Recent content by Steve Rieck

Couple things - now grounding the scope on pin 3 of the PDS slot for a shorter ground cable. No difference really. The NMI switch has no effect but it does go to pin 9 on the GLUE and pin 1 of RP8... can see the voltage drop at all positions when I push the switch, it has absolutely no effect...

interesting. Thank you so much for your help! I'm gonna check out all of this tomorrow.

Yep.. i've got square waves on the C3 and E clocks from the GLUE.... photos respectively

Here is what Y1 for example looks like on the scope. The frequency looks correct but it's definitely not a square wave. I assume it is supposed Sorry I'm just learning this stuff. Here is what Y1 for example looks like on the scope. The frequency looks correct but it's definitely not a square...

that's a great point. I do remember seeing that in the video. It's on one of the video pals I recall. When I was previously working on this port I remember confirming that this board didn't need it for some reason. But I'll double check

clipping the ground to the big metal whatchamacallit down there by the ports.

unfortunately getting the same trashy signal. so I think this clearly indicates something more serious than a bad ram diode or UH7 pal etc? That's why I'm suspecting the glue which came off a badly bombed board. Fortunately, I have a iicx board in the mail.

The data line signals on the video ROM and video RAM get this mess instead of nice square waves... I think it's a bad glue chip or maybe UH7.

yep sure did. Under the scope the whole reset circuit looks correct. 5 V to 0v

Just went through every single pin for every single address and data line per the schematic redraw matrixes.... exhausting. Everything checks ok.

No bridges.

KNOWN SO FAR CPU - Working Correctly (Swapped from good board) ROM SIMM - Working Correctly (Swapped from good board) RAM SIMMS - Working Correctly (Swapped from good board) VIDEO ROM - Working Correctly (Swapped from good board) VIDEO PALS - Working Correctly (Swapped from good board) VIDEO RAM...

I have a reloaded board in a Simasimac status. Current clock signals are: Y1 = 32Mhz in spec Y2 = 32Mhz in spec GLUE PIN 17 = 32Mhz in spec GLUE PIN 18 = 16Mhz in spec Y3 = Erratic, Intermittent supposed to be 16Mhz? Sometimes around 10, sometimes no reading. Anyone have any idea what might be...

This is so helpful. Thank you!

(for idiots perhaps...). I've got a Simasimac reloaded SE/30 board and I suspect the GLU chip is at fault. It cleaned up well but was kinda rough when I got it off the bombed board. I have checked all pin continuity several times and everything checks out to destinations. No bridges also...