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tengugurl

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hi!

I just recapped and re-heat-sinked my power supply on my blast city and I am getting zero +voltage reading from my multi-meter.

Any ideas what could be causing this?

The LED red bulb in the inside of the PSU cage is not turning on.
Odd thing is, I am able to get voltage out the back though via the 100v out port

The fuse has not blown. No smell, no burning... Wonder if the PSU needs to be under load to show a rating? I wouldn't assume that is the case but I am not sure.

What I did to debug my handwork:
1) verified all the caps are facing the right direction (no +legs in a -spot etc..)
2) checked the kit I got from arcade parts and repair and ticked off the list 2x to make sure I installed the caps in the right spots.
3) Made sure all connections were put back in their respective places.
4) multi-metered the jamma harness (0 rating DC)
5) checked the PSU connection to the Sega harness was butted up close.
6) got out a cheapy jamma board to see if a load would make it read... Nope

My assumptions...
The kit had a very interesting swap for capacitors on c36 and c44
Instead of the original electrolytic caps which were rated at 0.47 @50v, they were replaced with 0.47 if @50v tant style

The tant cap had a + marking on it so I made sure it was matching the original cap positioning.

Any ideas or suggestions would be helpful! ❤️
 
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Here is a pic of all the connections put back
 

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My assumptions...
The kit had a very interesting swap for capacitors on c36 and c44
Instead of the original electrolytic caps which were rated at 0.47 @50v, they were replaced with 0.47 if @50v tant style

The tant cap had a + marking on it so I made sure it was matching the original cap positioning.

Any ideas or suggestions would be helpful! ❤️
If you checked everything. Probably wouldnt hurt to put back the original caps back on c36 and c44 to rule out those tantalum caps.
 
Smart thinking, I am going to try that.
Oh I heard this might be causing me an issue too..

The service door has a kill switch
I just installed a new coin lock but it might not tripping/activating

Has anyone zip tied one?
 

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Silly question.. lol

What do I zip tie exactly?
I ordered an Amp Up bypass kill switch connector but, that's a few weeks from coming and I am impatient.

@RandomRetro

I wasnt too sure if I found the button but I crawled into my cab and had to lie on my back to see this box thing. I was only able to identify it by it's blue and pink cables
 

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I bet the red and blue wire is your AC line. Hold down the button on the interlock and see if your PSU powers up.
 
If that kill switch isn't pressed, the cab won't power up.

You could ziptie the switch or bypass it with a simple loopback wiring harness. If you leave it in, the problem is if you accidentally hit the service door (like with your knee), the cab can reset. Personally I removed all of mine and threw them in the trash.
 
I took the kill switch off its hanger and zip tied it *image attached

Still no luck... I am going to have to reverify my work soldering wise.

Luckily I took before and after pics to compare but, almost guarantee it's the random tant capacitors.

Wish me luck! ❤️
I am going to feel so dumb if I reversed a cap @_@

Not likely but, let's hope not
 

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Sucks but wishing you luck on sorting it out and hopefully it is an easy fix.
 
Just put back 2 original caps that were replaced with tantalum caps in the kit I ordered.

Still..no power


The jamma harness reads a short on the 5v+ pins.
When I disconnect the PSU, the short does not exist so it's def the PSU.

I looked at all my work and the caps are facing the right directions + side to + etc

Traced around the pins and noticed there is a big patch of gold PCB design that has pure continuity which is crazy because the cap legs should be one side + and the other -

:S
So confused.
I read in a random forum that someone light bar was causing the short

So I disconnected mine and still same prob.
Thanks to everyone who has commented this far

I am down to try anything to fix this..
Pat head, rub belly while placing PSU cord in, I'll give it a try haha

Please let me know if you have any pointers or have had a similar issue.

I don't know where to go
 
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Just put back 2 original caps that were replaced with tantalum caps in the kit I ordered.

Still..no power


The jamma harness reads a short on the 5v+ pins.
When I disconnect the PSU, the short does not exist so it's def the PSU.

