than a few indicators on the mini LCD on the keyboard end of the machine. Again, VGA out doesn't work, so I have to assume something deeper in the machine is flakey. The easily removed and modular parts may all be fine, but the core seems to be experiencing some issues.

I should be able to get SOME VGA out if the LCD is of issue right? I should be able to see screen errors telling me this thing is a problem.

[rkawakami]

Googling around for symptoms as you describe only results in a description of a 760ED. While not exactly like your problem, the advice was to check the standby switch activated when the lid is closed to see if it is stuck. I don't know where that is located on the 760L (sorry, I'm not exactly knowledgeable on this old system ) but it's most likely near the back of the base.

Also please confirm you are pressing the Fn+F7 key combination a couple of times after the system is turned on when attempting to ascertain if the VGA is working. The port is typically off until you force it to switch with that key press.

I've never played around with the 700 series but I understand that with some of the earlier Thinkpad power problems, it was due to a defective DC-DC board. I don't know if you're at the point of throwing $$$ at the problem but if it were me I'd start there, along with a CPU swap with a known good unit.

Yes, if just the LCD backlight is out or there's a problem with the inverter, then that really shouldn't affect video going out the VGA port.

I also provided the link to the Vol4 version of the HMM as it's newer. Both documents contain the 760-series systems.

[Norway Pad]

I assume you read this thread: http://forum.thinkpads.com/viewtopic.php?f=6&t=115215 A lot of troubleshooting was done, but the root cause was quite simple.

In your case though, with an icon flashing that really shouldn't be flashing, I might suspect something deeper inside to be wrong. At that point, swapping components for known good components is a way to go. But as Ray says, that might be to throw money into this that you didn't plan on spending on in the first place.

Maybe that1nerd has some of his surplus known good components from the thread above up for sale?

[Krysti]

The volume 4 manual seemed to have a different deconstruction of the CMOS battery than volume 3. It was depicting the CMOS battery over by the RAM module, this one is by the keyboard card (annoyingly so because its kinda flimsily in there).

I did test Fn+F7 to attempt to get the VGA port outputting and nothing.

The seller refunded me for the machine so I've lost no money on this thing now, if I could get a new, WORKING, 760 model (not XD or XL) then I should be good, hopefully I can find one this cheap again. I wanted to keep it between 90-133MHz so all the older DOS games aren't running too fast. He's letting me keep this DOA Thinkpad, if I get it working without investing into it I'll just give him the money back.

I wish I could get _some_ answers with what's wrong with this, I wish it would just return an error and some standard behaviour to diagnose the problem. The blinking audio icon tells me nothing.

My keyboard card appears in good condition, although I'm not sure how it looks under the board where the ribbons come out. The card itself has functional ribbon connectors, they connect nice and firmly. I'll do what I can to test the speakers for output, if they don't, I think I have some similar sized 8 ohm speakers I can drop in there. The beep indicator would certainly put my diagnostic in a forward direction.

Again, any further diagnostic suggestions are welcome. I'm wanting to figure out which part is bad and not seeing any easy solution without the pieces to swap/test on different machines, so any suggestions to diagnose with what I got, great.

Thanks everybody.

EDIT: Yes, I did check that guy's thread, it's what prompted me to check the connections by the keyboard card.

[that1nerd]

Maybe that1nerd has some of his surplus known good components from the thread above up for sale?

Yeah, I've still got them.

I have a complete system board assembly out of a 760XL, including all of the daughter cards. They should be completely interchangeable with the 760L.

I also have two completely working 760XLs that I'm currently selling in the marketplace. (Shameless self-advertising. )

[Krysti]

Yeah, I've still got them.

I have a complete system board assembly out of a 760XL, including all of the daughter cards. They should be completely interchangeable with the 760L.

I also have two completely working 760XLs that I'm currently selling in the marketplace. (Shameless self-advertising. )

The thing is I'm not sure where I should start replacing. Also as much as I'd like to buy a complete system off of you, I'm a little concerned the CPU is too fast for older DOS games so I got a no-go on the XD and XL. It just slightly spills over my comfort zone CPU speed wise.

