s plus board component gets very hot

[puckhead]

s plus, 10mz board. turn it on, the reels stiffen, the bill validator cycles. you get a brief 0 in winner paid, then no diplays.  the mpu get hot fast, and its this component getting hot.  what is it, why would it get hot? defective, or something else causing it ? i might have a bad old board somehere to steal one from.  thanks

[Stayouttadabunker]

Remove the screws that hold the MPU to the tray and look behind it.

I'd like to see what it looks like bak there.

Your board is cooking big time.

[Badbaud]

Check D3 in front of the regulator with a Ohm meter, that diode is a TVS type and when they go bad they short out.

[Trisail]

That is the 5 VDC regulator. It supplies 5 V to the entire machine. Mostly the components on the mpu but other IC's on the door pcb's. It is U47, an LM317 5V regulator. You can purchase them most anywhere, and the heatsink. Sometimes it is hard to remove the heatsink from the device without breaking it. I have the regulator and heatsink and could probably ship them cheaper than buying one each. PM if you need.
Because it supplies 5V to all the IC's, it may be difficult to determine the problem device or short. I would usually use a thermal camera and see if you could tell which device(s) are getting hot quick after power up. With the way the board is mounted in the machine, not realistic.  Would probably need to power up on a bench or see if you can disassemble enough to do it in the machine. I'm pretty sure other members have a way to bench repair the board. Could be a short somewhere, maybe disconnect the door boards that would use the 5 V to maybe narrow to the door wiring, boards or mpu. The 5 V is pretty much for the IC devices, nothing else really works on 5V in the machines.

Tony.

The TVS diode mentioned above is a good place to start.

[puckhead]

thanks to all. ive got a pile of bad s2000 boards, do they use the same diode and reg? i took a quick look, no s plus boards in my junk so far.
edit   i just looked at some schematics, no s2000 reg, its al lin that power supply. makes sense.

[Trisail]

The S2000 Vision schematic shows U78 as an LM340 5V regulator. That would work, good cross. I don't see any TVS diodes in the prints.  I will do a visual on a picture if a pcb and update later, not at my computer or near a board.

EDIT: The S2000 boards are mostly surface mount and the regulators are 5 pin devices. Does not look to me as though the S2000 boards will have anything you can use.

You can replace the regulator but -
With the machine not working, and the regulator getting hot - but still working, kind of, your problem is with some other device(s) pulling too much current. It could be a short or partial short in some wire some where, but most likely an IC device or protection device like the TVS diode. Putting another regulator in place of the one getting hot will most likely get hot also until the problem is determined to correct the over current problem. If you want to 'test' to see if the TVS diode is the problem, I would 1st use a meter and ohm it out to see if it is shorted or bad. Google testing a diode and you can try that. The TVS diode is a basic protection device - in this case it shunts voltage (current) above ~5V to ground to try to protect the devices down circuit.

I could recommend another test, but only if you are in a hurry and want to see what is bad. It would most likely be destructive and could cause more damage, possibly damage not easily repairable.

With this type of problem, trying to isolate the area of concern is best. I'm thinking mpu board itself or possibly something external.

Tony

Send me a PM if you want to talk about any of this.

[Trisail]

Quick thing to do - unplug the door display connections and see if the regulator still gets hot. I will assume it is pretty hot after you power down the machine, remove the MPU board and then notice the regulator is hot. It will be warm, but should not burn you if you touch it. Might narrow it down to the display boards at least.

Tony

[puckhead]

D3 is shorted. also , the + trace to cr12( tests good) is a bit fried from the heat. D2 checks good, as do the caps. im going to replace the regulator and D2. the diode is marked 8733.  the schematic doesnt indicate a number.  there are references in another thread to it being a 6373.  can you clear that up? thanks mike

[Trisail]

The schematic references an MPTE-5, obsolete but many replacements available. It is a 5V TVS diode. Here is a link for what Mouser has.

https://www.mouser.com/Circuit-Protection/ESD-Suppressors-TVS-Diodes/_/N-jy72?P=1y95zfoZ1yzv44wZ1yh8o3mZ1z0z819

SA5 units are pretty inexpensive. Shipping as usual.

I have the devices and can put them in 1st class USPS tomorrow, I can even ship a couple of each if you want. Even some of the other devices you may be concerned about for the same or less than what you can ship from the any of the electronic vendors. Up to you. PM me if you want.

Some numbers for others -
1N6373, SA5.xxx, 3KP5xx, 5KP5xx

Tony

Probably an electrical surge took the diode out. I am pretty sure if you replace it the board will be OK.

PS: D2 is for the 12VDC circuit so that would be a different TVS diode. 12V TVS diode.

[Badbaud]

Mic drop.

[puckhead]

i ordered the 2 parts, and will try it out. maybe i get lucky, maybe the whole board is fried.  i might wire in a 5v supply to test while im waiting.  i guess i should buy a spare board too, if anyone has one for sale, let me know

thanks

[Trisail]

Sounds good. 

Yes Alan, you have been there before. Nice job. Almost like the back of your hand by now. Keep it up.

Tony