IIci Cache Card

[Phipli]

Good afternoon folks.

I have a dead Apple branded 32k cache card that I'm trying to revive. I've replaced the actual Cache SRAM, the 74F32, recapped it and checked all the ceramic caps for shorts. Basically that leaves the main custom silicon and the TAG RAM... I can't get either it seems, plus if I keep buying parts... well, I already spent the value of the card in cache chips :s

Does anyone have a dead IIci Cache board, in the UK if possible, that they'd be willing to donate to the cause of bringing another back to life?

This is the card I mean, and its the P4C116-20JC chips that are eluding me. The MT5C1608DJ-20 and IDT6116SA20Y are probably an equivalent parts.

 

[rikerjoe]

I also started troubleshooting a Iici cache card with no luck so far. My non-working card has CY7C185 28-pin CACHE SRAM chips and MT5C1608 24-pin TAG SRAM chips. (I have a working card with P4C164 28-pin CACHE SRAM chips and P4C116 24-pin TAG SRAM chips.) I wondered about the MT-branded chips since they have a bad rep in the 8-bit computing world.

To date I replaced the 24-pin TAG SRAM MT-branded chips with Renesas 6116SA20SOG from Mouser. It's not an ideal match because the packages are different, but the data sheets for the original MT5C1608 versus Renesas show the exact same pin configurations. I was able to bend the pins on the new chips to align with the pads and confirmed good continuity after soldering. Unfortunately, the new chips did not resolve my problem, and I set the cache card aside to work on a separate restoration project.

Here is the before shot, showing the MT-branded 24-pin TAG SRAM chips:


Here is the after shot, showing the replaced chips:


I know this isn't of any help to you (plus I'm in the US) except to say that I'm a kindred spirit attempting to solve the same problem.

 

[Phipli]

I also started troubleshooting a Iici cache card with no luck so far. My non-working card has CY7C185 28-pin CACHE SRAM chips and MT5C1608 24-pin TAG SRAM chips. (I have a working card with P4C164 28-pin CACHE SRAM chips and P4C116 24-pin TAG SRAM chips.) I wondered about the MT-branded chips since they have a bad rep in the 8-bit computing world.

To date I replaced the 24-pin TAG SRAM MT-branded chips with Renesas 6116SA20SOG from Mouser. It's not an ideal match because the packages are different, but the data sheets for the original MT5C1608 versus Renesas show the exact same pin configurations. I was able to bend the pins on the new chips to align with the pads and confirmed good continuity after soldering. Unfortunately, the new chips did not resolve my problem, and I set the cache card aside to work on a separate restoration project.

Here is the before shot, showing the MT-branded 24-pin TAG SRAM chips:
View attachment 50865

Here is the after shot, showing the replaced chips:
View attachment 50866

I know this isn't of any help to you (plus I'm in the US) except to say that I'm a kindred spirit attempting to solve the same problem.

Interesting, most of the cards I've seen have the same P4C116 TAG RAM. I was finding equivalent parts by searching for 2kx8 20ns SRAM!

I'm worried the issue is the custom silicon.

Edit :
I meant to ask, what symptoms does your card show?

 

[rikerjoe]

Symptom is with the bad cache card my IIci chimes, then after about 20 seconds I hear the speaker pop faintly, but it remains with a black screen with no desktop or happy Mac appearing, and I see no disk activity on my internal BlueSCSI. With a good cache card, no cache card, or my Interware Booster 40-33 the desktop appears immediately after the faint speaker pop, and boot proceeds normally.

 

[Phipli]

Symptom is with the bad cache card my IIci chimes, then after about 20 seconds I hear the speaker pop faintly, but it remains with a black screen with no desktop or happy Mac appearing, and I see no disk activity on my internal BlueSCSI. With a good cache card, no cache card, or my Interware Booster 40-33 the desktop appears immediately after the faint speaker pop.

Yeah, same here - after the memory test the monitor powers on, but no signal comes through and the disk activity light comes on briefly... but nothing else happens. Possibly means it is the custom chip if I've replaced the Cache and you've replaced the TAG!

 

[Bolle]

Interesting, the TAG SRAMs are not actual cache tag chips but just basic SRAM… so the address comparison happens in the custom silicon. Never paid attention to that, always was under the impression they used tag chips.

 

[paulbruneau]

I have two IIci cache cards that I have recapped and both of them are showing that exact same black screen failure in a working IIci. Kind of a bummer!