Conversion of ROBE scanners to LED
Hi! This is an english version of my three posts in which i talked about my project — conversion of old fixtures with MSD/HSD/HMI/HTI lamps to a modern LED light source to give these fixtures one more life. Russian versions located on these links (with more photos): part 1 about ROBE scanners; part 2 about COB LED; part 3 about SSD-90 LED and final coversion. In this post i compiled most significant information.
This post is dedicated to my light collegue from Greece — The Light Project (here is link on his YouTube channel). We meet from phare «If you like scanners more then MHs — please write to me» and now talking about our countries and light design.
I apologize for my english. I have problems with it and know language only in present time. But i hope that information in this post is more important than my english. If you see hard mistakes or typos — you can send them to me by pressing Ctrl+Enter. Thank you.
Also, my blog in Russian. If you want to write me — please use my emal: firstname.lastname@example.org. Because sometimes i recieve SPAM emails in English — please set topic of the email to something readable. If you want to comment this post — you may register on my blog.
In my childhood my father worked in theatre and i saw many performances and shows (ex. christmas). All of them impressed me and i try to create my own projectors from carton boxes and lamps. At one of christmas shows i saw strange devices that radical differents of projectors i know: they moved light beam, change it’s colour and patterns. Few years ago i know that these devices called «Scanners». I start search pictures of them from internet and determine that scanners i saw in my childhood was ROBE Scan 575 XT (on 575 W MSD lamp).
Many time has come from these years. And suddenly for me 1,5 years ago (from 2018) i was impressed by track «Shadows» from «God is an Astronaut» and started to dream about creation of my own light shows at home room. I buy some simple fixtures for first light shows, start use them and in one lucky day found in internet shop of used things lot of two ROBE Scan 250 XT scanners with a low price (10 000 RUR — about 150 USD for two scanners).
When i recieve these scanners i get idea to change (convert) MSD lamp in them to the LED light source. I know that i will use these scanners only in home (because they are only implementation of my childhood’s dream) and decide get least light brightness than original MSD lamp abut get less weight and heating of fixture. I examined these scanners and learned how they works and tested two different LED sources — about all of that things i will tell in this post.
- 1. About ROBE Scanners. Description of functionality and inside mechanics.
- 2. My fixing and small upgrade of ROBE Scanners.
- 3. Conversion to LED: Ideas and Purposes.
- 4. COB LEDs: how they work. First conversion tests.
- 5. Conversion ROBE Scanners to COB LED: poor results.
- 6. Luminus SSD-90 powerful LED for moving heads.
- 7. Conversion ROBE Scanners to SSD-90 LED: good results.
- 8. Final. Comparsion of converted and original scanners.
1. About ROBE Scanners. Description of functionality and inside mechanics.
Sometimes ago ROBE scanners was the best of all others, because ROBE put very hot MSD lamp, lots of electronics and servomechanics into a very small case so their scanners was very compact and has a lots of functionality. I love inspect devices to find ideas that inspired device’s developers to made device’s construction. And ROBE scabbers also have lots of that ideas.
I bought two ROBE Scan 250 XT scanners from one strange man: he wrote that he urgently needs money and sold these scanners with a low price. When i talked to him by phone — he said that he used them in a home discotheque. But later i understand from our talking that he even does not have a DMX console to control them and he use them only in Test mode (WTF?!).
We made our argeement and he sent these scabbers to me with a transport company. When i got the scanners i was very angry because this man will not pack mirrors correctly and they can break! Also mirrors were removed by someone and re-glued on a double-sided tape (i’ll show more photos later).
ROBE Scan 250 XT scanner after little repair
In these scanners we use MSD lamps. MSD means «Metal Static Discharge» and on Russian we call them «Metallic-Haloide Lamp». This lamp produces light with color temperature (CTO) higher that CTO from halogen lamp. But MSD lamp has two important features: it can’t be dimmed and it must cool down before next power on. Light fixture must be projected to take account of this features. For example, fixtures use shutters for dimming and strobe effects.
Another things about MSD lamps are:
- They produce high temperature around lamp and must be strongly cooled;
- They can explode (ex. of water condensate if we take lamp from cold place to warm and immediatelly turn lamp on — one of my lamps is exploded in this situation);
- They produce some kind of UV light and components inside fixture must be UV-stable.
