Faulty Opto's

[ktm450]

I am having problems with the two optos in the ball lock on a TZ I am restoring.

A bit of fault finding:
The transmitter should always be 1.4v which it is.
The reciever should be 0.1-0.7v when the opto beam is unblocked and 11-13 when blocked.

These two particular recievers are showing approx 12v unblocked.

Tried cleaning the sender and recievers with windex, no change.

Was a bit unsure if it was a faulty connection as two optos so close together are playing up (but there are other optos on the same switching column that work fine) so unpluged connections cleaned with contact cleaner still no good.

Unscrewed optos from game, if you move them very close they actually work, but the recievers voltage only drops down to approx 6v.

Tried the trusty torch method and the voltage on the reciever dropped down to the correct 0.1v

This would suggest to me that the senders need replacing, am I correct?

If so are the 5mm infra red LEDs from Jaycar a good replacement
http://www.jaycar.com.au/productView.asp?ID=ZD1945&CATID=&keywords=ZD%2D1945&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

As Williams only supplied optos as a whole unit with bracket, it is hard to find any info on them, so hopefully someone can steer me in the right direction.

Thanks,
Matt.

[slammer]

They are the same LED I used when rebuilding the optos in my Getaway, they worked perfect.
Just carefully desolder the originals and solder in the new ones.
Take your time on it.

Cheers Angelo

[Nug]

also if the gap is large (think JD crane exit opto) then only the correct spec will work, the Jcar stuff is fine for trough...you can actually verify this very quickly by using a digital camera (phone!) and "see" the IR leds output brightness,etc sometimes they need slight 'misadjustment' if you know what i mean (off centre focus)

i just noticed its the ball "lock" trough trouble with, double check connectors for good IDC condition.

 
__________________

[ktm450]

Thanks guys 

[ktm450]

Fitted new opto senders yesterday, both working perfectly now 

[pinball god]

Had a similar problem with my new single board clock PCB. Tried lots of things and then the manufacturer sent me the you beaut ones and haven't looked back. Good to hear you solved your problem. I've taken some notes from this thread for future ref on my TZ

[Marty Machine]

Hi Guys,

Interesting fault.
It makes me wonder why the IR LED 'senders' would go faulty though? is there a design flaw and theyre running the wrong value current-limit resistor to the IR LED sender ???

LED's will work seemingly forever, and to see that a few machines are dropping LEDs smells like it'll happen again unless the fault truly cured.
The new leds may work now, and might even work all next year, but it may also be sloooowly frying away.

I'd love to see a circuit and see what's really going on in there 

Good Luck,
Marty.

[Pinball Fixers]

Hi Guys,

Interesting fault.
It makes me wonder why the IR LED 'senders' would go faulty though? is there a design flaw and theyre running the wrong value current-limit resistor to the IR LED sender ???

LED's will work seemingly forever, and to see that a few machines are dropping LEDs smells like it'll happen again unless the fault truly cured.
The new leds may work now, and might even work all next year, but it may also be sloooowly frying away.

I'd love to see a circuit and see what's really going on in there 

Good Luck,
Marty.

Actually, LED's do not last forever. They usually start to get dull over time, then eventually die.

The transmitter (IR) LED's are on the whole time the machine is on, so they will eventually fail.

The circuit on a Williams/Bally pinball is 12V going through a 270ohm resistor, through the IR LED to ground... that's it.

[Marty Machine]

aahhh 270ohm is far too low for 12v.
should be 560ohm (for 20mA) or upto 820ohm/1k for longer lasting.

MM.

[Pinball Fixers]

aahhh 270ohm is far too low for 12v.
should be 560ohm (for 20mA) or upto 820ohm/1k for longer lasting.

MM.

Yes, 560+ ohms for 20mA forward current, but the IR LED's used in the Williams pinballs have a max of 100mA forward current, so 270ohm (50mA) should make them last that bit longer, while having their viewing angle close to max for best operation.

[Marty Machine]

Fair enough, they can suck more juice, alrighty then 

MM.