CurtPalme.com Home Theater Forum

**Curt Palme**

Was working on a common CRT chassis, known for bad capacitors. This set had an orignal 677 hours on it. Got the set for $100, incl a Runco DLP and 3 video processors, ceiling bracket and manuals (!).

I always make it mandatory to test all the caps on this chassis due to the high failure rate, and sure enough, I found a bunch open. As I fired through the various boards, I found that only one value of cap was bad. I had about 8 of them bad in the set. Wide open. Picofarads instead of mucrofarads. Caps beside them were fine, and bang on value.

Mac, Mike or anyone else, has anyone ever seen this? One cap, all the same type are bad in one set? Bad cap run maybe, about 18 years ago? Smile

Sparky015 · Posted: Thu Apr 01, 2010 5:02 pm Post subject:

Not sure I would call it a bad cap run. I would call it a consistant one! Laughing

Unless that chassis is under warranty, I would say they did their job.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Dont know. My meter doesn't have a mucrofarads selection........ HAHAHAHAHAHAHAHAHAHAHAHA

Change the selector on your meter, lol. Your on the wrong setting.

Whats the ERS reading on them? Or is that your open reading? Then how about value test?

If the set is one that is common to have a large volume of bad caps then they used cheap made ones new and this would not be uncommon.

I've had tv's built in the early 90's where most of the caps in the set were bad and it was common from that manufacturer.

I guess there were many manufacturers trying to save money back then and bought stuff from shady suppliers.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

What brand are the caps?

mp20748 · Posted: Thu Apr 01, 2010 6:58 pm Post subject:

I don't think I've ever seen a particular value cap fail only. I'm more familiar with the caps going in certain circuits being more common.

Reading this is a first for me.

Concerning caps, My 9500Lc Ultra is either a 2002 or 2004 build year. It had about 40,000 standby hours, meaning it was on continuously for 40K hours before i got it.

In checking the caps, I've only found a few of them to have a problem. And when I changed out those few, it made no difference with the overall operation of the projector in performance or anything else.

caps continue at times to be very mysterious to me as well.. Sad

**Curt Palme** · Posted: Thu Apr 01, 2010 10:21 pm Post subject:

I agree Mike!

It was an older NEC PG. It was all one cap that was bad, same voltage, same value. All had leaked out the bottom, so they were easy to spot. As you said, even though about 5 on the board didn't read ANYTHING on the ESR meter, the set continued to work, and my intermittent no pix was a bad HV board. Posting another problem about this set in another thread...

Mac, dunno the brand, they were stock NEC caps.

Oh, I should add, the set had some syncing issues as well that replacing these caps did indeed fix, but yes, I'll bet I could have left 4 of the 6 caps without adverse effect.

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

Just when I think I'm getting the hang of the abuse of the alphabet youze techies use you throw new ones at me...

mucrofarads and ERS's..I Googled but came up empty. Wink

Serious questions now for the techies...

I built the Anatek Blue /Low Ohms ESR tester a while back from a kit (http://www.anatekcorp.com/esr_compare.htm) and put it aside without using it. I want to dig into the boards on my 8500; specifically the Astig Amp and Vertical board, and don't fully understand what the results mean.
I've read alot of their forum and tech materials and 'think' I have a handle on how to use it but I wanted to ask you all a couple questions on how YOU test caps:

1) How to determine the cap is 'open'
2) What the test result number means, eg, how would I know if the ESR is too high or low if I don't know what it SHOULD be?

Apologies for the segue/hijack attack. Embarassed

Tom.W · Joined: 09 Mar 2006 Posts: 6635

This might help

http://octopus.freeyellow.com/esr.html

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Here's a nice little chart for you Greg, if you dont already have one. Read the notes above and below the chart also.

http://www.your-book.co.uk/design/esrchart.htm

mp20748 · Posted: Fri Apr 02, 2010 6:20 pm Post subject:

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

mp20748 · Posted: Fri Apr 02, 2010 11:40 pm Post subject:

**Curt Palme** · Posted: Fri Apr 02, 2010 11:46 pm Post subject:

Mike, I think he's talking about you not getting into ESR. Frankly, I didn't either for the LONGEST time, but that ESR meter on eBay for $200 or so is the best investment I've made in a long time.

I run through boards now quickffast, and I find the strangest problems solved by caps with a high ESR.

Buy one, try it, and I guarantee that you'll find it damn handy.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

So still confused on ESR. I guess its my fault for not finishing the cap thread, lol.

ESR or equivalent series resistance is not a test of how a cap will perform in a circuit. It is not a test of quality of a cap. It is a test of the condition of a cap.

