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Compaq Portable POST error

PhilipA

Experienced Member
Joined
Aug 4, 2013
Messages
476
Location
Larose, LA, USA
Howdy, all

I've taken a bit of a look around, and the best I can come up with for the persistent error "301" on my Compaq portable 8088 is a keyboard error- but the keyboard is present and operational.

The only thing I can see on the board is what looks like the remains of a capacitor across two traces- snipped off at the base of the legs.

My question is thus: was my research correct, and is 301 indeed a keyboard failure? If so, is it anything specific, or a real generic error (being a low number in the 300's I'm guessing so).


Thanks

--Phil
 
It could be a stuck key. Is '301' all you get or is there more, like 'xy 301' or something like that, where x and y are numbers?
 
No. I've seen nnnn 201 when I've done things wrong with the memory, but the 301 is always just by itself.

I rebuilt the keyboard the way a few here have- foam padding and emergency blanket. Even with the keyboard stripped naked and the board by itself it still throws the 301.

--Phil
 
Unfortunately I don't have one. It's the funny built-in item that has a strange square Amphenol plug on the end, buried down inside the case- I'm guessing it's XT standard communications, but doesn't have the standard DIN plug.

--Phil
 
This is an original Compaq Portable or Compaq Portable Plus? The foam pads are notorious for disintegrating so you might very well have a one of the metal discs laying on the board inside.
 
Yes it's the Compaq Portable or Plus from the description of the square connector running into the back of the chassis. You said the keyboard does work though? I do agree it could be a stuck key or something throwing that error. If you disconnect the keyboard I guess you'd still end up with a keyboard error though lol. I can't remember, does it have a connector for an external AT keyboard? I'm thinking not but can't remember from memory alone. I only disconnected the keyboard recently but do remember it seemed possible to connect incorrectly back to the main board, I can't remember if it was truly keyed to prevent that or if they just figured you wouldn't go inside of the system too often for it to be an issue.
 
It's a Portable Plus, from what I understand. All the keys had disintegrated inside and none worked, so it's been thoroughly apart, had new foam and new Mylar assembled with some good contact adhesive. All the keys function normally.

With the keyboard unplugged it still throws 301, yes.

The connectors are keyed on both ends (the outside is a top-hat shape, can't insert it upside down into the keyboard on the inside nor the motherboard).

Beyond that, the keyboard operates as I'd expect it to... I can live with the error code (spurious or otherwise), but I was wondering if it was a keyboard fault, yes.

--Phil
 
...and now 7001 201 PARITY CHECK 2

Yet another MOSTEK chip gone bad. I think I left the spares at work. Bah.

--Phil
 
Given the condition of this computer when I got it, that could well be the case.

--Phil

That seems like a logical reason that you're getting an error. I have no idea how you'd test for that though...
 
I don't know either. Despite the error message, the keyboard works just fine.

I've put it down to a quirk, for now. Unfortunately the BIOS isn't particularly verbose when you send it through POST.

Phil
 
On a positive note, the new (well, ish, it's an old cordless phone battery) RTC battery I fitted yesterday took a charge, and upon retrieving the RTC from the board with SETCLOCK, it's within a few seconds of correct this morning.

Result.

Slowly getting there, though this thing has fought me every step of the way so far.


--Phil
 
Could be that snipped Capacitor may have been a Tantalum that shorted out. Tell ya what let me take a look at my keyboard and see if I can locate the Cap in question. That was in the Keyboard circuit board correct? Those caps are in there for a reason like filtering of the power supply voltages or even sometimes key debounce. And I would replace it. Give me a day or 2 to check mine out.
 
bigger question is could that single tantalum be causing his keyboard to throw a minor error but still function?

Possibly. If there is some noise on say the 5volt line then it could be making one of the support chips or even the controller act up. As I said the engineers put it there for a reason. Just a hunch.
 
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