Bio Rad / American Laser -> Need Help Identifying the Interlocks

[turbohead]

I recently purchased a "Bio Rad" Argon Laser. It is in very good physical condition. However, I am not able to find any information on the pin outs to the "Interface" plug (on the power supply) and laser head.





Even though the power supply is marked with a Bio Rad logo, there are labels identifying the power supply and laser head as "American Laser Corporation"

The power supply Model Number is: 1P49BR00
The argon laser head Model Number is: 1H49BR00

The key was broken off in the switch, so I took the key switch apart and now have a manual over-ride.

I have plugged the power supply into 220VAC with the cable from the laser head connected. When I switch on the power supply, the switch lights and an internal relay clicks on. There is no other signs of life; probably because the interlocks are open.

I am more familiar with JDSU and Cyonics lasers (I have several models of each) and I know that one of the interlocks is that a fan needs to be connected to the laser head. I search Sam's FAQ and have not been able to find information on this laser.

I would be very grateful if anyone can help me identify the pin-outs for the power supply interface and the plug at the rear of the laser head.

[mixedgas]

You wont find it. That has a optical isolation card in it. It uses a FM modulated signal to cross the optocoupler gap from the outside world to the inside of the PSU. Each one of those LM331 is either configured for voltage to frequency or frequency to voltage operation. The HCPL optocouplers determine what is what. I have schematics for all of them but that one.

So 2 of the LM331s will be the current input channel, two will be the light input channel and the rest will be for a isolated light level output to the user. Another opto some place will be the enable for the tube. In rare cases a second opto will take it out of idle.

Light and Current will usually be a "senior wins" circuit, which ever input is greater will be selected to drive the tube.

So you need to trace out the analog inputs to the LM331s from the remote connector.
Then you need to trace the optocoupler inputs from the connector.

I'll be nice and scan in a partial schematic in the morning, but it will not be identical to what you have. Mine calls for the 37 pin connector, not the 15 pin.
Steve

[turbohead]

Thank you for replying!

It sounds like this is more complicated than "placing a jumper across #1 and #3 and add a 5k potentiometer."

I would be interested in the circuit board schematics.

Do you know if the laser head can be operated from a more common ALC power supply?

[turbohead]

I am assuming by your response that there needs to be something connected to the "Interface" plug for the laser the operate?

[mixedgas]

Yes, you need some external voltages. No on using the other ALC supplies. The Biorad head is custom with an extended life tube with gas reservoir. The ignitor board is non-standard.
The PWM controller in the PSU looks similar to ALCs scientific lasers, not the older OEM line. I'll scan a schematic at lunch time. I've labeled the board in your picture to help you get started with the reverse engineering.

Steve

[mixedgas]

Attached is the isolation schematic for a 60CP with two isolated channels. Your hope is that ALC reused the LM331 (A4) portion of the circuit on this board on your board at four places. From what I can see in the picture, it does look similar. The connector numbers on the edge of the board will not match anything in this schematic. Yourself, a technician or engineer skilled in reading schematics can use this to quickly reverse engineer what you have on the 15 pin connector from looking at the traces. You/He/She will then have to locate the optoisolator(s) or optoisolator trigger circuit also connected to the 15 pin connector for enable or idle, by looking at the board traces.

I could do it if I had the board in front of me. However that runs the risk of damaging the PSU if you remove the board improperly. Also my boss would gripe if I don't bill you about 110$ an hour for doing so. :-)

Steve

[turbohead]

Hi Steve,

I compared the schematic you provided of the 60CP to the Interface circuit board in my BioRad Power supply. The BioRad board has a 15 pin connector - only pins 1, 2, 6, 7, and 8 are used.

Although there are similarities between the 60CP and the BioRad board, I am not able to make 1-for-1 connection (see attached).

I overlaid screen-shots from the 60CP schematic onto the BioRad board where there appears to be similar circuitry and connections to pins.

Can you please take a look at my comparison and see if there are enough similarities that would tell you how to interface to the BioRad board?

Thank you for your help.

Willie

[mixedgas]

I have a 5 hour flight coming up Monday, I'll take a look while I'm airborn.

Steve

[turbohead]

Here is a better version overlying the BioRad board to the ALC 60CP schematic.

[mixedgas]

One, Light Out
Two Power in, Voltage unknown, Minimum is five volts according to LM331 Data sheet, could be more. Suspect that when correct power is applied here, laser starts N seconds later.
Six, Current out
Seven Light In.
Eight, Input ground

Note Lm311 pin 8 is supply, pin 4 is ground.

Usually Whichever is greater, current or light input, wins. But that also depends on jumpers elsewhere.

Note pin 2 goes off somewhere else besides powering the LM331. This will be the "RUN ENABLE"

Slowly ramp up a variable power supply on pin two. Start at 5 volts. Have at least 2 volts on one of the inputs so the tube catches. Don't be surprised if there is a minimum current or a maximum current trip. ALC set their supplies up for 35 second delays, it may take a while.

Steve