I have used MSD lamp (left on the photo below) and new MSD lamp from China (right on the photo) — i bought it to make test comparison of oroginal scanner and my LED converted one.
MSD250 lamps for scanners or other light fixtures (original and from China)
Here is my scanners when i recieved if from transport company. You can see that mirrors are removed from scanners. This is not my deal — they’re falled down because previous user re-glued them.
Scanners ROBE Scan 250 XT after biying (mirrors was removed)
As i told before — ROBE placed all optics, lamp and condenser in a very small case. I was surprised that all this part of scanner is cooled by ONE 80×80 cooler!
Inside Robe Scan 250 XT
Next ROBE invention — is thee sockets that connects all electrcical wires from stepper motors and sensros to optical block! In other scanners and MHs we can see many bundles of wires that connects to mainboard with lots of sockets — we need to remebmer socket connections. But in ROBE we have 3 big sockets! This is wonderful!
Connectors for optical block of scanners ROBE Scan 250 XT
Disconnect these sockets, unscrew 3 bolts brom back — and you can easilly remove all optical block for cleaning or gobo replacing!
Optical block can be easilly removed from scanner after disconnection of sockets
After that we can see empty place and lamp part. I loved ROBE for this idea because it simplifies maitenance of this scanners — you even may not remove all scanner from backet!
Electrical parts of Robe Scan 250 XT (optical block removed)
Next construction invention is a hi-voltage part: power transformer, lamp ballast and ignitor are compactly placed in a bottom of lamp and its condenser.
Main power transformer and ballast with ignitor for MSD lamp
Scanners has a lamp safety circuit: it protects lamp to switch on when case cover is removed or when case temperature near lamp reaches about +70-80 celcium degrees.
This circuit consists of limit switch and thermostat. Even if contacts of relay that controls lamp was welded and lamp will work continiusly — thermostat will switch lamp off!
MSD lamp protection circuit: thermostat and lamp cover limit switch
Here is photo of optical condenser of ROBE scanners. It made by classic scheme: collecting and dissipated lenses plus reflector on a backside of lamp.
MSD lamp is instaled in optical condenser of scanner
Note that in a bottom of condenser placed a piece of steel that prevents hi-voltage part from MSD lamp light radiation. This is a idea that allowed to make compact scanner construction because on other scanners lamp condenser and hi-voltage part is placed sequently one by one.
Lets look on optical part and ROBE’s inventions! Here it is:
Optical mechanics part of ROBE Scan 250 XT scanner
ROBE has full indexation of Colors and Gobo Rotation. Color disk has option of half-colors. Here we can see color disk and rotationg gobos:
Color and Gobo disks
Also ROBE Scan 250 XT has electronic focusing. It made from lens that drived by a stepper motor. When scanner initialized, metal frame of lens rests on a one of stepper motors and scanners detects Focus zero position =)
Electronic focus mechanics
Next ROBE invention — is a lamp sensor. This is photodiode that placed in a part of optical block’s condenser side.
Optical block from lamp condenser side. Lamp status sensor
ROBE checks this sensor in two modes:
- If lamp relay is off and sensor show that lamp is working — ROBE Shows Sensor error.
- If lamp relay is on — ROBE checks the sensor state: if lamp can’t turn on — ROBE shows «La.Er» — Lamp Error and tries turn lamp on after 5 minutes.
Idea for lamp sensor was invented to protect lamp ignitor: if ROBE can’t see that lamp start working — it turns off ignitor. In many other fixtures ignitor will work continiusly and i think that is bad for it.
Let’s look on a front side of optical block. Here we see that ROBE scanners are not always pretty: ROBE places color correction filters and prism onto a single wheel of effects (effects wheel). So we can set only one effect: CTO filter or prism.
Optical block from objective side. Effects disk with prism and colour correction.
But this is not a ecenomy of bad thing. Is this scanners we have lots of effects: colors, rotating gobos (some of them is dichroic and colored), zoom, effects. Light will lost small parts of its power when it goes through all this lenses and filters. And if we select a dichroic gobo and prism and color correction filter — we will lost too much light brightness.
