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Author Topic: SNK Games (Neo Geo MVS/AES)  (Read 124532 times)

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Offline channelmaniac

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Re: SNK Games (Neo Geo MVS/AES)
« Reply #20 on: May 23, 2014, 08:47:57 PM »
Here's the NEO-257 @ location J2 on the 2 slot board. (MV-2)

Code: [Select]
Pin - function/chip connection/slot connection (cartridge pin function)
1 - Slot 2 B26 (CA15)
2 - Gnd
3 - Gnd
4 - Slot 1 A19 (CA0)
5 - Slot 2 A19 (CA0)
6 - Slot 1 B19 (CA1)
7 - Slot 2 B19 (CA1)
8 - ZMC2 - 15 C0 (CA0)
9 - ZMC2 - 19 C4 (CA1)
10 - Gnd
11 - ZMC2 - 16 C1 (CA2)
12 - ZMC2 - 20 C5 (CA3)
13 - Slot 1 A20 (CA2)
14 - Slot 2 A20 (CA2)
15 - Slot 1 B20 (CA3)
16 - Slot 2 B20 (CA3)
17 - Input (Slot) Select 1/2
18 - Gnd
19 - Slot 1 A21 (CA4)
20 - Slot 2 A21 (CA4)
21 - Slot 1 B21 (CA5)
22 - Slot 2 B21 (CA5)
23 - ZMC2 - 17 C2 (CA4)
24 - ZMC2 - 21 C6 (CA5)
25 - Gnd
26 - Vcc
27 - ZMC2 - 18 C3 (CA6)
28 - ZMC2 - 22 C7 (CA7)
29 - Slot 1 A22 (CA6)
30 - Slot 2 A22 (CA6)
31 - Slot 2 B22 (CA7)
32 - Slot 2 B22 (CA7)
33 - Gnd
34 - Gnd
35 - Vcc
36 - Slot 1 A23 (CA8)
37 - Slot 2 A23 (CA8)
38 - Slot 1 B23 (CA9)
39 - Slot 2 B23 (CA9)
40 - ZMC2 - 24 C8 (CA8)
41 - ZMC2 - 28 C12 (CA9)
42 - Gnd
43 - ZMC2 - 25 C9 (CA10)
44 - ZMC2 - 29 C13 (CA11)
45 - Slot 1 A24 (CA10)
46 - Slot 2 A24 (CA10)
47 - Slot 1 B24 (CA11)
48 - Slot 2 B24 (CA11)
49 - NC
50 - NC
51 - Slot 1 A25 (CA12)
52 - Slot 2 A25 (CA12)
53 - Slot 1 B25 (CA13)
54 - Slot 2 B25 (CA13)
55 - ZMC2 - 26 C10 (CA12)
56 - ZMC2 - 30 C14 (CA13)
57 - Gnd
58 - Vcc
59 - ZMC2 - 27 C11 (CA14)
60 - ZMC2 - 31 C15 (CA15)
61 - NC
62 - Slot 1 A26 (CA14)
63 - Slot 2 A26 (CA14)
64 - Slot 1 B26 (CA15)
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #21 on: May 23, 2014, 08:48:33 PM »
If you look at a 74257 data sheet you will see that it is a 2 to 1 data multiplexer. The NEO-257 is simply 4 of these chips combined into one package to save some board space.

The hard part is that I cannot tell which pins are for "output enable" like on the 74257 since the only function that isn't set to ground or +5v is the one for input select. It appears these chips are set to always be enabled.

Enjoy!

