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Macintosh Plus Chirping Noise


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Please take one good high-res shot of the outside of the analog board and another hi-res shot of the inside of the computer, showing as much as you can of the CRT, cables, etc.  So far, most of the small items that you have focused on have turned out to be alright, so it might be helpful to look over everything, including the current symptoms (if you could list them) and work our way to a diagnoses.

 

Oh, and be super careful not to touch anything while its plugged in or running.

Edited by Juror22
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Symptoms:

1: When together CRT makes a static-like noise. (like when a CRT is turned off but constant)

2: The Transformer behind the magnet with the "5A" on it (is it the low voltage?) makes a chirping type noise when distant, but when close can also hear a ticking sound as well.

3: Speaker makes "fup" noise only when the logic and analog board are together

4: There is no startup chime or an image on the screen.

5: When I got the Mac Plus the startup chime would sound but no picture would be on the screen, I however eventually read if I tap the left side swiftly and a image shows up that some of the solder joints were broken/damaged  and just needed soldered again.

6: The internal and external drives would make a horrible grinding noise constantly because both had a broken eject motor gear.

7: Unfortunately I was a bit of an idiot and had the Mac on with the external floppy drive connected and OPENED UP out the back "checking it out" (I didn't know about the gear yet), then the Mac shat out and went into its current state. Smoooooooth move on my part......:-/

 

I'm guessing ether my stupidity did it, or the Mac really just shat out on its own.

Soooooo... yeah these are the symptoms

 

Thanks for the help!

 

-Jack

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The only obvious thing I see is the solder joints on J4 (?), they seem to be cracked. Have you read chapters 5 and 6 of Macintosh Repair & Upgrade Secrets? I think those might be helpful here.

 

Looking at it some more, maybe a lot more solder joints could use a touch up, the flyback included.

Edited by mjhagen
typo, more observations
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20 hours ago, techknight said:

Check the secondary rectifier diodes for shorts. 

Alright, I'll do that

 

On 4/14/2018 at 6:08 AM, mjhagen said:

The only obvious thing I see is the solder joints on J4 (?), they seem to be cracked. Have you read chapters 5 and 6 of Macintosh Repair & Upgrade Secrets? I think those might be helpful here.

 

Looking at it some more, maybe a lot more solder joints could use a touch up, the flyback included.

I'll take a look and touch the solder joints up. And I don't think I've read any of the Macintosh Repair & Upgrade Secrets book, I'm looking at it now...

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  • 2 weeks later...

Hmm, that looks like the flyback for an iMac and I don't know if it can be used in an early compact Mac.

Maybe some of the other folks know.

(Very lame that ebay seller doesn't show a photo of the transformer, that why I wanted to see a photo.)

 

Try re-sizing your photos smaller, they're probably too large that's why you can't upload them.

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  • 6 months later...
  • 1 year later...

I believe I’ve found the problem

 

The wire harness that goes between the analog board and the logic board is finicky, whenever it is moved it causes many different symptoms.

 

 

Examples being:

 

1. A weird distorted checker board

2. A line going horizontally across the screen

3. A line going vertically across the screen

4. A chirping noise

5. Repeatedly rebooting

 

It’s friggin’ weird.

 

Edit:

I flipped the wire harness around and the Macintosh Plus seems to be fine, it boots up and doesn’t do anything weird.

I will have to keep watching it to confirm though.

 

I’ll feel pretty dumb if it was just the wire harness the whole time, but it seems to be fixed.

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I was working on a Mac Plus with 030 upgrade the other day and it had an analog board issue.  I was adjusting the video image size on the board and the video started cutting out.  Then it cut out completely.  Then I noticed that pressing on the analog board at a certain point slightly towards the Mac innards makes the video come back.  So I guess I have to resolder some joints too.  Problem is, the paper cover came off ... double stick tape blocks split down the middle.  I was lazy and didn't want to remove them and reapply, so I just used some rubber cement to glue the thing back on.  Makes it harder to take off now.  Doh!

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  • 3 weeks later...

I've had the chirping for awhile now in my Plus, it's driving me nuts. I've replaced so many components on the analog board, caps, resistors, diodes, transistors, ICs; I'm just at a loss. Even the axial caps on the logic board. Am I just gonna have to bite the bullet and buy one of those new flybacks for $100? And yet, when I completely disconnect the crt from the analog board, it continues to chirp....

As for the Plus's vinyl protector, I bought the plastic snaps recommended at some point in another thread, and they work great! (After cleaning off the tape residue)

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