Tron power supply +5

[SuperGunGuru]

Well, in the spirit of fixing what isn't broken, I decided to remove a hacked in computer power supply in my Tron and rebuild the original 90412. I tested it in my Domino Man and the Tron cabinet without a load and got good voltages. Under load however I'm only getting about a volt and a half. I tried popping the purple reset line wire out of the connector with no change. I'll double check my wire repairs (western union wraps, soldered, and heat shrink tubing to cover it), but anyone have other ideas that I might want to look at. I'll keep the arcadeshop type plug n play switcher kit in mind, but I'm somewhat of a stickler for originality.

 

[SuperGunGuru]

Also worth noting is the fact the fuse started glowing at one point and although it looked good it was of course bad. Trying only 1 of the 2 output connectors hooked up makes no difference in the volt and a half reading on the power board. The fuse became cloudy but did not fully open up.

 

[LPZ]

I upgraded my 90412 in my Spy Hunter with the Bob Roberts shotgun kit. Not a too tough job for the diy'er. Just follow his instructions and you'll be fine. Plus, all your power supply issues will go away for another 25 years. I like the original PS in my SH, so that's the route I went.

LPZ

 

[SuperGunGuru]

I upgraded my 90412 in my Spy Hunter with the Bob Roberts shotgun kit. Not a too tough job for the diy'er. Just follow his instructions and you'll be fine. Plus, all your power supply issues will go away for another 25 years. I like the original PS in my SH, so that's the route I went.

LPZ

Thanks for the reply. I actually installed Bob's rebuild kit on it last night before testing it today. During the initial tests (before hooking the boardset up), I found the fuse on the PS was blown and after replacing it, I had my 5 volts and my 12 volts. Now when you have the board plugged in you lose the 5 volts. The first replacement fuse started glowing and opened up and a second one has become cloudy, but hasn't opened up. For grins I unplugged the power connector at the Tron board but left the 2 output plugs from the power supply hooked up. There was no problem there, so hopefully my wiring fixes (which all occur on the wiring from the power supply to the pcb) aren't the problem. I know the board works, unless by some miracle it crapped out on me at this moment. Seems like something on the power supply that wans't in Bob's kit doesn't like being under load. I think I mentioned my power supply does not have the battery and the vbatt line is not tied to 5 volts, but would that cause the 5 volts to drop under load? I know it's a no-no, but I have a .5amp slow blow fuse in place of the 3/8ths slow blow it calls for. FWIW, my Domino Man has the same fuse on the PS and it's fine. I'm trying to avoid pulling the working 90412 from my Domino Man to test, but I guess worse case is I might blow a fuse.

 

[SuperGunGuru]

Update:
I pulled a known working 90412 from my Domino Man and it exhibited the same behavior. Fine without the board plugged in, but drops to a volt and a half with it plugged in. Being that I know the board was working fine and I've double checked my wiring work, I'm wondering if it could be a problem in the transformer assembly in the bottom. Thoughts?

 

[yukonblaze]

Rebuilt 2 power supplies as I experienced the same thing without resolve. Just bit the bullet and bought switching power supply and adapters for both my cabs. Hope you find out whats wrong cause I would be interested in trying to fix my old power supplies. Good Luck!!!

 

[SuperGunGuru]

Rebuilt 2 power supplies as I experienced the same thing without resolve. Just bit the bullet and bought switching power supply and adapters for both my cabs. Hope you find out whats wrong cause I would be interested in trying to fix my old power supplies. Good Luck!!!

I don't think it's the power supply, however. I tested a known working one in the Tron cabinet and it did the same thing as the suspect one. I guess this will teach me to fix what's not broken.

 

[SuperGunGuru]

Bump. Anyone care to venture what parts in the transformer could cause the +5 to drop under load? A known working 90412 does the same thing in the Tron and the board was working last time it was powered up with the switcher.

 

[modessitt]

Have you replaced the big caps in the power brick?

 

[SuperGunGuru]

Have you replaced the big caps in the power brick?

Not yet. The arcade I purchased this from was not in the best of shape and at one point they closed for the summer. During that time a portion of a wall collapsed and the Tron suffered severe water damage as a result. I'm beginning to wonder if that water could have damaged something in the bottom of the cab (other than the wood base I had to replace).

 

[modessitt]

Well, the big cap is there to regulate your +5, and a lot of +5 problems that aren't a result of a bad MCR power supply board are usually caused by bad "big blues" as their called, although I've also had a problem with a fuse clip cause +5 problems, too.

I just redid one in an Environmental Discs of Tron and it had two "big blues". I don't think the Tron had two, but I may be wrong. Been a few months since I been inside one...

 

[SuperGunGuru]

Yep they sure do. I would imagine all MCRII games are like this, such as my Domino Man. I think I'll use my meter's cap test setting just to see what that large cap says. I might as well check for AC ripple while I'm at it.

 

[modessitt]

You better have a damn good meter for testing those caps. One should be 55000uF and the other should be about 100000uF. Most meters don't read above 20uF....

 

[SuperGunGuru]

You better have a damn good meter for testing those caps. One should be 55000uF and the other should be about 100000uF. Most meters don't read above 20uF....

I guess I was hoping to find them way out of spec. My meter wasn't able to read the same ones in my Domino Man, but I thought these may have lost enough of their capacitance that the meter would show something. Of course it would have to lose a lot before my meter caught it. My meter is a Fluke 12B, which is quite handy for checking smaller caps at least.

 

[SuperGunGuru]

Bump! I replaced both large filter caps in the transformer and no joy. Since I had a bunch of extra on hand, I even replaced that AC startup cap. At that point I took the power supply and pcb over to my Domino Man and tested them; everything worked. So at this point, I know it has to be something in the wiring or in that damn transformer assembly. Whatever it it is, the fuse on the power supply board gets nice and hot and then opens up. Now when I re-spliced the wiring, I did not pay specific attention to which red +5 wires originally went together. I've always thought +5 is +5 and it didn't matter which wire originally went where as long as they were +5. Thoughts? What can the fuse on the power supply board getting that hot tell me? I'm too damn stubborn and close to fixing this to throw in a switcher kit, especially since the power supply board works.

 

[ELutz]

At this point, I would start doing process of elimination. Stick the transformer assembly in the Domino Man...see if the problem follows...And plug that Tron motherboard up in the Domino Man. See what happens. For testing purposes, you only have to plug the power connector up....it's the bigger .156 connector by itself on the MCR stack.

Edward

 

[jonathan1138]

Bumping this as it relates / i am having the same issue with an EDOT (check the Bringing and EDOT to life thread).

Anyone had the same experience / suggestion to resolve it? Thanks!

 

[SuperGunGuru]

Just for follow up as I mentioned to Jonathan via PM, I never figured this one out. I ended up putting in a MCR switcher kit and being done with it. The only thing I think I can safely say is this issue has something to do with the transformer assembly. I had replaced both of the big caps and even that other motor run cap and nothing made a difference. There are two diodes on top of one of the caps in my Tron that I was looking at, but I never got them really tested before I gave up. I'm not sure what mounting package they are called, but they kinda look like spark plugs.

 

[jonathan1138]

Great.... That helps.

The diodes (yes, they look like spark plugs I had no idea what they were) are also on EDOT under the transformer assembly. I have them on order, maybe they will get here tomorrow. I will report back after I replace all 4.

Also, You pointed out in your thread the wiring, so this lead me to take a closer look at my harness.... Some of the wiring is exposed, maybe shorting to other wires... I need to fix that.

Two leads is a good start. Thanks!