Code: [Select]
NEO-257 pinouts

1 - Input 16B
2 - Gnd
3 - Gnd
4 - Input 1A
5 - Input 1B
6 - Input 2A
7 - Input 2B
8 - Output 1
9 - Output 2
10 - Gnd
11 - Output 3
12 - Output 4
13 - Input 3A
14 - Input 3B
15 - Input 4A
16 - Input 4B
17 - Input Select A/B
18 - Gnd
19 - Input 5A
20 - Input 5B
21 - Input 6A
22 - Input 6B
23 - Output 5
24 - Output 6
25 - Gnd
26 - Vcc
27 - Output 7
28 - Output 8
29 - Input 7A
30 - Input 7B
31 - Input 8A
32 - Input 8B
33 - Gnd
34 - Gnd
35 - Vcc
36 - Input 9A
37 - Input 9B
38 - Input 10A
39 - Input 10B
40 - Output 9
41 - Output 10
42 - Gnd
43 - Output 11
44 - Output 12
45 - Input 11A
46 - Input 11B
47 - Input 12A
48 - Input 12B
49 - NC
50 - NC
51 - Input 13A
52 - Input 13B
53 - Input 14A
54 - Input 14B
55 - Output 13
56 - Output 14
57 - Gnd
58 - Vcc
59 - Output 15
60 - Output 16
61 - NC
62 - Input 15A
63 - Input 15B
64 - Input 16A
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #22 on: May 23, 2014, 08:48:55 PM »
Troubleshooting Color and Sync problems on MVS boards:

This post is from the perspective of repairing a MVS 2F board - the newer version of the 2 slot - but will work for most other MVS boards.

The output of the video subsection will go through the NEO-G0 chip then on to the Palette RAM (8k x 8bit SRAM) and the 74LS273 latches. From there it goes to a resistor ladder per color with a couple of the lines being buffered/amplified (higher current) by a 74LS05 IC before going out to the JAMMA connector.

When troubleshooting MVS color issues take a moment to divide the problem into sections.

1. Palette, or Color RAM error
2. No Sync (either horizontal or vertical)
3. Missing or incorrect colors

Part 1: Palette, or Color RAM error

If there are Palette RAM problems this can be caused by a problem in any of the ICs connected to that data bus: NEO-G0 chip, Palette SRAM, or the 74LS273 latches. The easiest thing to do is to power OFF the board and check the data lines on the SRAM ICs for shorts to +5v or ground connections. If there are none then replace the SRAM first.

If there is a short, remove the 74LS273 ICs first as they will be the most likely culprit. Check the data lines again. If the short is gone, replace the latches. If not, move on to the next chips, the SRAM. Repeat tests and replace the NEO-G0 last.

Part 2: No Sync (either Horizontal or Vertical)

The sync line goes from the NEO-I0 chip through a 100 ohm resistor to the JAMMA connector. It's also tied high to +5v through a 470 ohm resistor. Check both resistors. Replace if bad. If there is still no sync, replace the NEO-I0 chip.

Part 3: Missing or incorrect colors

Missing colors can be caused by any of the parts in the output section. Unless there's an esoteric problem with the Color RAM the digital part can be mostly taken out of the equation.

The output is made up of the 74LS273 latches, a series of resistors forming a ladder network, and 74LS05 Hex Buffer/Inverter IC.

With the power OFF, check the inputs and outputs of the 74LS05 IC for shorts to either +5v or ground connections. Replace the IC if any shorts are found. If there are shorts but the 74LS05 IC isn't it then replace the 74LS273 ICs. Next check the resistors for any that are burned.

If the RGB outputs are shorted the most likely culprits will the the 220 ohm and 150 ohm resistors as these are the lower value resistors. (The lower the value the higher the current that will flow through during a short.) check these resistors with an ohmmeter and replace any that are not reading correctly.

The next step is to check the outputs of the 74LS273 ICs with a logic probe. On the datasheet there are D and Q pins listed. The D is the input, the Q is the output. Check for signals on both sides. Replace the ICs that have inputs but no outputs between their D and Q pins.

Hook everything back up after replacing the parts and give it a test!

I had a board in the shop with missing red colors. There were no other symptoms on this board such as lines through images, etc... just screwy looking colors.

I replaced the NEO-G0 IC before stepping back and taking a better look at the circuit. After analyzing the circuit I replaced a shorted 74LS05 IC and two bad resistors to fix the board.

