Deksor wrote on 2020-05-02, 01:16:

Depending of how I insert it in the slot, the motherboard posts or doesn't post and crashes differently.
The motherboard is rock stable without the coast module.

I have a Amptron 9700, supposed to be same as PcChip 919 v3.4B/F but the cache socket is definitely slightly longer on one side of the key than the other. For mine there is only one way the cache fits though I do not have the proper Coast module for the board so can not show a picture of it to compare with yours. (for reference: http://th2chips.freeservers.com/m919/)
edit: fixed mistake...and add: I never found a proper coast so the board sits in a box as a cacheless 486 is somewhat useless to me ;p

Sounds pretty much like a bad SRAM chip on the module.

Oh well I can't insert it in both way, it's just that if I insert it slightly less in the slot or do it in an angle the board reacts differently.

Compressed air in the coast socket first. Sounds like there may be dust/paper/other crud in there. Use a magnifying glass to check for any defects on the contacts in the socket.

I've cleaned the motherboard entirely. Judge for yourself how clean that connector looks 😀

And here's the COAST module by the way :

I don't know what's wrong because the contacts in there must be good, but shaking it in the slot changes the behavior and it's not a solder joint problem either it seems

The contacts are clean indeed, the only thing I now can think of is that maybe one or two of them have broken or bent just enough for no 100% sure contact...

What voltage is your processor? There were 2 types of cache modules, 3.3V or 5V. The voltage was set with the same jumpers as for the processor. It seems that your module is for 3.3V.

Bellator wrote on 2020-05-02, 16:20:

There were 2 types of cache modules, 3.3V or 5V.

Source? First time I ever heard of this.

I own the M919 as well and played around with many CPUs. 4V Cyrix, 3.3V AMD, and finally 5V POD. Always with the same cache module. The manual doesn't mention different modules either. And it doesn't make sense, really. On no mainboard you ever had to set the voltage for cache memory.

derSammler wrote on 2020-05-02, 16:28:

Bellator wrote on 2020-05-02, 16:20:

There were 2 types of cache modules, 3.3V or 5V.

Source? First time I ever heard of this.

I own the M919 as well and played around with many CPUs. 4V Cyrix, 3.3V AMD, and finally 5V POD. Always with the same cache module. The manual doesn't mention different modules either. And it doesn't make sense, really. On no mainboard you ever had to set the voltage for cache memory.

This Vogons thread:
Lets make new M919 Cache sticks?

The Tosh chips on that Coast are 3.3v but there are two Vreg's on the board. I cannot follow the traces good enough to see if the cache gets it's power from one of them. http://www.bdtic.com/datasheet/TOSHIBA/TC55V3 … 55V328AJ-20.pdf

Bellator wrote on 2020-05-02, 16:37:

This Vogons thread:
Lets make new M919 Cache sticks?

Most likely limited to the Amptron DX-9700. You can see that the cache modules for the M919 are not "clearly marked for 3.3V or 5V" as the Amptron manual states. Pretty sure the M919 cache module uses SRAM chips that work with 3.3V and are 5V-tolerant. And, as said, such a passage does not exist in the M919 manual (I have the original manual here).

Well I didn't know that ... I don't know if my motherboard is a pcchips m919 or a amptron DX9700. I thought they were the same.
I tested my mobo with a Intel DX2-66. Do you think I may have fried it ?

I don't think the mainboards are different, though it's possible. Or Amptron did indeed sell two different cache modules for their board. But PC Chips certainly not, otherwise there would be a voltage info on the module - but there isn't. Only conclusion is that the M919 one works in either case.

The DX2-66 exists as 5V and 3.3V. Which one do you have?

Also, do you have a picture of your mainboard?

It's a 5V chip.

I'll shoot a photo of the mobo in a hour or two.
Does anyone know the coast connector's pinout ?