So ROBE made effects wheel for prevent light brightness loss: now you can’t get effects combination that made light darker =)
Careful readers will see that effects wheel have two empty holes instead one. Huh! This is a strange and funny thind: previous user removed (and throw away) frost filter from my scanners! WTF? WTF!!
Why he did that? Because he try use these scanners without DMX console and did not manual!! ROBE Scanners has test modes 1 and 2. Test mode 1 sets Pan-Tilt to 128 and opens shutter. It designed for correction of lamp placing and focusing. Test mode 2 turns on frost (check effects wheel) and plays test sequence (colors, gobos, pan-tilt moving).
Previous user runs these scanners in test mode 2!!! As i think — he said: «What a strange glass thing! It covers bright light beam! I will remove it»… Is he take time to read the manual — he will know that all ROBE scanners can play 3 stand-alone programs each up to 50 steps with different time for each step! If you does not have a DMX console — you can write offline show directly onto scanners, connect them in a Master-Slave modes and have show! =)
But this stupid man made my scanners defective! These scanners discontinued so i will not find a spare frost filter…
Here is a shutters to made dimmer and strobe effects. Also you can see stepper motor that controls prism rotation.
Shutters for light dimming and strobe effect
Here is a gobo rotation part. As you can see — ROBE constructed it scanners to use the same parts in different places: the gears that rotates prim and gobos are the same.
Gobo disk and Gobo rotation mechanics
In a sometime when i spend a lots of time with my scanners i seemed gobos everything. Even in a washbasin’s holes! =)
Light engineer's professional look see gobos even in a washbasin!
Optical block has sensors for position of color and gobo disks and even a temperature sensor. Here it is:
Gobo position sensor (magnetic) and scanner temperature sensor
How these sensors are work?
- Temperature sensor is placed near optical block and controls temperature inside of scanner. If this temperature reaches +45 celcium — it shows «HEAT» and switch off the lamp and cools down scanner.
- Color sensor is magnetic and used to determine color disk start zero position. The sensor of effects wheel is the same and simple.
- Gobo sensor (magnetic too) used to set zero for gobo disk and at the same time for gobo indexing: firstly scanner rotates gobo disk to reach out the sensor. One of rotating gobo also has magnet. When gobo disk reaches zero position — this gobo with magnet will be exactly near the gobo sensor. Scanner starts rotate gobos and check sensor again to get zero position of gobo indexing!
Also scanner shows errors of this two stages: «GoEr» — Gobo position error, «GIEr» — Gobo indexing error so we can check stepper motor or its driver.
I also was impressed by the cooling system of this scanners: in other fixture coolers are blowing directly onto lamp and developers need to use many coolers: one for lamp, one for PCB, etc. But ROBE made interest construction: they use only one cooler 80×80! This cooler placed in bottom of optical block and airflow from it firstly cooling optical mechanics to prevent it from damage of high temperature. Next, airflow comes to a termal sensor and flows past lamp and goes out through grid on case cover.
In this decition we solve many problems: first we cooling optical block and them a little warmed up air comes near very hot lamp. So hot air from lamp never will come to a PCB or optical block, because it has one way out — a grid near lamp!
Also cooler in ROBE is PWM controlled from DMX. Cooler can work in Auto, Hi, Low modes. If outside temperature is cool, scanner can stop cooler and get most silent. When termal sensor shows that temperature inside scanner is growing — scanner spins up cooler.
Here is video (on russian) where i show all parts of scanner in work (test mode 2):
2. My fixing and small upgrade of ROBE Scanners.
When i saw these scanners i determine three problems (or ideas) with them: i don’t want use short power cable that connected to scanner directly; i need to re-glue mirrors; the cooler was damaged and i need to replace it.
I know that i will convert this scanner to te LED light source and i know that i will frequently turn it on or off when testing LED or lenses. Originally scanner has a one meter power cable directly connected to it. For stage fixtures this is normal because no one have to trun fixtures on or off when they’re hanged at top of the stage. We simply put power plug into socket and turn scanners on.