The 150 ohm and 220 ohm resistors were bad and the 74LS05 gate driving the 150 ohm resistor was shorted to ground.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #23 on: May 23, 2014, 08:51:29 PM »
Model: MVS MV-4
Dignosing bad RAM ICs

Board is a NEO-MVH MV4 (4 slot)

Code: [Select]
Backup RAM Error:

Address    Write  Read
00D01406   AAAA   AA2A

The Read code is broken up into 2 parts... AA and 2A

The first 2 characters are the upper bits and are handled by the IC at D9
The second 2 characters are the lower bits and are handled by the IC at F9

--------

Code: [Select]
Video RAM Error:

Address    Write  Read
00000607   5555   5455

Same thing here... the Read code is broken up into 2 parts... 54 and 55

The first 2 characters are handled by the IC at L9
The second 2 characters are handled by the IC at K9

--------

Work RAM is laid out backwards from Backup RAM and Video RAM on the NEO-MVH MV4

Code: [Select]
Work RAM Error:

Address    Write  Read
xxxxxxxx   AAAA   AABA

(Yeah, I was too lazy to write down the exact address of the error...)

The first 2 characters are the upper bits and are handled by the IC at H9
The second 2 characters are the lower bits and are handled by the IC at G9
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #24 on: May 23, 2014, 08:52:05 PM »
Model: MVS MV-6
Diagnosing bad RAM ICs

Here's the info on the 6 slot board:

Upper Backup RAM: E9
Lower Backup RAM: F9

Upper Video RAM: L9
Lower Video RAM: K9

Upper Work RAM: J9
Lower Work RAM: H9

Just keep in mind that if you have an error at the bottom boundary then you need to check traces.

For example a video error of:

Code: [Select]
Video RAM Error:

Address    Write  Read
00000000   5555   5455

Shows up on the zero boundary. You need to check to see if the traces (wiring that is on the circuit board) are all good. A bad trace or a bad chip can each cause this type of error.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #25 on: May 23, 2014, 08:53:33 PM »
Model: All MVS boards
Troubleshooting Backup RAM Errors

If you see this for a Backup RAM Error:

Code: [Select]
Backup RAM Error:

Address    Write  Read
00D00000   5555   0000

Then you have a different problem all together.

This is caused by the chip not being selected properly for read/write access. This is almost always (well, I'd say > 99.5%) a problem with the chip or with the trace that is controlling the SRAM and NOT with the SRAM.

Look for broken traces whether from battery leakage or someone scraping something across the board which physically damaged the traces. If that's not it then trace back the chip control traces to see what chip is feeding it.

On the 32k x 8 SRAM ICs (the 62256 or equivalent) that are used for the Backup, Work, and Video RAM that would be:

Code: [Select]
Pin 27: *write (also known as *WE) - Write Enable
Pin 22: *G (also known as *OE) - Output Enable
Pin 20: *E (also known as *CE) - Chip Enable

OK, OK... the * in front means it is an active low signal. If it's high, it's not being signaled. If you get NO signal from your logic probe on one of the pins then you have an open trace for sure.

Pin 20: should always be grounded on the Work RAM and Video RAM. That pin is directly connected to ground and if it isn't then you have a physically damaged trace. On the Backup RAM it is used to put the chips into low power standby mode.

Pin 22 & 27 connect to different chips. These are the ones you are most concerned with when troubleshooting this type of problem. Follow the traces and repair corroded or otherwise damaged ones. (99.5% of the times this is the fix)

Oh, when troubleshooting these you WILL have to strip off the red cardboard and the black foam under the circuit board in order to follow the traces. Have fun cleaning all that crap off. Yuck.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: SNK Games (Neo Geo MVS/AES)
« Reply #26 on: May 23, 2014, 08:53:44 PM »
Board: MVS MV-2
Backup RAM locations

When diagnosing the Backup RAM problems on a NEO-MVH MV-2 2-slot board:

Upper Backup RAM location: H3
Lower Backup RAM location: H4
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: SNK Games (Neo Geo MVS/AES)
« Reply #27 on: May 23, 2014, 08:53:54 PM »
Model: MVS MV1FZS
Symptom: Crosshatch of Death

This board does not suffer from the same battery damage induced Crosshatch of Death as the old style 4 slot board.  The old-style 4 slot board's problem is one of legendary status and it should be documented that it is the ONLY board to consistently suffer from that kind of problem.

