ArcadEd
Member
Nevermind, thought I had something.
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Please post all monitor technical topics in the Technical - Videogames - Monitors section, not in the General Help section.
Logic Probe Experts Help (Super off road)
- Thread starter ArcadEd
- Start date
ArcadEd
Member
Well, even if I replace rom 67 in mame with a blank one, the game still boots.
Now, 3b on the other hand, if I replace that one with a blank rom, no game boot in mame
Now, 3b on the other hand, if I replace that one with a blank rom, no game boot in mame
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ArcadEd
Member
OK, according to Caesar roms 56, 57, 58, 59 are tied to the Master CPU.
So here is my reading from those.
U56
/CE - Low
/OE - No Signal
U57
/CE - Low
/OE - No Signal
U58
/CE - Low
/OE - No Signal
U59
/CE - Low
/OE - No Signal
They all read the same.
Playing with MAME, having U58 and/or u59 blank causes the game not to boot. Just having 56 and 57 blank, game boots. Wish CAESAR would give a little more specific info on the ROMS.
So here is my reading from those.
U56
/CE - Low
/OE - No Signal
U57
/CE - Low
/OE - No Signal
U58
/CE - Low
/OE - No Signal
U59
/CE - Low
/OE - No Signal
They all read the same.
Playing with MAME, having U58 and/or u59 blank causes the game not to boot. Just having 56 and 57 blank, game boots. Wish CAESAR would give a little more specific info on the ROMS.
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ArcadEd
Member
I may have found a new problem or the problem, just not sure what to make of it.
This board is suppose to run at 5.20v. My power supply out reads 5.20. At the end of the harness (not plugged into PCB) it reads 5.20v. Soon as I plug it into the PCB it reads 4.75v on all test points on the PCB, and the pins on the connector the harness plugs into.
And I really think I am crazy here. Here is a picture of the back and front of the main power connector. I see a trace for the 12v line, and I see a trace where there is no wire. I don't understand how the 5v is getting anywhere. I think I am losing it.
This board is suppose to run at 5.20v. My power supply out reads 5.20. At the end of the harness (not plugged into PCB) it reads 5.20v. Soon as I plug it into the PCB it reads 4.75v on all test points on the PCB, and the pins on the connector the harness plugs into.
And I really think I am crazy here. Here is a picture of the back and front of the main power connector. I see a trace for the 12v line, and I see a trace where there is no wire. I don't understand how the 5v is getting anywhere. I think I am losing it.
Attachments
Arcadenut
Well-known member
The 5.2 reading is not under Load. When you plug it into the board, it puts a load on the 5V line and drops it to 4.75. You can try to adjust the voltage up. Use your meter and adjust/watch the voltage while the game is on to 5V ON the board, not the connector.
ArcadEd
Member
Yeah, I understand that. Just seems like I have to adjust it a lot. (5.7ish on the ps)
Then my 12v jacks up to almost 15v on board.
I also seem to have about a .13 difference between my top and bottom boards.
Not that any of this fixes my current problem, but I am just wondering if the problem happened because something was getting way to much voltage over time.
Anyway, back to the main problem of getting this to boot.
Just wanted to post this info again so all this power talk doesn't get in the way. Sometimes I just go off
OK, according to Caesar roms 56, 57, 58, 59 are tied to the Master CPU.
So here is my reading from those.
U56
/CE - Low
/OE - No Signal
U57
/CE - Low
/OE - No Signal
U58
/CE - Low
/OE - No Signal
U59
/CE - Low
/OE - No Signal
They all read the same.
Playing with MAME, having U58 and/or u59 blank causes the game not to boot. Just having 56 and 57 blank, game boots. Wish CAESAR would give a little more specific info on the ROMS.
Also, there are 2 TTLs near both CPU that I am having a question about. Both are 74LS04. Simple Hex Inverters. Neither really seem to logic test right.
The near the master cpu reads (HL is both high and low lights on my probe, not exactly sure what that means, but I see it a lot).
1. HL
2. HL
3. HL
4. HL
5. HL
6. HL
7. L (Ground)
8. HL
9. HL
10 HL
11. High
12 HL
13 HL
One near slave cpu
1. Dead
2. Low
3. Dead
4. Low
5. HL
6. HL
7. Low (Ground)
8. HL
9. High
10. HL
11. HL
12. HL
13. HL
14. High (vcc)
I really want to learn how to repair PCBs and I am really trying. But I am starting to think this problem is just way out of my league.
Then my 12v jacks up to almost 15v on board.
I also seem to have about a .13 difference between my top and bottom boards.