But for me this power cable was too short. Also i need to wind it on scanner to store it. I decide cut off this cable and install standart IEC computer connector with power switch — i plan use any computer cable for this scanner (1,5 m or 3 m length).
I dismounted front panels, taked drill and file — and here is the result (also you can see first part of serial number — this is the year of production: 2003):
Modified front panels with IEC power socket and power switch
All parts of hi-voltage electric in scanners are connected on a clamps. This was good for me: i soldered all wires on front panel and connected all of them to the original clamps — we need only install front panel and clamps, no soldering need inside scanner!
New commutation of scanner power input
So lets do it. Now front panel is installed onto scanner and all wires is connected (here we can see scanner’s PCB — all stepper motors drivers has small heatsinks):
Modified front panel is instaled into scanner
And here is front panel view with connected IEC power cable:
View of modified front panel of Robe Scan 250 XT
After that all fixings and smal modding i have to re-glue mirrors back on a strong glue. Why previous user glued off mirrors? Why it glue them back on a double-sided tape?! This is terrible! When scanner works, stepper motors become warm to a 30-35 degrees celcium and tape glued off. Mirror can break or simply fall down to a one’s head!
Mirror driving unit of ROBE Scanners (mirror was glued on double-sided tape)
I went to the shop and asked for glue or sealant that can be strong and a little flexible. They recommended «Soudal Fix All» for me. One year has comed from mirror repair — all is normal, mirrors glued very hard.
Soudal Fix All glue for re-gluing mirrors back
Spreading glue onto mirror and drive unit…
Glue was spreaded onto mirror and its drive unit
Put them all together and wait for 24 hours. Firtsly, when glue was too liquid, mirror falled down from its place. I decided to turn on scanners, set Tilt to 255 and fix mirror with a paper tube from roll of paper towels. Tube stop mirror falling and glue can become strong.
Glued mirror fixator from roll of paper towels
After one night mirrors was strongly glued onto driving unit. I write some tests on my DMX console that set pan & tilt to 0 and 255 to get fast mirror moving and check: will mirror fall down or not — test are passed sucessfully! =)
Mirrors now is strongly glued! Hurray!
Now all my two scanners ready for use (if i install new lamps) or to LED conversion.
Some fixing of scanners is finished and ready to work
3. Conversion to LED: Ideas and Purposes.
Now, whe i am writing pot after all conversion projects and tests, i think that everyone sholud walk this path of bright idea of LED conversion and dissapoint in the last =) Firstly, when this idea comes to you, you’re think: «What problems may be? I simply remove lamp, install LED and will use fixture more and more! Why nobody never thinked about it?» and after a many tests and hard work you see that tis is not so simple and yo need to choose between normal work of optics designed for MSD lamp or between bright light.
But why we need to convert from MSD to LED? I try to describe:
- LED has a less weight that MSD lamp with ballast. So our fixture will be more light.
- LED has a bigger lifetime than MSD lamp — we need to change it often.
- LED does not produce high intensity UV light and does not shine around like MSD lamp; LED shines drirectly in one way.
- In some cases LED consts cheaply than MSD lamp
After this you can think that LED converison is that every one «must have». But you will bring together with most comlpex problem of this conversion: size of original optics designed for MSD lamp is bigger than LED needs. Ad this is a great task: place LED and new lenses correctly to get the same light beam diameter insdie optical block of scanner to become all effects (shutter-dimmer and prism) work correctly. If you can solve this problem — your LED conversion will be good. If cant — LED will dissapoint you.
After my small conversion experience i can say that in most cases LED conversion will be unsucessful because LED is smaller than original optics. But i don’t know what i did because in conversion process no one helped me with optical lenses: i don’t know optics to calculate them. I simply buy different lenses and tested my LEDs with them.
Let me tell you my two experiments and some peculiarites that will be important for peolpe who want to convert MSD to LED.
4. COB LEDs: how they work. First conversion tests.
What we inspire whe we hear «Big power LED»? Firstly it will be CREE LEDs with power up to 10 w. And if power need to be bigger? Of course, it will be a COB LEDs! In Russia we have a lots of china projectors (not for stage fixtures — only for steet lighting) with COB LEDs: 10, 20, 30, 50, 100W. That was my first experiment and bright idea. I’m tell it to all my friends: «Look! Look! I simply take the COB LED projector, remove LED from it and install into scanner!» =)
Before we beigin — lets look on other LED conversion projects. Here is video that i find on YouTube. This man from Italy (mybe) and he simply remove halogen lamp and install 100W COB led with a big computer heatsink.
