Anyone wanna help me troubleshoot my Simasimac Reloaded SE/30 board?

Steve Rieck · Thursday at 12:44 AM

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 - Working Correctly (Swapped from good board)
RAM Diodes - Corrected and Tested (one of Colin's boards)
New FPU
New CAPS
RESET Switch functioning correctly
RESET Circuit intact an operating correctly
NMI Switch has NO effect but is mechanically ok
GLUE Chip Continuity - All pins checked and ok
All Clock signals are present and correct.
I am NOT getting square waves on the ROM Adnress lines (Not walking)

UNKNOWN
All Address Line Continuity (Checking this next)
All Data Line Continuity (Checking this next)
Possibly damaged GLUE Chip - Pulled from bombed board
Damaged ASC or UB11 ? No sound at all

OTHER
Have a nice mildly bombed IICX board on the way for parts

Thanks for any thoughts!

Steve Rieck · Thursday at 12:46 AM

No bridges.

GreenBar0n · Thursday at 3:08 AM

According to the Simasimac Repair Guide, everything starts with the ASC UE10 chip, the Reset line is released from there before anything else will start. I would verify the Reset line on UE10 is operating correctly, first.

I would then check that the Data lines have continuity from the CPU to the ROM slot, with the ROM SIMM removed. The numbering of the ROM slot can be confusing, as the Data lines are listed in order, but the ROM slot pins skip around quite a bit, it's easy to get lost or confused, have to pay close attention to the Matrix pin order:

If all those signals are present, then check the Address line Matrix, from CPU to ROM slot.

Then I'd worry about the Clock signals and walking the bus.

Steve Rieck · 2026-05-09T00:55:14+0100

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

Everything checks ok.

GreenBar0n · 2026-05-09T01:02:11+0100

Have you checked all of the Reset pins yet? UB10 and 11 only Reset on Pin 5, don't worry about Pin 6.

Steve Rieck · 2026-05-09T01:17:21+0100

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

GreenBar0n · 2026-05-09T01:21:10+0100

Starting on Page 46 of the PDF, or Page 45 and 46 of the Simasimac Repair Guide: are you able to see the clock signals in the ROM slot without the SIMM installed?

Steve Rieck · 2026-05-09T01:26:13+0100

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.

GreenBar0n · 2026-05-09T01:36:04+0100

The ROM slot should be getting a solid square wave, what does Pin 4 of the ROM slot show? Make sure to press the Reset button a couple of times to see if the wave form changes at the ROM slot.

GreenBar0n · 2026-05-09T01:58:47+0100

Where are you clipping your scope ground to? Can you widen the picture to show your entire probe setup?

Steve Rieck · 2026-05-09T01:58:57+0100

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.

Steve Rieck · 2026-05-09T02:30:58+0100

GreenBar0n said:
Where are you clipping your scope ground to? Can you widen the picture to show your entire probe setup?

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

Froggy814 · 2026-05-09T02:33:54+0100

Didn't Colin from This does not compute have to add a bodge wire that they added from the factory that wasn't fixed on the reloaded board, did you add it?

GreenBar0n · 2026-05-09T02:36:28+0100

Froggy814 said:
Didn't Colin from This does not compute have to add a bodge wire that they added from the factory that wasn't fixed on the reloaded board, did you add it?

Good point, never asked if this was a V5 Reloaded board.

@Steve Rieck , In the first post it says all your clock signals are good, you are getting good square waves with your scope in other areas?

Steve Rieck · 2026-05-09T02:36:31+0100

Froggy814 said:
Didn't Colin from This does not compute have to add a bodge wire that they added from the factory that wasn't fixed on the reloaded board, did you add it?

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

Steve Rieck · 2026-05-09T02:44:28+0100

GreenBar0n said:
Good point, never asked if this was a V5 Reloaded board.

@Steve Rieck , In the first post it says all your clock signals are good, you are getting good square waves with your scope in other areas?

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.

GreenBar0n said:
Good point, never asked if this was a V5 Reloaded board.

@Steve Rieck , In the first post it says all your clock signals are good, you are getting good square waves with your scope in other areas?

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.

GreenBar0n · 2026-05-09T02:50:42+0100

Do you see a good square wave for C3 and the E clock, at UI8 GLUE chip?

Steve Rieck · 2026-05-09T02:57:44+0100

GreenBar0n said:
Do you see a good square wave for C3 and the E clock, at UI8 GLUE chip?

View attachment 28443

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

GreenBar0n · 2026-05-09T03:05:08+0100

Hard to believe the GLUE chip is bad, but with the correct clock signals at the those locations you showed above, the ROM slot should also be showing square waves.

Have the VIA chips both been toned out and have complete continuity? Those are the link between the CPU, GLUE and ROM slot.

Steve Rieck · 2026-05-09T03:09:57+0100

GreenBar0n said:
Hard to believe the GLUE chip is bad, but with the correct clock signals at the those locations you showed above, the ROM slot should also be showing square waves.

Have the VIA chips both been toned out and have complete continuity? Those are the link between the CPU, GLUE and ROM slot

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

Anyone wanna help me troubleshoot my Simasimac Reloaded SE/30 board?

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