Powered up the board and duplicated the symptoms. Looked for obvious signs of damage and found where the bottom of the board was gouged by something. Repaired 3 broken traces connecting to the cartridge slot resolve the crosshatch problem and repaired another 3 broken traces causing corrupt video.

Always check the boards you are working on for signs of physical damage. It's pretty common on arcade boards.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: SNK Games (Neo Geo MVS/AES)
« Reply #28 on: May 23, 2014, 08:54:47 PM »
Model: MVS MV-4F (newer style 4 slot)
Symptom: Z80 error and rapid audio click

Had a MV4F board that came in with a Z80 error and a rapid clicking sound in the speakers. Strange thing is that as the speakers clicked the picture on the monitor flickered.

(Little did I know this thing would kick my ass.)

Replaced the Z80 CPU to fix the Z80 error.

Now the system booted but flickered like mad. Audio ouptut was horribly distorted.

With the audio down the system worked fine except the audio output IC was getting very hot. Recapped the audio section. No help. Replaced the audio output IC. No help. Replaced the volume control. No help.

For some reason there was an oscillation happening in the audio circuit. This oscillation was causing the audio output IC to suck up large amounts of current. This was causing dropouts in the +12v output of my bench supply. These dropouts matched the screen flicker and the clicking of the speakers.

Checked every trace in the audio section - all were good. Replaced the 3 op-amps. No help. Checked all the film caps (the non-electrolytic caps)... all checked good.

All voltages looked OK but were a little lower than another MV4F board but they were within reason (+12v was a little low so the other voltages around the chip were correspondingly lower)... On a whim I removed both of the .1uf film caps on the speaker outputs. Audio was distorted but amplifier was stable.

Next I put them back in circuit one at a time. The one on the right speaker was the cause of the problem. Replaced the cap and problem was still there. It looks like there's an issue with the ground trace inside the board. Removed the cap and ran the board for an hour at 3/4 volume with no problems.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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Re: SNK Games (Neo Geo MVS/AES)
« Reply #29 on: May 23, 2014, 08:55:19 PM »
Model: MVS MV-4F
Troubleshooting reset lines

In working on a 4 slot board (MV4F) I encountered a Z80 error.

The board had other issues (documented elsewhere) and when those were fixed and the board not yet reassembled, it gave a Z80 error.

The reset line was held high.

The reset line goes through the 74AS245 IC at location E11. It goes through the latch on pins 2 and 18. If that IC is bad the reset line could be stuck high or low, causing the Z80 CPU to never boot.

That reset line must transistion from low to high to reset the Z80 CPU and make it start executing commands.

In this case the problem came because the IC at E11 was pulled from the board as a step in troubleshooting. Once the IC was placed back in the board the reset line cycled normally and the Z80 booted. (This was also tested by jumpering the reset line on pin 15 of IC A9 to pin 26 of the Z80 before replacing the IC)
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #30 on: May 23, 2014, 08:55:30 PM »
Model: MVS MV-4F
Symptom: Stuck in Watchdog (Click of Death)

Have a 4 slot board in to repair that was giving the click of death - stuck in watchdog - problem.

This can be caused by many different problems, including:

Bad CPU
Bad Work SRAM
Bad Backup SRAM
Missing control signals on Work or Backup SRAM
Shorted 74AS245 ICs buffering program ROMs on top board to CPU on bottom
Short on address bus
Short on data bus
Missing address or data signals to chips

First thing... Check for gouged traces. Found and fixed one. No effect.
Next... Substitute BIOS. Nothing.
Next... Check control signals on the Work RAM - Stuck high on pins 22 and 27.
Next... Check control signals on the Backup RAM - Stuck high on pins 22 and 27.
Next... Check control signals on the BIOS ROM - These were working.

So we had a problem somewhere in the system to where it was trying to read the BIOS but not able to initialize hardware.

Pulled the 74AS245 ICs buffering the data lines to the top board. Had no effect.

Checked for more broken traces. No more were found.

Checked the address and data lines going to the BIOS and SRAM ICs. All were good. Checked the data lines going to the NEO B1 chip. All were good. Checked the data lines. All were good.

Next checked the A22* and A23* alternate lines. Missing one one! Ran a jumper wire from Pin 55 of the NEO-E0 IC to pin 117 of the NEO-B1 IC and the board came up!

