VOGONS


First post, by kenabi

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anyone with one of these boards (working) and an oscilloscope with digital readout bored enough to probe the avasem clock PLLs pins (all) and give me a reading of what its supposed to be outputting? i can't even get beeps, and there's a wildly fluctuating signal off pin2 (xtal out), but nothing off pin 3 (xtal in), probing the xtal itself shows the same behavior. i'm trying to determine if the PLL is toasted or one of the passives or maybe something worse.

pin 1 is ~1.843mhz within tolerances.

pin 6 is partially on 16mhz, but dips down to 12, and sometimes down to 9. all fluxing is constant, and not just occasional.

pin 7 dips from ~24 down to 18 and some steps in between.

pin 8 goes from just under 12 down to 7 at points, at various steps.

i don't recall the readings from the rest, but it seems.. off.

power supply works fine with other motherboards and i don't have another at supply at hand to swap in and test. pci power 6 pin is not populated, voltage reading off the 3.3v rail is sub 1v.

pentium overdrive 83 in socket gets warm with the fan taken off, so the socket is getting voltage. setting is to 3.3. fsb is 33. known good video cards, only gives me fan noise with everything but the cpu removed. tossed in some other 486 chips, no response. tried recovery bios mode, nothing. probed the cache lines, no activity, so its not even starting to get anywhere.

trying to figure out where the fault is, and hoping it didn't take a power surge and kill something on it i can't find a replacement part for.

cheers.

Reply 1 of 13, by kenabi

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okay. no idea whats going on. with ram in and no settings changes it now beeps. once. once shall the holy hand gren.. er.. computer beep, and no more, no less.

pull the ram and is bpppppt's at me then beeps. no video, even with an isa card. regulator doesn't even get warm. do i need to worry about that? or is it just related to the 3.3v lines? the complete lack of info about this board is annoying AF hah.

isa bus lines have a sharp down pulse every so often, though i wasn't trying to figure the exact timing of it. looks like it might be a line request pulse? seems jaggy. several pins have very noisy data patterns, like a 4 year old scribbling, but clean up (a little, though it still has ghosting and that looks like the osc trace is having a seizure) if i zoom all the way in. nothing plugged into any of the slots.

at this point i only have the cpu and the ram plugged in. i'm getting voltage where i'm expecting there to be voltage, i just don't know what the output is supposed to be from the regulator, or even what regulator type is there. is it 5v? 3.3? no idea. and its got a soldered in spring retainer that covers the part #, what joy.

no visible corrosion, no broken traces, no bent pins.

as i'm going through and typing this i got frisky and bent the tab on the metal retainer. its not a regulator, its a IRFz44 mosfet. the nearby u7k1 is controlling it. 1.5ishv on pin 1, 2.5ish on pin 8, zero v on pins 2, 3, 7, 8, which seems very.. odd. (4, 5 are nc.)

i'm at a bit of a loss.

Reply 2 of 13, by Horun

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kenabi wrote on 2023-01-24, 01:16:

the complete lack of info about this board is annoying AF hah.

Actually there is a bit of info: https://theretroweb.com/motherboards/s/intel- … ninja#downloads

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 3 of 13, by kenabi

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Horun wrote on 2023-01-24, 01:41:
kenabi wrote on 2023-01-24, 01:16:

the complete lack of info about this board is annoying AF hah.

Actually there is a bit of info: https://theretroweb.com/motherboards/s/intel- … ninja#downloads

which, since i pointed out i had the vcc, fsb set, and attempted to boot into recovery should indicate i found that listing as i've been crawling that site religiously going through all my old boards.

it is sadly, however, not helpful when trying to track down component level faults.

