PowerBook 180c That’s Picky with RAM

[ian1035nr]

Howdy everyone, I have a PowerBook 180c that isn’t cooperating with a 10 megabyte RAM module I have. 
 

I plugged the module into my PowerBook 170, and it works perfectly. System 7.6 boots fully, and I ran it like that for a while and it never gave any trouble.

The 180c however, refuses to cooperate. It shows a gray screen, plays the death chime, and doesn’t do anything else. 
 

It works absolutely fine with a 6 megabyte module I have, along with some 2 and 4 megabyte modules. It’s just this one 10mb part that doesn’t work with it. 
 

The 10mb stick in question came from another 180c that was working (I bought it 13 years ago, and it had problems with the interconnect cable, it’s long gone now so I can’t try it with this stick), so it’s absolutely, 100% compatible with the 180c

I just can’t figure out what the problem is. I tried the obvious things like cleaning the socket on the motherboard and the connector on the RAM, I made sure it was fully inserted. I’m stumped. 
 

If anyone has any other options, I’ll try anything 

 

[ian1035nr]

So apparently I posted too soon. 
 

I was fiddling with the 10mb module and found that the PowerBook would POST successfully if the module is held at a very specific angle, a tilt of about 10 degrees. I placed a folded up business card between the top case and the module to act as a shim, and everything’s fine now. 
 

I don’t know why it’s like that with only this one specific RAM module, but I’m not about to look a gift horse in the mouth; this is good enough for me. 
 

I did notice a bit more friction when putting the 6mb RAM module back in my 170; I wonder if the 10mb’s connector wasn’t really manufactured to proper spec. Who knows, I sure don’t. 

 

[sutekh]

The connectors in that platform can be pretty finicky. I think it's a confluence of age-related factors. Surface oxidation on the contacts, diminished mechanical tension within the female connectors against the male pins. etc... I recently posted about a similar problem affecting the ribbon cable connector in my PB180c.

Others may disagree as what I'm about to propose can be risky if not done very carefully, but I've had good luck re-establishing a firm connection with all manner of similar connectors by ever so slightly bending the male pins (we're talking less than 0.5mm) causing them to press harder against their corresponding contacts on the other end. Shine a light into the female connector to see which side to preference.

 

[bigD]

Glad it worked! Incidentally I had my 180c apart today to fix a display issue (fixed!) and noticed that my 10MB memory module sits at a slight angle just like yours.

 

[ian1035nr]

Good to know mine isn’t the only unit that prefers lopsided 10mb modules. 
 

I’m tempted to bend the pins a bit as suggested by sutekh, but my hands aren’t all that steady anymore, and I don’t have a spare upper motherboard in case things go sour. Oh well, it’s fine as is for my own use