Luis' Build

[lrodriguezrullan]

Yes. 5V.

[lrodriguezrullan]

The Dual TOS jumper is open.

[exxos]

So you need to continuity check GLUE pins back to the socket you got the jumper wires on (remove the wires for now). Address bus, AS,UDS,LDS,DTACK etc

The put back the wires and check all those pins on the GLUE are all connected to GND. GLUE has to have all the address lines low to enable the ROM.

IIRC ROM2 should be set low on power up. If its not I then I can only assume the GLUE is faulty or not getting the 8mhz clock.

If ROM2 does go low on power up then the ROM jumper link above port #1 should be low also. If not , then maybe the small ic is blown.

That's all I can really suggest for now.

[lrodriguezrullan]

I apologize for my ignorance. Which pins in the glue socket should have continuity to which pins in the 5V bus IO port socket?

Thanks.

[exxos]

I apologize for my ignorance. Which pins in the glue socket should have continuity to which pins in the 5V bus IO port socket?

https://www.exxosforum.co.uk/forum/viewt ... =89&t=3457

[lrodriguezrullan]

Thanks. I'll take a look at those diagrams.

[lrodriguezrullan]

Just did the continuity test between the glue and a 5v IO port. There is no continuity on A18, A21, A22, and A23.

I checked the soldering on the glue socket and it looks good.

I am not sure if this helps, but if I close the ROM jumper, I get a black screen with a white border. A pattern with different color lines appears very briefly, leaving the black screen with the white border only. The pattern is similar to the one I've seen when the RAM is bad.

[lrodriguezrullan]

I got the diagnostics cart and am getting the following results over the serial port:

<FF><0D><0A>I1 RAM/data line error 0000000000000000 0000000100000000 000008

[PhilC]

I got the diagnostics cart and am getting the following results over the serial port:

<FF><0D><0A>I1 RAM/data line error 0000000000000000 0000000100000000 000008

You've got a stuck bit on one of the ram data lines, check your ram soldering :)

[lrodriguezrullan]

Thanks! I double-checked the solder of the SIMM socket and it looks OK. At least I don't see any solder touching multiple pins.