/shrug

the most annoying part is that i know that once upon a time this sort of info was floating around online i various places. as it is, the basic ISA spec docs are elusive. and i'm not sure if the pc104 spec's isa section is identical or not. if it is, then i'm not even getting close to the right signals out of the data lines, so there's a massive problem somewhere, and i need to track that down.

and the errata for the 420ex chipset is seemingly unobtainium, so i can't really compare the signals off the chip itself to know if _that_ is doing what it should.

it's quite vexing.

Reply 4 of 13, by Horun

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kenabi wrote on 2023-01-24, 02:42:
Horun wrote on 2023-01-24, 01:41:

which, since i pointed out i had the vcc, fsb set, and attempted to boot into recovery should indicate i found that listing as i've been crawling that site religiously going through all my old boards.
it is sadly, however, not helpful when trying to track down component level faults.

Welcome to Vogons and I had no idea where you checked for info.... you never said 😁
There is relatively not much info on older Intel branded boards and their chipsets, they kept that mostly in-house.
Maybe someone else here has the same board and can help...

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 5 of 13, by zyga64

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kenabi wrote on 2023-01-24, 02:42:

and the errata for the 420ex chipset is seemingly unobtainium, so i can't really compare the signals off the chip itself to know if _that_ is doing what it should.

it's quite vexing.

This topic should be interesting for you. There is even i420EX datasheet there (uploaded by Tiido).
Testing the Intel Classic-PCI Expandable Desktop (Ninja)

I can do some measures, if you want (I also have working Intel Classic PCI Ninja motherboard).

Scamp: 286@20 /4M /CL-GD5422 /CMI8330
Aries: 486DX33 /16M /TGUI9440 /GUS+ALS100+MT32PI
Triton: K6-2@400 /64M /Rage Pro PCI /ES1370+YMF718
Seattle: P!!!750 /256M /MX440 /Vibra16s+SBLive!
Panther Point: 3470s /4G /GTX750Ti /HDA

Reply 6 of 13, by kenabi

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zyga64 wrote on 2023-01-24, 06:50:
This topic should be interesting for you. There is even i420EX datasheet there (uploaded by Tiido). Testing the Intel Classic-PC […]
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kenabi wrote on 2023-01-24, 02:42:

and the errata for the 420ex chipset is seemingly unobtainium, so i can't really compare the signals off the chip itself to know if _that_ is doing what it should.

it's quite vexing.

This topic should be interesting for you. There is even i420EX datasheet there (uploaded by Tiido).
Testing the Intel Classic-PCI Expandable Desktop (Ninja)

I can do some measures, if you want (I also have working Intel Classic PCI Ninja motherboard).

verrrry nice, and yeah, i would love a set of readings off the pll pins. and if there's any flux going on, since mines bouncing. i really think i'm missing a signal someplace, i just need to know _where_. which is frustrating since the boards basically in pristine condition. but any leads on finding what isn't there when it should be, will help narrow down to other areas, i hope.

cheers.

Reply 7 of 13, by kenabi

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Horun wrote on 2023-01-24, 05:01:
Welcome to Vogons and I had no idea where you checked for info.... you never said :D There is relatively not much info on older […]
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kenabi wrote on 2023-01-24, 02:42:
Horun wrote on 2023-01-24, 01:41:

which, since i pointed out i had the vcc, fsb set, and attempted to boot into recovery should indicate i found that listing as i've been crawling that site religiously going through all my old boards.
it is sadly, however, not helpful when trying to track down component level faults.

Welcome to Vogons and I had no idea where you checked for info.... you never said 😁
There is relatively not much info on older Intel branded boards and their chipsets, they kept that mostly in-house.
Maybe someone else here has the same board and can help...

s'all good. but i've yet to find a single one of those info pages on there that has board level readings for a given chip/point 😉

cheers.

