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Old 05-06-2012, 10:19 AM   #1
caspermccormack
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Default cookerhood PCB Powerpoint ch581

Hello,

I have a Powerpoint CH581 extractor hood in the kitchen that works fine on all 3 speed settings but no longer lights the 4x12v halogen lights, I pulled out the pcb and found some parts of the board that had alot of heat but nothing I can see is fryed. There is a fuse resistor that I removed and tested, and it is fine. The nearest transformer to the light connector (connected with copper trace on the rear)has a split in the wraping, could this be the problem?

IMAG0327.jpg

IMAG0326.jpg

IMAG0328.jpg
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Old 05-06-2012, 12:24 PM   #2
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Default Re: cookerhood PCB Powerpoint ch581

Took out the transformer, have resistance on the fine wire coil and OL on the heavy wire coil, I'll change it if i can find out a part number for it, no markings on the unit whatever, how do I find out what to replace it with??

IMAG0329.jpg

IMAG0330.jpg

IMAG0331.jpg
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Old 05-06-2012, 01:36 PM   #3
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Default Re: cookerhood PCB Powerpoint ch581

Is there any +12V to the bulbs?
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Old 05-06-2012, 01:48 PM   #4
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Default Re: cookerhood PCB Powerpoint ch581

No, no voltage to the bulbs.
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Old 05-06-2012, 01:53 PM   #5
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Default Re: cookerhood PCB Powerpoint ch581

Quote:
Originally Posted by caspermccormack View Post
No, no voltage to the bulbs.
with or without bulbs?
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Old 05-06-2012, 02:18 PM   #6
caspermccormack
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Default Re: cookerhood PCB Powerpoint ch581

can't check, i have the board out and the hood is at my sisters 50 miles away! any way around to check it?
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Old 05-06-2012, 02:47 PM   #7
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Default Re: cookerhood PCB Powerpoint ch581

Quote:
Originally Posted by caspermccormack View Post
can't check, i have the board out and the hood is at my sisters 50 miles away! any way around to check it?
Without bulbs is good. I was just wondering if a bulb could be shorted and drawing too much current.

How's the main fuse?

Any output diodes (or is it AC output?)
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Old 05-06-2012, 03:12 PM   #8
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Default Re: cookerhood PCB Powerpoint ch581

Takes in 220v

Do you think the transformer is knackered?
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Old 05-06-2012, 03:22 PM   #9
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Default Re: cookerhood PCB Powerpoint ch581

Quote:
Originally Posted by caspermccormack View Post
Takes in 220v

Do you think the transformer is knackered?
Unlikely...

Does it give AC to bulbs or DC to bulbs?
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Old 05-07-2012, 05:50 AM   #10
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Default Re: cookerhood PCB Powerpoint ch581

I think it's AC, have a look at the photos you may have a better idea that me.
IMAG0332.jpg

IMAG0333.jpg

IMAG0334.jpg
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Old 05-07-2012, 06:59 AM   #11
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Default Re: cookerhood PCB Powerpoint ch581

Looks like DC. What's that black package on the board? Also, the connector looks a little discoloured... check for cold joints on it.
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Old 05-07-2012, 02:30 PM   #12
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Default Re: cookerhood PCB Powerpoint ch581

All the solder joints look good, The output pins to the lights look like the got hot before whatever eventually blew. This is a pic of the black box on the board, I think its a capacitor.
IMAG0335.jpg
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Old 05-07-2012, 02:38 PM   #13
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Default Re: cookerhood PCB Powerpoint ch581

Interesting... maybe a motor start/run cap?

It looks more like a normal AC transformer, in which case have you checked fuses? It could be simply o/c on one winding which is difficult to repair...
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Old 05-07-2012, 04:21 PM   #14
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Default Re: cookerhood PCB Powerpoint ch581

The black box in post #12 is a 5uF 450Volt capacitor. Common for small motors to use it. I have seen a lot of failure in ceiling 'paddle' fans, causing them to run slow even on high speed.

The transformer in the second post is bad. Large diameter windings, if good, should have very little resistance. OL on your meter means it's an open circuit.

Also, replace that discolored lamp harness connector. A bad connection will only heat up, causing more resistance, causing more heat. (thermal runaway). I have seen a lot of pin-socket failures for those 12v 50W MR-16 lamps.

Most manufacturers in the US have stopped using them in recessed lights and track lights due to problems with the electronic transformers and sockets. Most of the MR-16 family fixtures now use the GU-10 twist lock bases at line voltage (120)to the lamps.
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Old 05-08-2012, 02:10 AM   #15
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Default Re: cookerhood PCB Powerpoint ch581

As I said in the first post, the 3 speed settings are working fine only the lights(4x12v halogens) are not working, Switch control box lights up an LED to say they are on but nothing comes from the control board. There are no markings on the transformer so how do I know what to replace it with??
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Old 05-08-2012, 02:15 AM   #16
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Default Re: cookerhood PCB Powerpoint ch581

These are the bulbs


marks bulbs.jpg
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Old 05-08-2012, 04:20 AM   #17
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Default Re: cookerhood PCB Powerpoint ch581

Quote:
Originally Posted by caspermccormack View Post
As I said in the first post, the 3 speed settings are working fine only the lights(4x12v halogens) are not working, Switch control box lights up an LED to say they are on but nothing comes from the control board. There are no markings on the transformer so how do I know what to replace it with??
You could rip apart an old wall wart or halogen lamp power supply. A 12V, 5A SMPS sells on eBay for 5 now. Replace the caps in it and you'll have a reliable ~10 year power supply.
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Old 05-08-2012, 04:46 AM   #18
caspermccormack
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Default Re: cookerhood PCB Powerpoint ch581

Will i still be able to use the light switch thats on the hood to power the new power supply?
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Old 05-08-2012, 05:38 AM   #19
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Default Re: cookerhood PCB Powerpoint ch581

Quote:
Originally Posted by caspermccormack View Post
Will i still be able to use the light switch thats on the hood to power the new power supply?
If you wire it in series with the mains or lamps, yes.
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Old 05-08-2012, 07:05 AM   #20
caspermccormack
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Default Re: cookerhood PCB Powerpoint ch581

I think the switch on the hood is a low voltage so if I replace the power supply to the lights I'll need a 230v mains switch.

Also I can't see a bridge rectifier so I assume this circuit is AC????
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