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icecream · Sep 20, 2007, 09:43 AM

Hello all. New at this site and loving it. Thanks for having me. My question is this.

I'm having trouble with a disco light. This guy came in and dropped it. He says there might be wrong with the ic chip or it could be fuses.

OK first things first I replaced all the fuses with new ones. Powered it up with 120v source and fuses blew on the board. Any idea why its doing this? Too much load? I'm very new with dealing with circuit boards and wonder if anyone has any ideas.

tkrussell · Sep 20, 2007, 12:38 PM

Need more info, provide the make and model number of the unit in question so that the specs, circuitry, and sequence of operation can be reviewed.

icecream · Sep 20, 2007, 01:43 PM

Hi russ,

Its called a mp250fresno and made by coer.

OK so when I power up the fuse is blown. The light for the on switch is on but nothing else is ex: fan, light, etc. I checked all the wiring, all of them is in good condition. Anything to do with the ic chip? Nothing on the circuit board seems to be blow but the fuses. No marks or burnt markings on any other devices.

I really hope you can help me. I read some of your answers and you seem like a very intelligent guy.

Sorry about the stupid answers from the others post. I'll refrain myself now!

Thanks for reading buddy!

tkrussell · Sep 20, 2007, 06:39 PM

Yea, I know some stuff, but I don't know everything. You'll get the hang of this website, treat others as you like to be treated, have fun, be accurate and safe, and you will do fine.

Is this the unit?

A MP 250 Fresnel made by COEF:

MP250 Fresnel

Also found at the manufacturers website.

www.coef.it

Even with incorrect info I can find it, done a few stage/studio gigs myself.

Really helps to be as accurate as possible to get the best possible answers quickly. Everyone here is volunteer, and time is precious.

Here is the service manual:
http://www.coef.net/user/data/02E004_070327_100.pdf

This is a packed unit, with servo motors (AKA step motors) fan, lamp, and control board. Nice unit, must have set you back a few bucks.
There is a simple wiring diagram on page 8, I see three fuses on the board and the main unit circuit breaker.

They unfortunately do not show what fuse protects what. My guess is the three voltage circuits, 2-28 volt and 1-12 volt. If you clear all the peripherals from the main board, and if the fuse fails again the short is in the board. If not plug each harness in one at a time until the fuse blows.

I am no electronics expert, there are a couple of people here with that expertise, KISS and Donf. Hopefully they chime in to help beyond my basic troubleshooting.

I notice the manufacturer does not know how to spell "warranty".

donf · Sep 21, 2007, 02:08 AM

To really trouble shoot this problem, you need an actual schematic, not block diagrams. From what I saw in the manual, it looks like you need to go to Italy for tech support, on your dime.

The block diagrams show component placement, but not the lands on the board to see where the power is coming from and going to.

First, I would suggest that you see if you can trace a circuit on both sides of the fuses with a continuity tester. Be sure to pull the fuses before you build your circuit on paper.

Next, get the voltage and amperage ratings on all of the fuses. Then verify that your power IN is giving that to you. Unfortunately I did not see a diode bridge to act as a rectifier for the AC IN, but that does not mean it is not there.

To smoke the three fuses immediately means you are either putting too much Voltage or amperage in. OR there is a dead short in the power supply area of the circuits. Since this is a foreign unit you might want to make sure that the transformer if switchable is set for the correct voltage.

Stratmando · Sep 21, 2007, 06:35 AM

Actual Schematic would be very helpful, I would look closely at spot where unit made impact. Is it forcing board, component, or connector to case/ground? Chips are pretty tough. Would unplug fans, strobes and other outputs. Do the fans spin freely? I think they were all 12v 2.6 watts. Resistance test will reveal short.

donf · Sep 21, 2007, 07:01 AM

Russ,

Let's see if we can isolate the failure any better than we already have. Do you have a magnifying glass? If you do, then lets turn the board over and search the lands and joints on the bottom of the board. What you are looking for are burn marks or brown spots. Also look closely at the soldered joints to make sure that none of the joints are cracked, pitted or "Cold Joints" A cold joint is one where it moves and allows the component to move with it. If you find a cold joint, then make sure the component on the reverse side is not burned or loose on both sides.

Take a moment and measure the fuses to make sure that are at the proper resistance rating. Next I would pull all three fuses and meter the bottom of the posts to make sure that the input voltage is the correct level and sustained. Next I would put each fuse back, one at a time, and power the unit back on to see if I can isolate the failing the component.