ESR is frequency dependent. What that means is that ESR will be different at different frequencies. Now since there is fluid in a cap you cant test it with a basic ohm meter. Even this fluid has some resistance when passing a frequency. The less fluid there is the more effective resistance the cap will have. Other parts of the cap also have effective resistance but fluid loss will have the most effect over time as the cap wear out.

It had been found that the most efficient way to test ESR is to pass a 100khz signal through the cap and measure it on exit. This will then calculate how much resistance the cap has and when compared to what a known good cap should be you can determine if it is starting to fail.

Now, how will this affect the circuit its running in? Depending on how much ESR it has it may not affect it at all. Why? Remember I said that ESR is frequency dependent. Well if a cap is showing 10 ohms esr, meaning its is going bad, it may not show any resistance in the circuit its in because that circuit may be running at a frequency other then 100khz. So the circuits frequency may show a normal ESR at its frequency.

And your scope patterns would all be normal................................

So what does this mean?

It means that even though the cap is preforming well in the circuit that it is in...... it is still failing. Because the ESR test has shown the cap has lost some fluid and is starting to fail. How long before it fails? That depends.

If you remember the cap thread there are circumstances that will cause the core of the cap to over heat. And if the core is overheating it will cause the cap to fail even faster. And as more fluid is lost from this over heating the hotter the core gets until there is no fluid left and now the cap also fails a value test and the circuit is surely affected, possibly damaging other expensive parts.

So even is the cap is still performing in the circuit its in, based on a scope test or other, but the ESR test shows the cap is failing...... it needs to be changed. Because its failure rate is now increasing very, very quickly.

So your scope may show the cap is performing perfectly but 100 hrs from now it fails and takes out multiple other expensive parts along with it. ESR test is very important.

I think I covered it but if I missed something.... ask away...... Smile

mp20748 · Posted: Sat Apr 03, 2010 8:16 am Post subject:

Mac,
I appreciate your vast knowledge on caps and your experience on consumer electronics, which too have also been involved in.

But my comments is more geared toward commercial grade product, which does not and have not been using the same grade caps. therefore our experiences have been slightly different. So can you answer my question on which CRT projectors manufactured in the later 90's on had caps that leaked the same way that Curt indicated on that particular NEC, and why was the split later put on the top of the cap?

Or do you have any experience with the later commercial grade equipment and the caps used?

Concerning ESR. It would be nice to have a ESR meter and I plan to get one one day. But you'll be surprised at what one could do simply with a scope and the right equipment.

And my comments on the LVPS and ESR... If a marquee LVPS has been working flawlessly for thousands and thousands of hours, at what point did the high ESR cap caused it to fail. Forget the consumer stuff for now. no way would it ever get those hours of use on it and still maintain good scoped readouts.

No question I understand ESR. so don't think you need to finish a thread on caps to make sure I'm informed properly on it. And also keep in mind what I said about certain caps failing in certain circuits, which I find to be common because of the circuit. But regardless of the theories, what caps of the later batch used in commercial gear has had a high failure rate from drying out. leaking out on the board from the bottom. And other than the CT cap failures, which commercial grade CRT projector using the later caps has a history of ESR failing caps in the power supply that actually caused the supply to fail?

mp20748 · Posted: Sat Apr 03, 2010 9:04 am Post subject:

Quote:

Todays good quality cap manufacturers have made great advancements in their products but there are also those shady manufacturers making crap caps. And the crap caps are going in the devices at the electronics manufacturers. Then the repair guy has to replace them with high quality one.

Ok, so you are also acknowledging here that there are better made caps, as well, as there still being cheaply made caps.

Do you think these cheaply made caps would hold up in the switching power supply, deflection, etc. of one of the projectors I've mentioned?

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

So, to re-cap........ Mr. Green

kidding.

Very very informative for electronics toddlers such as myself. I followed some of the links at anatek.com and there's a Chinese (??) gentleman who used an analog VOM for years and years combined with a freq generator to test caps. He just recently started using the Blue ESR Anatek designed by Bob Parker. (What's with those Parker boys and what did they eat as kids to get so damn smart). Laughing

He's also peddling a line of e-books that boast anyone can fix almost any consumer electronics with a few 'simple' pieces of diagnostic test gear. uh huh.

Thanks for the chart Mac...soooooo much easier to digest than the simple graph stick(er) on chart anatek provided for the meter I built. It actually makes sense now that I see the one you pointed me to but 'yours' (Bob Parker circa 1998) is more detailed.