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Compaq Portable power on Issues

C

cbolvin

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Joined
Aug 20, 2014
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27
Location
Outside Chicago
About time I joined . I've been "lurking" off and on for a few years.

Anyway, One of my two Compaq portables decided it would refuse to boot properly. It's an early dual diskette version (No hard drives). It had been working up until this week when I was using it to compare with a recent acquisition of a Portable Plus and to start on restoring the keyboard (disintegrated keypads on both units). I added the Portable Plus to my existing collection that includes the Portable I (Dual diskette) a Portable II and two Portable III's (all working) and a fully restored dual diskette NorthStar Horizon with Televideo 910 terminal and my Hercules system with working vintage 3174, 3278 and 3287 gear.

When I turned the power on, I got a fan and nothing more, no screen, nuttin. Also the system light on the main board didn't light. So I'm thinking a bad board has affected the PS voltages. So I started by pulling the generic memory expansion/Clock/IO board and tried again.

This time I get the system light but the unit sounds a constant low tone for a minute or two followed by a low motor-boating sound followed by a constant high tone. The Drive 0 LED also comes on. All this with no screen or cursor. None of the diagnostic manuals seem to address this so I thought I'd throw it out for the group. Same thing when I pull the remaining boards (diskette controller and Video board). Not sure if I'm looking at a power supply issue here or not since the tones and diskette seem to indicate otherwise.

Any clues here?

Thanks!

Chuck
 
I recently got hold of a Compaq Portable I and had very similar issues with the screen not coming on. You would power it up and the fan could be heard but no cursor, it would also activate the A drive in the normal way. I noticed that it happened intermittently, especially after a warm re-boot. This lead me to check the connectors between the CRT and analog video board. I suspect on my machine, it is a bad solder joint on one of the connectors because after pressing down on all the connectors the problem has gone for now. I may pull the video board if it happens again to check the solder joints. This is a common problem with CRT video boards, I have two other systems that required re-soldering of the connectors on the video board.
 
Thanks for the tip! Sounds like a good idea. I'll give it a go tomorrow. Hopefully someone will have some insight on the remaining problem.

Thanks!
 
Well, some progress!

The screen is working. It turns out the brightness needed to be turned up all the way. Looks like the master brightness needs adjusting. And I did find a video pin with a cracked solder joint so I re-flowed all of them (thanks again for the tip!).

The POST codes are coming up 101 and 301. I already know the unit has keyboard issues but the 101 indicates an I/O ROM error. I'm not sure if the ROM is actually bad or what. I do get a prompt to insert a diskette so I don't think the entire system board is bad.

Could this be just a failed EPROM I wonder?

Chuck
 
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cbolvin said:
Well, some progress!

The screen is working. It turns out the brightness needed to be turned up all the way. Looks like the master brightness needs adjusting. And I did find a video pin with a cracked solder joint so I re-flowed all of them (thanks again for the tip!).

The POST codes are coming up 101 and 301. I already know the unit has keyboard issues but the 101 indicates an I/O ROM error. I'm not sure if the ROM is actually bad or what. I do get a prompt to insert a diskette so I don't think the entire system board is bad.

Could this be just a failed EPROM I wonder?

Chuck
Click to expand...

Good to hear the screen is working. Table 5-2 of the manual states "stuck key" as a 3xx error code. This is highly likely, I did a good clean out of the degraded foam in the keypads, then was able to test the keyboard using the bare pcd and a test key.
 
tkc8800 said:
Good to hear the screen is working. Table 5-2 of the manual states "stuck key" as a 3xx error code. This is highly likely, I did a good clean out of the degraded foam in the keypads, then was able to test the keyboard using the bare pcd and a test key.
Click to expand...

I have the keyboard already disassembled in preparation for rebuilding both my units and ran the last test with just the bare board connected and still got the 301. I'm going to try and swap the other keyboard as a quick test since most of those keys still work. However, I'm going to ignore the 301 for the time being and concentrating on the 101. This keyboard may be legitimately bad.
 
I pulled the EPROM and popped into my programmer and was able to read it but the verify failed. That would explain the 101 code. I'll need to replace the EPROM. I don't have a fresh copy of the BIOS or a way to erase the EPROM. I'm going to pull the EPROM from the Portable Plus and burn a new EEPROM and try it.
 
This is interesting. I pulled the BIOS rom from the other portable and it appears to be a mask rom, not an EPROM and not one that I can find a data sheet on.

AMD AM9265DPC. Before I can read it I need to what settings to use on my programmer.
 
http://bitsavers.informatik.uni-stuttgart.de/pdf/umc/UMC_Data_Book_1986.pdf

Have a look at that UMC IC handbook from 1986 in the link above. If you look at the cross reference table it shows that the AM9265 is pin compatible with the UM2366A. If you then search in the PDF for the UM2366A you will find the datasheet on page 23 of the PDF. Seems like a very standard ROM; your programmer should be able to read it.

Good luck!
 