OOPS. Z80 Error. Reset line stuck high. On a Z80 since the reset line did not transition from low to high the Z80 never booted. Ran a jumper and the audio section worked. Replaced the pulled 74AS245 ICs and the board wouldnt' boot. Reset was stuck low.

Turns out the reset line for the Z80 CPU and chips on the left side of the board goes through the 74AS245 IC at E11. Removed the jumper for the reset line and board booted normally.

Plugged the top board back in, inserted some test carts and played a couple of games.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

http://www.arcadecomponents.com

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Re: SNK Games (Neo Geo MVS/AES)
« Reply #31 on: May 23, 2014, 08:55:42 PM »
Model: MVS MV6
Symptom: Vertical lines in graphics

Some background objects had vertical lines in them - in this case the "shock Troopers, 2nd Squad" floating logo had lines. It's the logo that is on the screen when it is playing in demo mode. I traced it to connector CN8 and started tracing it on the bottom board.

UGH. It goes straight to NEO-CT0

As one final step before replacing that surface mount chip I checked the continuity between the top board and bottom. Bingo! No continuity. Next step - pull the boards apart and look at the connectors. They had something sticky on 2 of the pins and up in the socket.

Desoldered and disassembled the socket then cleaned the pins on both connectors. Reassembled, resoldered into place, and tested. Board is fixed.

Moral: Don't discount those board connections! Look at them closely to see if there is a foreign substance in there causing the problem.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #32 on: May 23, 2014, 08:56:06 PM »
Model: MVS MV4F
Symptom: Video RAM Error

This board had multiple problems due to liquid damage.

4F board came in with a Video RAM error. Replaced the upper Video RAM IC and error went away but video was glitchy and had bad colors.

Repaired a bad trace between the lower Video RAM IC and the LSPC2 IC.

Glitching was gone but the colors were bad. Test screen showed blank for red, blue for both blue and green, and white was a little off color. Put in a UniBIOS chip and noticed the green was off and the low end of red was missing AND a white block was in the place of the lowest red color. (SNK BIOS shows 4 color boxes, one for each color. The UniBIOS chip shows color spectrum bands for each color)

Checked the Color RAM and noticed that address line A2 was stuck low. Checked the NEO-B1 IC and noticed that A2 was stuck low there as well. Backtracked through the circuit and found that the TDI4 pin (pin 22 - signal name P16) was floating - no signal.

Checked the other ends of the signal - the 74LS245 IC buffering the L0 ROM and pin 134 of the LSPC2 IC. They had signals. The trace under the LSPC2 connecting to pin 134 was bad. Ran a jumper wire between the 74LS245 and the NEO-B1 chip to fix. (It was WAY easier to solder to the big pin on the 245 than the small one on the LSPC2!)

Audio was missing on one channel. Grabbed the oscilloscope and found that the volume control was bad. Replaced it with one off of a parts board.

Reassembled the game and tested. Slot 3 had vertical lines on the screen through graphics. Patched a corroded trace to fix. Played a few games to test.

Replaced the leaking battery then reassembled the board for one final test.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #33 on: May 23, 2014, 08:56:24 PM »
Model: MVS MV4F (newer smaller 4 slot)
Symptom: Missing/Garbled sound problem.

This board has been a pain to track down. The board had been worked on before  by another tech.

Fixed a broken trace on pin 15 of IC 4N (74AS245 - other tech damage - grrrrr!) and the board would play sounds but was distorted on the higher frequency digital music.

The sound ROMs are read through the YM2610 IC through data latches (74LS245) at board locations 2M and 2N. If the voice and lower frequency music notes are distorted then replace the IC at 2M. If the higher frequency music is distorted, replace the IC at 2N.

On this board the replacement of 2N did not fix it. Board had a damaged trace internal to the board and the ground pin on IC 2N was not connected. Ran a patch to fix the board.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #34 on: May 23, 2014, 08:56:34 PM »
Fixed: AES
Symptom: Lines in overlay graphics (text, health, etc) and no sound

Fixed a corroded trace leading to NEO-B1, pin 131, from the cartridge slot to restore the video.

