Neo Geo AES Work Ram Error

[ebichu]

Thanks for the replys again
Is there any shematic for checking the continuity between BIOS and CPU?
Like the one posted by MKL for the Work Ram? This would make it much more easier Should I check the continuity while the machine is turned on or what?

Make sure you didn't short across the data or address pins.

What does that mean exactly? I'm not that good in electronics. I solder every day @work and got alot of experience with that but I'm not the one who knows exactly about electronic stuff

 

[MKL]

Is there any shematic for checking the continuity between BIOS and CPU?

SP1

1----VCC
2----GND
3----68000-12 (54), LSPC2 (21), NEO G0 (50), 43256 (19) D2
4----68000-12 (55), LSPC2 (20), NEO G0 (49), 43256 (18) D2
5----68000-12 (56), LSPC2 (19), NEO G0 (48), 43256 (17) D2
6----68000-12 (57), LSPC2 (18), NEO G0 (47), 43256 (16) D2
7----68000-12 (58), LSPC2 (16), NEO G0 (34), 43256 (15) D2
8----68000-12 (59), LSPC2 (15), NEO G0 (33), 43256 (13) D2
9----68000-12 (60), LSPC2 (14), NEO G0 (32), 43256 (12) D2
10---68000-12 (61), LSPC2 (13), NEO G0 (31), 43256 (11) D2
11---GND
12---68000-12 (62), LSPC2 (10), NEO G0 (18), 43256 (19) C2
13---68000-12 (63), LSPC2 (9), NEO G0 (17), 43256 (18) C2
14---68000-12 (64), LSPC2 (8), NEO D0 (3), 43256 (17) C2
15---68000-12 (1), LSPC2 (7), NEO D0 (2), 43256 (16) C2
16---68000-12 (2), LSPC2 (5), NEO D0 (1), 43256 (15) C2
17---68000-12 (3), LSPC2 (4), NEO D0 (64), 43256 (13) C2
18---68000-12 (4), LSPC2 (3), NEO D0 (63), 43256 (12) C2
19---68000-12 (5), LSPC2 (2), NEO D0 (62), 43256 (11) C2
20---NEO E0 (59)
21---68000-12 (29), NEO E0 (64), 43256 (10) C2 D2, HC259 (1)
22---68000-12 (30), NEO E0 (1), 43256 (9) C2 D2, HC259 (2)
23---68000-12 (31), NEO E0 (2), 43256 (8) C2 D2, HC259 (3)
24---68000-12 (32), NEO E0 (3), 43256 (7) C2 D2, HC259 (13)
25---68000-12 (33), NEO E0 (4), 43256 (6) C2 D2
26---68000-12 (34), NEO E0 (15), 43256 (5) C2 D2
27---68000-12 (35), NEO E0 (16), 43256 (4) C2 D2
28---68000-12 (36), NEO E0 (17), 43256 (3) C2 D2
29---68000-12 (37), NEO E0 (18), 43256 (25) C2 D2
30---GND
31---68000-12 (38), NEO E0 (19), 43256 (24) C2 D2
32---68000-12 (39), NEO E0 (20), 43256 (21) C2 D2
33---68000-12 (40), NEO E0 (21), 43256 (23) C2 D2
34---68000-12 (41), NEO E0 (31), 43256 (2) C2 D2
35---68000-12 (42), NEO E0 (32), 43256 (26) C2 D2
36---68000-12 (43), NEO E0 (33), 43256 (1) C2 D2
37---68000-12 (44), NEO E0 (34)
38---VCC
39---VCC
40---VCC

 

[ebichu]

Again, thanks a lot, MKL!
Will check the traces at home and report again.
Where did you get those shematics from? Seems they can be very useful for the future

 

[ebichu]

Ok.. checked every trace and they seem all fine. Beeping all the time
Did I miss something? This must be repairable...

 

[Xian Xi]

Did you replace the work ram or just touch up on the soldering?

 

[channelmaniac]

What jumper wires did you install?

If you install a jumper incorrectly then you'll cross a data, address, or control line with another one and the system will be stuck in watchdog reset after that.

 

[ebichu]

@Xian Xi: Not yet because 1st of the corrosion that was on the pcb which obvisouly caused the problems (solid red screen) and 2nd I wanted to be sure, that the rest is fine before ordering new work ram chips.
@channelmaniac: I used lacquer wire / in german it's called 'Lackdraht' - don't know the english description for it. I made another photo for you guys:


Because of the damage which I already posted at the start post...



...I checked all traces regarding to MKL's shematic that he postet and already fixed the broken traces like you see here:




Thanks to the two wires the connectivity between the needed lines is back - but the result is the flickering red screen with 'click click click...' like I posted on the video before. Did I made a mistake on the 2nd picture?

