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gigabajcior
July 2nd, 2016, 10:18 AM
Hello all,

I have a problem with 5170 I found on attic.
It was "dead" but after some investigation I found that coprocessor was installed in wrong way, after fix I get a picture on a screen:

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I installed my POST card and I received: DD FF FE -> DD FF FE -> DD FF FE etc.

I found an info:


NOTE: If the BBBB portion (failing bits) contains many "F", example: "FFFE", then it is highly likely that non-existing RAM is being tested.
For example (one of many), this would occur if the machine SETUP is configured for 640K of RAM, but only 512K is fitted.
For example (one of many), a RAM card has failed completely.

http://minuszerodegrees.net/5170/post_errors/5170_post_errors.htm


So, I installed a fresh battery and a PARITY MEM. CARD 128KB I have but message is the same.

I was stuck because all 3 methods of SETUP require to go forward, into BASIC or booting procedure. But I have only an error message, without any "press F1" or something.
Even a procedure of clearing CMOS requires a BASIC (http://www.minuszerodegrees.net/5170/setup/5170_clear_cmos_rtc_ram.htm) :(

Do you have any idea how to push it forward?

Best regards

Artur

Stone
July 2nd, 2016, 10:53 AM
If I had to take a guess I would say the there is a bad chip(s) in the first memory bank.

modem7
July 2nd, 2016, 03:37 PM
Welcome to these forums.


I have a problem with 5170 I found on attic.
It was "dead" but after some investigation I found that coprocessor was installed in wrong way, after fix I get a picture on a screen:
"000000" is the very first memory address. In the IBM 5170, it is within the motherboard RAM.
So, you have a problem associated with motherboard RAM.

On a type 1 motherboard, there are two banks (2 lots of 18 RAM chips) of RAM. Address 000000 is in the first bank, bank 0.
Type 2 and 3 motherboards have only one bank (18 RAM chips) of RAM.

"FFFE" is serious. In a 5170, it indicates that all bits are faulty at the tested address.


I installed my POST card and I received: DD FF FE -> DD FF FE -> DD FF FE etc.
That is expected. In an IBM 5170, DD is the POST code that indicates RAM failure in bank 0.


So, I installed a fresh battery and a PARITY MEM. CARD 128KB I have but message is the same.
That is expected too.
* A good battery (and configured SETUP/CMOS settings) do not affect the ability of the 5170's POST to do a test of RAM bank 0.
* Adding a 'top up' RAM card does not impact on the good/bad status of motherboard RAM.


Do you have any idea how to push it forward?
I was able to replicate your exact error message. I did it by bringing my 5170 motherboard of type 3 out of storage, fitting it with a monochrome video card, removing all 18 RAM chips, then powering on the motherboard.

Is your motherboard missing the RAM chips ?

If you have a type 1 motherboard (has 2 banks of RAM), is it the case that only one of the banks is populated, but it was bank 1 that was populated instead of bank 0 ?


... I found that coprocessor was installed in wrong way ...
Are the motherboard's RAM chips in the right way?

If so, perhaps the previous owner of the motherboard accidentally inserted them the wrong way, and the chips were damaged when the motherboard was then powered on.

gigabajcior
July 2nd, 2016, 11:21 PM
Hello Modem7,

thank you for your time and your answer :)

My motherboard is type 1, both banks are fully populated, and I think all RAM chips are inserted in correct way.
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I thought that FFFE error means that there is a difference between SETUP settings and installed RAM, but if it means "I don't see any RAM" it is really more serious problem.
When I will back home with this machine I will play with multimeter and logic state analyzer, maybe I will find a reason.

Best regards

Artur

modem7
July 3rd, 2016, 02:20 AM
I thought that FFFE error means that there is a difference between SETUP settings and installed RAM ...
If it was just a CMOS/SETUP configuration issue, with nothing to boot from, the IBM 5170 would eventually jump into cassette BASIC (after displaying errors).

But the base of RAM is considered critical; it holds the interrupt vectors, the BDA, etc. If the 5170's POST detects a failure at the base of RAM (see the OF checkpoint at [here (http://www.minuszerodegrees.net/5170/post_errors/5170_post_codes.htm)]), an indication of failure is given, but the POST does not proceed any further.


... but if it means "I don't see any RAM" it is really more serious problem.
The breakdown of the 5170's 201 error is [here (http://www.minuszerodegrees.net/5170/ram/5170_ram_201_error_breakdown.jpg)].
The "000000 FFFE" equates to a failure of all bits, excepting bit 0, at address 000000.

You would expect that "FFFF" would be the bit error pattern shown if non-existent 16-bit RAM was tested, but in the IBM 5170, I have only ever seen "FFFE". One of these days, I will research the cause.


My motherboard is type 1, both banks are fully populated, and I think all RAM chips are inserted in correct way.
At least twice, I have put all 36 RAM chips in the wrong way. Of course, when I realised my error, I put them in the right way, but many of the RAM chips did not survive my stupidity. It is an expensive mistake.

gigabajcior
July 16th, 2016, 01:39 AM
Hello,

finally I had some time to play with this board.
I checked:
- a power supply on all chips, 5.11V everywhere,
- all clocks and dividers, all OK,
- transmissions on data and address buses connected with RAM chips, for me all looks OK,
- all additional signals on all RAM chips, like RAS, CAS etc. and this looks for me OK too, similar to charts in datasheet.
I keep searching.

BR

Artur

gigabajcior
March 5th, 2017, 10:30 AM
Hello,

finally mainboard works :)
Problem was in DS1010-200 delay chip.
I asked my friend for help and he discovered this by comparing with second mainboard.
I will post photos when I assemmble whole PC.

BR

Artur

modem7
March 5th, 2017, 09:45 PM
finally mainboard works :)
Problem was in DS1010-200 delay chip.
I asked my friend for help and he discovered this by comparing with second mainboard.
That is good news.
It is good to get feedback.
I have included your repair in the web page at [here (http://minuszerodegrees.net/vcf_motherboard_failure_history.htm)].

gigabajcior
May 1st, 2017, 10:29 AM
Hello,

some photos as promised :)

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More:
https://www.dropbox.com/sh/1ejabwj92aux6vh/AABbdJs0IGIjGqhbCq62R271a?dl=0