DT40-Wide Amps shutting down, and both LED's flashing

[planters]

If you want the best design wouldn't that be a linear vs. switching PSU? Even a company like Power One rates the V. ripple of it's switchers at 1% vs. 0.035 for it's linear supplies. Won't 1% ripple cause noticeable distortion of fine lines drawn over large angles?

[-bart-]

Won't 1% ripple cause noticeable distortion of fine lines drawn over large angles?

Most amp designs have excellent powers supply rejection ratio, besides that, it's a closed loop system in the first place.
Large angles are not the real problem, it's the sharp corners.
A galvo supply should be able to supply very high current spikes during mirror acceleration. In some frames the current is zero for 90% of the time. Low ripple regulation isn't necessarily a guarantee for fast and accurate response to current spikes.

If I got the opportunity I'll post some scope pics of these signals.

[Badpip]

Also ripple from a linear supply will be at 50/100Hz (EU) or 60/120Hz (US), while switchers are running kHz. The high frequency ripple is less likely to get past the capacitors on the drivers. Stray inductance in the wires kills some of it too.

/Thomas

[norty303]

Um, if they are supplying inadequate PSU's, has anyone actually fed this back to Dragon Tiger? Marc, aren't you a dealer/distributor?

[-bart-]

It might just be that the overcurrent detection is just too picky, and therefore less suitable for 'our' applications.

[Badpip]

This doesn't look bad:
LPQ112-B

+/- 5-25V 2.5A (adjustable) for the scanners
12V 4.5A for fans, shutters etc.
5V 9A for a green

Only downside is the minimum 2A draw on the 5V rail.

[Edit: Crap - it's just a floating 5-25V rail, need to read those damn datasheets completely through ]

/Thomas

[billwx]

Greetings,
I'm pulling this thread back up because we experienced the same "crapping out" of the scanners when the amplifiers needed more power than the stock supply could send out. I work in a planetarium and we needed to replace Cambridge scanners with DT40 Pros - because of cost. (We simply did not have the budget to get CT and they were failing during every show - because of age.) Yes, CT can refurbish, but we needed something reliable and FAST (for several sold-out shows that were coming up).
Anyway, we had purchased a Meanwell power supply that produced +/-24V at 2 amps, but was too noisy and made the images look like garbage. After talking with some technical friends, we figured the stock PSU is splitting that .8 amps to 2 amplifiers - so neither one is actually getting .8, but only half (.4 amps). So we inquired with the dealer of the DT40s and was able to get an identical .8 amp power supply. I wired it up and we now have BOTH power supplies running. Each one is going to ONE amplifier. (1 goes to X axis, the other goes to Y axis.) I simply "tucked away" the extra plug on each wire run, so if we go back to 1 PSU in the future, the wiring can be used again. Yes, it takes up more room in the case, but it's an old projector that used to have gas heads - and we converted to solid state, so there was a lot of room to deal with!)
I ran a couple of shows that would NOT run with the 1 PSU - making the scanners just "freeze" all over the place during certain images and it looked like crap. With 2 PSUs running the amp/scanners are working fine and all of our images don't cause the "freeze up" to occur.
I'm still investigating power supplies for a "1 PSU solution" that doesn't cost a lot and will fit inside the box - but for now, it works fine with 2 PSUs driving those amplifiers idependently. Unfortunately I haven't taken any pictures of the setup since installing the 2nd PSU, but could if there is an interest.

-Bill
Laserist at RVCC Planetarium,
Branchburg, NJ