Any "doctor" help me identify issues?

[NLS]

Call for help. Please read this:
These are hi-res photos of my Commodore systems.
5 first photos are of my Commodore 64.
27 following photos are of my A500.
The rest are of my A4000.

So. What I am looking for:
I visited my parents' home and I "quick n' dirty" opened all three computer cases. It was not possible to switch them on at the time, nor will I risk this before verifying I "should" be ok to do it.

Questions (and more info):

- My C64 (yeah I know I am in EAB), I think looks ok, verify from the pics? Someone told me I should check PSU if it works properly first and then I can try to switch it on.

- My heavily (hand-)modified (last) A500, also I THINK seems ok. Can you verify with what you see? Should I do any capacitor work? (I don't even know who can help me with that in Greece)

- This actually is not my first A500, my first was a first-gen KS1.2 one. But since Amiga was my main computer until late nineties, I also followed what update I could. So I got this Fat Agnus A500 and (now rediscovered) had made it with twin Kickstart (I believe 2.04 and 1.3) AND switchable (the huge metal switch at the back) 512Kb Chip, 512Kb Chip + 512Kb Fast, 1Mb Fast!

- The A4000 is more complex issue. I borrowed this to a friend, who managed to lose some parts (for example lost my original 040 daughterboard), but this is what I have now...

- I have EMPLANT on it, bought directly from Jim Drew (we briefly cooperated to sell in in Greece, he may remember).

- I now see I have Ariadne network card too. (left from my friend) I believe this is 10Mbit?

- Seems I now have a Cyberstorm MK1, which from the crystal believe it is an 040@40 (instead of 060 that my friend thought). I think this is "more compatible" anyway, so happy about it.

- Seems he has populated all RAM slots on board, but no RAM slot on MK1. Should I move them all on MK1? No? Should I leave something (a pair?) on board? Help me with this.

- You can see there was battery leakage, but I think minor. Verify? I heard good battery acid cleaning is done by either white vinegar or lemon (!?).

- I removed the battery, but broke one of the attaching metal plates. I believe this is minor damage?

- Someone also identified minor cap leakage, can you guys verify from what you see?

Any other help and advice welcome. I have also made a post in WinUAE section for the A4000 hard disk. Help me get my bearings.

THANKS IN ADVANCE anybody that helps and the rest that endure my post.

https://www.facebook.com/media/set/?...1&l=98166a0b2b

[nolunchman]

Originally Posted by NLS

- You can see there was battery leakage, but I think minor. Verify? I heard good battery acid cleaning is done by either white vinegar or lemon (!?).

- I removed the battery, but broke one of the attaching metal plates. I believe this is minor damage?

- Someone also identified minor cap leakage, can you guys verify from what you see?

the plates are part of the battery, so that is no big deal. actually its better to break it off at the plate than to risk ripping up a pad.

it will need a cap replacement whether or not the caps look good. commodore used cheap parts (but not to blame them really, what engineer thought people would using an amiga 4000 2 decades later?)

the battery damage is common and doesn't look bad, but power it up and pray it boots.

if it does, immediately pull all the socketed chips and neutralize the area with vinegar or lemon. i used vinegar (because i had some) but some people prefer lemon.

if it doesn't, it may only need some jumper wires, but if the corrosion went deeper it's not good. the ECS models have just top and bottom layers so you can bridge the vias with some wire. the 4000 is 4 layer board. obviously it will be hard to find, let alone fix any traces below the surface.

if it is dead, you at least have a challenging (and fun) project salvaging the chips and putting them on a new open source motherboard. from the looks of the A500, you are that type.

good luck and keep us updated!

[Vypr]

Originally Posted by NLS

- My C64 (yeah I know I am in EAB), I think looks ok, verify from the pics? Someone told me I should check PSU if it works properly first and then I can try to switch it on.

It's difficult to tell on a C64 if it's good or not from the photos, however I would recommend getting the caps replaced as a matter of course.

You should check the Power Supply when it's under load, C64 power supplies are famous for blowing the memory chips when the power goes out of spec, especially if it's one of the black brick power supplies. If it is a black brick PSU, don't even bother testing, it is highly likely to be gubbed as these had a very high failure rate. You can't even fix them as C64 PSU's tend to be filled with resin.

The C64 uses two separate lines, 9VAC and 5VDC and you want to check the 5V DC line as if this is out of spec it will cause damage, a general guide is:


4.95 - 5.1V Power supply functions normally
5.1 - 5.2V Minor concern, measure the power supply more often
5.2 - 5.5V The power supply is failing. You Commodore 64 will not die right away, but it is an unhealthy situation. Replacement or repair of the power supply is recommended.
5.5 - 6V Your Commodore 64 is in danger.
>6V In most situations where a Commodore 64 got killed by its power supply, the voltage had risen above 6V. Usually the RAM memory gets damaged first.

(taken from https://www.c64-wiki.com/wiki/Power_Supply)

If the PSU is out of spec you can get one of these to replace it:

https://www.amazon.co.uk/Commodore-r...ywords=c64+psu

You can get a capacitor replacement pack and other spares from here:

http://retroleum.co.uk/

The c64 uses through hole caps so they are much easier to replace than the Amiga's SMD components

[NLS]

Thanks people!