First that i saw — that he used additional lens with LED. Here is the screenshot:
Italian LED conversion screenshot: we see lens
In Russia some peolpe offers LED conversion too. Here is the sample from Martin SCX-700 scanner. This is strange and maybe wrong: LED is simply installed instead of lamp. But look onto photo: COB LED is placed near parabolic reflector’s hole and distance between LED and optics is too big.
Russian LED conversion screensot: 100W COB LED simply installed into condenser
Will it work bright or correct? Not! Look on other photo: 100W LED output is weaker than office lamp! This is not correct.
Russian LED conversion screensot: ight from 100W COB LED is weak
Why COB LEDs work so poor? Lets inspect them and see. What is a COB LED? COB means «Chip(s) On Board» — LED constructed from small LED matrix. Small LEDs sequently connected in electrical circuits, and circuits connected together. This is not good because some small LEDs parameters (ex. working current) will be different. As result in sequently connection — some LEDs will be more brighter or weaker then others.
I made drawing. LEDs with different parameters i marked with other color:
Scheme of LED COB matrix inside
Can you understand something? ;) Optical block originally designed for MSD lamp (spot, point light source) will not work correctly with big matrix of LEDs — we cannot focus this matrix in a point! COB LEDs maybe good for fixtures with a haloide lamp (like standart 24V/250W) because filament in this lamp is big and optics designed for this big light spot.
But COB LEDs has one more important thing: because ther’re produced like a matrix from a single LEDs — some of LEDs will not be placed correctly inside. They may be warped in different ways. What we get when we try to focus COB LED? Look on the next drawing:
Scheme of LED COB matrix focusing
Beams from each small LED (that placed correctly inside COB matrix) are focusing in one way. Beams from warped LEDs focusing outside of center point.
What we get next in a fixture? Some light beams will be focused in a wrong way and output spot will lost it brightness — a part of light power will go away! Yes, Yes! This is exactly like i showed on a drawing!
Output beam of fixture with COB LED: some beams are not in focus
And also COB LEDs have a bigger size when they have a bigger LED power. And 10W LED will be smaller than 100W LED. As s result: when we install a big 100W COB LED — at least of half of light power dissipate of from lenses of a fixture. This describes why after Russian conversion they get weak light output =)
But i knew it only after my conversion experiments. This is a why i write this post on english — to prevent other people of wrong experiments from COB LEDs!
My first tests with COB lead me to a wrong way because i bought small 10W LED projector. As you know now — 10W LED is smaller and still looks like a point light source for scanner’s optics.
Disassembling of COB LED projector to a parts
I cut off the projectors case (it used as heatsink in these projectors) with LED and hanged it on wires instead of MSD lamp:
First test: 10W COB LED placed in original condensor
Here is the result of my first test. Near is the light projector with 30W LED power. As we can see — vortex gobo looks brighter than 30W projector. I was happy and think that i need only a more powerful LED… heh!
First test: 10W COB LED beam (gobo)
If we close a little diafragm on my still camera — we will se that edges of gobo lightened weaker that center part.
Light in a borders of gobo is weak
What i can conclude (without knowing things about COB LED)? Of course: «I need more powerful LED! Its size will be bigger and it light up all gobos!». I designed easy (as i thought) conversion project with original condenser. We simply remove reflector and install COB LED with a heatsink like that:
Conversion of ROBE Scan 250 XT to COB LED diagram
ROBE has very useful condenser construction — it made like stack of plates with lenses. So i plan remove one plate and fix heatsink to other plate with PCB board stands.
5. Conversion ROBE Scanners to COB LED: poor results.
Here is ROBE condenser and heatsink that i plan to use with my LED:
Heatsink and original condenser are prepeared for conversion
I disassembled condenser and marked all axises and holes for drilling:
Marking of drill holes in process
I took LEDs from the sameCOB LED projectors with 50W power — i thought that if i see bright light from 10W — 50 W will be enough.
