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You made a great deal.
I also have this docking station with TP360CE or 760LD attached to it. And this is an excellent setup for DOS gaming.
The only downside of your 755CSE is the DSTN screen, as you already mentioned. It also has MWAVE based sound card, according to Thinkwiki. Is it indeed the case? From my experience MVAWE it works okay, but I'd disable it and install a proper sound card with MIDI DB in the ISA slot inside the dock.
It may also be tricky to find the CD-ROM for it. I bought the installation kit (66G3536 ) for mine on ebay, but see none available now.

There is a very nice thread about this device - 486 Thinkpad with genuine Sound Blaster Pro 2

Bondi wrote on 2020-04-27, 16:14:

You made a great deal. I also have this docking station with TP360CE or 760LD attached to it. And this is an excellent setup for […]
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You made a great deal.
I also have this docking station with TP360CE or 760LD attached to it. And this is an excellent setup for DOS gaming.
The only downside of your 755CSE is the DSTN screen, as you already mentioned. It also has MWAVE based sound card, according to Thinkwiki. Is it indeed the case? From my experience MVAWE it works okay, but I'd disable it and install a proper sound card with MIDI DB in the ISA slot inside the dock.
It may also be tricky to find the CD-ROM for it. I bought the installation kit (66G3536 ) for mine on ebay, but see none available now.

There is a very nice thread about this device - 486 Thinkpad with genuine Sound Blaster Pro 2

I have some questions.
1) When the dock is locked does it also lock the computer screen ?
2) Do you have a link to the docking station manual ?
3) What ISA sound cards work in this dock ?
4) Does Win95 perform okay in this laptop with a 486dx4-100 CPU ?

There is no actually screen lock. The lock has 3 positions - left(2) - computer cannot be turned on at all, middle - TP can be undocked, right(1) - can be turned on. So, in the position of your lock it can boot, but cannot be undocked.
http://download.lenovo.com/ibmdl/pub/pc/pccbb … les/dock1ug.pdf - User's guide
http://download.lenovo.com/ibmdl/pub/pc/pccbb … kpad/tpvol1.pdf - HMM
The dock can take any full length and hight isa card with a daughtherboard.
Win95 works acceptable if you have enough RAM. There are videos of 755CD(same CPU) running W95 on YT.

Did you try to remove the BIOS battery to clear the password? There should be 2 batteries, one is standby battery the other one is BIOS battery. If you're lucky it's the boot password, and not supervisor pasword.

Yes, I removed the batteries and turned on the laptop.
I received 2 beeps and then it reboots. it just goes in a cycle.
I did not see any lock on the screen however.

I also tried to open the bottom but the key is locked so I could not open the bottom cover.
Can you post a photo of the key. I want to try to have a local locksmith make a key.

Do you start it with main battery removed? I had exactly the same problem. Removing the battery did the trick.
Here is the key.

Thanks for your help.
Yes, I removed the main battery and the two other batteries. One was a yellow coin battery and the other was a green battery.
They both look bad with corrosion.
See photo.

Just checked beep symptom table https://download.lenovo.com/ibmdl/pub/pc/pccb … iles/tpvol2.pdf

Two short beeps with blank screen. - 1. System Board

Bondi wrote on 2020-04-30, 11:57:

Just checked beep symptom table https://download.lenovo.com/ibmdl/pub/pc/pccb … iles/tpvol2.pdf

Two short beeps with blank screen. - 1. System Board

Yeah, I saw that document. It’s almost like for any beeps they quote ( -1. System board ).

I am going to take it to the lock smith maybe next week to get a key made.
Once I get it off the dock I can more comfortably work on it.

Thanks for your help.

I am going to work on this this month and have it ready for Christmas.
It has an original ISA sound card in the dock.
Not sure what kind.

I have a new donor thinkpad so I should be able to make at least one good one out of these.

What are the odds!

*Almost* the same key

Yes, I still have to take this to the local locksmith and get a key made.
I have been putting it off because of the lockdown.
At least I have a working 755 thinkpad.

But I have some new sound cards too.

I'm working on a similar project a frankenpad with parts a 760ED, 760EL, 755c and a Dock I 3545.
The dock was locked when I got it. I'm little more impatient than the OP and started taking screws out and managed to remove the bottom panel.
I admit it did take a little force and my dock was in rough shape to begin with and wasn't risking much
(I got the Dock and the 755c with busted lcd together off ebay for $80).
I then removed the back of the lock and rotated the metal plate 90 degrees so it was in the unlocked position but the lock itself was locked.
Dock works fine

BTW, I'm working with a 760XL and the same dock right now - the name of the dock in the photos is "Dock I" (model 3545-001), not SelectaDock.