3pcedev said:
http://bitsavers.informatik.uni-stuttgart.de/pdf/umc/UMC_Data_Book_1986.pdf

Have a look at that UMC IC handbook from 1986 in the link above. If you look at the cross reference table it shows that the AM9265 is pin compatible with the UM2366A. If you then search in the PDF for the UM2366A you will find the datasheet on page 23 of the PDF. Seems like a very standard ROM; your programmer should be able to read it.

Good luck!
Click to expand...

Out STANDING! I didn't think to look at bitsavers! The sheet says the UM2366A is pin compatible with the 2764 which should work. Now to give it a go.

Thanks for the assist!

Chuck
 
Well, it's not the ROM. I trieda fresh ROM with two different BIOS versions and get the same behavior. I tested the old ROM and was able to get a good read and checksum so I'm thinking it's been fine all along. Turns out I used an incorrect procedure on the programmer. What I did notice is the beep sounds are the same even when the ROM socket is empty.

So next step was to verify voltages. The voltages are all there but not the most robust I've seen. +5 is actually +4.4, -5 is -4.4, +12 is more like +11 and -12 is -11. The same regardless if the system board is connected or not.

My other Portable I voltages are better. +5 is about +4.8 and +12 is closer to +11.5. Better but not dramatically better. This is with System Board disconnected. That unit powers up and runs fine. It's a Plus so it also has the 20MB hard drive.

The voltages on the problem unit are out of tolerance (5%) according to the maintenance and service guide, but not dramatically.

Anyone know how picky these system boards are?

Chuck
 
Doesn't appear to be power supply either. I connected the bad system board to the known good power supply on the other Portable and same symptoms. I tried a POST card and evidently the Compaq doesn't display post codes on the bus. It however shows that one particular card, the no name clock/ram multifunction card causes the +5 line to shut down.

So I started looking at possible system board shorts. I thought I may have had a shorted tantalum and unsoldered one leg of all the tantalums and tested again. Same problem. I tested each of the tantalums and they seem to be ok since they do react like an electrolytic should when you use an ohmmeter on them.

I'm running out of things to check for since there doesn't seem to be a troubleshooting procedure that addresses this problem. I may end up just using the unit for parts at this point. Crap...
 
- Voltages too low: Are you sure it's not your multimeter?
- beep sounds? Could it be that there are multiple ROMs in the computer and you only found one? Are these from the speaker?

Unfortunately it seems not so easy to find a photo of the mainboard.
 
H-A-L-9000 said:
- Voltages too low: Are you sure it's not your multimeter?
- beep sounds? Could it be that there are multiple ROMs in the computer and you only found one? Are these from the speaker?

Unfortunately it seems not so easy to find a photo of the mainboard.
Click to expand...

This is a Version 1 board with only one ROM which I've already replaced as part of the testing. If you look at my initial posts, I referenced the sounds and the POST codes that show up if the display board is plugged in. 101 and 301 (System ROM and keyboard). I've fixed the keyboard but still encountering the ROM issue. I'm beginning to think there's a blown IC but at this point I'm not sure where to start without schematics or a procedure.

The board has been tested with another Portable with a known good power supply that is fully functional and the board still fails so it's not power supply at this point.
 
Guess it's time for the SuperSoft ROM.

Can you confirm?
- The sound is from the PC speaker, not a fan or drive motor
- In case this BIOS does a memory test/count, is the sound audible during this timespan or does it start later? (if it starts later it may be the code execution running out of control, otherwise the timer or PIO responding to bus accesses they shouldn't)
 
H-A-L-9000 said:
Guess it's time for the SuperSoft ROM.

Can you confirm?
- The sound is from the PC speaker, not a fan or drive motor
- In case this BIOS does a memory test/count, is the sound audible during this timespan or does it start later? (if it starts later it may be the code execution running out of control, otherwise the timer or PIO responding to bus accesses they shouldn't)
Click to expand...

Sounds are definitely from the speaker. It's not hard to tell the difference between a fan or disk noise and speaker tones ;)

There is no BIOS memory count in a Compaq Portable I. That didn't come into play until the 286's AFAIK. The sounds start the instant the power is turned on. Low tone for several seconds followed by a kind of a growl for a short time then high tone from then on.

The POST Analyzer card I have does at least indicate all the voltages are there along with clock signal, IRDY and FRAME signals on the bus.

The SuperSoft ROM sounds interesting. Will it work in a non-IBM machine like the Compaq Portable I ?? The Portable I uses 2764 EPROMS so would I need the special adapter? I wouldn't think so but???
 
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Well, SuperSoft ROM to the Rescue! A big thank you for the suggestion H-A-L-9000 and 3pcedev!

I programmed up a 28C64B EEPROM, plugged it in and it took off running!

Looks like a dead keyboard controller. I have a known good keyboard on the machine and it's still throwing the error. And that seems to be the only error! I'm letting it run for a few hours to make sure there aren't any other problems once the machine warms up.

Now to figure out where the issue is as I don't think Compaq uses an actual keyboard controller but sends serial keyboard data to an 8255 on the system board.

Anyone have the system board keyboard connector pin-outs on the Portable I? I'm seeing +12V on one of the pins and that doesn't sound right. Unless Compaq uses 12V to power the keyboard. All the PC and XT pin-outs I see show +5.

Portable I SS ROM.jpg
 
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