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I'm late to this party, searching for clues on my own LC II restoration.. but I agree with @zigzagjoe on cap removal: I have a pair of micro-snippers set aside just for this method. Gently depress the cap to prevent any lifting while using the dedicated snippers to cut the cap's can in half. I...

To clarify, I found only sketchy descriptions of the early 68LC040 mask FPU errata, and they all made it sound unrecoverable. But I also found that these masks were common in many Centris and LC lines of the day. I found an E23G in an LC 475. So, the problem is not insurmountable. I like what...

I am nearly done repairing a Centris 610 of unknown provenance, literally pulled from the trash. I thought to look at the CPU and it's a D39H mask LC040 (20MHz). I can't be certain it shipped with that CPU. I had a spare E23G (25MHz) and swapped it in, if only for cooler temps. So the D39H is...

Thanks to an assist from @eharmon, my IIcx's Nubus RasterOps 8L video card is now a Nubus RasterOps 24L video card. Using a blank EEPROM left over from that IIcx's boot ROM repairs and a ROM dump eharmon had in his library, the VRAMs I found to fully populate my old 8L now allow it to show not...

FWIW, the comparison of the factory ROM contents versus what my ROMs had. You can see that with only two exceptions, they happen on 0x__700 and 0x__F00 boundaries; each fault persists for eight bytes. Possibly the 27C512 page (row) size. They always happen in the right-most byte, which is the...

Corrections to my sleepy-eyed success post: The patches I mentioned are necessary only for System 7.5 and beyond, I think. I recalled it incorrectly as System 7.1 and beyond last night. My RasterOps 8L doesn't do Millions of colors. I did expand its VRAM to the max, but without the ROM from a...

@Boctor - I evacuated the solder from 26 of 28 pads by applying a little flux, heating the joint, and wicking the easy parts away, then repeating where needed using a simple thumb-pumped solder sucker instead of wick. The last pins, Ground and Vcc, had too much copper nearby and resisted several...

And the saga .. CONCLUDES 🔔🔔🔔🔔 The second IIcx was up and running and playing sounds for about thirty minutes just now. It's late so, I'll do a more proper burn-in tomorrow. What changed? I was almost asleep when I had a vague memory that if I boot through a ROMinator II into System 7.1 or...

@Callan - for a while, I lived four blocks from a Fry's Electronics. In the 90s and early 2000s, they still sold - retail - everything from 7400-series chips to CPUs, oscilloscopes and static RAMs. They folded a few years ago, sad to say. The real loss out here was when WeirdStuff Warehouse...

The second IIcx now happy-chimes with no ROMinator. I dumped my ROMs with Test Manager and compared them to a reference ROM file, and sure enough, 64 words had the highest-addressed byte corrupted. The low nibble was always the cause. I live a short drive/medium walk from Jameco Electronics...

After more study of the existing posts, I think the ROM Checksum Test (*T0004...) '8' is telling me that the LL ROM did not match its checksum. I like the ROMinator I have, but aim to have as authentic an antique as possible. So off to investigate a replacement EEPROM and conjure up an ad-hoc...

I saw @zigzagjoe 's suggestion to replace the ethernet chip's crystal after I had started to remove the ethernet chip, but had not gotten far. I ordered a new 20MHz crystal and tacked down the leads on the chip that I had freed. It did lose one very corroded power pin. After double-checking...

Using knowledge gained from other IIcx restores on this site and with links provided by @SuperSVGA , progress was made on the remaining sad-chime IIcx. For other novices such as myself, the Test Manager is a serial debugging tool in the ROM code. A thorough guide to it can be found here - be...

I'm not sure what the timing requirements are.. my gut tells me they went with (pricier) ALS for speed and/or fanout? And being unsure of why, I'm ill equipped to make any swap there. But thanks for the offer! I think we have a fair amount of reason to think that the problem is elsewhere at...

In my ongoing self-education about the ST-NIC DP83902 chip, I found this design note describing how one can develop a NIC for the old PC-XT bus with it. In it, they describe using a small PAL for the decode, although for classic PC-XT the I/O addresses were in low memory (.. everything was ..)...

@volvo242gt - are those PSUs different than the IIcx? Sorry if I was too brief (I generally say too much...); this bracket is part of the PSU; is the same bracket within the 650/7100/IIvx ? The beta replacement partially installed, with a generic NMB 12V fan:

I would have to let more knowledgeable restorers comment to be sure, but I think the IIcx requires memory in Bank A or the memory sizing and bank configuration will fail. I know nothing of the SE/30, however, and maybe its bank detection code is compatible with the hardware on the IIcx and frees...

Idle hands while awaiting the next delivery of restoration electronic parts... Both of my Mac IIcx power supplies came with broken fan brackets - missing one of the major retainer clips, or the lesser snaps that keep it flush with the bottom of the enclosure have lost their heads. Just brittle...

I decided to lift the ST-NIC. The only real corrosion on the board was at its lower right corner near C44, and while we seem to all suspect the FPGA first, I thought maybe I would find some damage under it that might explain things. I replaced the can caps including C44 as soon as I got the...

I can't replace the 74ALS640's without buying $250 of them, so.. I'll just hope the bus interface is OK. @joevt also encouraged me to inspect memory directly, and indeed that was this thread's original direction.. I got bad accesses but did not trust my use of the memory map. Today I double...