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Thanks. I've checked twice every connection from the RAM chips to the LSs and the large VLSI chip. Also between the RAM chips everything is as it should be, as far as I can tell. Also on the back side of the PCB the resistors which sit inbetween the adress lines on the RAM chips and the VLSI are...

Yes, and its known good. The PSU is also from an working LC.

Yes, I know. But I need a starter. The result of the serial diag leads me to believe that those two 245s are likely candidates for such an error of no RAM seen at all. The error code also does not change when I populate the SIMM slots.

Yes, would be a good idea. The temps are 33°C on the CPU and 30°C on the 245s on the good machine vs. 37°C on the CPU and 35°C on the 245s on the bad logic board. All temps measured on the same spots an about 25°C ambient. Not much difference but noticable.

In the meantime I checked the temps of both LS245s. They are warmer then I think is usual. Right after power on they are warm to the touch. Also the CPU gots warm in short time. The RAM chips are stone cold like the other chips on the board. I think I'll swap the ICs. I have a battery bombed...

Yes. The sockets are also uncommon for the time. Those are round type precision sockets not the usual double or single wipe sockets.

This was done from factory I suppose. I only changed the SMD ones. It is glued onto the chip below and also the soldering on the back side looks factory.

Long time ago I aquired an spare LC motherboard which I safely put away and forgot about it. As far as I remember it was sold as non working. Upon getting the board I removed all caps, right before they started leaking. Only one pad was lost. Recently I recapped my LC475 and wanted to attack the...

Yes, it does not report any memory error. I think all those errors are follow-up errors. As mentioned before the "waiting for ..." error still happens. When I monitor the clock in pin on the 6502 the clock frequency is fluctuating. After a while the freqency stabilizes and the machine is...

Sorry, no soldered RAM but one, I replaced some times ago. I used a dead test ROM (https://github.com/misterblack1/appleII_deadtest) to check for RAM faults. I get one beep which should be data bit zero. This should be RAM at location F10 if I'm correct. Also the "summary" screen of the RAM...

Thanks for your feedback. I should have tested it beforehand. Unfortunately all voltages are present and stable. I also used another Pico ATX based PSU I long since built but never used. The errors are also present using this modern PSU. :-(

My IIe needs some help. It was put away for quite some time but I wanted to do somthing now. Now it does not start up reliable. One time it starts up normally, the second time the startup beep is played noticeably slower and what looks like output from the machine language monitor is displayed...

The dead analog board went upwards in my "to be fixed" pile of stuff. I changed C3,C24,C27, C28,C30, C31 and C32 to new caps. The 2200uf ones only test about 1800uf in my components tester. After replacing them the AB does not flup flup anymore. But it also does not power up the screen. No high...

I once replaced a blown Q4 on an SuperDrive with diodes I got from AliExpress. The drive works to this day. https://68kmla.org/bb/index.php?threads/blown-component-on-sony-mp-f75w.44807/#post-515317

I got myself another Mac Plus and an additional logic board for a decent price. The machine is in good condition but does not work. The AB has battery damage inside the battery compartment and for whatever reason on the Optocoupler IC. I reflowed (nearly) every joint and tried powering it on...

Yes, such a black box was also inside the machine.

Update: I found this in the Internet Archive: https://web.archive.org/web/20100615035229/http://myoldmac.net/SELL/Apple-Card-GSP-Tablet-Interface.htm So this card isn´t an serial card as I thought. It´s an interface card for a graphics tablet. Case closed.

Thanks. I found this thread while searching. Unfortunately the user with such a card was last online 15 years ago and the Internet Archive did not catch the picture URL he posted. :-(

In my recently purchased Apple IIe there was an serial card but which lacks two ICs. Unfortunately I was not able to identify the card and subsequently I could not check which ICs where originally installed on this card. Does anyone recognize this card? I searched the internet but to no avail.

No harm done other that the arm was modified. But this arm was broken as I got it. If sometime in the future 3D parts for this appear the drive can drive can be repaired with it.