Film-Tech Forum ARCHIVE: irratic change in brightness of LED on CE reverse scan

This is topic irratic change in brightness of LED on CE reverse scan in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Bernie Anderson Jr (Member # 410) on 10-20-2010, 12:35 AM:

Never seen this before. I just hooked up a used CE Reverse Scan with a LS-30-M power supply. At the end of a test reel, I lost power to the LED altogether. I'd figured maybe I hit a wire. Checked all connections, Tried a different LED too. Nothing. I swapped power supplies with another one from the Digital side. LED worked fine. I swapped back to the original power supply and the LED was lit! I watched another test reel and it was fine then all of a sudden, I lost volume, almost by half. I looked at the LED, it was as if it was on a dimmer, fading away, then back to bright again, finally dying out to nothing. Has anyone seen this before? The reverse scan sat for about a year unused before I got it. Prior to this it was in service without a problem for 7 years.

Posted by Tony Bandiera Jr (Member # 2365) on 10-20-2010, 01:54 PM:

Hi Bernie. The problem is in the power supply, either a bad filter cap that is shorting out and shutting down the internal voltage regulator, or the voltage regulator is bad.

You will need to get the power supply serviced soon, before the failure escalates and blows the internal fuse.

Contact CE I believe they can do a repair-exchange, or if you have a local electronic repair tech he should be able to fix it for you.

Posted by Bernie Anderson Jr (Member # 410) on 10-20-2010, 06:53 PM:

You're talking about the 1000uf 16v cap in the middle of the board? It doesn't matter how the physical power supply is mounted? I'm thinking of cooling and venting.

Thanks

Bernie

Posted by Randy Stankey (Member # 64) on 10-20-2010, 07:43 PM:

I agree. I'm 90% sure the problem is the power supply.

Here's the gambit you face:

1) You can find a workaround or do nothing and it will steadily get worse, in which case you'll have to replace the unit or parts therein. When it fails, it will likely happen at the worst possible moment. So says, Mr. Murphy.

2) You can try to perform component level repair on it yourself. If you're knowledgeable, you'll be able to fix it. If not, you're just farting around. If you are able to repair it, good. If not, you're out of luck. There is always the chance that your fix will only be temporary and it will blow again. Hello, Mr. Murphy.

3) You can repair-exchange it at the manufacturer. In which case, you'll have reasonable assurance that you're getting a good, working piece of equipment that won't fail on you again.

The bottom line is that you either fix it yourself or have them do it for you. If you follow the manufacturer's advice, you know who to call to complain. If you do the work yourself, you have nobody else to blame. Further, if you fix it yourself and fail, the factory can say that you tampered with it, thereby putting you on the hook for buying a whole new one.

I don't doubt your ability to make the repair. If I was in your place, I'd be considering the same thing. However, I'd also be weighing all my options and considering the possible outcomes. All I'm doing is pointing that out.

Posted by Tony Bandiera Jr (Member # 2365) on 10-23-2010, 08:32 PM:

Hi Bernie:

Yeah if I remember right that is the capacitor..it has been a while since I opened one up.

Like Randy said you have several repair options. The best option is to do the repair/exchange with CE to ensure that it is done right.

Mounting and cooling should not be an issue unless you've got the supply right above a hot amplifier or rectifier.