ttl blanking - wow got me worried

[dave321]

hi guys and gals, i just got my 100mw economy model from china and connected the red wire to pin (3 ilda) and the red/black marked wire to pin 16 (which connected to ground pin 25 (ilda) for blanking. The output blanked totally and the wires got noticably hot.....i disconnected immediately.......the laser still works along with scanners etc :? ops: .......any ideas whats going on ? i thought i'd blown the laser.....think i got lucky............i'm reluctant to use the ttl now............

[Spec]

It sounds like they just physically clip the drive current through the blanking leads because it has a lower resistance ground(pin 25)... Thats painfully cheap of them and dangerous to the diode.

And to think, all this to save 4 cents on an optocoupler.

Thats crap-tastic. Pop the top of the power supply and take pictures for me.

[dave321]

It sounds like they just physically clip the drive current through the blanking leads because it has a lower resistance ground(pin 25)... Thats painfully cheap of them and dangerous to the diode.

And to think, all this to save 4 cents on an optocoupler.

Thats crap-tastic. Pop the top of the power supply and take pictures for me.

spec, not sure whether this will help, this is the best i can do. the two red,red/black ttl wires are at the topleft of the image. appreciate you trying but the photo may have limited interpretation

[Spec]

Well, its not surprising, this image here is the *older* version of the same power supply, it was pretty trashy also...

I cant believe they cheapened the circuit more...

Can you get closer shots of the front and back of the riser card? There may be a cheap solution in there assuming they didnt gut the circuitry.

[dave321]

hi, spec, made a few more simple measurements

applying 4.5 volts and then 6 volts to the blanking wires through a 10k resistor on the + volt supply failed to blank either way round

the laser blanks when touching the 2 wires together, therefore measured the voltage output, .....4.92volts...........is this correct ? i thought i had to apply 5volts,
i'm a bit confused :roll: . i'm not keen on taking the psu apart for more photos, at least i have a reasonable beams with a bit of smoke, can't afford to waste the money and blow it..........if necessary i'll not use the ttl wires and do without blanking
dave

[Astroguy]

hi, spec, made a few more simple measurements

applying 4.5 volts and then 6 volts to the blanking wires through a 10k resistor on the + volt supply failed to blank either way round

the laser blanks when touching the 2 wires together, therefore measured the voltage output, .....4.92volts...........is this correct ? i thought i had to apply 5volts,
i'm a bit confused :roll: . i'm not keen on taking the psu apart for more photos, at least i have a reasonable beams with a bit of smoke, can't afford to waste the money and blow it..........if necessary i'll not use the ttl wires and do without blanking
dave

If your software pirmits it try reverse blanking, that should work.

[dave]

And to think, all this to save 4 cents on an optocoupler.

Hi Spec,

i had a chance to look over one of the 100mw's. The blanking arrangment is non standard, but it appears to have a opto on the riser board. Its a bit hard to be certain, as the markings are removed from the chips in true chinese style..

Anyway i threw together a mod to suit these, only a couple of transistors and a optocoupler, i ave a schematic for anyone who may need it..

[dave321]

looks like thats sorted the problem out , excellent !! thanks a lot
dave[/quote]

[Groover]

Is it possible to convert one of these into analog blanking?

[liteglow]

my laser is analog, and i got the same model ?
I got 3 wires from my supply, but on this pictures there is only 2 !