Need some advice about a couple A500's

[techie]

Hi everyone,
I've got some questions that I'm  hoping someone here can answer for me :-)

You see, recently I picked up a couple Amiga 500's off eBay; The first one was damaged during transport along with an A570 CD-Rom I had also purchased (Thank You Canada Post >) the second seems to work okay but it is missing the right Alt key. Now I'm still kind of hoping that the first Amiga (and CDRom) can be salvaged as most of the damage appears to be cosmetic but if not then I was hoping for some advice on which components I might want to steal to create one really good Amiga 500.

Now so far I've only been testing the units for about half an hour but here is what I've come up with:

First Amiga (damaged in transport):
- Does not boot with Ram Expansion installed (only tested one expansion so far haven't tried the other)
- Does boot to Kickstart 1.3 screen when Expansion removed
- Does not boot games (thinking disk drive is either dirty or damaged)
- Does not load Workbench (brings up error message saying disk is corrupt)
- Only Shows Kickstart screen when A570 CD attached and Game inserted. (Power light comes on and stays on access light comes on then turns off)

Specs:
- Ram: Unknown (assuming 512kb without expansion)
- Motherboard Revision: 6A (says 512kb/1mb near Agnus)


Second Amiga:
- Does boot with Ram Expansion (tested with other module)
- Does boot games
- Does boot Workbench (shows 896552 of memory available)
- Only Shows Kickstart 1.3 screen when A570 CD attached and Game inserted.(Power light comes on and stays on access light comes on then turns off)

Specs:
- Ram: about 1MB (with expansion)
- Motherboard Revision 5 (says 512kb near Agnus)



Now here are my questions:
1) Would I be able to use a PC Floppy Disk cleaner to clean the First Amiga's drive? Or would it have to be an Amiga Cleaning disk? (I know Amiga's can read 720kb PC disks so I was hoping that a Cleaning disk might work).

2) When the A570 drive is working and a game disc is inserted does it boot directly into a game or does it boot to a CDTV Rom Screen?  (Sorry never had a A570 before so I really know nothing about it) If it's supposed to boot the game directly what might be stopping mine?

3) If I do end up gutting one of these machines would it be best to use the revision 6 motherboard (despite coming out of the damaged Amiga) and if so would it be possible to steal memory from the revision 5 board to use on the revision 6 board? (I've heard that a revision 6 motherboard can have up to 1mb of chip ram on board by adding additional chips but I'm not sure if a revision 5 board would have the right kind of memory)

Any Advice would be greatly appreciated :-)

[TjLaZer]

Yes a 3.5" disk drive cleaning kit is universal, it makes no difference on the computers disk file system, nor the density of the drive!

Not sure if you know, the A570 volume knob needs to be turned "on" for it to work.  IE like you are turning up the volume on it.  You should see a CDTV boot screen with a spinning CD.  The games should autoboot if they are a CDTV game.

The first Amiga might already have 1MB of RAM on the motherboard so it will crash if you install the 512K RAM card.  Check the RAM on it.  I have a Rev 6A board with 1MB RAM soldered on board so the expansion slot cannot be used in this case.  The drive sounds dirty or bad.  Try cleaning the heads, if that does not work get another drive or swap the other one in it.

[techie]

@TjLaZer
Actually no I didn't know that  :-o thanks for telling me  :-)

Well that sorta helped, I stuck in Lemmings for CDTV and the game does start to boot but then it gets to the game opening and all the graphics and sounds are corrupted  :-? Could be have something to do with disc though as it looks to be pretty scratched up.

Thanks for the cleaning disk tip too I'll have to try that out  :-)

[Argus]

TJ is right, try cleaning the disk drive internals with Qtips and isopropyl alcohol (rubbing alcohol).  The heads are probably dirty and give that characteristic grinding sound when so impaired.  There are stronger head cleaning solvents about but isopropyl usually does the trick.  I don't recommend a disk drive cleaning kit, as the pads on these can be too abrasive and the Amiga drive doesn't spin unless you prompt it to do so like on other computers.

Regarding the damaged A500, I've yet to see an A500 that was killed in transport.  These are rugged little buggers, and cosmetic damage does not end their lives.  More than likely something inside comes loose during transport.  Smartly Commodore (unlike the Atari ST), put most of the big chips inside the A500 in sockets so a quick push can reseat them or you can extract a bad chip and replace without soldering.  Try that on an ST!  Just take standard antistatic precautions (e.g. touch some grounded metal before you touch a chip).

[Tenacious]

You could swap the keyboards to get a complete unit.  My A570 is sensitive where it connects to the A500.  Try cleaning the contacts with isopropyl and a toothbrush.

The sysytem has to be powered 'on' in sequence, first the A570, then the A500.

If you have ambitions to expand, the A570 doesn't like accelerators (timing issues, I think).  I run with OS 2.1, fast ram (a Supra 500RX), and SCSI-TV.

If you can make bootable CDs elsewhere, it's not bad without a hard drive.

[TjLaZer]

Yes badly scratched discs will lead to read errors.  Try to copy the disc onto another CDR, the A570 should be able to read them just fine.  You could also get a disc repair device, they buff and remove scratches on discs, they work great!

[motrucker]

If the unit took a sharp hit, it could easily have knocked the floppy disk drive out of alignment. This can be had to fix, unless you have a 'scope or alignment disk (I believe Free Spirit Software used to make one. Be aware that you need an original - this type of disk can not be coppied, period).
Believe it or not, you are better off with the 1.3 ROMs using an A570. 2.x have issues with many CDTV games!)
          Good luck.

[techie]

@all
Thanks for the advice everyone :-) I will try to repair the CDTV game and see if that solves my A570 problem.

One thing I am still curious about though that no one here has mentioned yet, is it possible to expand the Chip memory on the R6A Motherboard to 1MB by taking memory from the Revision 5 Motherboard? I thought I read somewhere that this is possible but just thought I'd double check.

If it is possible would the memory expansion in the trapdoor then be seen as fast ram? Or would it not be read anymore.
Thanks again for answering my questions   :-)

[Argus]

The easiest way to get 1MB chipram on a Rev. 6 is to put a 1/2 meg expansion card in the trapdoor slot of the A500 and then modify a couple jumpers to access the extra 512K as chipram rather than the default slow/fast ram.  You'll need to have an 8372A 'Fat Agnus' chip though as well.  Most(all?) Rev. 6 m/b's should have shipped with an 8372A Agnus, though they're cheap to come by on ebay nowadays.

A similar mod can be done on a Rev. 5, though this revision is missing the jumper near the trapdoor slot, so it involves cutting a trace.  Rev. 5's afaik almost all shipped with the 'Thin Agnus' 8370 chip (NTSC), so unless the previous owner updated to 8372A, you'll definitely need the chip for the Rev. 5 board.  Open it up and take a look.

There's even a way to supposedly modify a Rev 3. A500, which is a very rare and buggy m/b version.  I used to have one but could never get it to work with 1MB chipram.

Instructions for these simple modifications are on the net.