SR is available, but it's still always possible there were revisions
over time.
The datasheet for the socket doesn't show the shape or dimensions of the
contacts:
https://github.com/bkw777/pcb2molex8878/blob/master/references/015299282_sd_corrected.pdf
The datasheet for the carrier shows the shape and dimensions of the
installed chip legs, but that is several solid mm of vertical length.
When measuring a socket with calipers, I get a measurement of 3.9mm
from the socket floor to the center of the curved part of the contact,
the point that actually makes the contact. And if the PCB is 1.6mm, that
gives an elevation of 3.1mm from the socket floor to the bottom of the pcb.
However, in actual testing, many many times with several different
sockets and machines, while designing this pcb carrier:
https://github.com/bkw777/pcb2molex8878
I arrived at the following, from:
https://github.com/bkw777/pcb2molex8878/blob/master/Carrier/pcb2molex8878.scad
"
// 1.6mm pcb
pcb_elev = 2.2; // bottom of pcb above socket floor. Min 1.9 - Max 2.4
"
So the bottom of the pcb is 2.2mm from the floor of the socket, with
notes that say you could go as low as 1.9mm or as high as 2.4mm.
It's true it's a tight window, simply because a DIP installed on the
official carrier provides a huge tall straight flat smooth side of a
chip leg, rounded away from the socket contact at both top & bottom, and
the socket has a comparatively sharp contact point that is free to slide
along and land anywhere along that several mm of chip leg. The chip
provides all the slop to make the combined system reliable.
But with a pcb, you're having to get two narrow things exactly lined up,
with the added stress that you don't DARE err in one direction and let
it go too deep since that results in damage.
Maybe it would be worth it to make a little block or 3d printed tool
that fills the socket and compresses the contacts, which would let you
extract a trapped board like that safely.
--
bkw
On 12/19/20 8:13 PM, Jeffrey Birt wrote:
Thanks for the pictures. I did see where it had something glued to the
bottom. This one also had all the pins flattened over. No doubt because
the cardboard was missing.
I tried to shim it up 2mm to 2.5mm but if it is high enough to not get
stuck in the socket it pops right out. The electrical connection even
when it is ‘stuck’ in the socket is also poor. I can wiggle it and get
it work well enough for the SR menu to pop up but when I try to select
any one of the 4 programs it locks up.
I’m really surprised that the PCB and a cardboard shim was all there was
too it.
Has this ROM been dumped? I may go ahead and pull it off the PCB to try
and dump it to at least confirm the EEPROM itself it good.
Thanks for your help.
Jeff Birt
*From:* M100 <m100-boun...@lists.bitchin100.com> *On Behalf Of *Greg Swallow
*Sent:* Saturday, December 19, 2020 6:56 PM
*To:* Jeffrey Birt <m...@bitchin100.com>
*Subject:* Re: [M100] SuperROM
Jeff,
The SR should've had a shim/cardboard attached to it's underside. I'll
try and micrometer one and give you a thickness.
GregS <><
Dec 19, 2020 5:47:48 PM Jeffrey Birt <bir...@soigeneris.com
<mailto:bir...@soigeneris.com>>:
SuperROM –
Working on an M100 now that came with a SuperROM that had stuck in
the socket and the socket managed getting it out. Socket replaced,
but I am confused as to how the SuperROM (SR) was ever intended to
fit properly.
The SR gets stuck as while the Pin1/28 side is held up from the
bottom of the socket by the pin 1 tab on the SR PCB, the opposite
end drops down so far that the PCB falls below the bend of the
contacts. This lets the contacts spring out over the top of the PCB
and thus it is stuck.
If I shim up the SR enough to prevent it getting stuck then it pops
out very easily. It seems to be a very poor design. Perhaps there is
some part of this one that is missing? I could not find any images
on the web that clearly showed the SR board to compare to though.
The contact is also really poor, sometimes it will make contact in
the socket and sometimes not. It may be that the PCB was damaged
when it was wrestled out.
Lastly, has this ROM been dumped? If not, I’ll pull it off the PCB
and read it.
Thanks,
Jeff Birt
--
bkw