What you are looking for, if you can get all three fuses installed and working is a component that gets really hot really fast.
'
Given the history of the unit being dropped, I'd also consider taking this back to the seller and let them know that you would appreciate a working lamp.

icecream · Sep 21, 2007, 07:58 AM

Thanks for all your great response.

i'll start with Russ,

It didn't cost me that much only cause its not working. Well it was when my buddy had it till it stopped working for some reason. He wasn't able to fix it, which is why he gave it too me for a dirt price.

I did what you asked and removed the all peripherals from the board. And yes, the fuses blew once again. So now we determined the short is on the board.

Hahaha @ warranty!

Hi Donf,

Thanks for your reply buddy.

I have checked t he continuity on the fuses and they have connection.
The voltage and amperage ratings on all of the fuses are correct.
ABout the transformer you mention. I really need too look into. I think maybe that's what causing it to blow. But I talked to my budddy and he said he didn't touch the transformer... hmmm

Any other ideas on what to do would be awsome.

Hi stratmando,

I agree an actual schematic would be helpful. Unfortunately I couldn't find it on net. The fan don't spin at all. The only sense of power I'm getting is on the "on" switch (glows red)

Hello donf again,

I have looked very closely at the board more than once and I see no burns or brown spots or cold joints.
I did test each fuse one at a time and I found out that F2 and F3 are fine alone or together when putting power through them. But when F1 is tested alone it smokes.

Thanks again for all your posts. Again, any other suggestions is welcome.

icecream · Sep 21, 2007, 08:01 AM

Hmmm if it was an ic chip... which one would you guys recommend on replacing?

donf · Sep 21, 2007, 01:22 PM

To know that would mean we have a schematic and a chip map. There are only a few million Integrated Chips on the market with all manner of And, Nor, Xor gates.

Do you have a digital camera that you could take a picture of the board for us?

Also, why are you saying that the fuses blow. If you have end to end continuity, then the fuses did not blow.

icecream · Sep 21, 2007, 01:39 PM

I'll have pictures for you tomorrow. I really hope we can tackle this. I really want it working :(

tkrussell · Sep 22, 2007, 04:21 AM

There is a photo of the board in the manual I provided, but your picture should be closer and clearer to read the model numbers on the components.

Try contacting the manufacturers tech support? They can tell you exactly what the fuse protects and narrow down the troubleshooting.

Look closely at any component or jack that has pins, to be sure no pins are bent and shorting. Try following the trace on the back of the board to follow the circuit from fuse. If you find it feeds a component that you can unplug or easily remove, try that to see if fuse stays.

icecream · Sep 24, 2007, 01:43 PM

Thank you for all your great reply.

I took your advise russ and contacted their help desk. They said to trouble shoot the driver chips and that's what I did.

I replaced all fuses with new ones. Disconnected all connectors and removed all chips. I powered the unit and sure enough the fuse did not smoke. So one by one I started to put back the driver chips back in its proper location and sure enough one of them tripped the fuses causing it too smoke. I replaced the defective part and viooollllaaa!. I finally got power to my unit!

There's still some things wrong with the unit. Errors are showing that the tilt and rot gobos motor. I guess I'll have to check that out or maybe replace it. It is making funny loud noises.

Any suggestions about these morors would be cool.

Thanks again guys.!

Stratmando · Sep 24, 2007, 02:08 PM

Can you see anything physically causing the noise. It is possible the impact could have it caused it to jump a tooth on a gear. I wonder if impact caused binding, loading down driver. Is the new chip for your tilt and rotate?

icecream · Sep 24, 2007, 03:17 PM

Originally Posted by Stratmando

Is the new chip for your tilt and rotate?

Hi,

Really good question. That I couldn't tell you. It does not say on the drawings that russ found. Also, it doesn't seem like its caught in anything. It just sits there on test (suppose to be turning) when I touch the wheel it stops. Do I seriously need a new motor I wonder? I looked in the net and couldn't find the right one. I'll keep looking.

Any other ideas?

icecream · Sep 24, 2007, 03:18 PM

Originally Posted by Stratmando

Is the new chip for your tilt and rotate?

Hi,

Really good question. That I couldn't tell you. It does not say on the drawings that russ provided. Also, it doesn't seem like its caught in anything. It just sits there on test (suppose to be turning). When I touch the wheel, the noise stops. Do I seriously need a new motor, I wonder? I looked in the net and couldn't find the right one. I'll keep looking.

Any other ideas?