9" S+ power supply fuses

[racergiant]

Hey all -

I've had my only slot - a 9" S+ for almost 2 years and all the sudden today the "middle" fuse of the three fuses on the front of the power supply blew out.

The fuse I pulled out of it was labelled F8AL250V.  I'm old enough to recognize that it's a simple glass automotive type fuse. 

Is that the correct rated fuse?

What would cause the fuse to blow? 

I do turn off the slot everynight.  Would the power surge every morning when I turn it on be enough - over time - to cause the fuse to blow?
The lower glass flourescent bulb is burned out - could that be the cause?
Is there something I should put a meter on to check power?

[stayouttadabunker]

Racer,
Any 8A 250V quick blow fuse will work in the middle fuse holder on your power supply.
Don't use the slow blow fuses...the 8 amp fuse filament looks like a thin, wavy silver wire.
The slow blows look like a thick, off-white ceramic...don't use these.
They take too long to blow.
By the time they blow, something in your machine will fry.
You want fuses to blow as quickly as possible to save your machine.

I'd start pulling the wires at the connections anywhere that's involved with your fluorescent light.
See if they are loose at the connections and repair them before you turn the lights back on.
One way to test is to pull the corresponding light molex plug out of the top of the power supply.
Turn on the machine, if the fuse blows when you stick it back in and turn it on -
then you know somethings wrong with that lighting harness somewhere.

Remember, you're dealing with 115Volts AC. Turn off the power before
removing or re-installing molexes concerning the lights.
IGT used color coded 115VAC wires as black and white w/red stripe.
Click on the picture to see the thin, fuse wire inside the glass tube clearer...! >>>

[racergiant]

So I guess it would not be a good idea to replace the 8 amp fuse with a 10 amp fuse...   LOL

I guess I'll have to make a stop at Radio Hack (oops - did I forget an "s"?)

Thanks!

[racergiant]

Well, I replaced the 8 amp fuse.  

When I turned on the slot I heard a hum coming from the power supply area.  Couldn't hear the fuse pop because the bill changer started it's startup routine.
Maybe the power suply went bad?

How hard is it to take out the power supply from the cabinet?  I figured I'd open it up to see what I could see.

[rickhunter]

Pretty easy, couple of retaining screws and you are done.

[racergiant]

Checked out the inside of the power supply - everything looks normal (?)

Put the power supply back in and plugged things in one at a time.  When I plugged in all the connectors on the top the middle 8A fuse was fine.  As soon as I plugged in the big connector on the side the hum came back and the fuse popped.

Decided to put in my 2nd board and a fresh fuse.  Things were fine.

Looked at the 1st board and it seems that the component at U47 may have given up.  The big capacitor directly below the U47 heatsink and the smaller cap above it have a coating of that brownish powder.

What is that component at U47?  (and where would I get a new one?)

[jay]

A picture is worth a thousand words.....

[stayouttadabunker]

I'm afraid it might be worse than you think.
It might be a lot cheaper to buy a back up MPU board from one of our vendors,no?

Look down on this list I've posted up for you.
You'll see the U47 part you're looking for...

From there you can enter it in a search on a website like mouser.com
and see if they have it for ya!
Click on the photo to enlarge it!>>>

[stayouttadabunker]

I typed in the mouser search box the number "LM317T" and
this is the list of parts they have available.
You just have to match one of them up with another number
on the U47 part description I posted above^^^

It appears to be a 1.5Amp Regulator that is covered up with a
huge heat-sink to dissipate the heat it puts out.
Looks like a simple fix...
Unsolder three pins and solder in your new one and put the heat-sink back on it.

However, that may not be the end of your problems with that board...
that's why I recommend you to ask our vendors for a replacement S+ MPU board...
it may be a lot easier than doing board repairs when you don't have the parts on hand.

http://mouser.com/Search/Refine.aspx?Keyword=LM317T

Here's a photo of this puppy!
Click on it to enlarge...>>>

[racergiant]

Yes - that's exactly the component that I was talking about...

Like you were trying to tell me...  You can replace the chip easy enough but...   Did it blow on it's own or did something somewhere else cause it to pop?

I guess I will look for a replacement.  Anyone have an S+ 10 mHz board for sale?    PM me, please...

[Jim]

your problem is not with U-47, that 's the +5vdc regulator,and its ac voltage comes from the 24 vac which is controlled by F-1 the 6 amp fuse. I believe your problem  is with the 8 vac  which is controlled by F-2 the 8 amp fuse. I would check CR1 and CR2  and D2. you will probably find one of these shorted. these components along with C21 and C23 make up the power supply for +Vb.


Jim

[racergiant]

Thats why this site is so great.   We have people here that know circuit paths and can tell you which components to checlk.   K+ to you Jim...

I checked CR1, CR2 & D2 - they "look" ok...  However...  CR1 has a dusting of powder under it and from the backside the board is darker than the surrounding area probably due to heat.

C21 and C23 both have that same 'dusting' of powdery substance around the base. 

I'm just going to look for another board...

Thanks Jim ! !

[Jim]

the only true way to know is to check them with a meter, set the meter to resistance (ohms) test . check the component both ways (black and red leads one way , observe the reading, then reverse the leads and observe the reading.

Jim

[stayouttadabunker]

What would be a good reference material for these fellas to use to help these guys
know what are acceptable limits  when cross-reading S+ board components with an ohm-meter?

[Jim]

Mark    the only way is to actually test them out of the circuit, this way you can see what readings are typical  and then when you test in circuit you have a rough idea of what it should be. The diodes in question CR1 ,CR2 : only work one way , meaning they will conduct current in one direction only.so when you put a meter across it ( there is a battery inside your meter that is used to check resistance) this battery has a polarity to it ( +, - ) so depending on the polarity of your meters leads , when you place the black lead on the cathode side ( the side of the diode with the Line on it) and the red lead on the side of the anode ( the triangle) you forward bias the diode and you will get a Resistance reading. when you reverse the leads you are reverse biasing the diode and you will get no reading,  so if you test a diode and you get a reading both ways the diode is bad ( shorted) if you test a diode and you get no reading either way , then your diode is open.  usually you would set it on the X1k scale.
the best way is to get some diodes and just check them with a meter and you will get used to the readings.
D2 is a zenier diode  works a little different, but still readings only one direction  probably higher than with signal diodes.
Hope this helps
Jim

[stayouttadabunker]

It does help Jim...
The pinball guys have it all written down with specific read limits.
The slot guys really have nothing like that at all.
The cool thing about pinball boards are the TP (Test Points) where you can
check various components to see if they're putting out the right voltages.
I would like to undertake a reading of every board component in an S+ so this may help others in the future.
Luckily, many components are of the same types.