Lexel 88a

[ronny]

Hi,

i get recently some Lexel 88a heads.

Now i have the problem to find out the correct connections which are needed. I checked the "sams laser faq" where i found a schematic (http://www.eio.com/repairfaq/sam/88hsch.pdf) of the head and can "reverse" with these docs some connections but not all and mainly not 100% for sure.

On the head itself i have these kind of connector: http://www.ewoks.de/laser/l88a_mains.jpg

On the first look i assume the following connections:

from right to left
pin7 (cathode) -> P1W
pin6 (cathode) -> P1X
pin5 (anode /hv) -> P1P

just these ones i recognized (hopefully) right

Is there perhaps a kind of user manual or something which documents this connector?

thx in adance

[dave]

We have a rough manual and schematics for the OEM switch mode power supply, nothing on the head tho....

[marco]

Hi Ronny,

some years ago we had arround 30 of them...
funny to that they are still in use

I think that i still have the complet documentation of
them... when remebering it correctly
the connection is like this (from right to left)

- Cathode (AC 3V from Fillament Transformer)
- Cathode (AC 3V from Fillament Transformer)
- Anode (DC 175V / 20A)
- Magnet (DC 150V - 180V 3A)
- Magnet (DC 150V - 180V 3A)
- Starter (GND)
- Starter (+12)

Please make shure that that this informations are correct
bevor pluging the PSU to the head.
Start with the 12V for the Starter, you will hear a loud "click" when
this is working. The Magent will have a resistance of 40-50 Ohm,
measure if one leg of the magnet has a connection to cathode
or anode ! For the magent you will need a Transformer or a circuit
that will switch the magent to the psu when the laser tube
has started... never connect the magent directly to the psu, because
the psu will deliver 300V when the tube is not started - this will kill
the magent !!!

greetings,
marco

[ronny]

Hi,

cool, thx!

This seems to be ok. The first 2 pins go to the starter (it clicks , btw the 2nd ones i have about 57Ohm and no connections to either anode or cathode.

When i take a closer look to the magnet wires there is a interconnection to the igniter you can see this on the schematic from sams laser too.

Is the igniter powered by the magnet voltage?

Perhaps its easier to have an extra transformer for the magnet supply (to avoid the switch you mentiond).

thx
ronny

[dave]

we are using a extra transformer for the magnet power. A much better method IMO

[marco]

Hi Ronny,

yes, the starter get's power from the magnet supply.
We used the volatage from the psu to power the starter
and a relais to switch the magnet on after the tube
has started, this works very well and you don't need
a large Transformer for the magnet.

greetings,
marco