Kyoraku sun scarlett fuses blowing

[Agent21]

So the power supply from the transformer to the motherboard keeps blowing is 3 amp fuse. The only alterations I have done to the motherboard is replaced 2 caps in the power circuit that were leaking/buldged. I used the same value caps. No bridges I can see. Any thought? Startimg to think the transformer has blown. Its a 12-24v 1.79 amp. I was getting 16v ajd 2v out of it, now getting zero.20240908_192447.jpg 20240908_192447.jpg20240908_192529.jpg20240908_192529.jpg20240908_192529.jpg

[Agent21]

Ok back to 16.3 volts out of the fransformer on both sides and blowing both fuses

[Drunkenclam]

Has the machine ever been plugged into a mains supply without a 24v step down transformer?

I'm not good with switching voltage PSUs as that's more advanced than basic electronics.

[Agent21]

So the step down transformer is built into the unit. To my knowledge it has not been over voltaged with 110 but the previous owners had just used this as wall art. I have managed to get everything cleaned and working, just need the mobo to power on for the electronic sensors and leds. Working on getting some 3 amp circuit breakers for easier/cheaper diagnostic.20240831_235851.jpg20240831_235851.jpg

[Drunkenclam]

I would remove all other wires execpt for the incoming 24vac supply. Then check the state of the diode marked DZ1

http://www.learningaboutelectronics....-a-zener-diode

[Agent21]

I think I also found another cap that is burnt. I have replacements for the whole board but I have been trying not to introduce new variables. Will check the diode tonight.

[Agent21]

20240909_211545.jpg Ok the two caps with lines on them show internally shorted. One is power circuit, the other sound. Zenor checks out find 490 in one direction, infinite in the other. Voltage regulator tests bad, shorted input to ground. Its a 78005ap which seems to be hard to find. Should I replace the shorted caps? They oddly aren't the burnt ones. Side note huge Top Gear fan, you got kicked out by the original hosts?

[takethecastle57]

Capacitors have a best by date of around a Decade especially the electrolytic ones so alot of components rely on the capacitors to be within tolerance . It's just good to replace the capacitors just so the other components are happy.

Just my Two Tokens worth .

[Drunkenclam]

It certainty would be better to replace them.

Judging by the data sheet the 78005 is quite a high current. Compared to other 5v regulators

Yes. It was the original host of Jeremy Clarkson. The clip was also being used on BBC America's episode preview on their website for a while.

[Agent21]

I'll get working on the cap replacements. I also have another 78005ap coming. So this transformer is a 2 channel putting out 16.3 volts on each channel. The mother board also has 2 fused lines coming out of it with 3 amp fuses. There are about 8 20v 48amp bulbs controlled by the board on the playing field side. As well as the reel leds, the hal sensors for when the balls go through the start tulips, one solenoid for the jackpot mode, and some random small leds. The bulbs might be why there is so much voltage. I can't see much more to replace on the board.

[Agent21]

UPDATE: Ok its not blowing fuses anymore, though they are circuit breakers now. The speaker is making a humming noise and voltage is going through the board. However the D880 transistor in the power circuit tests bad and there are no other signs of life, IE the LEDs or light bulbs. So now ordering the D880

[Drunkenclam]

Glad your making an effort to save this machine.

[Agent21]

D880 is in, 5 volts to the cpu and nadda. No response. Now kinda stuck.

[MrGneiss]

I really wish I knew about electronics!! It's really cool that you've been trying to save this poor machine!!

[Drunkenclam]

by the looks of it. in standby mode. the only thing to be lite is the 7 seg display

https://www.youtube.com/watch?v=SNnHqKy5oCc


for fun?

https://aucview.aucfan.com/yahoo/g1039944921/

[Agent21]

I got no leds or the seg display. I am worried now the z80 got blown when the voltage regulator and the d880 blew up. I reflowed the cpus and still nadda. The speaker just squeals and voltage is coming out of the board but nothing lights up.

[Drunkenclam]

Its all behond my skill level

[Agent21]

Big Progress! Replaced the z80 cpu, which had a large scorch mark below it on the mobo, and boom! lights are on and obnoxious music plays!!! Still going to need more work though. Lcd reels still not lightining and nothing happens when you put a ball in a tulip. 20241016_232657.jpg20241016_232657.jpg20241016_223631.jpg

[takethecastle57]

[MrGneiss]

Yay, obnoxious music!!