After all driling process i have two sets of LEDs, LEDs drivers, heatsinks and protection thermostats. I took thermostat protection idea from original ROBE construction and buy 60 celcium degree thermostats to protect LED from overheating: thermostat will disconnect 230V power from LED driver.
All parts are ready to assebmly
Here is my tests of mounting heatsink with LED. When i started my tests i see that LED distance from lens must be near 15 mm. So i bought PCB board stand 15 mm length and mount heatsink on them:
New condensor with COB LED is assembled
And here is the result of my new condenser:
Final assebly of new condenser
So, now is the way of no turning back — i need to remove all MSD lamp circuits from scanner and place LED driver instead of them. In ROBE all hi-voltage parts and transformers are placed on metal panel. If you unscrew this panel — you can get access to all hi-voltage parts.
Removing of MSD lamp parts from scanner
Now i am ready to install my new LED to scanner. And — first fail! =) Condenser does not worked correctly! Dissipating lens gave wrong focus of this so big LED (on 10W LED all worked normally). I made next test and leave only colleting lens with this LED.
Here is my new condenser installed into scanner:
New optical condenser with LED is installed to scanner
Next fail was with heatsink — COB LED produced many heat (this is normal for it, but heat from LED is less than heat from MSD lamp) and i added many heatsinks. After that LED in scanner worked correctly: i leaved scanner on for 4 hours and see 30 celsium drees temperature inside it.
First powering on scanner with LED installed
Lets test light from this scanner. Put it on the window… What is this?! Why light is so weak?
Test of 50W COB LED: very poor results
BEcause you know COB LEDs theory and how thery’re working — you know where problem lies. Lets look on light spot directly from collecting lens. The spot is bigger than scanner’s optics hole. At least 50 or even 70% of light is go past hole.
Light spot with original lenses is too wide - big part of light goes away
This is the COB LED’s problem: if you will try to focus LED into smaller spot — you will only get a negative image of COB matrix instead of single spot. Scanner will simply project COB matrix like a gobo.
But we can try a other lens that called in some shops like a «60 degree COB LED lens». This lens has smaller size that lens from ROBE condenser and i hoped that it solves my problems.
COB LED with 60-degree lens installed
I made some tests and saw that light becomes more bright if LED with lens will placed near from optical hole. So i rebuild my new LED optics and fix it directly on optical block with the same PCB stands like that:
Second version of LED optics with 60-degree lens
Now after that i get more bright result. But light power was poor. Scanner worked bright in dark room but when i turn on light (i mean generic luster with lamps) light becomes very poor. And this is — on 50W COB LED!
Here is a russian video with test of COB LED:
What we can conclude? We saw that my knowlege about COB LEDs are right: about a half (!!) of light power goes away from optics and output light brightness is very weak. We cannot focus COB LED matrix in a single spot: matrix size is too big and maximum what we can get — is a image (like a gobo) of COB matrix.
So COB matrix does not applicable for spot or beam fixtures conversion. Maybe COB LEDs will be applicable to convert Wash or ambient light fixtures (like a fill or footlights).
I was dissapointed that my idea of conversion will not be realized easy and start thinking: what LED can be used like a point light source as a discharge point from MSD lamp?
6. Luminus SSD-90 powerful LED for moving heads.
Let’s look on the popular china LED Spot moving heads (for example like that on AliExpress — LED SPot 90W). I took one photo from AliExpress to my post and show LED condenser by white arrow:
Optical part of LED Spot moving head from China with SSD-90 LED
I don’t know parameters of this condenser and can’t buy this MHs to disassembly and examine it’s optics, but in a one day (when i started learn stage lights) i bought a strange china scanners with LED source (russian version of this post located here; you can see many photos). I removed LED condenser from one of these scanners and see it:
Optical condensor for SSD-90 LED from a China scanner
Also some advertisments on russian sites offers «New spare LED for moving heads». Here is the photo of burned LED from china MH:
Burned out SSD-90 LED from China moving head
It was a surprise — in one of my china scanners the same LED was installed! It called SSD-90 and here is photo os this led in my scanner:
SSD-90 LED on a heatsink (from China LED scanner)
I searched AliExpress for that LEDs and find them! Here is characteristics of this LED for 60W power (it tooks 2,5..3 Vols DC and about 13 Amps):
60W SSD-90 LED datasheet (from AliExpress)
Main advantage of SSD-90 LED — is that this LED really look like a point light source! Its power is very high — from 1 cm distance it burns a white paper! Next advantage — that all LED crystalls are placed on one base — they’re all aligned directly to the LED output. And last advantage is that all LEDs electrically independent (not sequential connected) and powered up by parallel curcuit: if one small LED has different parameters — it will not affect other LEDs.
