exxos's Atari, Amiga & retro forum

stephen_usher wrote: 12 Nov 2024 19:53 Well, I found the fault... and it's not the +5V, though that is high, but it's about the same on the mono monitor PSU and it drops to 5.2V once fully loaded. Still a bit uncomfortably high but just within TTL specs.

I found no -5V on pin 8 of the monitor/power socket. Traced it to cracked joints on all three of the pins in that area. Obviously the system hangs early in the boot process if there's no -5V somewhere.

Reflowed all the joints on the PSU, re-fitted and the system boots normally. Phew!

Good find 😁

:girldance:

One more full day at work, then a half day... then nothing for the foreseeable future.

After 32.5 years this is my last day working for the University of Oxford Department of Earth Sciences.

Sad day.

stephen_usher wrote: 15 Nov 2024 07:46 After 32.5 years this is my last day working for the University of Oxford Department of Earth Sciences.

Sad day.

That's a long time to work in one place, I can imagine that it's a pretty awful day for you and I hope it goes as well as it can.

Best of luck for the future @stephen_usher, take some time and do the things you never had time to do whilst working :)

Had a look at the Toshiba Satellite 4080XCDT I picked up from the junk pile at work as few weeks ago.

No schematics so very much in the dark.

Something in the power circuit is not working. Tried diagnosis but got nowhere, so put it back together again. Maybe a 4MHz(?) crystal not oscillating connected to the power control chip??? But I don't know if it should be quiescent and that's not the power control chip. No idea.

Maybe someone else can look into it at some later date.

I've got an old Toshiba laptop somewhere which might be similar...and IIRC has a broken power connector (probably needs resoldering).

If I can find it quickly I'll check the model number and let you know...

Over the weekend I won an auction for an Amiga 500, bought in preparation for next year's Retro Computer Festival. It was a bit expensive after the commission, coming in at ~£97 all in.

Anyway, today I drove over to Tetbury to pick it up. To my surprise the lot also included an external floppy drive, and not one with a Citizen unit with the dodgy belt drive. There was also the power supply (also not mentioned in the lot) plus manuals and a Logitech mouse, all in the original box.

Having got it home I opened the trap door to find a 512K RAM upgrade (and no clock). Sweet.

So, maybe it was worth the £97 after all.

The warrenty seal was partly broken, but not enough to allow access to the screw, so the machine hadn't been tampered with. I did open it up to check though... and *SO* many dust bunnies. I wonder if it had been stored next to a tumble dryer... Oh, and lots of cat hair too.

After the initial check I powered it up using my modern PSU and... unfortunately... it worked fine.

I managed to get an Amiga Test Kit floppy made using the A1200 and it passed all the tests, and so did the external floppy drive.


All the manuals were included, but no floppies...


It will need a bit of a clean and it's mildly sun tanned, so will need mild retrobrightening.


After trying games I determined that the internal floppy was a bit gummed up so I gave it a service. Again, *SO* much fluff and cat hair... and very dry grease, which is why the drive was having a few issues. It also gave me a chance to check out the date codes on the chips... mid-'89.

It's also got a red power LED, which is supposed to be rarer than the green one, apparently, as if it makes any difference.

Anyway, I've no got it on soak test running the Putty attract screen as that intermittently loads from floppy, giving that an exercise.

Today the belt for the Citizen external floppy drive for the Amiga arrived.

A bit of a faff fitting it but I managed it OK.

Running tests showed the drive working but it was giving rubbing and slightly squeaky sounds, so I decided to re-lubricate it... Trying to lubricate the spindle from the top was a bad idea... managed to get oil on the outside where the rubber belt runs and capillary action took it right around where the belt contacted the spindle... so off with the belt again and lots of IPA to try to clean the belt and the spindles... as it had contaminated the motor spindle by now too.

Even after a full clean the belt kept slipping on the motor spindle. Some 600 gauge sand paper roughing up the motor spindle sorted that.

Oiled the motor bearings whilst I was at it, and discovered that the spindle bearing was actually exposed on the underneath of the drive!!!

Anyway, all fitted back together again and it works. Not only that but after using Amiga Test Kit to keep the motor running for a bit and multiple read test cycles the drive is now really quiet. No more sounds as if it's scraping the surface off the disk, which I thought it was doing originally.

Those Citizen drives are a right pain to work upon and I couldn't see how I could take the mechanism off without first removing the upper head, which I'd never want to do as it would lose its alignment.

The next thing I think I'll try is adding another 512K of RAM onto the A500's motherboard. If it doesn't work then it can stay as 512K machine. If it does then it'll have 1MB of CHIP RAM.

Nice haul, I wouldn't mind an A500 as that's what I had BITD, not the 1200 I have now. I felt the 500 was a bit more special.