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The same behavior also occurs with the original 3.6V battery. If the computer is connected to the mains but is switched off, everything seems to be fine. However, as soon as I switch off the mains and the computer is left for a while, the PRAM is erased. The battery is not discharged. The...

I took a closer look and it turns out that the pram stays active for a while after it is switched off but is lost overnight. I'm now going back to the original 3.6V battery...

Looking for the Q700 IIcx Power Supply schematics ...

Yes I think so ... I change the cell fro a new one (maybe a 3V cell is to low?)

I successfully repaired my Macintosh IIsi ... https://68kmla.org/bb/index.php?threads/iisi-fault.47209/ ... but I noticed that the computer has a problem with the PRAM, it always loses the settings it has made after switching it off and rarely but not. What could be the error and where should I...

... nevertheless trouble with the RAM, more precisely with the ALS245 chips. UF5 Pin18 (D8) has no contact with the Simm socket pin3 UG5 Pin13 (D21) has no contact with the SIMM socket pin20 Unfortunately the VIA from D8 was under the ALS245 and had to put a wire around the board. On D21 I was...

The new electrolytic capacitors were in the mail today. I equipped the power supply with new electrolytic capacitors and now the IIsi reacts correctly to the power button and can also be switched off again, which was no longer possible before. The chime of death is coming straight away now...

There are relatively many Nubus monochrome graphics cards with a DB9 video output. Are these always TTL outputs or are they mostly ECL outputs? TTL outputs can simply be passively connected to a VGA connection. Is there a pinout somewhere for the different DB9 video outputs?

The coil cell works well but empties quickly !

The PowerSupply caps looking good ... ... except the 56uF capacitor on the side that had leaked. I install some new electrolytic capacitors but not all of them ... Is there a schematic from the Sony IIsi PowerSupply?

replace it but nothing has changed ...

forgotten ...

I soldered the one ram on the Powersuppy connector a little messily because you can't get to it without unsoldering the connector, it doesn't look that great but it's okay

I think next is recapped the PowerSupply but my Voltagemeter say the +5Volt is fine ... But I do it. What surprises me is that the error sound takes a long time to appear. And when you plug in the power, the computer turns on immediately, which is strange ...

I recapped the Mainboard last Year with Tantal ones and all was fine. The PowerSupply is original and not recapped.

I have a IIsi that works before fine and now it take some time until the sound of dead sounds up. The motherboard looks good except for a little oxidation on the four 74ALS245 chips. I desoldered these all and cleaned everything up and checked connections and soldered on four new chips but the...

I think the Performa 475 has 512kB Video Ram build in and can be updated to 1MB in total so you can at two 256kB Module ...

I would like to build a null modem cable. Does anyone have the schematics for me between Quadra700 RS422 and PC RS232 9pin serial port ...?

Video are UA2 (RamDAC) and UA3 (Video Chip) I think ...

I also had the problem that the start sound was fine but the computer didn't bring up a picture onto the monitor and didn't boot. The reason was bad contacts (oxidized) on the video controller chip. New/re-soldered and now everything is good ... On other computer systems there are diagnostic...