I am lengthen wires for this LED and carry out it from china scanner to make tests with them (i dont want to get risk immediatelly buy LEDs from AliExpress). Add some haze — and begin!
I want to remind you that i know absolutely nothing about optical rules and lenses. So i operate with beam angles and sort my lenses like «big angle», «middle angle», «too small angle». None of my friends was familiar with optics — so nothing can help me at this time.
Here is a light from original ROBE’s condenser lens. Angle is too big and so big part of light will be loss.
Optical beam from original ROBE lens
Here is light beam from LED scanner’s condenser: light angle is too small, light diameter will not light up big ROBE optics correctly.
Optical beam from LED scanner condensor
Also i darken my room and begin testing LED scanner condenser with ROBE scanner. Here is russian video. You can see in it that even if light diameter from LED scanner’s condenser is small — LED is powerful and ROBE scanner works excellent!
After that i conclude that we really necessary point light source for us! Let’s try to install it into ROBE scanner!
7. Conversion ROBE Scanners to SSD-90 LED: good results.
Before finish my project a made some tests with my different lenses (photo of them are below) and conclude that for this LED only one lens will be enough, but this lens must be placed maximum nearly of first disk — GOBO.
This is wrong! Maybe i need to take two lenses to get more small beam angle: output beam angle of my scanner was too big. Maybe i continue my tests and build a next version of optics.
Lenses from AliExpress (packed) to test with SSD-90 LEDs
After tests i order new SSD-90 LEDs from AliExpress and power supplies and drivers for them. Also i bought big heatsink (it produced for cooling powerful thyristors).
Here is my new components: LED, heatsink and thermostat:
Components for SSD-90 LED conversion: LED, heatsink and protection thermostat
Now i took into account that LED must be near of optical block and mount it on a edge of heatsink: heatsink will be installed at the left of rotating gobo stepper motor to prevent meddling wtih it.
SSD-90 is mount on a heatsink
My lens was fixed with a part of steel from old electrical panel. I pushed central hole with a hydraulic press matrix. That was funny: diameter of matrix exactly coincide with lens diameter. Optical sensor was isolated from metal lens holder and was aimed to the LED.
New LED lens placed onto DIY holder
This is my test construction: i am adjusted LED position with a file.
All new optics is mounted directly onto optical block
First tests a made with external power supply. I have a debug power supply that can give up to 30 VDC and up to 5 A maximum. I set my supply to stabilize current and set output cirrent to maximum — 5 A. Here is the first tests of my scanner:
Light brightness comparsion between SSD-90 china scanner and converted ROBE scanner (prism is off)
«LED Sc 10» means a very weak LED scanner with a 10W LED, «LED Sc 60» means a second LED scanner with the same LED (which i took from it to test with ROBE). We can see that LED brightness of China LED scanner and my ROBE are near.
Prism in my scanner was not lighten correctly, and also we see that prism cause brightness loss — but this is normal for every prism.
Light brightness comparsion between SSD-90 china scanner and converted ROBE scanner (prism is on)
These test are answered my expectations and i decided to install LED and all its components in scanner finally.
This LED needs special driver — current ctabilizer. On ALiExpress this driver called «TOC-90» and can drive only 60W SSD-90 LEDs (SSD-90 can be in 90W version, but it needs about 23 A current) with PWM. Im my scanner i cannot use PWM dimmer for this led because scanner is designed for work with shutters.
