Omnichrome 532 Argon help needed.

[jeff]

Unfortunately I don't know anyone with a 532 head to test the PSU with or vice versa.

One thing I noticed was the AC LED on the laser head does not turn on. So what would your suggestion be in this case?

I do hear the cathode heat delay relay click 38 seconds after turning the key. It's clearly audible.

Edit2: Connecting pins 1,25 and 6 to the wiper on the 100k pot. I did not get anything different. (This is with pins 36,37 connected.)

I'll get back to you after I do further testing.

Edit: on the note of age, I am over 18. I'm actually 25. Not sure if you remember me but we met last year at Selem. I had the blue hair.

[mixedgas]

For the Head Led:

Check fuses line F6 and F7.

IF the LED is good:
Low Voltage PS -15V is missing to the LED in the head. Suggesting the LVPS is damaged or something is shorted on the main board. Check Fuse F2 (1.5 amp) on the main board. Some of the fuses are "microfuses" that look like small resistors, but are fuses. Then see if you have +/- 15V. At VR1 and VR2. Pinouts for the LM7815 and LM7915 are on line in data sheets.

Assuming F2 is good:

If +15 is present the supply will try to start. If -15 is not present he supply t will have no feedback control and not much will happen. Check the 7915 voltage regulator, the diode D2, and the surrounding capacitors C2, C5, and C6. Diagram is in upper left of Sam's redrawn schematic. I'll post the actual schematic soon.

So here is the power subsection:

http://www.repairfaq.org/sam/150rpsch.gif

See description also attached.

Steve

[jeff]

Okay, if these are the F6 and F7 fuses. The fuse with the blue rings, is blown. It reads 0 ohms of resistance which leads me to believe its blown.

I have some glass fuses here (if these are the fuses in question) but none near that tiny. Let me know if I should look for a specific value fuse to rig up or bypass these.

http://imgur.com/a/2cRbY

Edit: Okay after reviewing the photos on my laptop. These are clearly fuses.

Edit2: Okay, I'm pretty sure these are the F6 F7 fuses which are 20A fuses. I checked and I have some SFE 20's I could replace the bad one with. Would you suggest doing this or do I need to replace the bad one with a special microfuse. I also do not see any other fuses on the board.

I also noticed this capacitor that is shorted out. I'm not sure of its supposed to be or not.

http://imgur.com/92Gt9Bg

[mixedgas]

Fuses read zero ohms when good. Much more then zero ohms, ie infinity, when bad. Fuse reading should be about the same thing you see when on the low Ohms scale and your test leads are shorted, for example.

The worse problem in that picture is that the gate clamp Zener diode has been deliberately shorted by a jumper. Which means everything in the Gate circuit needs replaced.
You need at least the .1 uF 50V capacitor, the 1N4744A Zener, The 1N914A Diode and possibly the Power FETs.

We need to see why you don't have the low voltage first. With that short in place you have no drive to the FET gates, so it wont have ANY anode current, which is one of the reasons its not starting.

This is not going to be a quick fix. In fact its a mess. Have patience.


Steve

[jeff]

Sorry for the misunderstanding on my end Steve. Let me rephrase. The green fuse reads 0 ohms. The blue one doesn't give me a reading. I am quite sure it's blown.

[mixedgas]

Ok, so one of the microfuses is blown. That was expected, on nearly every one of these I've ever repaired, a microfuse was toasted.

Which of the following is not working? May be more then one.

Head Fan
PSU Fan
Low voltage PSU

Each of the above uses a microfuse. The question is which is which.

See fuses circled in red in this schematic:

F6 and F7 are going to be big 3AG size fuses. You need to find the big fuseholders. The cathode would be not glowing if they were bad, so ignore them for a while.


Note blue red and black dots corresponding to Ground, +15 and -15V control supplies. We need to measure those next. Attached is drawings of the regulator pinouts, where to put the meter probes. The tab is away from you, the black regulator body with numbering is towards you, in that view.

[jeff]

Mariomaster would like to know if we could use a JDSU Uniphase 2201-40MLA PSU to power the 532 head.

F6 and F7 are going to be big 3AG size fuses

OH those! Yes those are both fine. They were the first thing I've tested. Okay I understand a bit more how this schematic works.

Which of the following is not working? May be more then one.

Head Fan
PSU Fan
Low voltage PSU

Moving on. The head fan works. The PSU fan works but doesn't kick on until the relay triggers after the key is turned. I'm not entirely sure about the low voltage power supply yet. Have not gotten that far.

Going to locate the rest of these fuses that you have marked on that schematic and update this post.

[mixedgas]

[QUOTE=jeff;289085]Mariomaster would like to know if we could use a JDSU Uniphase 2201-40MLA PSU to power the 532 head.

Not easily, would be a major conversion project. Unless he has a dead JDSU head with working ignitor to hack.

Steve

[jeff]

I'm going to take a break on this project for today. Some things came up. Steve, I can't thank you enough for the one on one help. It means a real lot to me. I'll get back to this project tomorrow I hope. Mariomaster does not have a spare JDSU unfortunately. All his are working.

[mixedgas]

I'm going to take a break on this project for today. Some things came up. Steve, I can't thank you enough for the one on one help. It means a real lot to me. I'll get back to this project tomorrow I hope. Mariomaster does not have a spare JDSU unfortunately. All his are working.

Please Lift up/unbolt the grey insulating cover board on the heatsink, to see if the previous owner left you any more "Easter Eggs".
Then the goal is to get the negative rail up and gate drive up. I'll be glad to make you a list of parts to replace before refiring the unit, but I have to ask at what point your time and labor starts to exceed the cost of a used and tested unit off Ebay? If you wish to learn, I'll be glad to help you continue.

Steve