Power problem with Frogger

[wboatwright]

Okay, new to trying to repair an arcade machine.  I have a Frogger upright (sega-gremlin) 1980's machine.  I can't figure out what is wrong with the power.  When I plug it in the monitor makes a sound for about 1 second but nothing else.  I changed the fuses and still no luck.  I think I have a bad power supply.  I tested all the power cords to the different parts.  Some of the little power plugs get power and some do not. Any suggestions as to what kind of new power supply I could get?  I have included a picture of the current power supply.

Thanks for any help.

[iankellogg]

Do you have a multimeter? If you don't you can't say you have a bad power supply.

As for the monitor, if you turn up the flyback brightness does the screen turn white?

[wboatwright]

First thanks for the reply.

When I test the 5v, I get almost 5v.  When I test the 100v, I only get about 5v. I have not changed any wires.  From top to bottom on the power supply there is a wire connected to the 5v spot, then one connected to the GND, none on the ones labled NC, and then there is one wire on each of the ones labled AC 100v. I can't figure out why I don't get 100v on the ones labled 100v??

[wboatwright]

To make sure I am asking guestions about the right parts, can someone tell me what these 3 parts are called?

Please

[iankellogg]

Are you measuring 100 vac with ac voltage mode.

I'm not understanding how you are measuring 5v at the 5v output but not 100 vac

[offset]

You may need to level up a bit more on your basic electronics and how to measure electricity.

Not sure if this video covers measuring AC, as you measure it differently than DC.
https://www.youtube.com/watch?v=IYr_PRG61ZM

The Frogger manual may help also - see Page 85 - http://www.arcade-museum.com/manuals-videogames/F/Frogger.pdf

According to the manual:
Part 1 is the Switching Regulator (aka power supply)
Part 2 is the Regulator Unit, looks like some square 4-way bridge rectifiers to convert from A/C to DC voltages
Part 3 is the Power Transformer

Some generic background as well on AC wiring in arcade cabinets, the Frogger manual is the best reference for how your cabinet is wired.
http://www.therealbobroberts.net/acwiring.html

Given that the wiring for a Sega/Gremlin Frogger PCB requires, +5v, -5v, and +12v, looks like Part 2 is probably providing the -5v and +12v as your Part 1 power supply only has 100vAC and +5v DC.

Wiring pinouts for Frogger - http://www.arcade-museum.com/pinouts-game/7857.html

[Otaku]

I agree it sounds like you might be measuring the 100V AC with the DC setting, possibly.

If you're getting 5V it frankly doesn't matter if the AC can't be read (which I would say is a meter problem) because that AC is an input for the other voltages, not an output. It is what makes the entire power supply be live and "power up", so if you're getting a 5V reading correctly on the 5V terminal, it sounds like you're fine with the input voltage and that the problem might lie elsewhere. Try testing the 5V on the PCB which can be done by going to the edge of the board and following the 5V trace to a chip or other good test point and see what you get there. The ground on the power supply can still be used or the ground on the board could also be used and is likely a better solution to test that as well if you're getting nothing.

Also definitely test the -5V pin on the game PCB board for voltage and since you're already getting less than 5V off of the power supply, it only gets lower as it goes to the board and you'll need to adjust the output voltages using the knob (if there is one) on your switching power supply. This adjusts the 5V voltage and basically takes all of the other output voltages "for a ride". Make sure they're not too high to too low as you're doing this as well and I would suggest adjusting the power supply with the game board unplugged from the harness edge connector, but you do not need to take any wires off of the power supply.

[wboatwright]

Thanks everyone.  I will read this weekend and make sure I understand what I am measuring.  Everything posted has been a big help.  Thanks for your time and help with my questions.

[wboatwright]

AC power is fine.  Now looking at DC power.

I watched the video posted and read the instructions posted.  I now have the AC power working (at least I have power to the Frogger marquee).  I tested each set of wires that is for AC power and I think they are all okay.  Someone before me had cut each of the AC lines and taped them back together (with duct-tape). 

I did a test and I think I am getting 5v to the main board but I am still a little unsure if I am getting the correct power to the monitor and still no sound?  Not sure what it needs.

[wboatwright]

Okay, I found a wiring problem and fixed it.  Now I can hear the game playing.  But I do not see video.  Any suggestions.

[iankellogg]

quick list of what to check
is the monitor power plugged in
is the monitor video plugged in
is there neckglow (the tube glows orange where the neckboard is)
is the fuse blown
what monitor is it, take a photo of the monitor PCB

[wboatwright]

Thanks for the reply.  The fuse test okay and I am getting power to the monitor.  I will check the other things and post.

Here are the pictures.

[wboatwright]

Might have found the problem with monitor?

[iankellogg]

The cap in the picture 6 is fine. the big white thing in picture 7. thats a flyback and thats physically damaged. do not turn this on anymore, that is now a hazard.


you will want to buy this
http://www.twistedquarter.com/index.php?main_page=product_info&cPath=206_208&products_id=783
or from someone else and replace the one you have broken now.
There is a chance the horizontal output transistor is also damaged so you will want to maybe check that.
http://www.instructables.com/id/HOW-TO-TEST-YOUR-TRANSISTORS-WITH-YOUR-MULTIMETERS/
you have to remove it from the monitor to test.

the transistor is most likely a 2SD870, it is a bottle cap style transistor so it isn't on the PCB but attached in this case to the metal right next to the flyback transformer (The thing the cracked)

[wboatwright]

THANK YOU SO MUCH