68kMLA Classic Interface
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| LCII Squealing noise from speaker | |
| Posted by: reallyrandy on 2024-08-10 12:56:12 I pulled out a spare LCII board I had to see if it worked and it chimes and boots fine but it squeals from the speaker. When I push and pull on the speaker connector the pitch goes up and down. Attached is a video. Any ideas? | |
| Posted by: Arbee on 2024-08-10 12:58:42 Has that board been recapped? If not, I'd strongly suspect goo from leaky capacitors. | |
| Posted by: reallyrandy on 2024-08-10 13:00:43 That's what I suspected but figured I'd ask around first. | |
| Posted by: ymk on 2024-08-10 14:53:36 Right, a recap should come first. On the LCIII, the noise can persist after a recap. Changing one of the cap values breaks the oscillation. This may also apply to the LCII, though likely with a different designator: My LC III wants to be a DJ.When powered on, my LC III intermittently emits whining noises in varying tones through its speaker. I've swapped the speaker to no avail. The kicker is that if I touch miscellaneous chips on the motherboard with varying degrees of pressure, I can alter the pitch and repetition rate of the...
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| Posted by: mikes-macs on 2024-08-10 15:08:02 My Performa 400 did this too. After recap the screeching sound stopped. | |
| Posted by: reallyrandy on 2024-08-10 15:26:54 I'll have to recap it first I guess. I hesitated because I just recapped my other one and it still gets no chime and a black screen. LCs are a pain to recap, lot's of caps and some are in really tight spots, like C10. | |
| Posted by: mitchW on 2024-09-01 19:22:57 I can also confirm that I repaired multiple LCIIs that all did this. Every time the problem were capacitors. They are just bad. And the first one that I came across with this problem was back in 2011, so at that time the machine was "merely" 19 years old, this is the same age now a G5 iMac or a late Pentium 4 machine is. Also they need PSU recapped, especially if they are TDK brand. | |
| Posted by: reallyrandy on 2024-09-02 09:29:56 After recap all is well. | |
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