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MH-660 problems


dubious

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I am having difficulty with two MH-660's. The first has been giving me a pan error, so I opened it up to look for problems etc and figured out that the magnetic stop switch is cooked (I swapped it with one from another light and the error resolved). I'm guessing I just need to solder new sensors on but I have no idea where to find them. They are small, black, three pin and the writing on them appears to be "506/A 1494". The other light works fine on its own but as soon as I plug in the DMX it goes haywire and also makes every other light in the chain go haywire. I'm guessing that the DMX chip is fried. Is that something I can find a replacement for? I've inlcuded relevent pics.

 

Thanks

 

 

EDIT: And the chip in the third pic is the same as the one in the second pic, just with the sticker scratched off.

 

 

http://img.photobucket.com/albums/v473/1dubious1/IMG_1072.jpg

 

http://img.photobucket.com/albums/v473/1dubious1/IMG_1073.jpg

 

http://img.photobucket.com/albums/v473/1dubious1/IMG_1074.jpg

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The pan sensor is a hall effect sensor, 506A is the part number the rest is the date code (14th week of 94), and the full part number seems likely to be a HAL 506/A (The /A specifies a high temp version).

 

The PIC is a micro controller and any replacement would need to be programmed to work, but I am very surprised to see DMX being applied directly to the PIC, are you sure there is no 8 (or just possibly 14) pin chip near those sockets (Possibly with 485 in the part number?), it might be on the back of the board (This will be the actual line receiver and would very likely be the fault (much easier to obtain).

 

Regards, Dan.

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Thanks for the reply! Any idea where I can buy a few 506/A? I can only find them online in thousands. Or tens of thousands.

 

As for the DMX, I did not even think to look on the underside of the board. Could it be one of the two chips with the heatsinks? I'm guessing one of them is the pan motor controller. This my first time spelunking through a fixture like this so I could be wrong though. Also, wouldn't there be a bunch of contacts in rows on the top of the PCB if there was a chip on the bottom?

 

Curt

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http://www.micronas.com/en/automotive_and_...ticlelistpage=3

Scroll down to the 506/A and hit the buy button or try for a free sample.

Failing that, Allegro Microsystems have some parts that should include something suitable available from Farnell.

 

The heatsinked parts will be stepper and possibly solonoid drivers, pull the board, turn it over and trace the tracks from pin one and two of the XLRs, odds are they disappear into a line receiver chip which will be very much smaller then that PIC (probably 8 pins only).

 

It may be a surface mount package however (Anti social line receivers should be socketed for exactly this reason).

 

Regards, Dan.

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The Futurelight MH660 (made by Robe, this one, sim. to a Club Spot 250) uses a texas instruments SN75176 DMX transceiver chip so this is the first port of call. The DMX ttl data goes through the ribbon cable that connects the control panel before being processed by the CPU, this might also be faulty. Check the front panel isnt soaked in smoke fluid as they dont like it.

The hall effect pan limit sensor isnt really critical, you can get a honeywell equivalent from RS or Farnell if you're stuck.

I assume you've checked that the DMX mode has been set to match the others, this might make it seem like its doing crazy things to the DMX. I dont just mean the address, I mean the channel assignments in the parameters. Do a fac reset if you want, it may have been set to Master-Slave mode and is re-transmitting master commands to the next in the chain.

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This should do for the sensor

http://uk.rs-online.com/web/search/searchB...p;x=31&y=14

 

But I'd check the wiring first and for dry joints etc. There should be 5v on Pin 1, 0v on pin 2 and pin 3 should go low when the magnet is in close proximity to the sensor. I quite often find the molex connectors and ribbon cables play up on these.

 

As for the DMX trouble..

 

When you say the other fixtures in the chain go haywire - do they do so receiving valid DMX, or just framing errors?

 

Looking at the service manual (PM me with an email address and I'll send a pdf) the DMX in/out XLRs are hard wired together so the signal should just pass through the unit unchanged. If, as the OP suggests, this is not happening correctly, the tranceiver chip - SN7516 as indicated elsewhere in the thread, may well be fried. From memory it's an 8 pin surface mount job underneath the main PCB. Bit of a fiddle to change!

 

It does seem that the PIC on the display PCB can switch the 75176 into transmit mode via the 10-way ribbon cable between the main and display PCBs. It maybe worth checking that this is connected properly. (not sure why this is like this as I don't think these have a master/slave mode so I can't see why the unit should ever want to transmit DMX). But a dodgy connection could cause the chip to flip into TX mode.

