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Just to state the obvious: there are no "5V LEDs", but it's normal to measure 5V when the LED is broken/not connected, since without the LED no current is drawn - hence no voltage drop across the series resistor, so you measure the full 5V supply voltage. Depending on the replacement LED you may...

Look! It's working again... :giggle: It's a beautiful color display (for a monitor from 1984). I finally took the time to restore this monitor. It was super filthy, everything inside covered in thick black dust. Yuck. Required a good cleaning anyway: I replaced various degraded caps, none...

I'm progressing with the restoration of my ebay M24. After fixing the faulty PSU, reviving the harddrive (Tandon TM502: fortunately wiping the metal tab contacting motor "spindle" on the bottom of the drive with contact cleaner was enough to make it spin again), and completely...

The AT&T 6300 is a relabeled Olivetti M24. I just reworked my PSU a while ago. What exactly is your question concerning the wires? If you refer to the yellow-green ground wires: they are additional grounding wires. Of course the drives are already connected to ground through the normal...

It's been a while - almost a year since I posted above. In case anyone was interested, or also working on an M24 PSU, here's a report/blog post on fixing my M24 PSU. It hasn't been my "main project" (I'm mainly into 8bit systems :) ), and I needed several sessions for this PSU. Multiple times I...

The thing with the resistors is not about simple orientation. Of course the resistors are all oriented consistently. Even a beginner hobbyist with a bit of pride in his build takes care of consistently orienting resistors, so the board looks neat. As I understood it, the question of alignment...

Well, my favourite supplier still has the 328p chip (not the Arduino module) on offer for about $3.50... However: "in stock: 0. Expected delivery date: January 2023". There is the catch. :)

The apple II keyboard returns a 7bit data value (plain ASCII). The top most bit ist set, when a new key is pressed. The bit is cleared by accessing $C010 (that's why the "sta $c010" is there). This indicates that the keypress event was already handled. The code above compares the original...

Thanks! Sure. Same guy, same name... :) Btw, if you click on a user, you can still see previous names. But, yes, seems to be a more or less unnecessary and confusing option.

'Account details' has the option to change the name. Says you can only change it once a month (so, it's an ultra rare exception).

... and the "mystery card" is now for sale on fleebay. Part of the B&H system. Yours right now for US $3,925.00. Quick! :ROFLMAO: https://www.ebay.com/itm/255637857744

Yes, that's what I said. I was refering to the pinout there. The CPU pinout never changed for any Apple II(e) mainboard. No matter whether using a 6502 or (Rockwell) 65C02.

Just to correct the confusion above concerning 6502, 65c02 pinouts and enhanced Apple IIes. There are different 65c02s: the enhanced Apple IIe used a Rockwell 65c02. This is fully pin-compatible with the original 6502. There are no pinout differences compared with the original 6502. See...

Remove the P5 PROM from the problematic card and see if the machine boots when the card (without P5) is plugged. My guess is, it will boot then (but of course not access the drive). If it boots, then either the P5 ROM is bad. Or, if you have already excluded that by swapping the ROM with the...

I've never realigned drive heads, so s.o. else has to help you there. The LS323 and LS299 are very similar, only differing in the reset signal being synchronous vs asynchronous. For the disk II interface it probably doesn't even matter. My guess is both would work anyway. You mentioned one...

Yep, you're right, it's pin 29/NMI. Seems I was counting the holes and indeed skipped the ground pin.

The flipflop's set and reset inputs are each a wired with a 1K pull-up resistor. The toggle switch connects either input low. So it either sets or resets the flipflop. The flipflop output is directly connected to /INTIN (slot pin #28), the normal interrupt input. So, yes, this was a simple...

In any case, keep the original ICs. I stashed mine inside the IIe, so they cannot get lost and stick with the machine, and the mainboard can always be reverted to its original state.

These photos don't really help. It would have helped to add a photo of the top side (so we can read the markings on the IC) and a photo of the bottom side (so we can see how the IC and switch are wired to the slot).

Thanks so far for your replies. Yes, I'm careful with these boards. And I'm not a beginner - though PSU's are not really my preferred toys. And just as a word of warning for any future readers: I've seen some comments/descriptions referring to these two PSU boards as a "high voltage" and a...