My Miggie 2K

[irishmike]

I have not had a real chance to sit down and play with my new Amiga 2k.  I am borrowing a C= Monitor (but eventually plan to purchase Jens' Indivision VGA adapter when it is released).

I acquired the 3.1 ROM for the unit and I am looking to install a new RTC battery.  The old one having been removed to prevent PCB damage.  I have been advised to perhaps use 2 AA batteries, but wanted to find out if anyone has ever used a button cell and what might be involved in installing that kind of solution.  For example:  would I need to install a diode to insure that the system does not try to "charge" the CR2085?  Should I worry about this same kind of issue with the 2AA cell holder idea?

Also I am thinking of installing a SCSI CD-ROM and I am not sure if I am going to put it inside the case or just find a nice external model.

Help/Suggestions always appreciated.

[Damion]

I acquired the 3.1 ROM for the unit and I am looking to install a new RTC battery.  The old one having been removed to prevent PCB damage.  I have been advised to perhaps use 2 AA batteries, but wanted to find out if anyone has ever used a button cell and what might be involved in installing that kind of solution.  For example:  would I need to install a diode to insure that the system does not try to "charge" the CR2085?  Should I worry about this same kind of issue with the 2AA cell holder idea?

My solution was to install a 2032 coin socket directly on the motherboard, then remove R803 (charge limiting resistor for the original Ni-Cad) and install a germanium diode... I used a 1N60 IIRC. Looks nice, and very inexpensive. I'll post a pic of it later this eve.

[irishmike]

@damion:  Would like to see the pic.  Thanks.

[gertsy]

Ive done an A2000 mod where Ive mounted "with a clip" the CR2032 holder behind the A2000 LED mount (where it fits perfectly). Ive then run 2 wires, one with an inline diode, down under the Floppy/Pwr Supply cradle to the MB.
Much easier to change CR2032s then.

Gertsy

[irishmike]

So I guess the remaining question is, do you place the diode on the postive lead or the negative lead...I assume you want the direction of current flow towards the mainboard if on the positive lead preventing the charging circuit from being able to reverse the polarity if the voltage drops?  I have not decided whether or not I want to mount the holder on the mainboard or attach leads, that I will determine at a later time.

[Damion]

So I guess the remaining question is, do you place the diode on the postive lead or the negative lead...I assume you want the direction of current flow towards the mainboard if on the positive lead preventing the charging circuit from being able to reverse the polarity if the voltage drops?  I have not decided whether or not I want to mount the holder on the mainboard or attach leads, that I will determine at a later time.

On the positive lead, with the stripe facing away from the battery. Going to try to get that pic up today... camera died, so I have to bum my gf's.

[Beast96GT]

Or you can turn the holder before soldering it down so that you can get the battery in and out without the chip being in the way.  

Here's a pic of my setup:

[Matt_H]

This will simplify things: tiny PCB with integrated diode and coin socket for direct drop-in replacement.

[irishmike]

@Matt H:  That would be great if it weren't sold out!

@everyone:  I have ordered my parts from Mouser and I decided to go with the vertical cr2032 battery holder and diode, I think it may be a little easier to orient my setup this way.  The cost of the parts was like $2 USD... the battery will be around $4 USD so for $6 I have a workable replacement.  I did figure on something like beast96GT's setup.  That doesn't look bad at all.

I still have thinking to do on my particular setup.  BTW:  forgot to mention that shipping was terrible on this order... it cost triple the cost just to have the items shipped USPS from there so I need to remember that if I want two small parts in the future... oh well, for the love of the Miggie!

[Damion]

Had the cover off of my A2K today, but wasn't able to get a good shot without removing the CPU card and drive cage. Fortunately, the posted pic pretty much shows everything. The only thing I did differently was to install the 1N60 diode at R803, with the stripe facing away from the drive cage.