PDA

View Full Version : Working fuse doesn't work!



pinnies4me
28th July 2008, 07:40 PM
Anyone else come across this problem before? Trying to track down why I had no playfield lights on a Gottlieb System 1 game (and yes, all relevant connectors repinned etc). I had run out of ideas - even replaced some stuff in desperation like the bridge rectifier which was reading a tiny bit off, all to no avail. So I started again - first the fuse - yes works - then.... hang on, for the 10 cents I'll just replace the fuse... Now it works! I don't know any way to test a fuse except for continuity, and it works, but somehow it doesn't pass enough current to power up the lights.

Any gurus out there able to explain?

David_AVD
28th July 2008, 07:45 PM
Sounds like the fuse wire was not connected properly at one of the end caps. Pressing the meter probes on the ends brings it good for the test. Release the probes and it's open circuit again.

You normally only see this with the larger amperage fuses where the "fuse wire" is more like a fuse bar. They're internally spot welded I suspect but the welds break. Lower current fuses where the wire goes through the cap ends and is soldered don't suffer from this problem.

LOTR4U
28th July 2008, 07:48 PM
I had/have the same problem, continuity works but the lights don't :confused:

The fuse kind of half blows but not fully. :unsure

pinnies4me
28th July 2008, 08:07 PM
Sounds like the fuse wire was not connected properly at one of the end caps.

That was what I thought, but even the lightest touch, even on the side rather than the ends still works with the meter.

David_AVD
28th July 2008, 08:09 PM
It must be intermittent or have a cracked / high resistance joint internally. See if you can pull the end caps off.

pinnies4me
28th July 2008, 08:09 PM
The fuse kind of half blows but not fully. :unsure

Well I am adding to the Gottlieb System 1 rebuild checklist:

1. Repin all connectors;
2. Repin all connectors;
3. Repin all connectors; and
4. Replace all fuses forget if they seem to test OK save the three hours chasing your tail....


See if you can pull the end caps off.

Nope, tight as a drum!

AskJacob
28th July 2008, 08:32 PM
Must only just have the last whiff of magic smoke left inside it then. Slow leak:lol

You can test the fuse in the board and under load by measuring voltage across it when powered up.... 0v to .1v or less and the fuse is good, if you see more than that fuse is bad, but not blown bad.

Cheers

dj10555
28th July 2008, 08:58 PM
Was the fuse tarnished or corroded or the fuse holder corroded? Did you measure the resistance or check for continuity? Its got me wondering what the fault was. I think you did pretty well to find the problem after 3 hours.

Strangeways
28th July 2008, 09:03 PM
Anyone else come across this problem before? Trying to track down why I had no playfield lights on a Gottlieb System 1 game (and yes, all relevant connectors repinned etc). I had run out of ideas - even replaced some stuff in desperation like the bridge rectifier which was reading a tiny bit off, all to no avail. So I started again - first the fuse - yes works - then.... hang on, for the 10 cents I'll just replace the fuse... Now it works! I don't know any way to test a fuse except for continuity, and it works, but somehow it doesn't pass enough current to power up the lights.

Any gurus out there able to explain?

I can't explain it - covered on the thread already...

But it has happened to me once before.. 5 Amp SB fuse in a TAF.. No matter where I used this fuse after isolating it - it never worked... Yet it had to have worked at some stage. Measured fine with the mutimeter....

LOTR4U
28th July 2008, 09:08 PM
I can't explain it - covered on the thread already...

But it has happened to me once before.. 5 Amp SB fuse in a TAF.. No matter where I used this fuse after isolating it - it never worked... Yet it had to have worked at some stage. Measured fine with the mutimeter....

Same with me :( 5amp slow blow. :cry i want my mommy!

pinnies4me
28th July 2008, 09:55 PM
Same with me :( 5amp slow blow. :cry i want my mommy!

OK, that's spooky - mine was a 5 amp slo-blo too! :)

ToyTech
4th December 2008, 08:56 PM
Ahhhh the old "fuse-works-but-it-doesn't" dilemma.....


2 things i learnt many years ago was never judge a fuse by looking to see if the wire is in tact (they often break up inside the endcap) and 2, never measure a fuse by measuring on the actual fuse itself, ALWAYS measure on the fuseholder clips, or, better still, on the next closest component legs.

This method will prove that the fuse socket is actually working too and no dry solder joints.

Pressing a probe onto a fuse (or fuseholder) can often re-engage a loose solder joint underneath, and removing the probs will relax the connection 'open' again.

These dodgy checks are usually faster to eliminate by re-soldering the obvious connections underneath the PCB.

Hope it helps ;-)
Marty.

Fish Tales
4th December 2008, 09:19 PM
had a 5amp blow in my nugent the otherday. To look at it you would swear it was fine.

ToyTech
4th December 2008, 09:57 PM
...and you'd expect it to at least be black or silvered glass inside, but nope, clean as a new one.....very sneaky failure.

David_AVD
4th December 2008, 10:40 PM
How's this for coincidence - I read the last couple of posts, went to play my FS and the GI circuit was dead. The 20A fuse had fractured internally (at end cap) since yesterday! :rolleyes

ToyTech
4th December 2008, 11:10 PM
That's weird, i went to play my machine during all these posts, and my GI has blown it's 20amp too, and it still 'looks' ok, but it's open.

Tomorrows job will be to trace yet another shorted globe or dodgy wire ;-)

David_AVD
4th December 2008, 11:18 PM
I think we've entered the "Twilight Zone" !!! LOL

ToyTech
4th December 2008, 11:26 PM
I knew i shouldn't have come in here trying to help ;-)

Damn fuse virus !

Fish Tales
5th December 2008, 07:06 AM
Yep seems like the govt has ordered power companies to spike our appliances....this is to promote spending and stimulate the economy
;)

ToyTech
5th December 2008, 10:51 AM
someone should stimulate the government with a spike, and soon !!! :evil

pinball god
5th December 2008, 10:16 PM
Ahhhh the old "fuse-works-but-it-doesn't" dilemma.....


2 things i learnt many years ago was never judge a fuse by looking to see if the wire is in tact (they often break up inside the endcap) and 2, never measure a fuse by measuring on the actual fuse itself, ALWAYS measure on the fuseholder clips, or, better still, on the next closest component legs.

This method will prove that the fuse socket is actually working too and no dry solder joints.

Pressing a probe onto a fuse (or fuseholder) can often re-engage a loose solder joint underneath, and removing the probs will relax the connection 'open' again.

These dodgy checks are usually faster to eliminate by re-soldering the obvious connections underneath the PCB.

Hope it helps ;-)
Marty.

That kind of happened to me. Fuse ok but dry soler joint on fuse circuit on my ToM GI. Was down for weeks coz it all checked ok.

Ballypinball
5th December 2008, 10:24 PM
most people check fuses in curcuit

you cant, do that

as it reads back through the board.

List one end

ToyTech
6th December 2008, 12:50 AM
Yep, that one actually caught me out today, i wasn't thinking about the transformer secondary and all the lamps acting as en entire loop that would appear as a short (or low ohms) across the fuseclip.

Once i drew out the basic circuit on paper, i saw immediately that the fuse needs to be removed of lifted at one end and measure the fuse itself.

I bet that's a sneaky gotcha for a lot of people.



most people check fuses in curcuit

you cant, do that

as it reads back through the board.

List one end

Ballypinball
6th December 2008, 12:54 AM
it happens a lot, one guy replaced all the transistors and some chips etc, dropped his board in for repair to us.

I called him as he was driving down the road to say its fixed.