Tech: Help with Whitewater Opto (general understanding needed)

[Max Pinball]

so my whirlpool exit opto is not working and I really don't understand
the basics to this.

The emitter seems to be emitting when I view this under a digital
camera. ok.

the receiver, has 4.5v to both sides of the bulb legs (not sure that
is what it should be or not).

The opto does not register in the switch test.

I changed the reciever board w/ led and that did not fix the problem.

Pinwiki details about optos is WEAK...

help is appreciated. thx.

[cal50]

I think you should be seeing 12 volts at the power supply connector for
the transmitter opto.

Shine a flashlight into the receiver opto and see if it registers and if
its does its the correct switch number. There should be a voltage shift
/ change on the receiver legs if it registers.

Likely a bad LM339 is my guess.


I had a JY that threw switch errors from a bad opto. The replacement
opto (receiver) was put in the wrong way. The indexing flat matched the
stencil on the board but it registered wrong. I turned it 180 degrees
and all was well.

Send me a email / PM and I can give you some trouble shooting info.


--
cal50

RGP Archive and posting Gateway
This USENET post sent from http://rgparchive.com

[Tony @ GLM]

The receiver opto acts like a variable resistor. One leg is tied to
12V and the other leg is tied to the opto driver board.

When there is no light shining into the receiver, the opto has a very
high resistance, like 200K and higher. If you are reading a voltage
directly across the receiver, you should read something pretty high,
like 10 to 12V.

When light is shining into the receiver, the resistance drops to 2K or
less. A volt meter reading should give you something less than 6V or
so.

So if you have blocked all the light coming in and it's still reading
low, the receiver is likely bad.

This is assuming that 1) the opto is installed correctly and 2) the
opto driver board isn't the problem.

As I mentioned above, the receivers act as a variable resistor, so
another test that you can do that is easy and can eliminate opto
driver problems is to unplug the optos from the opto driver board and
then use your resistance setting (2M Ohms usually works fine) and
measure across the receiver. Generally I'd expect to see 200K or so
for a _good_ receiver with no light shining in. I have seen them also
in the 47-60K range, but those I generally replace.

With light shining in, the resistance should be around or less than 2K
Ohms. You might want to compare values against ones in your game that
DO work, just for comparison.

Hope that helps!

Tony
www.greatlakesmodular.com - Re-Engineered Pinball Parts!

So if you block the transmitter, the

[Max Pinball]

thnaks, I believe that when I was testing this, the game was on
(obviously) and that the emitter was shining into the receiver. I
tested each leg of the led (other DMM lead was to ground) and I got
4.5v ish on each leg. I will check if the voltage goes high wne the
light beam is blocked.

If the voltage does go high, and low when the beam is shining that
would indicate the opto is working properly, but not registering.

Does that then get me back to the problem being at the opto driver
board. I never once had an issue with this, maybe I have been lucky.

[Tony @ GLM]

Ah, okay, well with the DMM lead referenced at ground, the numbers you
will read are the opposite of what I mentioned before.

So when referencing to ground:

When the opto doesn't have any light shining into it, the voltage
should read low, and when the opto has light shining into it, it
should read high.

You should definitely check the values against other working optos in
the game.

A good way to do this is to just measure the voltages at the opto
driver board. The 7 opto board has 3 headers, the large main power/
switch matrix header, and then the two smaller opto connectors, one is
the transmitters, one is the receivers.

Remove all the balls in the game and make sure all the optos are not
blocked. Then measure the voltage at each pin on the receiver
header. This should give you a good baseline reading for all the
receivers when unblocked.

Then unplug the transmitter header (effectively blocking all the opto
switches) and then measure the receivers again. This will give you
the baseline reading for all the receivers when blocked.

Just a note, sometimes a receiver may be positioned very close to a GI
lamp and can cause a false reading. You may need to physically block
those receivers to get a proper reading.

[Beemus]

May be worth replacing BOTH the receiver and opto as a pair with known
matching components.