Anyone up for some IIcx troubleshooting assistance? We have clocks but no activity...

[GRudolf94]

Adding to previous table

pin 3 – high​

​

GAB​

​

Asserted – buffer is driving NuBus state into NuChip – seems normal?​

pin 3 – low​

​

GAB​

​

Deasserted – buffer confirmed to be tristated​

A quick test that's probably harmless: yank all UD/UC13-9 chips. It eliminates the NuBus as a variable.

 

[joshc]

IIcx boards, for some reason, seem to suffer really bad from corroded vias/traces and really can be in very bad condition. This has been my experience after repairing several of them.

I would be following the entire startup circuit, buzzing out everything there and checking every single trace for breaks - some may not be visible. As I'm sure you know, sometimes a trace can look good but test bad.

But yeah - it's really important to have the Sound chips there and everything in that vicinity cleaned up very well because those are part of the reset circuit. A weird thing but that's how it is on Macs of this era.

Just from the last pic you took, I can see lots of very supicious looking traces. Have they all been checked?

 

[Sideburn]

On all of these, some lows are higher than others and some highs are lower than others
The only highs that hit the 5v mark were 21-24.
I figure this is to be expected…

UD9:

1 low
2 high
3 low
4 high
5 high
6 high
7 high
8 low
9 high
10 high
11 high
12 low
13 low
14 low
15 low
16 low
17 low
18 low
19 low
20 low
21 high 5v
22 high 5v
23 high 5v
24 high 5v

UD13

1 low
2 high
3 low
4 high
5 high
6 high
7 high
8 high
9 high
10 high
11 high
12 low
13 low
14 low
15 low
16 low
17 low
18 low
19 low
20 low
21 high 5v
22 high 5v
23 high 5v
24 high 5v

 

[Sideburn]

Adding to previous table

pin 3 – high​

​

GAB​

​

Asserted – buffer is driving NuBus state into NuChip – seems normal?​

pin 3 – low​

​

GAB​

​

Deasserted – buffer confirmed to be tristated​

A quick test that's probably harmless: yank all UD/UC13-9 chips. It eliminates the NuBus as a variable.

Ok I will and clean the whole area up.

 

[Sideburn]

IIcx boards, for some reason, seem to suffer really bad from corroded vias/traces and really can be in very bad condition. This has been my experience after repairing several of them.

I would be following the entire startup circuit, buzzing out everything there and checking every single trace for breaks - some may not be visible. As I'm sure you know, sometimes a trace can look good but test bad.

But yeah - it's really important to have the Sound chips there and everything in that vicinity cleaned up very well because those are part of the reset circuit. A weird thing but that's how it is on Macs of this era.

Just from the last pic you took, I can see lots of very supicious looking traces. Have they all been checked?

View attachment 58929

Yeah there’s lots of questionable areas. No I haven’t checked everything at all. I need to.

 

[Sideburn]

I’m calling it quits for now. It’s 1am. I’ll pull the chips tomorrow and do some continuity checking and cleanup.

 

[Sideburn]

I bought another board and a cap kit for it today as well. I probably paid too much ($90). Oh well at least I’ll have a reference board. That is if I can get it running too haha. It was as is but looks pretty clean.

 

[GRudolf94]

Yeah, sounds good. I don't think I have a single Mac for which I've paid $90 lol. The Duo 230 cost me that, I think, but I sold it at cost (machine+PSU+battery+caps) to a friend.

 

[Sideburn]

Fleee bay. Prices are going through the roof. I know most of my retro machines were given to me broken or I’ve had them since they were new. Like this one.

 

[GRudolf94]

Latest ePay purchase came in at $40ish after tax and shipping. Will take maybe another 30 to revive, if I can do it. Let's see how it goes.

 

[Phipli]

I try to play with cheap machines. I've mostly being messing with G3s/ G4s lately. £10 will get you a G3 iMac logic board if you're willing to bring it up in a random case.

Good enough to play F/A-18 Hornet Korean with OpenGL.

 

[Sideburn]

Latest ePay purchase came in at $40ish after tax and shipping. Will take maybe another 30 to revive, if I can do it. Let's see how it goes.

You don’t even want to know what I payed off there for a broken dirty old Macintosh portable that looked like it belonged in a landfill. But hey it came out nice!

 

[joshc]

£10 will get you a G3 iMac logic board if you're willing to bring it up in a random case.

This is where Lego comes into its own.

 

[joshc]

£10 will get you a G3 iMac logic board if you're willing to bring it up in a random case.

Also stop putting ideas in my head

 

[Sideburn]

This is where Lego comes into its own.

Haha or some 3d printing…

 

[Phipli]

This is where Lego comes into its own.

If I was a youngster, I suspect my main retro machine would be an iMac G3 board in a lego case.

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You know you want to.

 

[Sideburn]

All 8 chips pulled and traces cleaned. Another broken trace found and fixed. No change.

 

[GRudolf94]

I'm kinda running out of ideas here. My scratchpad now just has bad CPU and bad FPU. Even if there were broken traces that prevented it from booting, we should see more out of the CPU. You're absolutely sure it has good clocks, right? I would also check pins /DS and /STATUS (yeah, now the pin named as such)

 

[Sideburn]

If it’s the cpu, it’s surprising to me since the area around it is is pretty clean. But if I could find one I have no problem swapping it out and socketing it if possible.

 

[GRudolf94]

It's a pretty drastic measure, and CPUs tend to not fail unless overvolted. Statistically, that's not likely to be the problem (albeit not impossible).