Laserscope 800 / ALE YD4 Arc Lamp Power Supply

[planters]

An affirmation from Sir Planters is very much appreciated. I'm not even in your league.

Don't be silly, just don't give up. The existing ALE is a great starting point.

When I said you could modulate the current, I meant REALLY modulate it. I had looked into (thought experiment only) taking the existing LS head and adding an additional flash lamp pulsed pumping source to goose the rod, however, why get so complicated? If the existing power supply can provide an increased current to the lamp and this is coordinated with the cavity dump of the Q switch then the average power to the rod might remain constant, but the power is input when the cavity is actually lasing. The efficiency of energy storage in the crystal can't be 100% between Q switching pulses. Also, the heating of the crystal would more closely follow the energy output of the crystal. It would be periodic. The beam quality might also improve?

What about modulating the output for marking or display? You might avoid a galvo modulator.

[dave]

Q1 on the trigger board is indeed a diac. The schema set I have here shows it as a 1N5761 ( Q1 on the trigger board ).. Looks like it could be a difficult part to locate tho. A quick search with www.findchips.com came up with nothing, and although it seems like there is a NTE equivalent, I try to avoid all NTE 'equivalents' like the plague as they usually aren't very close at all.

Hope this helps

edit: These guys here have them. http://store.americanmicrosemiconductor.com/1n5761.html wonder what this company is like? Any experiences anyone?

[turbohead]

I have bought from American Microsemi for some very old transistors for a CDV-700 Geiger Counter.

It seems I would be able to find a diac with similar properties as the original 1N5761.

Would you be willing to post the schematic that shows this component?

Thank you for your help!

[dsli_jon]

Heya Turbo -

..if you could please let me know what this part is so that I can order the correct one,..

..Yep, as Dave states, the 'Q1' is a diac.. Most-specifically, a 32V 'trigger diode', and, as a diac, it's 'bi-directional' (..which is a) why 'ohming it out' = ∞ and b) why the 'stripe' is in the Center, since it don't matter 'which way you stuff it'.. Why it was 'bad' <shrug> but I certainly believe you that it was, and, yes, if it's borked, it won't trigger the next-chochkie, in line, which-is..

..As-to the 'spark gap' (..and, this is why I didn't recall the 'form-factor' / ever-replacing "the spark gap"..) in the -LS models, there *isn't one*.. Well, at least not a 'typical' one.. See the big ol' honking SCR, there? *That's* used as the 'spark gapper', in the -LS, and, ya - if it's also borked, you won't light the lampola..

..Still, this was a 'good excersize thread', here, since I'd always thought / understood that it was just a 'regular-ol SCR', didn't know they used it for 'the gapper' (but, it makes perfect-sense), so.. learned-somethin, today.. As-to 'replacement', well that-one should be fairly-easy to find.. I have a couple-spares in the NY road-box, and I have replaced those before, so, nothin doin.. When they are disconnected, anode > cath should be ∞, so if you see any 'leakage', time to 'pop' for a new one..

..ALSO, this 'lesson' underscores the 'danger' of trusting what was posted on 'DJ Doomsday's site, there.. There's quite a bit of *incorrect* / non-ideal info, and that has burnt many-a forager, in so-gleaning.. ie: The ideal 'control diagram' for the YD-LS, is *not* the one published.. (..I mean, come-on.. Are you *really* gonna put slinging 40W average-power KTP-beams (w/ kW peaks, mind-you..) in the hands of a 'bar-napkin sketch' drawn by some guy named "Spankey"?? )... Nor is it the same for a 'stock' -4 or -6... The one ALE-supplies with the -LS service manual, is, and no, Sorry, won't be 'published, here', at least not by me..

..And, I don't think schems are appropriate 'public-fodder', either.. What you 'do in PM'? well.. that's yer business..

.02
j

[Draco]

kinda off topic but it is about the spark gap thingie by Bourns, I used to come across them along on the ballasts to DLP and Sony's Failed LCoS projection tvs and in HID ballasts quite a lot. i have never seen one fail but have seen them light up when there is a lamp strike fail, but in that application they act to shunt the high voltage to ground and protect the rest of the device from the high voltage that would have fired the lamp

[turbohead]

Q1 on the trigger board is indeed a diac...there is a NTE equivalent...

UPDATE: I replaced the defective diac with the NTE equivalent (NTE6408) and the trigger board is now operational!

[turbohead]

The power supply is now exhibiting another issue. After the arc lamp lights and is manually extinguished, subsequent attempts to light the arc lamp first results in a over-current error on the power supply front panel (an LED indicator light). After resetting the power supply, the over current error does not occur. However, another attempt to strike the arc lamp cause the over current error to occur again.

Does anyone know if any of the trim pots on the control board sets the sensitivity of the current sense circuit?

[dsli_jon]

The power supply is now exhibiting another issue.

a) Which supply, the -4? or the -LS? And, b) Which 'controller diagram' are you using to control this all, the ones DJ Duncecap posted?? >_< Lemme know / go from there.. You should *not* need to be adjusting 'current sense pots' (unless You adjusted them..) Something else is borked / fried, OR, it's a controller-issue - yet again..

j

[turbohead]

This is for the YD-LS power supply.

I made a "controller" based on the one posted on the web by Mr. DJ (redrawn version). I checked the wiring diagram posted on the web with the interlock diagram in the manual available from TDK-Lambda, and they agree:

http://www.us.tdk-lambda.com/hp/product_html/legacy.htm

The controller works on my other ALE without any issues.

The over-current LED only switches on intermittently. Even when I run the attached ND:YAG laser at very low power, the over-current error come on.

Let me know what you think. Thank you!

[mixedgas]

Mr DJ's schematic does not line up with ALL YLS. Not to mention he has the ribbon orientation FUBAREDed. I finally just pulled the bloody interface card and reverse engineered it to produce my own proper documentation.

It also helps to run the opto inputs off proper current sources, instead of his resistors. SOME ALE show marginal function if the OPTO LED bias current is not correct.

Steve