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SE/30 simasimac and speaker clicking after recap


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This is my first post and first Mac restoration project.  I was given a Mac SE/30 that had been put on a shelf display and not used for 20 years.  It had the simasimac problem and no startup tones.  I removed the logic board and saw a few corroded spots from leaky capacitors, but overall, the board looked clean.  I washed it with soap, water, and a toothbrush.  Then I soaked it in 99.9% rubbing alcohol for 30 minutes and brushed and rinsed with alcohol again.  After drying it for a few days, I replaced the capacitors with the tantalum capacitor kit from console5.com.  I have only a little soldering experience, but I believe I was successful and did not accidently make any unwanted connections.  Now I still get the simasimac screen, but I also get a clicking noise from the speaker when I boot up or press the interrupt button.  I am not quite what to do next to troubleshoot.  I cannot see any broken traces or lifted pads with my eyes, but am worried that there may be unseen corrosion underneath the chips.  The most corrosion was near C2 and also under the JI12 SCSI as can be seen in my first photo.

 

I have a multimeter and did a continuity check on every rom pin to its corresponding pin on the cpu and it all had continuity where it should have.  I also checked continuity from the rom socket to the actual rom card to make sure the socket made contact.  I did notice that if I touched any Vcc pin to a ground pin, multimeter would beep for a split second, but then go away.  I'm not quite sure what Vcc is, but I'm hoping this is normal and simply from bleeding capacitance or from some other normal explanation.

 

Tonight I just got 8 16mb ram cards from OWC and they make no difference.  I also ordered a ROM-inator II and will try that when it arrives.  The original rom card looks pristine though and I doubt that's the problem.  I've attached some pictures of the logic board at various stages in the project and also a video of the startup clicks I am getting from the front speaker.  I have not touched the analog board or the Sony PSU.  Any suggestions on what I should do next?  I am in southern California and would welcome any help if someone is in the area.  I'm also not opposed to paying someone or a shop to repair the board for me if such a service exists.  I just want to save this old board from the scrapheap and also be able to show my children what computers were like when I was a kid.  Thanks everyone!

 

IMG_20210303_211723.thumb.jpg.be1e41238d190155a19150f576a7f966.jpgIMG_20210303_211937.thumb.jpg.01ccc11e712c3ab22987b4a0360bd0f8.jpgIMG_20210304_153545.thumb.jpg.a2bed43e83ea33eea2e88fef509bb7cf.jpgIMG_20210312_192608.thumb.jpg.2905ea3196f95d3454cafe81cf085a8a.jpg

 

 

Edited by LinemanDoc
fixed pictures
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Welcome to the forum! Hopefully this Macintosh can be brought back to life! It looks like you have done all of the right troubleshooting steps so far. Your recapping work looks pretty clean and professional.

 

For troubleshooting purposes, I would only use the original ROM and RAM at first, as aftermarket chips sometimes cause errors similar to what your computer is showing. Because the computer is not chiming after the power switch is flipped, I believe this means that the ROM is not being accessed correctly. From what I remember, a bad connection to the ROM, or when no ROM is installed, results in the pattern your computer is displaying onscreen.

 

I would recommend checking all of the connections from the ROM to the other parts of the computer using a schematic. I think there is likely a break somewhere.

 

Are you able to measure the voltages at the back of the floppy port as well? This would verify that your PSU is functioning properly. Place the ground probe of a multimeter on the metal housing of the floppy port, and insert a paperclip into the 12V and 5V holes to take your measurements. These readings should be pretty close to 12V and 5V.

floppyVoltage.png

se30recap.png

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Thanks for the reply.  I have already checked the ROM pinouts using the following image from https://ronangaillard.github.io/posts/my-mac-se30-is-back-alive/ and they have continuity to the corresponding Motorola CPU pins.  I also checked the ROM pins to themselves to verify that there are no shorts between pins.  I will use your posted images to check the capacitor pinouts and voltages tonight when I get more time.  Is it normal to have a split second beep from the continuity tester when first touching VCC to GND?

.rom-socket-matching.thumb.jpg.3980c2b7cc2f66039137299841cce93c.jpg

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Voltages were good at the floppy connector.  All the capacitor pinouts also good, except I believe the chart has C1 polarity reversed.  My board has C1 negative terminal going directly to ground and + goes to J12 pin 12.  I believe it to be an error in the chart and not my board.

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On 3/13/2021 at 5:48 AM, LinemanDoc said:

I believe the chart has C1 polarity reversed.  My board has C1 negative terminal going directly to ground and + goes to J12 pin 12.  I believe it to be an error in the chart and not my board.

I think I've observed the same issue with the chart as well on some of my boards.

 

On 3/12/2021 at 6:19 PM, LinemanDoc said:

Is it normal to have a split second beep from the continuity tester when first touching VCC to GND?

I'm not certain of this, but I think this is okay as long as the continuity beep is not permanent. I think that since the voltages at the floppy connector are good, this means that the ground isn't shorted to the voltage rails.

 

You may wish to continue checking the continuity of the address and data buses on the logic board. I would still guess that there is a break somewhere. The schematics I've linked above include a handy matrix of all of the pins to help make this easier. It is good that the CPU and ROM are hooked up correctly, but the ROM connects to several other important chips as well. I also observed a lot of corrosion around some of the video chips, such as UD8, UE8, and UF8, and perhaps a trace is broken in that general area, or one of those chips has gone bad.

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I downloaded the redrawn schematics and they are much easier to read.  Thanks to everyone who helped with that project.  I have the last week of the month off of work and will have the time to tediously check every trace that involves the ROM and RAM or is simply near the leaky capacitors.

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  • 1 month later...

I just wanted to update this thread with some kind of resolution in case anyone reads this later and wonders what happened.  I ended up finding a complete replacement logic board, recapped that, and got it running.  I donated this problem board to another forum member who I am sure can put it to good use.  Hopefully he is able to fix it and his post results on this thread, but I can't speak for him.  Thanks davidg5678 and others who read this.  I learned alot from your tips.

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