Spectra-Physics Millennia Vs SHG tower temp regulation problem

[iggythebrush]

Hello fellow Laserjocks,

I'm having issues with my Millennia Vs. There is a problem with the tempertaure regulation circuit of the SHG tower, so that the oven is permanently on, the SHG crystal rapidly overheats and the pump diode supplies go overcurrent (in power stabilisation mode) whilst hunting photons. In current mode, the 532nm output just gently fades to grey...

I need to check the SHG thermistor and associated circuitry, but they are difficult to access. I already discovered that the X-head support plates are shimmed (and all the shims dropped out, of course, when I took it off the SHG tower).

Does anyone have documentation and/or experience in the Millennia Vs head (AKA Millennia Pro s)? In particular, alignment of the SHG tower and telescope after disassembly, as well as any info on the thermistor location/type and the circuitry on the control PCB in the head. A few scanned pages of the service manual would be a treat (S-P no longer support this laser in any case, AFAIK).

Note that this is the short version of the Millennia with the "X" type optics, not the original "Z" head.

Much appreciated,
Ilya

[kecked]

I had a similar problem on the z version. The FAP thermal went out so I shorted it with a 22k resistor to fool it into thinking the temp was ok. Ran fine till I got a new fap. Steve yea that one.....

[iggythebrush]

I had a similar problem on the z version. The FAP thermal went out so I shorted it with a 22k resistor to fool it into thinking the temp was ok. Ran fine till I got a new fap. Steve yea that one.....

Thanks Kecked, but this is not the FAP - it's the thermistor (or the circuit) in the head by the SHG that's the problem - and I can't even work out how to safely get to it - or how to realign everything properly afterwards... I'm sure there must have been a service manual for this head for use by field technicians, or at least the circuit so I can figure out which wires to follow into the head...

[mixedgas]

Did you backflush the laser yet with the pink commercial solution suggested in the manual for removing aluminum chips in the coolant channel ?
Start there before heading to more drastic measures.
Otherwise I doubt a service manual ever made it to the outside world.

Steve

[iggythebrush]

Did you backflush the laser yet with the pink commercial solution suggested in the manual for removing aluminum chips in the coolant channel ?
Start there before heading to more drastic measures.
Otherwise I doubt a service manual ever made it to the outside world.

Steve

Thanks Steve,

My manual doesn't mention this anywhere...

[mixedgas]

Thanks Steve,

My manual doesn't mention this anywhere...

We have the OEM version of that laser built into one of our Ti:Saphs.

I'll pull up the details tomorrow at work. Before you do anything flush the head bi-directionally with the pink stuff... Worse case your out say 50$ for the solution and a week's delay.

Tower temp errors and the related faults are usually corrosion.. No promises, but on two lasers at two universities this is what cleared the fault.

Steve

[mixedgas]

Attached is a an ops manual..

I'll get the chemical name in the morning.

Steve

[mixedgas]

1607-0546 from SP is the "Pink Solution" from Nalco
1607-0547 from SP is the cleaning solution from Nalco
SP SERVICE CAN TELL YOU WHAT THEY ARE IN EUROPE FROM NALCO.


Steve

[iggythebrush]

1607-0546 from SP is the "Pink Solution" from Nalco
1607-0547 from SP is the cleaning solution from Nalco
SP SERVICE CAN TELL YOU WHAT THEY ARE IN EUROPE FROM NALCO.


Steve

Thanks very much Steve, that is incredibly useful. I'll give it a try and put an update here.

Ilya

[buffo]

the pink commercial solution suggested in the manual for removing aluminum chips in the coolant channel

Let me guess: Diluted mixture of sodium hydroxide and DI water (say, .1 N) with some added surfactant?

Adam