So i plan to turn on LED with MSD lamp control relay to let the lamp sensor work correctly and use original light dimming and strobing construction with shutters. I took small PWM module to set PWM on 100 percent (or control PWM if LED will become too hot on 100% power) and small power supply:
Components for driving SSD-90: power supply, driver and PWM module
To get a lots of space for LED heatsink i throwed away mount plate of hi-voltage parts and fixed main transformer directly to a back wall of scanner:
Main power transformer is moved from platform directly onto case to get more free place
Now i install power supply (it contacts side of power transistors with scanners case to dissipate heat), LED driver and PWM module:
Installed all components for driving SSD-90 LED
And now all was finished: optical block with LED and heatsink is installed:
Optical part is instaled into scanner and LED is connected
Lets power up scanner and start tests!
Testing of scanner conversion (SSD-90 LED)
First problem was with overheat (thanks to my protection thermostat): LED worked about 5 minutes and thermostat switched it off. I simply (for test) added more coolers directly on a LED heatsink:
More coolers added
Coolers need to cut off shield from scanner’s cover. Now this is normal because LED placed far away from this point of cover.
Saw cut in a scanner cover to install coolers
Now i can finally say that my scanner is working. But how good it lights? Lets see it!
8. Final. Comparsion of converted and original scanners.
I have a two scanners. One is now sonverter to SSD-90 LED and second is originally with MSD lamp. I put them all together, powered them and took a visual comparsion of light and effects. Here is video with russian and english comments. I am again apologize for my english — when i recorded this video i was excited and forgot many english words.
Here is screenshots from this video and small description of them. What test cases we have:
- LED scanner lights from a distance of 2-2,5 meters
- MSD scanner placed on the table and lights from distance of 1-1,5 meters
- Wall for projection colored in yellow-orange, so some solors does not look white.
- LED scanner has bigger beam angle than MSD scanner.
- With LED lens optical focus was changed and now we see all defects in gobo and color wheel. Maybe i continue experiments tiwh LEDs and try to select different lenses.
Here is white colors ot the wall. We sse that spot from lamp has different lighting in center and borders. Spot from LED bigger, but looks more full and plain.
ROBE Scan 250 XT SSD-90 LED comparsion: light on the wall
Here is a half-color effect of the scanners. Original optics works good, in my LED optics we see that focus placed directly on color wheel: we can sse a border of light filters. Also we see reflected image from the LED.
ROBE Scan 250 XT SSD-90 LED comparsion: half colours
Colored gobo. On MSD lamp optics again work normally, on LED version we see all specks of dust from gobo.
ROBE Scan 250 XT SSD-90 LED comparsion: gobos
Prism. Here is problems because starting diameter of my light’s beam is small and cannot light up all the prism. In some pats of prism light power is loss.
ROBE Scan 250 XT SSD-90 LED comparsion: prism
Last test. I compared scanners on a floor. We see that in a wooden fllor scanner brightness is about the same: MSD lamp a little more bright than my LED version.
ROBE Scan 250 XT SSD-90 LED comparsion: light brightness on the floor
All effects together:
ROBE Scan 250 XT SSD-90 LED comparsion: all effects
Now the converterd scanner is hanged into a workplace and i plan convert second scanner and hang them together.
ROBE Scan 250 XT is in work
What i can conclude?
- COB LEDs are mismatch for LED conversion! Even if you place 100W COB LED — about a 50% of its power will loss because COB LEDs is bigger than original fixture’s optics.
- SSD-90 or same CREE LEDs are good for conversion, but you need to know optics for calculate focus dimension and lens diameters.
- Optical focus of MSD lamps fixtures is always placed to a BACK part of condenser — lamp reflector! So you have two ways: place LED into a condenser’s focus — but dimension from LED to first condenser lens cause light dissipate and output ligh power loss; or place LED in near first effects (color, gobo) wheel — LED power will not loss, but you will see a parts of effects wheels in output.
You should convert fixtures to LED only when you know that you will use them at home or small places. If you plan use fixtures for thay originally designed for — don’t try to experiment with LEDs.
So my scanner works now like a «Beam+Wash» fixture — it creates a big dissipated beam fo back effects. You can see it on this small demo video (it lights from back):
And here is other demo on Sash — Equador. ROBE scanner is still hanged on a back of my «stage»: