Chameleon Technology ALC60x PSU problem, help?

[Diachi]

Hey Guys.

Got a nice ALC60x projector from Jim ( smogthemog ) the other day and it was working fine, 120mW 6 lines . Decided to open it up and add the colour card, found out that a filter cap had blown itself off, so I fixed that. Put it all back together and got it up and running, was working fine then it just winked out. Figured it was a temperature interlock, but it doesn't seem that it is. The head will still try to start and lase on the starting pulse but the tube won't light.

I tested the voltage across the anode - cathode and it read 0V, or around 89V when it tried to start ( My DMM isn't fast enough to read the starting pulse ).

Any ideas what could be wrong? I figured that it's a transistor or a relay that's packed in, but I'm not certain.

Any help would be great, some pictures to come soon.

Cheers!


EDIT WITH PICTURES:


Anode and Cathode labelled on the PSU.



Caps shown before and after repair :

BEFORE



AFTER



Beam shot from when it was working, green and blue lines split using dichros.

[mixedgas]

Dont put your DMM across the starting pulse! That results in a dead DMM. 89V, if a true reading, is not enough to start the tube. If you feel the need to read the voltage, desolder the UJT on the ignite card.

Which cap did you replace and what was its size and value? The psu you have looks like a clone of a commercial supply, so we might be able to guess what went wrong.

Steve

[Diachi]

Dont put your DMM across the starting pulse! That results in a dead DMM. 89V, if a true reading, is not enough to start the tube. If you feel the need to read the voltage, desolder the UJT on the ignite card.

Which cap did you replace and what was its size and value? The psu you have looks like a clone of a commercial supply, so we might be able to guess what went wrong.

Steve

Dead DMM eh? It's only reading 89V because my DMM is a slow, cheap DMM. Only cost me £5. Takes a while for the reading to rise to what it actually is on anything.

It certainly lases on the start pulse, so it should be arcing on that pulse? It just keeps firing though, lases on every pulse.

But, I got ya there on the start pulse and DMM

It was one of the large filter caps that I replaced, the original was hanging off when I opened it up. It's the exact same value of cap that's on it.

[smogthemog]

All I can suggest is stripping it down and checking all other components and solder joints, it is an old laser
I had the PSU bottom off before to have a look what was going on under the hood but never got around to looking at the controller.

The only time it ever played up with me is if it had been outside in my shed for a while and I struck it up - It would do exactly as you are describing but after it had struck, usually after about 5 try's, it would be OK. It likes a warm room

Quazar is the man to talk to on these as he know George Duff the owner of Chamtech.

[Diachi]

All I can suggest is stripping it down and checking all other components and solder joints, it is an old laser
I had the PSU bottom off before to have a look what was going on under the hood but never got around to looking at the controller.

The only time it ever played up with me is if it had been outside in my shed for a while and I struck it up - It would do exactly as you are describing but after it had struck, usually after about 5 try's, it would be OK. It likes a warm room

Quazar is the man to talk to on these as he know George Duff the owner of Chamtech.

Ahh right, I might strip it down and do that then. If I can't see anything wrong with it then I'll need help from Steve or Quazar.

My room is always freezing, so if the cold effects it as you say then that may be whats wrong. I'll need to turn the heating on and close the window and let it heat up for an hour or so then try it. If that fails then I'll strip it down again next weekend , took me a fair time to do it yestarday!

Cheers!

EDIT: Heating things up would be much easier if I had the fan for my JDSU argon !

[danielbriggs]

My argon was doing similar things. Turned out the umbilical cord connection wasn't in right

EDIT: Heating things up would be much easier if I had the fan for my JDSU argon !

Is it the square boxy type ones?
I think I have a spare 24V fan which is suitable. Lemme know if you want it and I'll waz it to Surfleet...
(The only thing is the onboard power supply for the fan is 115V IIRC, so you'd need an external power supply - I run mine on a 12V supply - works wonders)

[Diachi]

My argon was doing similar things. Turned out the umbilical cord connection wasn't in right



Is it the square boxy type ones?
I think I have a spare 24V fan which is suitable. Lemme know if you want it and I'll waz it to Surfleet...
(The only thing is the onboard power supply for the fan is 115V IIRC, so you'd need an external power supply - I run mine on a 12V supply - works wonders)

I've checked the umbilical, may check it again next weekend when I take it apart anyway. Maybe a pin is dead.

It is the box type, but I've already ordered a 150CFM fan for it anyway. It's just taking a while to ship.

Now that everything in this room is very hot, it still doesn't work. Cathode is lit, I've checked that. What could be wrong then?

Sometimes when I try to start it it fires a couple of times , then stops firing. It doesn't lase though, and the brewster stems don't have that nice glow about them. However looking down the bore the cathode glow seems brighter and it seems to have an almost purple glow. the cathode end brewster doesn't seem any brighter than it did when there was no "glow" looking down the bore.

It also doesn't get hot like it would if the tube had struck an arc, even if it was at a lower current

[QUAZAR]

I will ask George about this and see what he comes up with.

[Diachi]

I will ask George about this and see what he comes up with.

that's great! Gonna strip it down this weekend and see if I can spot anything myself, cold solder joint or something like that.


Will finally have some 60/40 tin/lead solder to use to repair anything that's damaged, that 99% tin stuff isn't very good

Looking forward to results.

[Hemlock Mike]

You might try warming it a bit with a hair dryer. Let it get real warm. This worked on my Lasos 50 mW. I had been over cooling it.

Mike