128k/512k repair questions

[Brooklyn]

Hello, I have a couple repair questions for 128k/512k machines.

1) I have 2 of these machines that show no video unless the analog board is flexed, then BAM is pops on and looks great. I assume this a solder joint issue? Any joints likely to fail so I don't have to go through them all?

2) Where is a good place to buy replacement batteries? eBay has them, but they are $12+ a piece with shipping.

 

[mcdermd]

The solder joints to the logic board harness are suspect as well as the larger harness to the yoke. Sucking the old solder and freshing them up isnt going to hurt.

$12 isn't that bad considering that I seem to remember paying $14 at Radio Shack about five or six years ago.

 

[trag]

The last time I checked, Frys had the 1/2AA batteries for $5.99. But if there is not one near you, the shipping will probably bring your price up to the RS level. There are also various Ebay sellers with pretty good prices on them.

 

[mcdermd]

It's not a 3.6v 1/2 AA battery, it's a 4.5v Everready number 523 battery. According to the pickle's FAQ -

Equivalents are ANSI 1306AP, IEC 3LR50, NEDA 1306AP, Panasonic PX21, and Varta V21PX

 

[trag]

Oops. Sorry. I wasn't paying close attention.

However, Frys did also have a battery which works in the Plus for $5.99, which is not 4.5V, but is the right size, and apparently it is enough voltage to maintain the PRAM and RTC.

Unfortunately, I don't have the part number handy, although I did post it in a different thread some years back.

 

[Brooklyn]

Good news! Reflowing/resoldering fixed both machines.

Now I have floppy woes. I have a 128k and a 512k that have broken floppy drives. When you try to put a disk in, the disk doesn't articulate down no matter how hard you press. So I took apart the 512k's drive and was able to force the disk to engage by pulling the manual release mechanism in the opposite direction. I powered it up and it seemed to be spinning the disk, but soon I had a burning smell . So I think I ruined one drive.

 

[trag]

Ohhhh, don't force those drives. With time, the lubricant Apple used on them turns to glue or varnish. Forcing the mechanism is likely to bend parts.

Carefully clean the mechanism with swabs and alcohol. Don't spray it with WD-40.

Then relubricate the moving surfaces with a good silicon grease.

 

[Brooklyn]

I'll give this a shot with the 128k drive...

 

[trag]

Back in the mid 90s I had two 400K mechanisms still new in the beautifully folded anti-static bags from Apple.

Both drives were locked up tight. The mechanisms would not move when one attempted to insert a disk. The "lubricant" applied at the factory really hardens up after the VOCs evaporate.

All that was required was to clean the sliding metal parts, easily accessible on the sides of the drive. No disassembly required. And then relubricate.

Of course, your drives may have a different problem, but the method that worked for me is non-destructive, low risk and a good place to start.

 

[jonathan]

I have a 661-0345 Disk Drive 800K -Red Serial # (MFD-51W-03) from a plus that may be in working condition. If you want it, I'll test it and see if it works ...

 

[Brooklyn]

I am not sure if the 512k rom's can handle an 800k drive, do you know?

 

[Mac128]

Depends on the drive. A late model 800K drive can format disks as MFS 400K or 800K and read and write with no problems. The OS will format 800K under 512K, but won't work under a 128K as it does not have enough memory. The HD20 INIT can also be used to substitute for the 128K ROMs ... Only you cannot boot from an 800K disk ... The early 800K drives can only be accessed using the HD20 INIT.

 

[Brooklyn]

Update, I disassembled and cleaned the slides and mechanisms on the 128k drive and now it works perfectly!

Going to try it on the 512k drive soon and hope it is not permanently damaged. :-/