 

[Xian Xi]

Hold up the board to the sun and check if you can see any broken traces anywhere on the board. The PCB in the AES passes light very good.

http://jamma-nation-x.com/jammax/tutorials.html?show=aestrace

 

[ebichu]

With "anywhere" you mean anywhere?
Because that's a fucking lot
So you will tell me that I can't do anything more because the traces are all good and the work ram isn't defective?
I can search for broken traces at work under my microscope with light from the underside. Will do this then but also want to make sure that there isn't any other solution?

Edit: Sun.. funny because here in germany the sun went away weeks ago (damn cold winter this year with -20 degrees at night actually..)

 

[Xian Xi]

On the link I posted is one of the places where I had a broken trace which was causing the clicking.

 

[ebichu]

All good there... would be a big coincidence if the same trace at the same spot were broken, too..

 

[Xian Xi]

That wasn't the point but ok.

 

[ebichu]

There is no guarantee that the work ram is defective or not, hm?
I mean, some sort of fact that you can say "okay, at this point it only could be XXX which is causing the malfunction.." ?

The thing is, it's not my ng, I just promised that I'll have a look and it would be a great thing if this baby will run again

 

[Xian Xi]

It could be the work ram, I get clicking when the work ram is dying sometimes. Point was though to just double check your work. Looking at traces makes you crazy sometimes when you see too many of them. You can easily overlook something.

So you said you have 100% continuity from Work ram >CPU? And 100% from CPU >Bios?

 

[ebichu]

It could be the work ram, I get clicking when the work ram is dying sometimes. Point was though to just double check your work. Looking at traces makes you crazy sometimes when you see too many of them. You can easily overlook something.

I hear you and I will check the traces at work with bright light.

So you said you have 100% continuity from Work ram >CPU? And 100% from CPU >Bios?

101%

 

[Hewitson]

ebichu, firstly, that is the crappiest wire I've ever seen in my life. I couldn't source wire that thin if I tried. Of course, it will still work.

What you need to do is use your multimeter on its continuity setting and check that you have not accidentally connected any of the data or address lines together when soldering your wiring.

XX: Wow, the amount of light that passes through that PCB is very impressive. Wonder if its because they used cheaper materials?

 

[channelmaniac]

#1, you're right... that really is the wrong wire for patching boards. I use 30ga Kynar wire. The wire he used is called "magnet wire" in the USA and is used for winding motors or transformers. It only works if he scrapes the insulation off the wire before soldering.

#2: It's because it's a 2 layer PC board and doesn't have the internal ground or power traces. There are versions that have the internal ground plane which makes it impossible to see the light through.

RJ

 

[ebichu]

Guys.. are you kidding me?
It's EXACTLY that kind of wire, what channelmaniac describes.
Examples:
http://www.cnc-modellsport.de/images/lackdraht-10m-0.5.jpg
http://www.elosal.de/images/spulen_460.jpg
http://www.elektronikbasteln.de/Bastelidee/lackdraht.jpg

You have to scrape off the insulation, you don't get any contact if you don't.
It's almost that thin like traces that you peel out of the pcb. So what's wrong with it? I don't get it.. really.

What you need to do is use your multimeter on its continuity setting and check that you have not accidentally connected any of the data or address lines together when soldering your wiring.

What does this mean exactly? I just bridged the contact that weren't there. Where could I have accidentally connected those data/adress lines in my soldering?




PS. Just for the record: would it be helpful if I install a Unibios? Will this give me any better information? It's not my favourite solution because it's not my machine, I first have to ask if it's okay to install it. That's not THE solution for me, main goal is to fix this without Unibios

 

[Hewitson]

Not sure how you think a unibios would help if your machine wont even boot..

Say you have d0 and d1 next to eachother on a chip. You can easily bridge them together when soldering a wire to one of them.

 

[ebichu]

Because the UniBios gives out an error screen sometimes. I had almost the same problem back in the days and told Razoola the errors which the Bios gave me out. This could help sometimes but I'm not sure if the system will boot - like you already wrote.

There are no bridges, I can guarantee that. I may be not the best in reading electronic stuff but I seriously know how to solder Hope someone has some more tipps

 

[Hewitson]

You can't guarantee theres no bridges unless you've checked with a multimeter. They can't always be seen with the naked eye.

Quite frankly, you should have checked that before even posting here. Its the very first thing I would have done.

 

[ebichu]

And you should check my postings first :P
As I wrote already: I own a multimeter and already checked every single trace posted by MKL. There are no bridges, also checked under a microscope here at work (I solder smd party every day).

 

[Hewitson]

You said you can guarantee there are no bridges, you didn't say you had actually verified that.

If all continuity is fine between BIOS, RAM, and CPU, system will boot unless one is fucked. This is where a logic probe comes in.

Viel erfolg

 

[ebichu]

What is a logic probe doing if I may ask? Never heard of it.

 

[channelmaniac]

What is a logic probe doing if I may ask? Never heard of it.

http://www.lmgtfy.com/?q=how+to+use+a+logic+probe