Looked at the YM3016 Sound DAC and there was no serial clock or data flowing from the YM2610 sound chip. Checked the Z80 CPU and it appeared good. Looked at the clock signal on the YM2610, pin 63, and it was dead. Traced it back to a 74AS04, pin 1 near location K4 and found a corroded plate thru hole on the trace. Patched the trace to finish the board repair.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #35 on: May 23, 2014, 08:57:01 PM »
Fixed: AES
Symptom: Garbage on screen

Swapped out the Video RAM (62256 surface mount) chips and system would then give a yellow screen indicating a video RAM error. Checked the VRAM with a logic probe and saw that the address lines were pulsing regularly and were not pulsing erratic indicating they were being used when the system would run the Video RAM tests.  Data lines, CE*, and W* lines appeared to be working normally. Checked the pins on the LSPC2 and found address line A1 was not pulsing with data. Traced it back to the BIOS chip and found the upper pad missing from the address line A1 pin.

Ran a short jumper to fix the board.

When someone replaced the BIOS on the console with the UniBIOS chip they socketed it, but not before pulling the upper pad and platethru removing the old chip.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #36 on: May 23, 2014, 08:57:17 PM »
Fixed: AES
Symptom: No video, would play blind

Repaired bad trace on pin 126 of the NEO-B1 IC to fix the video clock and bring back the video.

Fixed a bad trace on pin 125 of the NEO-B1 IC to fix a graphics corruption problem.

Board played for about 10 minutes then rebooted to a red screen - bad Work RAM. Replaced the surface mount 62256 SRAM at R6 to bring it back from the dead. Finish the repair by running the game for a half hour to burn it in.

From the last couple of repairs it appears that the AES suffers from the same random board corrosion problems that some of the MVS boards do. Some of the boards weren't cleaned very well at the factory and gunk left on them would eat random traces.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #37 on: May 23, 2014, 08:57:33 PM »
Resurrected: AES Parts Board
Symptoms: Dead, multiple cut traces, no video out.

Had a complete parts board (no missing chips or damaged SMT chips) that was dead. Multiple solder bridges, traces cut, and missing the daughterboard.

Installed a replacement daughterboard and patched 3 cut video (RGB) traces. Patched a broken trace connecting to pin 112 of the PRO-CT0 chip. Removed multiple solder bridges. Board would then try to boot but was stuck with garbage on the screen. Shorting out 2 data lines would result in a watchdog reset. No W* or CE* activity on the video RAM but did have activity on the work RAM and the system BIOS ROM. Board was trying to boot but never making through self test enough to put a color on the screen indicating what RAM was bad.

Replaced the work RAM at R6 and the board would then boot to a blue screen with no cartridge plugged in indicating system's RAM was working properly. The video output was distorted and would fade in and out during the self test. Checked the CXA1145 RGB Encoder chip for broken traces as that chip looked to have been replaced before. Found a break between the pad and trace on Pin 13 (I REF connection.) Patched the trace to fix the video.

Board would then boot and run but had connection problems with the cartridges. The slot connectors were very loose - basically worn out. Replaced both connectors (100 pins per connector!) with ones pulled off of a parts board to fix the slot problems.

Unit had a Japanese BIOS. Swapped that out for a European BIOS and socketed it.

Board played until it got hot then would randomly reboot. Board would also reboot when tapped or flexed. Used an eraser attached to a #2 pencil to just barely touch each pin on the NEO chipset chips and found the LSPC-A0 IC was the culprit. Resoldered the IC then was able to shake and tap the board without it rebooting. Let the board play for an hour to test.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #38 on: May 23, 2014, 08:57:51 PM »
Model: MVS MV-2F
Symptom: Audio would cut in & out

Cleaned corrosion off of 2 ICs, installed an audio cap kit, and reset the backup RAM.
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Re: SNK Games (Neo Geo MVS/AES)
« Reply #39 on: May 23, 2014, 08:58:01 PM »
Model: MVS MV4
Symptom: Audio would cut in & out

Installed an audio cap kit, and reset the backup RAM.
I have too many hobbies! Electronics, gunsmithing, Miatas, arcade games, metal detecting, etc...

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