I looked at all my work and the caps are facing the right directions + side to + etc

Traced around the pins and noticed there is a big patch of gold PCB design that has pure continuity which is crazy because the cap legs should be one side + and the other -

:S
So confused.
I read in a random forum that someone light bar was causing the short

So I disconnected mine and still same prob.
Thanks to everyone who has commented this far

I am down to try anything to fix this..
Pat head, rub belly while placing PSU cord in, I'll give it a try haha

Please let me know if you have any pointers or have had a similar issue.

I don't know where to go
Its normal to get continuity between the GND and 5V if your PSU is connected.
Check your AC input connector on the PSU to see if you're getting 120VAC. Make sure you have the zip tie on the kill switch when you do this.

If you measure 0VAC then trace you AC input power throughout your cab. Its possible a connector came loose.
 
if you can stand taking the boards out of the case again, snap some photos and put em on imgur or some other image host (the forum has a max size limit). We can take a look, maybe we will notice something. Front and back side.

Just to be sure... the blast has two power switches. Inside the control panel and behind on the psu.

When you say you have a short... what pins are you testing for continuity? It’s set to test continuity or are you on ohms for resistance? You get zero ohms between 5v and ground?

Where in the USA are you? Maybe it’s ship-able to someone who can plug it into their blast.
 
Blast city psu cap replacement https://imgur.com/gallery/N5FB53H
I added a few high res pics here^

I was testing the voltage via DC 20v option on my multimeter anticipating on reading ~ 5.25v+ on my jamma edge but I was getting 0.0v

Turned it off and for laughs I checked with the continuity option an the the 5v+ and gnd and sure enough it has a perfect continuity, so I assume it's shorting out somehow

Didn't measure resistance yet.

I am in Colorado
 
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Ps, I feel silly... I didn't have the switch on the control panel (front of cab) flipped up while doing this testing.

I will have to try that soon but, if I am still getting a reading of closed circuit (continuity) between 5v+ and gnd on my jamma edge, I might still have room to hesitate trying it with the PSU hooked up and both switches turned on
Aka switch 1 on back of PSU (back of cab)
And switch 2 control panel (front of cab)

Guess it's good I don't know much about my cab yet lol (location wise)
My not hitting the on button up front could have saved me from damaging something.

Can anyone try reading their blast city's jamma edge with the power off up front (control panel) and power on in the back PSU and seeing if they get the same closed circuit (continuity) on the 5v+ and gnd?

That will make me worry less before I try turning the front control panel on
 
by closed circuit, you mean you hear a beep and then it goes away? or that it is a continuous beep?

switch to resistance. put one probe on pin 1 or 2 (ground), the other on pin 3 or 4 (+5v), let us know what the meter reads.
 
I just tested continuity between +5V and GND on the jamma harness in my Blast and my multimeter beeps for a while too. It doesn't necessarily mean there's a short.

Your gallery link doesn't work for me.

EDIT: a-ha, power switch under the CP. That's caught me off guard too!
 
Not out of the ordinary behaviour as the power line(s) are most likely grounded via a filtering capacitor.
 
yep, my guess is you don't have a short. the meter will beep briefly but not in a sustained manner. That happens in my blasts. Showing 0 ohms in resistance mode will tell you that there's a short to ground, but I don't think you'll see that.

between the two power switches and the kill switch you already found, it's 3 sensors before it turns on! By the way, the ziptie will come loose sometimes and that's annoying. Make sure that is super tight too. I just cut mine off and tied the wires together, but it looks like something like this would be more elegant: https://www.arcaniac.com/products/sega-blast-city-cabinet-service-door-power-kill-switch-bypass
 
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I ordered the just hookup yesterday :)
I can't wait till that comes in!

Thanks for giving it a test on your cab @nem

So... Bad news

Turned the PSU switch on, turned the cp switch on and made sure the kill switch was tight and my fan didn't turn on nor did the red led on the PSU turn on.

I was told on the Japanese candy cabs group on FB that the next thing to check out would be the NEC ic chips to see if they need replacing.
Look for bad solder joints and find a pinout if possible

@_@

Any other suggestions? Wonder if the cable I am using would be an issue?
Using a thick 16awg 125v standard 3 prong to a 100v stepdown converter

*Ps try the link once more, I made sure it was public a second ago
 
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