Sounds like timer failure.

This kind of beep code is pretty normal for a Phoenix BIOS. Well, of course, it's not normal to hear this beep code, it does point you to a mainboard problem, but the code issuing the beep is likely running properly. See http://www.bioscentral.com/beepcodes/phoenixbeep.htm for a phoenix beep code reference. In your case, you get the code 1-2-1 (one beep, pause, two beeps, pause, one beep) which means "PIT failure". The PIT is the "programmable interval timer", which was the Intel 8253 on the PC/XT and the Intel 8254 since the AT. More modern boards do not have all the individual Intel chips, but have all the "classic Intel chips" of the AT mainboard integrated into the 82c206. Your board features the '206 by the original inventor, Chips & Technologies, but it was heavily cloned by nearly every PC chipset company in the 90s. I was very surprised that this UMC-based board doesn't use the widespread UMC 82c206, but probably your board is older than UMCs clone.

"PIT failure" on your board most likely means that the processor is unable to properly communicate with the 82c206 chip. Looking at the board photo, it looks like some of the pin contacts in the socket might be bent. I'm very positive that the reason is improper contact of the '206 in the socket, or broken traces on the board going towards the '206 socket. If the socket is still fine, re-seating the '206 chip might help, too.

mkarcher wrote on 2022-11-19, 16:30:

This kind of beep code is pretty normal for a Phoenix BIOS. Well, of course, it's not normal to hear this beep code, it does point you to a mainboard problem, but the code issuing the beep is likely running properly. See http://www.bioscentral.com/beepcodes/phoenixbeep.htm for a phoenix beep code reference. In your case, you get the code 1-2-1 (one beep, pause, two beeps, pause, one beep) which means "PIT failure". The PIT is the "programmable interval timer", which was the Intel 8253 on the PC/XT and the Intel 8254 since the AT. More modern boards do not have all the individual Intel chips, but have all the "classic Intel chips" of the AT mainboard integrated into the 82c206. Your board features the '206 by the original inventor, Chips & Technologies, but it was heavily cloned by nearly every PC chipset company in the 90s. I was very surprised that this UMC-based board doesn't use the widespread UMC 82c206, but probably your board is older than UMCs clone.

"PIT failure" on your board most likely means that the processor is unable to properly communicate with the 82c206 chip. Looking at the board photo, it looks like some of the pin contacts in the socket might be bent. I'm very positive that the reason is improper contact of the '206 in the socket, or broken traces on the board going towards the '206 socket. If the socket is still fine, re-seating the '206 chip might help, too.

Hallo and thank you very much! My toughts were pointing the same way but I was not able to "decode" the beepings according the chart. You may have better ears! It make sence why the chip is socketed as those were prone to failure more then others (as far as other guys told me). PLC socket looks good - no cracks. But the board is pretty old and yes - may be dirty. There are no scratches or corrosion as this board has no battery - it comes probably from an OEM system with an external battery pack - the board is even sending the voltage to the battery pins in order to charge the pack. Not like the other 386/486 boards...
Do you have any suggestion how to safely take out the PLC chip? I have ordered and eeprom programmer which comes with a special tweezer - it may help here as well. Maybe I will wait tilk it comes. Thank you - I will try it. Hope the chip is not dead but MAY BE I have one spare in my box stolen years ago from a board...
I have added the board to the TRW. It seems to be rare.

Disruptor wrote on 2022-11-19, 16:21:

Sounds like timer failure.

Thanx. It looks like. It may be fixable. I Hope.

H.W.Necromancer wrote on 2022-11-20, 08:03:

It make sence why the chip is socketed as those were prone to failure more then others (as far as other guys told me).

At that time, socketing expensive chips in PLCC case (like your 82c206) was common. One contributing factor was indeed that you can just swap the chip in case it failed, and don't have to replace the whole board (or do on-site rework if it failed at a customer's site). Another factor contributing to socketing PLCC chips is that you can manufacture the boards even before you have the PLCC chips in stock. As these chips are expensive, the sunk cost of boards in storage go down, and these chips can easily be added by lightly trained personnel at the time of packaging the board for shipping. In the 80286 days, boards were common with all chipset components being socketed. In case of your board, the major chipset components by UMC are no longer in PLCC case (easily socketable), but in QFP. QFP allows the pins to be closer than PLCC, allowing more pins per chip. Pin count was a serious design constraint those times. There are no cheap, easy to operate and reliable QFP sockets.

