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MSD250 to Platinum 5R / 7R. Possible?


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Hey guys, I'm wondering if I can convert some older MSD250 moving heads to 5R/7R? Has anyone here ever tried this? Here are my assumptions and feel free to correct me harshly if I'm wrong. From what I can reason, the 5R systems run independently of the main boards/driver boards of most units. Upon startup, the display sends/receives a signal from the ballast via a 5 wire harness when the lamp strikes and the lamp remains on constantly, similar to the MSD250 so the existing main board / driver boards with not be affected by the lamp. I'm assuming the issues will be as follows:

1. Proper cooling of the Platinum lamp (VERY IMPORTANT!!).

2. Replacing the lamp housing from the existing MSD to Platinum 5R. This may be a little tricky and will involve removing the existing lamp reflector and also I'll have to get some metal work done, not impossible. Another question, why stop at 5R, why not step up to 10R? Once I can assure that the fan is properly cooled and a thermostat is in place in the event that ###### happens.

3. Scrapping out of the existing HEAVY ballast/transformer/ignitor system and replacing these heavy components with a compatible PSU to drive the fans, mainboard and 5R ballast. The existing main board will probably have an 18VAC or 20VAC input from the voltage transformer which then converts to DC so I could make a direct DC connection from the PSU to the main board once voltages are confirmed.

4. Most importantly, that 5 wire harness from the ballast to the display. I can't replace the original display with something from a 5R/7R unit as the functions between the two displays will be completely different. How do I work around this?

Anything else I should consider here? Remember, this is just a thought to recycle some old usable units


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  • 5 months later...

I had this same thought and stumbled across your post while searching for info on how the driver and power supplies for these lamps worked.  What I eventually did was buy one of the cheap Sharpy clones that use the 7R lamp to eliminate some of the guess work on how to make the individual pieces operate. There's another project I've been considering that would use the whole, intact fixture, so it seemed like a reasonable investment at the time...

Anyway, I only did a quick check of the signals between the main control card and the driver, but it does appear to basically just be two opto-isolated inputs for lamp-on & lamp-off, and one output for lamp status.  If you have or can get schematics for the main board in whatever fixtures you're planning to use, then it should be possible to design a relatively simple circuit to interface with the driver.  If you don't already know how to read and understand the schematic for something as complex as the control card of a moving light, then you may need to enlist the help of someone with more electronics knowledge.  It's definitely not a beginner project.

I didn't spend a lot of time on the electronics because I was more interested in testing the optics of sticking that lamp in an older MSD250 fixture--in my case a Technobeam.  Since I have working lamps/ballasts/igniters in the fixtures currently, the project would only be worthwhile to me if I was able to get more output than the original.  That's theoretically possible because only about a quarter of the lamp lumens actually make it out the front of the fixture due to inefficiency of the original optical design.  No shade on the designers--they actually did pretty well with the technology they had at the time...  At first glance the results did seem pretty promising, but I eventually realized that it was mostly because the beam was really uneven.  Some parts of it were definitely brighter than a stock fixture, but the average brightness was roughly the same (based on measurements with a phone app rather than any sort of real tool).  While the 7R lamp and its prefocus reflector are more efficient, unfortunately their optical characteristics just aren't a good match for the rest of the optics in the fixture.  One obvious tell is that the gate and gobos in the Sharpy clone are much smaller than the Technobeam, so the result shouldn't have really been that surprising.

So... at that point I decided it probably wasn't going to be worth the time and money to move forward with this.  I was looking at about $100/fixture just for the cheapest power supply, driver, and lamp combination I could find.  Add on some additional fans, electronics, metal work, and a whole lot of design & fabrication time, and the cost just wasn't worth the result of something roughly equal to (but less even than) the original.


TLDR: yes, this is theoretically possible, but the optics will probably not be great, and it's pretty complicated to make work.

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Hi malabaristo, my thoughts were that running the driver mainboard off of a DC power supply may be possible instead of the huge and heavy transformer. I'm assuming the the mainboard (can't remember the internals of the unit per se) receives AC voltage (probably 24 ~ 48 VAC) from the transformer and this AC voltage is converted to DC via a bridge rectifier and a regulator and I can power the mainboard directly via a DC power supply, bypassing the bridge rectifier (???). The issue I can't picture resolving is the lamp strike. The ballasts in these Platinum units receive a signal from the display via a 5 pin harness and I'll have to reproduce this signal from the original display PCB (via your circuit design?). I figure that if I can resolve this ballast/display lamp strike signal problem then I can take on the challenge of the mounting of the lamp in the existing housing. If I can get that sorted, then I'll still have the issue of the optics to sort out after.

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Yes, in the case of the Technobeam the board gets something like 36VAC and 9VAC that are converted to ~24VDC motor power and 5VDC logic power respectively.  The 7R power supply does have multiple voltage outputs that are similar and could probably be adapted, but you would have to know and understand the design of your fixture to figure all that out.  For lamp strike, 3 of the five pins are: common, lamp on, & lamp off, and it looks like the on/off signals are held one way or the other to change state.  The other two pins are (presumably) lamp status from the driver to the controller.  On the Technobeam the lamp strike circuit has one pin that pulses for lamp-on and another that pulses for lamp-off.  The adaptive circuit I mentioned would have to watch for those pulses and provide the corresponding signal to the 7R driver board.  You'd also need to look at how your fixture checks lamp status and inject that signal based on the output from the driver to avoid lamp error messages  Like I said: not a beginner project (and not one I'm going to pursue any further).

So, yeah.  If you do all that, then (at least for the Technobeam) you'd be able to eliminate the igniter & capacitor, the ballast transformer, and the complicated multi-tap transformer that provides power to the motors and controls.  Fitting the differently shaped 7R driver and power supply might be tricky depending on the fixture you're using...  Anyway, that's all probably possible--not cost-effective in my opinion, but possible.  Fixing the optical issues, however, isn't possible without basically starting over from scratch.  You would need different lenses, possibly different spacing between components, different gobos, and so on.  If your goal is to learn some new things and you have the time and money to spare, then it might be worth it to you.  If your goal is more about making usable fixtures, then this isn't a worthwhile approach.

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