[CB_HK]

Here’s the write up I did a while back for the same issue with my Crimson. The SRAM chips are different manufacturers but it looks identical otherwise. Maybe this will help.

Fixing Crimson Dallas Chip

Edit: I see your question was in reference to what geoman did with his. I’ll leave this post in case anyone ends up with the same issue and needs to sort the Dallas on a Crimson or Professional IRIS.

[jan-jaap]

Here’s the write up I did a while back for the same issue with my Crimson. The SRAM chips are different manufacturers but it looks identical otherwise. Maybe this will help.

Fixing Crimson Dallas Chip

Edit: I see your question was in reference to what geoman did with his. I’ll leave this post in case anyone ends up with the same issue and needs to sort the Dallas on a Crimson or Professional IRIS.

Thanks, that's exactly what I was looking for!

[Geoman]

What an interesting read and a fine work done!

As for the "Dallas-sandwich-chips", 2 days ago I have done the deed and excavated the expoxy whith both coin cells in it with a dremel and had the bare PCB. The quarz oscillator got damaged in the process, so I soldered a new one in. Then I attached 2 cables with a coin cell holder. In the end the thing looks very clean, much cleaner than in the image. I dared to do this, because I had 2 times success with my Indigo2s (see picture).

So If my Crimson works fine with this hack, I can offer to repeat the process on your Dallas chip, now that I know whats inside the layer of epoxy.

The NVRAM has two parts: the RTC with embedded batteries and an SRAM on top of it (with the SONY logo).

Where does the SRAM go now?

Yes, as CB_HK excellently described in his thread, the SRAM is on Crimson the SRM2016C12-Chip, which has to be removed via chip-puller, and underneath is another package, which is socketed in Crimson and has also be removed.

It is an "DS1216B". According to Maxim there is a replacement for this chip, the DS1243Y-120+ (but not in the "16kb/2k x 8" configuration):

Replacement alternatives

Original Datasheet

I was way more aggressive than CB_HK and excavated via dremel the underside of the DS1216B. Then I soldered directly on the PCB, where the 2 coin-cell were, the 2 wires for the CR2032 and put everything back in place.

[jan-jaap]

I found some original NOS Motorola 2N6678 transistors :-)



On the bench it can supply 40A with sense feedback from the load to the PSU, without oscillation or strange noises.



Here's why I don't like blind component swaps in something like this. There's half a dozen undocumented adjustment points here for the 5V output alone, not counting the V1 ADJ. if I start replacing components I'll almost certainly have to recalibrate it. Without schematics or a service manual that's a no-go.



Fingers crossed it still behaves when I put it back in the system.

[Geoman]

A documentary vlogs of your repairs on YouTube would certainly get a lot of views!

Something I wanted to ask is: are there RIFA capacitors (the infamous magic smoking ones) outside of the power supples in PowerSeries or Crimson? Someone somewhere wrote that he replaced them in a Crimson, but I never saw any.

[jan-jaap]

A documentary vlogs of your repairs on YouTube would certainly get a lot of views!

Yeah but then I'd have to film it and it would take 10x longer to do the actual work. I intend to dedicate a website to my collection and my exploits, but again ... it takes time.

Something I wanted to ask is: are there RIFA capacitors (the infamous magic smoking ones) outside of the power supples in PowerSeries or Crimson? Someone somewhere wrote that he replaced them in a Crimson, but I never saw any.

I don't think so. Elco's for sure, smaller ones on the circuit boards, bigger on the backplane. I tried to solder a component off an Onyx IO4 once and it failed miserably. Those are some thick PCBs.  I would leave them alone for as long as it doesn't leak.

[Geoman]

"regulated 5V output - but it makes a horrible noise"

Marc heard a similar noise while repairing an LH Research PSU for the Xerox Alto.

[jan-jaap]

"regulated 5V output - but it makes a horrible noise"

Marc heard a similar noise while repairing an LH Research PSU for the Xerox Alto.

Thanks. The noise from mine was really bad. Much worse than this. A sort of screeching noise you would be able to hear through a closed door. Totally unbearable.