Macintosh SE/30 Upgrades (Early Christmas)

[croissantking]

First upgrade was something I picked up from @tt. Although the stock factory power supply was working fine, I had received this fancy new modern one as part of a trade so I decided to install it. Board looks so nice, it sucks it's never seen buried inside the enclosure!

For testing purposes only: You need to set your PSU to more than 5v if you want to hit 5V at the LB, due to voltage drop over the leads. Generally you'll want to start with something like 5.5v at a low current limit and monitor voltage at the point where you're injecting power, then adjust current/voltage on the PSU until you reach your target voltage. The axial cap near the LB connector is my usual choice if I need to power a SE/30 board from a bench PSU. Make sure you turn off the bench PSU before turning off system power.

@jmacz power supply is a modern replacement - those don’t generally have an adjustable pot afaik…

 

[zigzagjoe]

@jmacz power supply is a modern replacement - those don’t generally have an adjustable pot afaik…

Ah, sorry, that procedure was for using a bench PSU to bring up 5v as he had mentioned in the last post. Not the retrofit PSU.

 

[croissantking]

Ah, sorry, that procedure was for using a bench PSU to bring up 5v as he had mentioned in the last post. Not the retrofit PSU.

Oops - missed that.

 

[jmacz]

Yeah, this was for a bench supply.. I was running it at 5.2-5.3V. But sounds like this is a problem bigger than my skillset.

I'm curious whether the P33/P34 will have a different (better) behavior than my P31 PowerCache. Also curious whether I would encounter the same problem if I punt on the DayStar (leave it for my IIci) and pick up one of your socketed boosters?

 

[zigzagjoe]

Yeah, this was for a bench supply.. I was running it at 5.2-5.3V. But sounds like this is a problem bigger than my skillset.

I'm curious whether the P33/P34 will have a different (better) behavior than my P31 PowerCache. Also curious whether I would encounter the same problem if I punt on the DayStar (leave it for my IIci) and pick up one of your socketed boosters?

It should work in that setup, though it will be a bit slower than the PowerCache due to lack of cache.

 

[Huxley]

I have nothing of value to add here, but I'm glad that you told me to check out this thread when we met up earlier @jmacz - it's amazing what you've accomplished with this build! The crashes you're experiencing on (cold) boot must be annoying, but weirdly it reminds me of my first car, which similarly failed to start from a cold stop most of the time, but once it was warm, ran like a champ

I look forward to reading any further progress you make with this build, and (hopefully) recreating it myself someday!

Huxley