Hot swap carts?

[+FarmerPotato]

8 hours ago, mizapf said:

The question is, could there be a higher risk of damage when the console is powered on? The problem is usually static discharge, but this may also happen on cold plugging. Could, in turn, a powered connector even clear the static charge better than an unpowered one?

 

Inserting a cartridge will cause noise on the data bus, which usually leads to a crash, but for that reason the console is automatically reset shortly after plugging in. However, we have to consider both sides, so could this be more harmful to the cartridge or to the console?

 

The cartridge port became a bit unstable on my console back in those days, but the reason may simply be the insertion and removal of cartridges, independent of the power state. It just wore out and became dirty.

 

As far as I know, the hot-pluggable connections on the PC (like USB) first connect the ground pin, then the other pins, so there seems to be some technical reason.

 

 

TTL chips can be damaged if any signals are input before supply pin power is up. Not being grounded might be worse. 

The mini memory, for one, has a longer ground pad that makes contact first (or ought to.) This is a good practice. 

 

[Stuart]

13 hours ago, Willsy said:

 

Agree. Unless that short is through some sort of current-limiting resistor (which would have to be fitted to the cartridge) I would imagine that you could at the very least take out the -5V supply if the short was in place for too long.

It's an instantenous short through a capacitor in the console. It only lasts for a fraction of a second as the capacitor charges up. Later cartridges have a current-limiting resistor as well.

[Tursi]

3 hours ago, Stuart said:

It's an instantenous short through a capacitor in the console. It only lasts for a fraction of a second as the capacitor charges up. Later cartridges have a current-limiting resistor as well.

I didn't see a cap on the line in the schematics... the cap is there in the cartridge though.

 

I guess I do have an open console..  I read direct connection from the -5v line on the power supply to the pin on the cart port. I'm not familiar with the glass caps in my XB, but I think they are 100uF. If I math right, that means it'll be trying for more than 5 Amps for about 30 uS, and more than 1 Amp for about 100 uS. Mind you, the page I used to measure it won't allow a dead short, so I used a 0.5 ohm resistor, and that depends on something being able to /provide/ that current... it's really more the voltage on the data lines as they come up that bugs me.

 

I dunno. It's a hack in my eyes and I don't like it myself. But with 40 years of data I think most people agree it hasn't broken anything in normal use.

 

Where's our TI repair tech from the plant itself - would love his insight.

 

[Willsy]

10 hours ago, Stuart said:

It's an instantenous short through a capacitor in the console. It only lasts for a fraction of a second as the capacitor charges up. Later cartridges have a current-limiting resistor as well.

Thanks for the clarification, Stuart!