AES Palette RAM error fix?

[ucprod]

Hello

I posted this in another thread, but this is a more appropriate place for this question:

I have an J-AES system that is not working properly. I get a green screen (Palette RAM error) when I power it up with no cart.

I've searched the forum for a fix to this issue but there doesn't seem to be an easy solution. (I have never handled a soldering iron, let alone modded a system.)

Is there something painless that I am missing? Or is is the only real fix to replace the video ram chips?

Thanks!

 

[Xian Xi]

Check for broken traces. You can find palette ram pinouts all over this forum, use google advanced search for best results.

 

[ucprod]

Hi there, I did look for broken traces -- and I found your tutorial helpful for that -- but couldn't see any.

Would they be located around the video ram chip?

 

[Xian Xi]

Did you check the pinouts? What version AES do you have?

NEO-AES3-6   COLOR RAM

F1

1	VCC
2	HC259 (12)
3	NEO-B1 (12)
4	NEO-B1 (11)
5	NEO-B1 (9)
6	NEO-B1 (8)
7	NEO-B1 (3)
8	NEO-B1 (2)
9	NEO-B1 (159)
10	NEO-B1 (158)
11	LS273 (8) H1, NEO-G0 (35)
12	LS273 (13) H1, NEO-G0 (36)
13	LS273 (14) H1, NEO-G0 (37)
14	GND
15	LS273 (17) H1, NEO-G0 (38)
16	LS273 (3) H2, NEO-G0 (53)
17	LS273 (14) H2, NEO-G0 (54)
18	LS273 (7) H1, NEO-G0 (55)
19	LS273 (18) H1, NEO-G0 (56)
20	GND
21	NEO-B1 (31)
22	GND
23	NEO-B1 (32)
24	NEO-B1 (29)
25	NEO-B1 (28)
26	VCC
27	NEO-G0 (41)
28	VCC

G1

1	VCC
2	HC259 (12)
3	NEO-B1 (12)
4	NEO-B1 (11)
5	NEO-B1 (9)
6	NEO-B1 (8)
7	NEO-B1 (3)
8	NEO-B1 (2)
9	NEO-B1 (159)
10	NEO-B1 (158)
11	LS273 (4) H2, NEO-G0 (62)
12	LS273 (7) H2, NEO-G0 (63)
13	LS273 (8) H2, NEO-G0 (64)
14	GND
15	LS273 (13) H2, NEO-G0 (1)
16	LS273 (17) H2, NEO-G0 (21)
17	LS273 (18) H2, NEO-G0 (22)
18	LS273 (3) H1, NEO-G0 (23)
19	LS273 (4) H1, NEO-G0 (24)
20	GND
21	NEO-B1 (31)
22	GND
23	NEO-B1 (32)
24	NEO-B1 (29)
25	NEO-B1 (28)
26	VCC
27	NEO-G0 (41)
28	VCC

 

[ucprod]

My system is a NEO-O model with a serial number in the 12XXXX range.

I have visually looked at the traces and I can't locate any breaks. From reading the forum, I figured that the Sony CXK5864BSP-10L chips are the Video Ram. I visually inspected the connectors and couldn't see anything wrong.

Unfortunately, I have no experience with repairing electronics and I'm not sure how to read the chart you attached. Although, I'm willing to learn.

 

[Pedrobear]

You should post your board revision.

Dead ram is an easy fix granted you can find a replacement chip and someone who can service you the swap.

 

[ucprod]

Hi Pedrobear

I've just open it up and my board revision is NEO-AES-3-5.

 

[Pedrobear]

Did you locate palette ram? Two 24 pins chips on close to left board edge.

To read Xian Xi chart:

G1 <- chip location (letters and numbers across board edges to locate chips)

1 VCC <- pin 1 of the chip should go to vcc
2 HC259 (12) <- pin 2 of the chip should go to pin 12 of the HC259 chip
3 NEO-B1 (12) <- pin 3 of the chip should go to pin 12 of the NEO-B1 chip
etc etc, have fun

 

[ucprod]

Thanks for the tip! The chart makes sense now.

Since I can't see any broken traces, the next step would probably be to get a logic probe and test the traces that way?

 

[Pedrobear]

You can test continuity with about any multimeter

 

[ucprod]

Cool! Any multimeter brands you recommend?

 

[Pedrobear]

No idea, just go cheap if you ask me, considering your usage.

 

[ucprod]

Thanks, I'll look into getting one tomorrow.

 

[kosami]

since i still cant make threads, i will revive this one, hope you dont mind guys.

i am stuck here
basicaly, i want to start checking points, with my multimeter, but i will lose sanity, if i dont find the pinouts somewhere

mine is an aes 3-5, are the pinouts same as 3-6? i guess ?

i followed, neo B1 pin 77. pic attached. and i can not find continuity betwen the start and the end on the track

definitivly a problem here, can you confirm me that ?

this baby has a green screen, i will appreciate any input

 

[kosami]

Did you check the pinouts? What version AES do you have?