Reply 8 of 13, by kenabi

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so, no idea what i did, but i got everything but pin 17 (2xcpu) on the PLL chip rock stable at what the datasheets seem to say are the correct values with a 33 fsb speed set by the jumpers.

still single beep, no video, no drive activity on a known working and booting dos drive.

buuuut.. i probed around for various signals. irq12' pin in the isa is high and stays high. DRQ 0' also stays high. no other DMA/IRQ/DRQ/DACKS show any activity.

and then i started probing the data lines on the cache chip sockets. oh boy. that ain't right. (ignore the voltages, those aren't right. the settings are off)

i'll admit, my knowledge of the 486 bus systems are limited, but even i know you shouldn't have what appears to be 3 signals over each other all the time. and its only on the cache data lines. adjusting the capture settings on the osc doesn't appear to rectify that, and all the usual cleanup tricks for signals don't alter it any. though on some lines the faintest of the three varies from barely there to a bit stronger than this image i've attached.

this behavior persists with all the 486 cpus i have swapped in.

so it appears i've definitely got something wrong. but i don't even begin to know where to start.

anyone have any thoughts?

Reply 9 of 13, by pentiumspeed

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Your scope is set up wrong. It is displaying two waveforms from two channels this is confusing. You need to separate them or probe with one waveform on and turn second channel off by turning off the channel 2 switch. Or rolling because trigger is set up wrong. Turn the trigger frequency (1/t) or change trigger on or off.

Where is your grounding clip is located when probing this? Be very cautious with this. High frequency measurement requires you to have ground clip about a inch away or so and is short wire from the probe's body.

What does multimeter say to you on voltages everywhere on the motherboard? The jumpy frequencies is indication of unstable board, the voltages could be jumping too or board is in boot looping.

Basics:
Used known good memory module like Micron branded, Samsung or Hynix?
Known good CPU?
Good power supply (did you check it with scope and multimeter?

Cheers,

Great Northern aka Canada.

Reply 10 of 13, by kenabi

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pentiumspeed wrote on 2023-02-13, 01:05:
Your scope is set up wrong. It is displaying two waveforms from two channels this is confusing. You need to separate them o […]
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Your scope is set up wrong. It is displaying two waveforms from two channels this is confusing. You need to separate them or probe with one waveform on and turn second channel off by turning off the channel 2 switch. Or rolling because trigger is set up wrong. Turn the trigger frequency (1/t) or change trigger on or off.

Where is your grounding clip is located when probing this? Be very cautious with this. High frequency measurement requires you to have ground clip about a inch away or so and is short wire from the probe's body.

What does multimeter say to you on voltages everywhere on the motherboard? The jumpy frequencies is indication of unstable board, the voltages could be jumping too or board is in boot looping.

Basics:
Used known good memory module like Micron branded, Samsung or Hynix?
Known good CPU?
Good power supply (did you check it with scope and multimeter?

Cheers,

1; nope. single channel.

2; the screw hole via/ground adjacent to the RTC and cache sockets. bit over an inch from the nearest cache socket.

the rest of my probing shows no overlapping signal issues, now that i've managed to get my pll freqencies (aside from 2xcpu, but i don't know if thats supposed to bounce from 66 up to sometimes 100) stable. voltages are all within tolerances, give or take a few .01's. all of those signals are clean.

the _only_ place i'm seeing this issue atm the moment is the cache data lines. and its 3 full waves overlaid on each other, i've counted.

all 3 cpus i have handy here for this work in other boards, no issues. i've tried every stick of ram i have, and tested them all in two other boards with memtest.

i've tested the psu with other boards as well, and probed the voltages with a dmm under load. zero real issues that i could find. a bit of drop, but thats to be expected (couple mv).

aside from the visual setting (the boxes below the x/y grid, and getting rid of a couple i didn't want), its the same general settings aside from the horiz div to show the actual waveform. still rolling, still going. channels 2, 3, and 4 are _off_. it doesn't show here, but they're dimmer than 1, the lights are 'off', the traces aren't there. they're also different colored traces.

the problem is with the board, i just need to either pick the brain of someone who knows where to poke to find out, or stumble across wherever that point may be.