Not that any of this fixes my current problem, but I am just wondering if the problem happened because something was getting way to much voltage over time.
Anyway, back to the main problem of getting this to boot.
Just wanted to post this info again so all this power talk doesn't get in the way. Sometimes I just go off
OK, according to Caesar roms 56, 57, 58, 59 are tied to the Master CPU.
So here is my reading from those.
U56
/CE - Low
/OE - No Signal
U57
/CE - Low
/OE - No Signal
U58
/CE - Low
/OE - No Signal
U59
/CE - Low
/OE - No Signal
They all read the same.
Playing with MAME, having U58 and/or u59 blank causes the game not to boot. Just having 56 and 57 blank, game boots. Wish CAESAR would give a little more specific info on the ROMS.
Also, there are 2 TTLs near both CPU that I am having a question about. Both are 74LS04. Simple Hex Inverters. Neither really seem to logic test right.
The near the master cpu reads (HL is both high and low lights on my probe, not exactly sure what that means, but I see it a lot).
1. HL
2. HL
3. HL
4. HL
5. HL
6. HL
7. L (Ground)
8. HL
9. HL
10 HL
11. High
12 HL
13 HL
One near slave cpu
1. Dead
2. Low
3. Dead
4. Low
5. HL
6. HL
7. Low (Ground)
8. HL
9. High
10. HL
11. HL
12. HL
13. HL
14. High (vcc)
I really want to learn how to repair PCBs and I am really trying. But I am starting to think this problem is just way out of my league.
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ArcadEd
Member
I guess most of my confusion is coming to the 2 things.
1. When my logic tester lights up both High and Low. The instructions say that mean Square Wave < 200khz. I don't understand that. I thought everything would test, Low, High or nothing.
2. When a PCB doesn't even boot, how accurate is logic testing TTLs? Seems like their proper logic state depends on the CPUs running. Is that correct?
I am appreciating all the help.
1. When my logic tester lights up both High and Low. The instructions say that mean Square Wave < 200khz. I don't understand that. I thought everything would test, Low, High or nothing.
2. When a PCB doesn't even boot, how accurate is logic testing TTLs? Seems like their proper logic state depends on the CPUs running. Is that correct?
I am appreciating all the help.
It means the logic is changing levels from high to low, low to high, etc...
It helps, but doesn't show everything. The logic chip's output could be stuck low or high and you won't see that unless there is a moving signal on the inputs of the gates... Logic probes also don't show you WHEN the signals are changing which could mean the difference of an AND gate showing a logic level low or high on the output.
ArcadEd
Member
OK, thanks for the info RJ.
Any idea what my next step should be regarding my PCB? Seems like I spit out a bunch of info above and I am not sure if any of it is relevant.
Any idea what my next step should be regarding my PCB? Seems like I spit out a bunch of info above and I am not sure if any of it is relevant.
ArcadEd
Member
I started a new thread here
http://newlifegames.net/nlg/index.php?topic=11822.new#new
I figured might as well start fresh and have someone experienced try to help me through it.
http://newlifegames.net/nlg/index.php?topic=11822.new#new
I figured might as well start fresh and have someone experienced try to help me through it.
bumping this for some love hopefully.
Hey channelmanic, you feel like fixing 200 of these boards for all of us?
Hey channelmanic, you feel like fixing 200 of these boards for all of us?
Ghostnuke
Well-known member
bumping this for some love hopefully.
Hey channelmanic, you feel like fixing 200 of these boards for all of us?
Or at least just mine.
But seriously, when you're accepting work again, please tell me you work on these?
EclipseEye
Well-known member
- Joined
- Oct 18, 2010
- Messages
- 1,594
- Reaction score
- 102
Really enjoying this thread, I hope you solve it!
kb0jjn
New member
Did you ever get the board(s) up and running?
I am very happy to see you learning about the electronics and hope you continue. Do NOT give up, if you get frustrated, just leave it for some time and come back to it.
I still don't fully understand about the timing of things as far as data and address lines but I am learning more each day.
You have been doing well so far, keep it up.
I am very happy to see you learning about the electronics and hope you continue. Do NOT give up, if you get frustrated, just leave it for some time and come back to it.
I still don't fully understand about the timing of things as far as data and address lines but I am learning more each day.
You have been doing well so far, keep it up.
Agree 100%! I've learned a number of things just working with a logic probe and trying to understand the various signals on logic boards and it's probably the cheapest and easiest tool to get started in some board repair. It's helped me fix a few boards so far and ideally I'd like to get a decent test bench going so it makes it a bit easier. Trying to look at thing still hooked up to a full cab can be a pain.
