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First Generation Compaq Portable - Nothing on startup!

F

Fireflite

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Joined
Sep 24, 2015
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Location
Florida :D
Hey everyone, back after a long absence with this find!

I was pretty excited to pick this little (not very little, actually :p) Compaq Portable up today, cool old computers like these don't show up too often down here! I bought it from a man who claimed to be the original owner since 1985, and a date stamp inside the machine says April 18th 1984.

I got the machine home and hooked it up, turned it on, and got nothing except the whirring of the fan. The screen was cold, no disk could be heard or anything. I found out the keyboard cord was not connected to anything inside the machine, and there's a grey cable laying disconnected inside (see photo). I think I might be missing a HDD? Or does this machine boot from a disk? I've seen models with 1 floppy drive in front and an HDD in front, mine has dual floppies in front. I'm also missing ALL of the peripheral cards, which leads me to believe my machine may have been used for parts in it's life? Not sure but it would be cool to get this thing going again!

What parts am I missing, what cards would've originally came with this machine?
Thanks everyone, sorry if this seems like a dumb post, I'm really new to the vintage computer scene haha :D
Additional pictures/info/anything available upon request ;)

Eggs.jpg101_0947.jpg
 
My 2nd portable did that when I first got it... two of the tantalum capacitors had shorted out making the power supply trip out. The fan is powered right off 120v so it keeps running.

I figured out which cap was bad by putting my multimeter at the motherboard's power supply connector ground and working backwards. IIRC the shorted cap was on the 5v rail. By measuring resistance between things with a +5v connection and ground I could narrow in on the area of the board where the short was. You'll need an accurate meter with good probes to do this.

Looking back at the pictures I took I think this was one of the bad caps:

P87843900.jpg


This one was bad too:

P87844502.jpg


You'll want to read up on KeyTronic foam & foil keyboards. Likely yours will need to be rebuilt.

-J
 
So I've been getting my Portable going as well. First time I turned it on this year another tantalum in the PSU blew. I'd forgotten one blew a couple years ago when I set the system aside. Replaced them, and a couple others which I had the correct value of on hand.

IMG_20160505_214705.jpg


The machine worked great for about 2 hours, then click... just the fan again. After some testing I found the tantalum in the PSU on the -12v rail had shorted out. This cap is a real PITA to get at as it's buried between a heatsink and the big caps on the 5V rail.

IMG_20160506_220925.jpg

The small bright bulb is on the -12v rail, the large bright bulb is on +12v, and the dim headlight bulb is on +5 :)

I think I'll stop playing whack a mole with these stupid tantalums and replace them all before I put it back together.

-J
 
@compu_85

Thanks for posting.
By the way, can you dump the BIOS file from EPROM or DEBUG.EXE?
 
Isn't the grey cable (leading to the white molex connector) in the 2nd picture the main power cable to the motherboard from the PSU? You can just make out the pins on the motherboard that it should be connected to as well.

If so that should be connected and then you can continue fault finding.
 
3pcedev said:
Isn't the grey cable (leading to the white molex connector) in the 2nd picture the main power cable to the motherboard from the PSU?
Click to expand...

You're right... I missed that earlier. The header it plugs into on the MB is the first picture I posted in post 3. You access it by popping the bottom off the machine, then loosening the 2 screws (don't have to remove them) on the small cover over the motherboard's power, speaker, and keyboard connections.

I'd suggest turning the machine on and measuring the power at the floppy connectors before hooking the motherboard up. That will let you know if the PSU is working. If the power goes away when you plug in the MB there's a short on it someplace. Plug in just the MB first. If it powers up then add the cards.

FS550, I'll grab a copy of the ROM now :) My machine is from 1984. I don't know what ROM revision it is.

-J
 
fs5500 said:
@compu_85

Thanks for posting.
By the way, can you dump the BIOS file from EPROM or DEBUG.EXE?
Click to expand...

Turns out my programmer can't read 8kb roms? :confused:

Any hints on how to do this with Debug? My machine has a Rev. F motherboard and a 100666-001 Rev C. Rom.
 
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