Recent content by arroz

On top of the non-material value of having a very rare piece of Apple history, I found a reference to one that sold for just over 1500 USD. So definitely don’t throw it away nor sell the shield for the copper...

That’s awesome! I want to do something like that, design my own analog board with a MeanWell PSU hanging from it, the pico, speaker, switch etc. I just didn’t have enough time and energy to dedicate to that yet (it would be my first PCB so lots to learn). Let us know when you have the screen, I...

Hi! Can you post a picture of your MacTCP configuration (both the main window and the detailed configuration window)? As others said those cards tend to work without drivers more often than not. And if you can see the Mac on your router it’s very likely working. So it’s just a matter of IP...

The small caps should be fine, the problem tends to the electrolytic ones. I haven't actually replaced mine (mostly because the tantalums in that format are prohibitively expensive and I already had a large enough shopping cart on Mouser), but they are ~40y old, so… I should, even if with new...

Since you have no chime and apparently no reset, start with the chip that handles both: the SND chip (schematic here). Check the multiple power pins (that chip is powered by the 5 and 12V rails) and GND, and then check with a logic analyzer or a scope if the output ^RES pin actually issues a...

I'm glad to hear that! 😊 Did it work on the SE without any modifications? I thought the SE didn't use inverted video like the Plus, but I don't have one to test.

BTW I was looking for VRAM and I found this! Perfect. This is exactly what I was looking for!

Hi, AA-style batteries leak all the time. I have a drawer with a bunch and every time I go grab one, there’s new leakage. We’re talking about less than 10 year old batteries. A friend ordered a BIOS battery for an old 486 already during the pandemic and it already leaked. Although I have...

Hi! Well that at least clarifies that mystery, i was wondering what was that chip. Yeah this is probably not a problem. I’m just surprised there’s apparently nothing protecting voltage from going in the battery or against the battery being installed the wrong way. Maybe the chip has an...

Hi! I'm thinking about adapting my LCs to use CR2032 instead of the prone to leak 3.6V batteries. However, I looked into the schematic and realized there is no diode preventing reverse voltage, only a 1K resistor. I powered on one of the Macs without any battery in the slot, and I measured...

@cgp its not just humidity. One of the LCs I have has the top shield with rust, the bottom one like new. Both shields were obviously exposed to the same amount of humidity. The difference is the materials. A magnet will attach to the rusty one but not to the pristine one.

Hi, I just fixed a 475 with a somewhat similar symptom, it would not see the onboard RAM (although it could see the one on the slot, but would play the chime of death way more often that actually booting). The problem was a broken trace between pin 4 of the first and second DRAM chips (DRAS 0...

Confirmed! I think I'll use the (missing) ROM SIMM pin for the patch. Not sure if I can do it today because my desoldering pump broke… but yeah, this machine will live again. :)

Well, problem found! Pin 22 (A4) on the video chip has a broken trace.

Hi! So just finished recapping. Board works but the washed out video problem remains. I managed to switch to (I think) 1 bit while barely seeing what's on the screen, and now I have the entire screen displaying gray. Very weird… the investigation continues, and will have to install Timbuktu on...