 

Also , the DMX lines do have resistors to the +ve and -ve rails, so another explanation could be that the PSU has gone noisy. However I would have thought this would stop the unit working properly even without a DMX input. Always worth looking at the power rails on a 'scope though to check that it's nice smooth DC. Failed capacitors are quite a common cause of trouble on ageing electronic gear, especially electrolytics used to smooth power supplies.

 

Let us know how you get on - I have 4 of these which are becoming increasingly high-maintenance so could well end up with similar problems in future.

 

Eddie

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WOW you guys are awesome! None of the local guys I talk to have even heard of futurelight, never mind the MH-660.

 

I have my 5 "free sample" sensors on order from micronas, so I'll just replace the ones I suspect are faulty. Seems like the simplest fix.

----That being said (because these were two separate lights) I took the pan sensor from the light with the DMX issues and put it in the other one= one light working perfectly

 

As for the light with the DMX difficulty, I must confess I never tried doing a factory reset. I should also mention that I hadn't looked at these lights for about six months prior to last week so any memory I have about exact behavior is sketchy at best. I just remember a long time spent troubleshooting my whole chain (of eight of these) came down to this light making everything retarded. So I just put it aside. I'll try plugging it back in sometime this week to see exactly what happens.

 

Now that you mention it, Keven, I do remember seeing a little rounded chip underneath the main CPU, so at least I know what that is now.

 

Last but not least, this light must be the bastard child of Robe and futurelight. I have noticed in the past that the menu options have never quite lined up with what the manual says they should be, but I never thought (until now) to check to manual for the robe spot 250. Guess what? Identical. I have the only MH-660's in the known universe with master/slave mode. Lucky me.

 

Thanks everyone for the help! I'll let you know as soon as I look into the problem further.

 

Curt

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Curt,

 

Oddly enough I've just acquired a couple more of these, and when checking yesterday one of them went haywire when I plugged the DMX in, after apparently booting and resetting OK. It did eventually settle down, but waggling the XLR made it go mad again. I noticed that the DMX input XLR was loose.

 

I've not had a chance to properly investigate yet but I suspect that the connection from the DMX in socket to the PCB is intermittent. It seems that intermittent DMX may cause these lights to "go haywire", and of course the rest of the chain will get the same intermittent signal.

 

My next question was going to be "is the rest of the chain all MH-660s or a mixture of different fixtures which all go haywire" bit I think you've answered that.

 

Will send manual asap

 

Regards

Eddie

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Alright, went back to the church yesterday and plugged it into the chain. All 7 of the other lights started moving randomly. No patterns, no set intervals, mostly short movements though. The colors/gobos stayed correct about 80% of the time. I should also mention that the busted light was at the end of the chain. I have it apart on the bench... uh... coffee table right now. Anybody got any ideas on how to diagnose that DMX chip?

 

Curt

 

A concurrent post has been automatically merged from this point on.

 

Scratch that... I think this is out of my league. Pan sensors I can do. Soldering tiny IC's... not so much. I have an email in to Robe to see what they'll charge for a new board.

 

 

A short while later

 

Well the pan encoder and prism position sensor have also bought the farm. I think this thing is officially a parts machine. Thanks all for the input!

 

Curt

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None of the local guys I talk to have even heard of futurelight

 

I dont think they're particularly well-represented in the UK any more. They were one of those german brands that had their units made by Robe before Robe were themselves known very well. They are extremely well made and were not cheap!

 

These days Futurelight is distributed directly from Germany, their designs reflect the earlier Robe-made stuff though various posts on BR have shown it is now most likely made by Guangzhou Hao Yang Electronics Company whose brands include 'Terbly' and 'Golden Sea'.

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I've bought spare parts in the last year or so from Robe - many of the 250XT parts are the same. I have only bought lenses though, so not sure about boards/software etc. but I guess they will still have the software version you need. I did enquire earlier this year about boards when the pan died on one of mine. A new main board is a couple of hundred quid so quite a pricey shot in the dark, if you're not absolutely sure that's where the fault lies. The DMX receiver chip is on the main board, but the signal is passed straight to the display board which seems to do the actual DMX decoding etc. So it could be either board, or the 10-way cable between them.

 

I don't claim to be an expert at these things but I've fixed mine 4 times now, one sensor magnet fell out, 2 were dodgy multiway connectors and only 1 was a chip failure - the D/A in the pan driver circuit as mentioned earlier.

 

Depending on how confident you are with a 'scope and a meter I'd seriously check power supplies and interconnects first as these are more likely to be the problem. Maybe swap the 10-way cable from the Main to Display board with one from another unit? Or try swapping the display boards as they only have the one connection so are quite easy to remove.

 

As Kevin says these are quality units so worth persevering - good luck!

 

Eddie

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