Recapped Analog Board Macintosh Plus Stuck at the First Screen

[Paulo G Camara]

Hi,
I recapped my Macintosh Plus analog board with the Console% kit.

When it turns on, the voltages at the FDD port are -12,14V +12,10 V and 5,01 V.

There are no strange noises or hissing. It's completely silent.

I don't get the turn on chime, neither the FDD seeks or rotates, although it has a startup disk inside.

I get a stable and sharp video but only with the desktop pattern.

There's no happy or sad mac icon, neither mouse pointer, nothing....

I think this suggests it's a Logic Board issue, right?

The dead mac scrolls book doesn't have this scenario.

Any help?

Best regards,
--
PGC

 

[Muz_]

Hi there,

Did you get any video before the recap?

 

[bibilit]

Yes, probably an issue with the logic board.
Half working if i can say, the chime is a sign that the logic board is ok (Ram, Rom…)

 

[Paulo G Camara]

Hi there,

Did you get any video before the recap?

Hi! It was equal before the analog board recap. I didn't do the logic board capacitors yet. I'm waiting for the new capacitors to arrive. Thanks.

 

[Paulo G Camara]

Yes, probably an issue with the logic board.
Half working if i can say, the chime is a sign that the logic board is ok (Ram, Rom…)

Hi! It doesn't give the chime sound, neither the FDD moves.

I only get this screen, no mouse pointer nothing.

If I press reset it resets and goes to the same screen. I'm going to repac the logic board. The clock signal taken at CPU pin 15 is wavy at the low edge and perfectly square above. Maybe the capacitors need to be replaced.

 

[dochilli]

Did you try to clean and reseat RAM and ROM? Sometimes Plus ROMs are defect and you have to burn new ones.

 

[Paulo G Camara]

Did you try to clean and reseat RAM and ROM? Sometimes Plus ROMs are defect and you have to burn new ones.

Hi Thanks for the reply.

Indeed I removed both ROM chips and RAM SIMMs.

Cleaned all contacts with De-ox and contact cleanner. Same result.

But, yes you're right, sometimes MAC ROMs can get defective and, after recapping the logic board, if the symptons persist, I'll go that way.

It will be a perfect excuse to buy an EEPROM writer....

 

[dochilli]

Burning a ROM:

Create Macintosh Plus ROMs

Create Macintosh Plus ROMs: This Instructable will guide you through the process of "ripping" EPROM images from from your Macintosh Plus ROM chips and (or) "burning" the images to new chips. The process will basically be performed twice to create both "hi" and "lo" ROM chips f…

www.instructables.com

Macintosh Plus - Repair Help

Hello, I purchased this Macintosh Plus knowing there was some Bad Things™ going on. I describe the steps I've taken below but I need suggestions from more experienced folks. Before we begin, I want to point out that I did not recap the logic or analog board — they appear pristine. I've recapped...

68kmla.org

 

[Paulo G Camara]

Burning a ROM:

Create Macintosh Plus ROMs

Create Macintosh Plus ROMs: This Instructable will guide you through the process of "ripping" EPROM images from from your Macintosh Plus ROM chips and (or) "burning" the images to new chips. The process will basically be performed twice to create both "hi" and "lo" ROM chips f…

www.instructables.com

Macintosh Plus - Repair Help

Hello, I purchased this Macintosh Plus knowing there was some Bad Things™ going on. I describe the steps I've taken below but I need suggestions from more experienced folks. Before we begin, I want to point out that I did not recap the logic or analog board — they appear pristine. I've recapped...

68kmla.org

Thanks!

 

[Phipli]

Why... Do you think it is the ROM? The ROM has a checksum that will have passed if it is showing a halftone background?

Don't buy ROMs yet. Not unless there is a good reason to spend money.

I'd start by unplugging the floppy drive and seeing what happens then.

 

[Phipli]

So step 2 is happening, but step 3 isn't. This may mean that SCSI is confused? All the startup process info I have is either for older machines or newer machines sadly, so I don't have something that exactly matches the Plus.



Have you tried powering on with nothing other than the power cable? No keyboard, no mouse, no SCSI, no serial devices. Even leave the internal floppy drive unplugged. What happens?

 

[Paulo G Camara]

So step 2 is happening, but step 3 isn't. This may mean that SCSI is confused? All the startup process info I have is either for older machines or newer machines sadly, so I don't have something that exactly matches the Plus.

View attachment 72471

Have you tried powering on with nothing other than the power cable? No keyboard, no mouse, no SCSI, no serial devices. Even leave the internal floppy drive unplugged. What happens?

Hi

So step 2 is happening, but step 3 isn't. This may mean that SCSI is confused? All the startup process info I have is either for older machines or newer machines sadly, so I don't have something that exactly matches the Plus.

View attachment 72471

Have you tried powering on with nothing other than the power cable? No keyboard, no mouse, no SCSI, no serial devices. Even leave the internal floppy drive unplugged. What happens?

Hi! Yes I've tried with the floppy, keyboard, mouse and everything completely disconnected, but the outcome is the same....

 

[Paulo G Camara]

So step 2 is happening, but step 3 isn't. This may mean that SCSI is confused? All the startup process info I have is either for older machines or newer machines sadly, so I don't have something that exactly matches the Plus.

View attachment 72471

Have you tried powering on with nothing other than the power cable? No keyboard, no mouse, no SCSI, no serial devices. Even leave the internal floppy drive unplugged. What happens?

Thanks for the info. I probed CPU pin 15 (clock) with the oscilloscope and got the attached signal. Don't know if it's normal because I don't have another functioning mac to test. Anyone can confirm if this signal is normal?

 

[Phipli]

Hi! Yes I've tried with the floppy, keyboard, mouse and everything completely disconnected, but the outcome is the same....

OK, that's a shame.

Then I recommend that you take some high resolution, well lit photos of both sides of the logic board and share them.

Thanks for the info. I probed CPU pin 15 (clock) with the oscilloscope and got the attached signal. Don't know if it's normal because I don't have another functioning mac to test. Anyone can confirm if this signal is normal?

I've never been able to afford a scope fast enough for my needs so I don't know, but again, the half tone pattern is software drawn, so it is managing to fill the framebuffer with a pattern - it is getting so very far into the boot process that QuickDraw has initialised and is working.

It feels likely that a peripheral chip has a bad connection or something.

It's late here so I'm going to vanish, but... don't buy things like ROMs before you have done a bit of diagnosis.

 

[Paulo G Camara]

OK, that's a shame.

Then I recommend that you take some high resolution, well lit photos of both sides of the logic board and share them.


I've never been able to afford a scope fast enough for my needs so I don't know, but again, the half tone pattern is software drawn, so it is managing to fill the framebuffer with a pattern - it is getting so very far into the boot process that QuickDraw has initialised and is working.

It feels likely that a peripheral chip has a bad connection or something.

It's late here so I'm going to vanish, but... don't buy things like ROMs before you have done a bit of diagnosis.

Thanks for the helpful information. Not going to buy new ROMs yet. I'll recap the logic board and in the meantime I'll take the high res photos and post them here.

 

[Phipli]

Thanks for the helpful information. Not going to buy new ROMs yet. I'll recap the logic board and in the meantime I'll take the high res photos and post them here.

It's fairly uncommon that a Plus logic board needs recapping... not impossible, but those caps last much longer than later 68k macs. I'd be inspecting for visible signs of damage first.

That and reflowing the connections between the logic board and analogue board if you haven't already. No real specific reason, just it is one less thing to worry about later.

After powering it down for a day!

 

[Paulo G Camara]

It's fairly uncommon that a Plus logic board needs recapping... not impossible, but those caps last much longer than later 68k macs. I'd be inspecting for visible signs of damage first.

That and reflowing the connections between the logic board and analogue board if you haven't already. No real specific reason, just it is one less thing to worry about later.

After powering it down for a day!

Ok! I'll do that this weekend and post the high res photos. (I've already reflowed all connectors at the analog and logic board...)

 

[dochilli]

You do not have to buy new ROMs. You can test the ROMs by reading and comparing them with a burner with ROMs you can download from the net.

https://macintoshgarden.org/apps/macintosh-rom-archive

The plus had three versions of ROMs.

 

[Paulo G Camara]

You do not have to buy new ROMs. You can test the ROMs by reading and comparing them with a burner with ROMs you can download from the net.

https://macintoshgarden.org/apps/macintosh-rom-archive

The plus had three versions of ROMs.

Hi! Thanks for the advice and reference. I'll have to buy the EEPROM reader/writer to test. Either I'll buy or do a project like the one Ben Eater has on his Youtube channel Build an Arduino EEPROM programmer (youtube.com) (This is part of the fun )

 

[cheesestraws]

To echo what @Phipli said - I would be very surprised if it turned out to be the ROMs. Not impossible, but there are more likely options. FWIW I've seen them wedge like this when either the SCSI controller or IWM are broken in ways that look "half functional" to the computer, but there may be other causes as well.