NEO-AES3-6   COLOR RAM

F1

1	VCC
2	HC259 (12)
3	NEO-B1 (12)
4	NEO-B1 (11)
5	NEO-B1 (9)
6	NEO-B1 (8)
7	NEO-B1 (3)
8	NEO-B1 (2)
9	NEO-B1 (159)
10	NEO-B1 (158)
11	LS273 (8) H1, NEO-G0 (35)
12	LS273 (13) H1, NEO-G0 (36)
13	LS273 (14) H1, NEO-G0 (37)
14	GND
15	LS273 (17) H1, NEO-G0 (38)
16	LS273 (3) H2, NEO-G0 (53)
17	LS273 (14) H2, NEO-G0 (54)
18	LS273 (7) H1, NEO-G0 (55)
19	LS273 (18) H1, NEO-G0 (56)
20	GND
21	NEO-B1 (31)
22	GND
23	NEO-B1 (32)
24	NEO-B1 (29)
25	NEO-B1 (28)
26	VCC
27	NEO-G0 (41)
28	VCC

G1

1	VCC
2	HC259 (12)
3	NEO-B1 (12)
4	NEO-B1 (11)
5	NEO-B1 (9)
6	NEO-B1 (8)
7	NEO-B1 (3)
8	NEO-B1 (2)
9	NEO-B1 (159)
10	NEO-B1 (158)
11	LS273 (4) H2, NEO-G0 (62)
12	LS273 (7) H2, NEO-G0 (63)
13	LS273 (8) H2, NEO-G0 (64)
14	GND
15	LS273 (13) H2, NEO-G0 (1)
16	LS273 (17) H2, NEO-G0 (21)
17	LS273 (18) H2, NEO-G0 (22)
18	LS273 (3) H1, NEO-G0 (23)
19	LS273 (4) H1, NEO-G0 (24)
20	GND
21	NEO-B1 (31)
22	GND
23	NEO-B1 (32)
24	NEO-B1 (29)
25	NEO-B1 (28)
26	VCC
27	NEO-G0 (41)
28	VCC

according to this, everything is fine, except for F1 and G1 pin 27, they are not connected also they dont connect to neo-G0 (41)
but again, i own a 5-6

everything else in this list, its wired and OK.

 

[Xian Xi]

Neo-G0(41) is probably the most important one. If there is no continuity then connect them.

 

[kosami]

Thanks a lot Xian Xi, seems like you do own this forum

just to recap, aes 3-5. green screen.

if you can point me where to find pinouts for neo-B1, i need to know where supposed to go from 70 to 80 (damaged zone in pics)

and thank you for the pinouts for F1/G1 dude, it saved me lot of time

tomorrow ill check NEO-G0(41) i will follow the traces, just to confirm, before the mad soldering hell falls over me...

 

[Xian Xi]

You can get the pinouts from the NG Dev wiki page. Just search on Google.

 

[kosami]

i double - triple check the list you give
turns out i made a mistake , everything is ok in that list, even neo-G0

i only need to focus on neo-B1, found the pinout, BUT thats it. i dont know still where they should go
you give not only pinouts, but directions, wich is what im looking for.. cant find that on the dev wiki
but nevermind, i already did follow the tracks

obviously i need insane soldering skills, wich i lack.
i will search somebody with the skill, or do train first with some broken ic's.. not ready for this yet.
thanks alot for your input, i will post more when i move ahead.

 

[Xian Xi]

i double - triple check the list you give
turns out i made a mistake , everything is ok in that list, even neo-G0

i only need to focus on neo-B1, found the pinout, BUT thats it. i dont know still where they should go
you give not only pinouts, but directions, wich is what im looking for.. cant find that on the dev wiki
but nevermind, i already did follow the tracks

obviously i need insane soldering skills, wich i lack.
i will search somebody with the skill, or do train first with some broken ic's.. not ready for this yet.
thanks alot for your input, i will post more when i move ahead.

Make a diagnostic bios so you can run tests on your AES so you can get an error message.

 

[kosami]

that involves de-soldering the original bios, dosent?

considering the unit was never open before
i will try first to repair the two broken traces already spotted

i think its just some dust that went into the machine via cartridge slot, and ended up resting on top of the legs of neo-B1
with the time, this little dust corrupted the end of the leg, wich has no continuity with the track
thats all about it, or i hope so

if that goes nowhere, then i will reconsider the bios thing...

 

[aha2940]

that involves de-soldering the original bios, dosent?

It does involve desoldering the original BIOS, putting a socket in place of it and installing an EPROM with the diagnostics BIOS written in it. I would recommend doing it, even if you fix your AES, it will help you install a UniBIOS which IMO is a must for any neo-geo owner.

Regards.

 

[kosami]

thanks for your input, i think i have an idea
i played before with arduino and my z80, even have the correct zif socket & my willems programmer
my fear is to damage the board fuhrer with my soldering skills.
they are ussualy ok. they do the work. but NEO-B1 is damn small, more than i am used to.

 

[kosami]

i replaced the broken traces with wires, now i have blue screen

sometimes i keep having the green screen

the point is, most of the time, it will stay blue, sometimes i can heard the sound flicking (i guess its watchdog pushing the reset button)
and my game wont work

i guess i will have to do the bios surgery

 

[kosami]

PD: also pins 79 & 80 from neo-B1 are connected, i dont think they should, 79 is FLIP: Horizontal flip pixel line, and 80 is VCC
but unless i cut the leg, i dont know where they melt

perhaps it should be like that? i cant even search theyr traces, too tired today