[that1nerd]

You might be better off with a 486 desktop for DOS games. I exclusively built a 486DX4 machine for that very reason.

The 760s are better suited for running Windows 9x era games that won't run on modern hardware/OSes, but I've all but lost patience with these things. What with the constant IRQ conflicts, software incompatibilities, and questionable stability. In that regard, I've had better luck with the 770X that I purchased recently.

As for your laptop, it's kind of difficult to tell what's wrong without being able to run diagnostics from within Easy Setup.

But I've seen what you're describing happen before, with one of the 760s that I have. After removing both the standby battery and CMOS battery, it finally came back up. Just be cautious in regard to the small momentary switch on the keyboard card. It's quite fragile.

[RealBlackStuff]

By sheer coincidence I found this today in my parts-corner.

It is a complete LCD assembly (lid, 12.1" XGA LCD, LCD cable) for a Thinkpad 760.
On the LCD cable is a label with P/N 46H6006 and FRU 82H8486.
Per HMM tpvol3.pdf this is for 760E CD Upgradable Type or 760ED, but it may also fit yours.
There are some scuff marks on the outside, and on the edges some of the paint has come off.
Plastics are 100%
The LCD looks in great shape, with no scratches or dents, but I cannot test it.

If you (or anybody else) need it, $20 incl. shipping to CONUS.
PM me if interested.

[that1nerd]

By sheer coincidence I found this today in my parts-corner.

It is a complete LCD assembly (lid, 12.1" XGA LCD, LCD cable) for a Thinkpad 760.
On the LCD cable is a label with P/N 46H6006 and FRU 82H8486.
Per HMM tpvol3.pdf this is for 760E CD Upgradable Type or 760ED, but it may also fit yours.
There are some scuff marks on the outside, and on the edges some of the paint has come off.
Plastics are 100%
The LCD looks in great shape, with no scratches or dents, but I cannot test it.

If you (or anybody else) need it, $20 incl. shipping to CONUS.
PM me if interested.

I actually got my hands on a parts unit 760EL, but the LCD shell isn't thick enough to fit onto a 760XD. After sitting them side-by-side, the 760XD/XL is about a 1/4 inch thicker than the other 760s to account for the popup keyboard.

Thanks for the offer, though.

[Krysti]

I have doubts that this is an LCD issue on my end. I should be able to activate the VGA and it's not responding at all in the way of beeps, LEDs or really anything but that darn blinking audio icon on my mini LCD on the system. What I *COULD* use is a new planar board for the 760L. If anyone has one of those sitting around in spare parts, known to be working, would appreciate it.

[that1nerd]

What I *COULD* use is a new planar board for the 760L. If anyone has one of those sitting around in spare parts, known to be working, would appreciate it.

As I said before, I have the complete set of boards out of a 760XL that I could part with. The internal "guts" of the 760s are completely interchangeable with each other, with the processor and model specific addons (MWave) being the only differences between them.

Hit me up with a PM if you're interested.

[Krysti]

What I *COULD* use is a new planar board for the 760L. If anyone has one of those sitting around in spare parts, known to be working, would appreciate it.

As I said before, I have the complete set of boards out of a 760XL that I could part with. The internal "guts" of the 760s are completely interchangeable with each other, with the processor and model specific addons (MWave) being the only differences between them.

Hit me up with a PM if you're interested.

I don't want the CPU to be that fast. As much as I'd love to fix this, that overshoots my comfort zone with the kinda gaming I want done with this. Thanks though, I appreciate the offer.

[that1nerd]

I don't want the CPU to be that fast. As much as I'd love to fix this, that overshoots my comfort zone with the kinda gaming I want done with this. Thanks though, I appreciate the offer.

You'd just have to swap the processor card from your 760L onto the new board. That's what I'm trying to tell you.

[Krysti]

I don't want the CPU to be that fast. As much as I'd love to fix this, that overshoots my comfort zone with the kinda gaming I want done with this. Thanks though, I appreciate the offer.

You'd just have to swap the processor card from your 760L onto the new board. That's what I'm trying to tell you.

Oh, I gotcha. I haven't been in that part of the computer yet so I wasn't aware it was that easy to do.