Not sure how to test the PSU "under load"... doesn't this mean turning on the C64 and risking it? And how do I check the voltages if it is plugged?
Yeah, not very comfortable (any more) with such things.
It is not the black brick (it is the big one same color with C64), but I might just buy a new one anyway, right?

Why do I need to remove chips (I don't have an IC extractor readily available) from A4000 to perform the cleaning? After all not all chips can be removed.

[NLS]

As for the software part (for my A4000), here is the progress:
http://eab.abime.net/showthread.php?t=91798
...better than expected.

[nolunchman]

Originally Posted by NLS

Thanks people!
Why do I need to remove chips (I don't have an IC extractor readily available) from A4000 to perform the cleaning? After all not all chips can be removed.

remove just the socketed ones. you will be pouring liquid all over the motherboard and the socketed chips will have gaps where the liquid can collect, mix with salts and gunk and either bridge an unwanted connection (ie short) or insulate a connection when power is applied.

IC extractors suck, IMHO. they are really hard to use if a chip has been siezed by corrosion. you can remove the ROMs *carefully* with a flat head screwdriver by twisting the flat head to lever the ROM up evenly from both sides. don't pry it up like a prybar.

you will need a PLCC extractor for the ECS chips though. they're only about $5.

if you're not comfortable with doing that stuff, you should send it out.

[BMD]

Originally Posted by Vypr

You can't even fix them as C64 PSU's tend to be filled with resin.

Not true, Resin has no conductive properties and is in ALL electronics even today in the solder and can be cleaned. Thats not to say the PSU is totally fooked, but resin has no issues with electronics, its used to make them...

There is even a chemical you can buy, forgot the name, that will dissolve the resin down to the board and components without harming them.

[Rotareneg]

C64 power supplies generally were completely filled with potting compound, rendering them a solid block of plastic.

[project23]

Originally Posted by BMD

Not true, Resin has no conductive properties and is in ALL electronics even today in the solder and can be cleaned. Thats not to say the PSU is totally fooked, but resin has no issues with electronics, its used to make them...

There is even a chemical you can buy, forgot the name, that will dissolve the resin down to the board and components without harming them.

I think you're confusing resin with rosin.

As Rotareneg said I've heard myself before that C64 PSU's are like solid plastic bricks. Probably a cheap way of (at the time at least) satisfying the double enclosure safety standard or something.

John

[Vypr]

Originally Posted by NLS

Thanks people!

Not sure how to test the PSU "under load"... doesn't this mean turning on the C64 and risking it? And how do I check the voltages if it is plugged?
Yeah, not very comfortable (any more) with such things.
It is not the black brick (it is the big one same color with C64), but I might just buy a new one anyway, right?

It wouldn't hurt to buy a new one but to test, you will need to plug the PSU in and power on the C65.
Get a multimeter and check the voltage between Pin 8 on any of the RAM chips and Gnd.

From the picture you supplied your board is Assy number 250425 so there should be 8 RAM chips on the board marked U9-U12 and U21-24 (With the modulator at the rear, they should be in the lower left of the board)

See http://personalpages.tds.net/~rcarls...MATICS/250425/ for schematics and the board layout.

[Vypr]

Originally Posted by project23

I think you're confusing resin with rosin.

As Rotareneg said I've heard myself before that C64 PSU's are like solid plastic bricks. Probably a cheap way of (at the time at least) satisfying the double enclosure safety standard or something.

John

Yes, a lot of C64 PSU's are a solid block of resin, see this page for an example.


https://wej.k.vu/broken_stuff/c64_power_supply_repair/

It's much easier just to buy a modern PSU than attempt a repair

[NLS]

Thanks for the info.

[project23]

Originally Posted by Vypr

Yes, a lot of C64 PSU's are a solid block of resin, see this page for an example.


https://wej.k.vu/broken_stuff/c64_power_supply_repair/

It's much easier just to buy a modern PSU than attempt a repair

God, thats amazing, hahaha

I'd love to 'dissolve' that resin to find out what they have hiding underneath

John

[BMD]

Regardless of the reply's to my post, i will find the chemical to remove the resin (sorry i got my resin and rosin mixed up rofl) and post it here. It totally dissolves the rosin to the board and you can repair it.
I have done it on several jet ski ignition modules and scooter spark control modules. It is a life saver considering the fluid is $15 and those modules are round $100+ when all you need to do is replace caps or a fuse...

EDIT: This stuff here is it, just leave it soaking in it and it just turns to liquid.

https://www.gesswein.com/p-5097-atta...hoCIkMQAvD_BwE

[NLS]

thanks

[JimDrew]

@NLS - yes, I do remember a dealer in Greece!

[NLS]

Well, it was me and my friend (later best man) Lucas.

Nice to see you again (although it is not the first time we talk in EAB... you just probably didn't know who we are).

[JimDrew]

Yes, this true!