bibilit

The Sound chip can be bad, happened to me a least twice, sound was faint at well through the speaker jack. You can have a try lifting the sound chip, cleaning underneath and soldering back.

You are right, the Plus will perform a slow or distorted sound with bad Ram and probably Sad Mac codes as well (sometimes screen is black with only the blinking folder present), don't know about the SE, most are bulletproof, but yes probably a sad mac error at least with no particular sound whatsoever. Never noticed that the Chimes came on later models... Anyway, if the SE still boots properly, don't think is a Ram issue.

Can also just be a coincidence. I will try to get back to the former ram for a test, also, the SE has a jumper on the Logic Board to select increased ram size (if this is the case) can be an issue with the A Board (same as the Plus, bad solder joint on the upper connector) can happen out of the blue. A ram issue will probably also lead to chimes of death at some point, but anything can be possible. Just my two cents...

Can be wrong, but i have seen a lot of 128 units with bad Ram, and never had this issue (always get a sad mac and fault code, even with many bad chips) so thinking not a ram issue here. I don't understand why you can't reset the LB with the 512 Roms, looks like something stuck in the process.

DP3 and DP4 are known for being « leaky » so tests are ok with a multimeter, but are bad most of the time. One is directly connected to the TDA and CNY, so in the regulation side. I have had a lot of issues with this two diodes, from completely dead AB to unstable video. I will replace both of them first.

Yes indeed. The cable was in a drawer doing nothing, don’t remember the former purpose of it. This small hack also works on the PowerBook 100 and IIsi, probably on all boards also needing soft power from the keyboard.

ADB connector should be shorted to get it going.

Yes, i have seen this issue too often, Classic II and CC are affected a lot (probably pretty close from the surrounding capacitors) in my opinion even a thorough cleaning is unable to solve the issue (or maybe probably using a ultrasonic process)

I will lift both sound chips, clean underneath and solder back again. Sound chips are used in the boot sequence, and from the picture, legs are looking dull or contaminated. Had as one issue related to that problem.

I only see the 79L12 (negative regulator) on this line that can be faulty. Problem is, fan is + 12 volts driven so don’t see any relationship between both issues.

tube is the same

Probably one of the Ux8 chips or a broken trace. Usually UE8 goes bad frequently

So more swapping. MMU / IOU / PAL-HAL / Keyboard Rom and all chips already socketed... no effect. i have a hunch on the 74LS374...anyone knows how the TEXT mode is generated on the Apple II ?

yes, to be honest, can't figured out how to read the information in your picture. To be honest those Mt chips are notorious for being unreliable, i will replace all of them to be in the safe side, or at least use sockets

Try piggybacking chips.