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Can MVS carts be repaired

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Flinnster View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Flinnster Quote  Post ReplyReply Direct Link To This Post Posted: 10 August 2017 at 12:33am
Wonder if anyone can help. I have a Viewpoint cart that has stopped booting. It acts like nothing is connected, going to the monitor test grid.

Looking carefully at the front of board 1, and comparing to MVS scans, I can see I have a surface mount component missing or broken at location PC2:
MVS scans:
http://mvs-scans.com/images/f/f7/Viewpoint_set1_b1_front.jpg

Mine:


My question is how can I tell what these 'PC' surface mount components are. Are they capacitors? And if so, how can I tell the value? They're just a beige / brown colour overall.
Wanted:
- PCBs: Rainbow Islands, Bomb Jack, Rolling Thunder
- Parts: Naomi non-swivel castor wheel, coin mech metal clip for Dino King Door
- House Extension
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ic3b4ll View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ic3b4ll Quote  Post ReplyReply Direct Link To This Post Posted: 10 August 2017 at 1:04pm
Hi mate!

They look like capacitors, and it makes sense given their placement (decoupling?), but the designator is non-standard (would normally be just 'C'). You could desolder one and check its capacitance with, erm, a capacitance-o-meter thingy and replace accordingly. 
Can you tell me the board type of that cart? I can check if I have a similar one around and investigate further. 
EDIT: Nevermind it's a PROG-G2, I've seen it now. 


Cheers


Edited by ic3b4ll - 10 August 2017 at 1:18pm
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Flinnster View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Flinnster Quote  Post ReplyReply Direct Link To This Post Posted: 10 August 2017 at 1:22pm
Hi, yep it's the top board of the Set1 version of Viewpoint labelled NEO-MVS PROG-G2.
(photo link above, from MVS scans)

Looking at the pour areas around that component and how they trace back to the edge connector pins, I can see the left is ground, and the right is VCC / +ve power (from the reference here).
So yep, decoupling sounds likely. I just wish I could measure the capacitance of those surface mount bits in situ without having to desolder!
Wanted:
- PCBs: Rainbow Islands, Bomb Jack, Rolling Thunder
- Parts: Naomi non-swivel castor wheel, coin mech metal clip for Dino King Door
- House Extension
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pulstar View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pulstar Quote  Post ReplyReply Direct Link To This Post Posted: 10 August 2017 at 1:39pm
It's doubtful that that being missing is the problem to be honest. Check continuity with the P1 rom and the edge, make sure the pins on the edge are good and clean (use some contact cleaner to make sure it is properly clean). And if that's all good then you'd need to desolder and dump the P1 rom to check that that is good. 

If the connections to the P1 are good and the actual ROM are good it should boot. Any problems with this and it won't boot.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Flinnster Quote  Post ReplyReply Direct Link To This Post Posted: 10 August 2017 at 11:49pm
Well b#####r me! The edge connectors were already clean I swear. But I cleaned them again, double checked continuity to the edge was all OK and the thing now boots up! What the hell?! Big smile


Edited by Flinnster - 10 August 2017 at 11:59pm
Wanted:
- PCBs: Rainbow Islands, Bomb Jack, Rolling Thunder
- Parts: Naomi non-swivel castor wheel, coin mech metal clip for Dino King Door
- House Extension
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el capitan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote el capitan Quote  Post ReplyReply Direct Link To This Post Posted: 10 August 2017 at 11:53pm
Originally posted by Flinnster Flinnster wrote:

Well b#####r me! The edge connector were already clean I swear. But I cleaned them again, double checked continuity to the edge was all OK and the thing now boots up! What the hell?! Big smile

Good stuff.

I had issues with a nes with the blinking red light. Ordered a new connector, replaced it.. same issues...

So I cleaned the contacts in the carts... as in used a fine sandpaper. And every single cart worked...

And I was sure I had cleaned them before, but there must have still been bad connections.

Edited by el capitan - 10 August 2017 at 11:54pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pulstar Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2017 at 10:28am
Originally posted by Flinnster Flinnster wrote:

Well b#####r me! The edge connectors were already clean I swear. But I cleaned them again, double checked continuity to the edge was all OK and the thing now boots up! What the hell?! Big smile

ExcellentSmile Sometimes the pins look clean but aren't 100% clean and that's what causes the problems. Glad you got it fixed.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote venom Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2017 at 11:58am
Also it can be the mobo being pain in ass. Check your voltage. Used to piss me off swapping a cart a few times and would suddenly stop working again. Glad it's working leave it in there !!! I left a multipart in mine and sold it with my cabinet!! I find neo geo running in mane never let's me down!! The only game I could tell was different was andro dunos verticl scrolling at beginning just looked different to my cart .
Owner Supreme video, a Woodie and Thunderbirds pachislo.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Flinnster Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2017 at 12:19pm
Yep I'm still encountering a few oddities on this mobo. I set the clock yesterday and it's gone again today. Also my highscore entry of 'DAV' has become 'D' followed by some japanese characters, and the demo sounds have turned themselves off. So either the drum battery is on the way out (I should do the CR2032 mod anyway tbh) or I have an oncoming backup ram chip problem :-/
Wanted:
- PCBs: Rainbow Islands, Bomb Jack, Rolling Thunder
- Parts: Naomi non-swivel castor wheel, coin mech metal clip for Dino King Door
- House Extension
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pulstar Quote  Post ReplyReply Direct Link To This Post Posted: 11 August 2017 at 8:52pm
I would get the battery out and put a CR2032 in as soon as possible really. They destroy motherboards (especially if you change out the board for a little while and forget about it). 

Also, it might just need to have the backup ram cleared. Turn all the dips on, switch on the motherboard for about five minutes (should come up with WORK RAM TEST on screen), then switch off and turn them all off again (or whichever ones you had on before). Sometimes little problems like you've described can be solved by clearing the backup RAM in this way.


Edited by pulstar - 15 August 2017 at 4:40pm
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ic3b4ll View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ic3b4ll Quote  Post ReplyReply Direct Link To This Post Posted: 12 August 2017 at 1:25am
I've replaced the battery on mine with a CR2430. The voltage is the same and it should last a bit longer. I have a frigging huge 4 slot board though and I don't know if it would fit on the smaller ones...
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