So I wouldn't infer that the board manufacturer considered the 82c206 likely to fail, just because that's the only socketed chipset component. The 82c206 is a proven "low frequency" chip (it is connected to the ISA bus at nominally 8MHz), whereas the UMC chips are newer and mostly run at FSB frequency (25MHz with some signals even at 50MHz). The UMC chips are very likely more delicate. Assuming the chance of getting a similar ESD spike is equally high for the C&T 82c206 and the UMC 82C38x chips, I would expect the UMC chips to be more susceptible to damage. It was just "how everyone did it" at that time to socket complicated DIP and PLCC chips, and not socket QFP chips.

In my experience, broken traces and correded contacts are more often a problem than broken chip, but I have to admit that my experience is more about slightly later boards, and things have changed over time. People fix C64 computers by replacing dead chips all around youtube. In case the 82c206 is actually bad, you should have no problem sourcing a replacement from ebay. It shouldn't matter whether you use the original Chips one or the SAB82c206 (manufactured by Siemens) that also comes up a lot. Most likely it's identical. Siemens did a lot of second-source production at that time. There also are 8088 and 8086 chips manufactured by Siemens.

H.W.Necromancer wrote on 2022-11-20, 08:03:

I have added the board to the TRW. It seems to be rare.

Thanks for that!

mkarcher wrote on 2022-11-19, 16:30:

This kind of beep code is pretty normal for a Phoenix BIOS. Well, of course, it's not normal to hear this beep code, it does point you to a mainboard problem, but the code issuing the beep is likely running properly. See http://www.bioscentral.com/beepcodes/phoenixbeep.htm for a phoenix beep code reference. In your case, you get the code 1-2-1 (one beep, pause, two beeps, pause, one beep) which means "PIT failure". The PIT is the "programmable interval timer", which was the Intel 8253 on the PC/XT and the Intel 8254 since the AT. More modern boards do not have all the individual Intel chips, but have all the "classic Intel chips" of the AT mainboard integrated into the 82c206. Your board features the '206 by the original inventor, Chips & Technologies, but it was heavily cloned by nearly every PC chipset company in the 90s. I was very surprised that this UMC-based board doesn't use the widespread UMC 82c206, but probably your board is older than UMCs clone.

"PIT failure" on your board most likely means that the processor is unable to properly communicate with the 82c206 chip. Looking at the board photo, it looks like some of the pin contacts in the socket might be bent. I'm very positive that the reason is improper contact of the '206 in the socket, or broken traces on the board going towards the '206 socket. If the socket is still fine, re-seating the '206 chip might help, too.

Hallo, the POST card has arrived and it says - 0403. It may help. I have to search more on Phoenix codes.
In some list I have found 04 as a "checking CPU type". I don ´t think my cpu is a toast but I know nothing about the board history and nothing about the bunch of dip switches and it is unusual for DX no-cache board to have so many jimpers! ??

H.W.Necromancer wrote on 2022-11-24, 14:28:

Hallo, the POST card has arrived and it says - 0403. It may help. I have to search more on Phoenix codes.
In some list I have found 04 as a "checking CPU type".

04 = "checking CPU type" is for considerably newer Phonix BIOS versions, mostly versions with PCI support. Classic Phoenix BIOS POST code references list 04 = "Programmable Interval Timer Failure", which also matches the beep code. I'm thus still suspecting a fault around the 82c206. If you have a scope, please check whether the signal at pin 23 (TMRCLK) has a 1.193MHz square wave input. This clock is used as base frequency for the PIT.

mkarcher wrote on 2022-11-24, 18:05:

H.W.Necromancer wrote on 2022-11-24, 14:28:

Hallo, the POST card has arrived and it says - 0403. It may help. I have to search more on Phoenix codes.
In some list I have found 04 as a "checking CPU type".

04 = "checking CPU type" is for considerably newer Phonix BIOS versions, mostly versions with PCI support. Classic Phoenix BIOS POST code references list 04 = "Programmable Interval Timer Failure", which also matches the beep code. I'm thus still suspecting a fault around the 82c206. If you have a scope, please check whether the signal at pin 23 (TMRCLK) has a 1.193MHz square wave input. This clock is used as base frequency for the PIT.

Hallo and thank you! I do not have a scope. I am planning to buy one later on. But what I think the chip itself is most likely OK. I have found one in my spare box and replace it and the board behaves just same with the new chip. But what I don ´t know it the function of the DIP switch blocks and maybe there is a problem in it...(?).

Guys thank you for all the help. This project is now on hold untill I will get myself an osciloscope. Eye balling and DMM probing dis not bring any change. So far I think 82c206 is Ok, and bios was dumped and tested in an emulator. Many different RAM configuration tried. Still searching for a manual or some owner of the board in order to get some knowledge about the jumpers.