if the 2xcpu is supposed to be stable, that may well be whats causing it, but i also go hrmmm, because i have no idea what would be using that. it has a dedicated isa speed output, and the pci clk output should run off the same clock signal as the 1xcpu line. and a quick confirmation shows that yes, the pci clk signal is a flat stable 33mhz, and traces back to the 1xcpu pin. no 'ghosting'.

someplace between the cpu and the cache or ram, there appears to be something dead/malfunctioning? except for most of it, its just straight traces with no passives, and no visible damage to said traces at all. they also test out for continuity.

and hitting single for giggles did nothing but give me a slice of the same nonsense, vs the rolling constant read.

so again, not sure what the issue is, but its not the test equip from what i can tell.

Reply 11 of 13, by kenabi

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alright so. i picked up one of those isa/pci diagnostic cards, as well as set up my benchtop supply to feed 3.3 to the pci slots (since otherwise you get no 3.3 to them, as thats fed through the aux power connector, and not anything else, apparently. or, it wasn't for me at any rate.)

plugged in the card, single beep at 00, which is supposed to be the handoff to the int19h call, which means its trying to boot from a drive.

except no video, from literally any video card i've tried (and all work in every other board i have that supports them).

so it appears either i need a compatible card, or its not calling the video init, and i have no idea which one it is.

nor do i know what would and wouldn't be compatible in regards to cards if thats the case.

of the cards i have, i've tried various pci matrox cards, a voodoo 3 pci, an advance logic 1mb, s3 virge dx, just about every single pci variant of all ati rage and earlier cards, and an orchid 1280 farenheit.

i swapped ram, i tried using a 4mb AT ram card (doesn't see it at all)

changed through all my socket 3 cpus trying all of these things on each.

the only change in behavior i can elicit is if i pull all the ram out of the board, in which case it throws a memory error. nothing else does anything. boots to 00 and the single beep, no video. it doesn't appear to see the video card at all, but it doesn't complain if there isn't one in a slot.

i literally don't know anymore, and i've run out of things to try. the only two anomalous behaviors are the cache signal lines having the overlays, and the lack of video.

its looking like this one gets tossed in the i don't know pile, and left there until i can find another angle to test it with.

Reply 12 of 13, by CoffeeOne

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kenabi wrote on 2023-04-24, 21:13:
alright so. i picked up one of those isa/pci diagnostic cards, as well as set up my benchtop supply to feed 3.3 to the pci slots […]
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alright so. i picked up one of those isa/pci diagnostic cards, as well as set up my benchtop supply to feed 3.3 to the pci slots (since otherwise you get no 3.3 to them, as thats fed through the aux power connector, and not anything else, apparently. or, it wasn't for me at any rate.)

plugged in the card, single beep at 00, which is supposed to be the handoff to the int19h call, which means its trying to boot from a drive.

except no video, from literally any video card i've tried (and all work in every other board i have that supports them).

so it appears either i need a compatible card, or its not calling the video init, and i have no idea which one it is.

nor do i know what would and wouldn't be compatible in regards to cards if thats the case.

of the cards i have, i've tried various pci matrox cards, a voodoo 3 pci, an advance logic 1mb, s3 virge dx, just about every single pci variant of all ati rage and earlier cards, and an orchid 1280 farenheit.

i swapped ram, i tried using a 4mb AT ram card (doesn't see it at all)

changed through all my socket 3 cpus trying all of these things on each.

the only change in behavior i can elicit is if i pull all the ram out of the board, in which case it throws a memory error. nothing else does anything. boots to 00 and the single beep, no video. it doesn't appear to see the video card at all, but it doesn't complain if there isn't one in a slot.

i literally don't know anymore, and i've run out of things to try. the only two anomalous behaviors are the cache signal lines having the overlays, and the lack of video.

its looking like this one gets tossed in the i don't know pile, and left there until i can find another angle to test it with.

Did you try an ISA graphics card?