Great Caps=Bad result (DVP642)

[relkin67]

Has anyone ever experienced worse results or failures when using low esr caps as replacements? I just have...

I have a Philips DVP642 DiVX/DVD player. It worked fine but would garble the audio on .avi files after extended play. Yes, I know the "setup key" trick but that became less and less useful the farther you into the DVD of .avi files (the garbling would come back within 30 seconds).

I had already used Arctic Silver to cement heatsinks on the hot components (which did help). Having lurked here for a while, I decided to rebuild the power supply with some high quality capacitors to assure that super clean power was reaching the board. I used Rubycon MBZs on a 1000uf/10V & 470uF/16V cap & Nichicon PW(M) or Xicon low esr (from Mouser) on smaller caps.

Guess what? Now it wouldn't power on. I checked the 5V line and it was quickly cycling between 4.6 and 4.95 - totally erratic and unstable.

I had a 5 year old Panasonic FC 1000uF/16V (still in the Digi-Key plastic - left over from a recap project long, long ago). Now I knew that this probably was going to be totally out of spec (Rubicon only gives a 6 month shelf life spec on low esr caps, 2 yrs on standard). And when I put it in, the 5V voltage was low (1.54) but stable.

Now I can't let this thing go. I run over to RadioShack and pay through the nose for a Xicon 1000uF/35V 85C standard cap (replacing the pany that replaced the ruby). I put it in and now the 5V line reads a steady 4.09 V. Hmmm...

I then went back and (very regretably) pulled the Ruby 470/16, a Nichy 220/35 & two Xicon 220/25s. Put the board back in the DVD player and NOW IT WORKS FINE!! 5V is 5.15 and the player is running happy.

So my first hand experience here is that the boilerplate "use great low esr caps" does not always seem to be the best advice.

I'm not trying to cause trouble here. I've just recaped a Mac LC and Power Mac 7500 power supplies with Rubys and couldn't be happier with the results - both are now very stable. I was just very surprised that using great low esr caps in the Philips player caused such problems that were completely fixed by putting the old crappy Su'scon caps back in. I have a Lasonic DVD/HDD DiVX player loaded with Fuhyjjus that I was going to recap with Nichicon PW(M)s but now I'm hesitant to do so. They haven't leaked yet and replacing them with low esr caps might be worse.

So can anyone comment on my DVP642 experience? What's going on here?

[starfury1]

Re: Great Caps=Bad result (DVP642)

Hi and Welcome

well no idea on the units PSU design but if you look at the recommendations its output caps on SMPSU ans VRM thats Low good quality ESR caps are recommended for.

I assume thats what you replaced on it still you are quite correct in saying that its not the ultimate answer to replace every cap with them.

My only thoughts is that some aspect of the design relies on on some aspect of different specs of the capacitor, its impedance whatever at a certain frequency possibly.

this possibly threw the whole PSU out of whack is all I can assume.

normally the design should dictate what happens but components are selected based on certain criteria for the circuit so it seems this is a case of 1 cap don't suit all situations.

I found a pic but doest really show the psu in this thread here

http://club.cdfreaks.com/showthread.php?t=211343

looks like a switcher so this is somewhat strange

also comment on it here on BC... (seems they have the usual swollen cap issues? C316)

https://www.badcaps.net/forum/showthread.php?t=1051

barring some issue with the psu or your handy work

The short answer is if you replaced the O/P caps with the Low ESR it shouldn't have been a problem...as fas as I am aware

So i'll have to leave that to someone that knows cause I don't.

I searched for a photo to have a better look at the pcb but no luck.

Maybe if you took a decent one can you post it please?

Probably need a reference photo here anyway seems they are common and have caps problems

looking at some of the posts I see why you wanted to fit decent caps...and rightly so

Anyway Cheers

[davmax]

Re: Great Caps=Bad result (DVP642)

My experience with low ESR replacement on a 642 was good. Your problem is definitely related to changing caps. The initial symptom of cycling seemed like s short circuit somewhere. This can be caused by a small piece of solder or a reversed cap. A standard 85C is not recommended for switch mode power supplies as in this equipment.

[gonzo0815]

Re: Great Caps=Bad result (DVP642)

May be the cap should have been reformated before use after this long storage time.
Any way, i have replaced caps in several DVD units with Panasonic FM and Rubycon MCZ & ZL and have had absolute no trouble there.

Theoretically it is quite possible, that an too low ESR could cause bad regulation or oscillation.
Personally, i haven`t experienced this, but i have learned it from the application sheets of some older simple switchers.

[Harvey]

Re: Great Caps=Bad result (DVP642)

..remember we're talking of a PHILIPS designed circuit here, which in my experience means "odd".

[relkin67]

Re: Great Caps=Bad result (DVP642)

Thanks davmax. I was wondering if anyone else had encountered this problem & it seems you performed the same surgery w/o problems. I was concerned, as gonzo0815 points out, that the circuit was designed in such a way that the low esr caps were fooling the zeners (of course, I took circuit analysis in 1987 and didn't do so well so my knowledge is far from good). I recently reconditioned a Mac Plus and replacing the 21 year old motherboard 33uF/16V 85C electrolytics with tantalums caused some bizzaro effects until I tweaked the analog board voltage back into spec. The 642 PS has no such controls so I was worried.

BTW, that 1000uF cap in the 642's PS runs HOT to the touch. Definitely needs a 105C in there at least. The case should also have been vented which could easily have been incorporated into the design when the top case was punched. But I digress...

[davmax]

Re: Great Caps=Bad result (DVP642)

Harvey, you talk of odd designs. See my post/thread on the Benq Q&T3 LCD monitor
https://www.badcaps.net/forum/showth...38612#poststop

[kc8adu]

Re: Great Caps=Bad result (DVP642)

i have had a panasonic fm that was shrinkwrapped wrong.
- stripe on same side as long(+) lead
it happens even on the best parts.

[Krankshaft]

Re: Great Caps=Bad result (DVP642)

i have had a panasonic fm that was shrinkwrapped wrong.
- stripe on same side as long(+) lead
it happens even on the best parts.

Yeah but the positive lead is longer then the negative .

But if I got that cap I probably would have installed it by looking at the band too I'm lazy in that respect.

I EXPECT it to be right crazy me .

[Krankshaft]

Re: Great Caps=Bad result (DVP642)

I have seen cheap switching power supplies namely in Xbox video game consoles that use the parasitic capacitance of its components to run properly.

These supplies are complete crap and are "lowest bidder" quality. When I repaired Xboxes 2 years back I didn't even bother fixing them I just threw them out.

I feel that you may have a cheapy supply as well in this unit.

If you replace cheapy caps with high quality ones the power supply goes crazy.

I would first research the Su'Scons I have seen them before on a cheap piece of audio equipment. Are they Low ESR or general purpose if they are not low ESR replace them with a good brands general purpose caps I use Nippon Chemicon KMG series caps for this purpose on my repairs.

Xicons okay too I used to use them with success as well. Just make sure to not put in 85 C caps where 105 C used to go I know all Ratshack has is 85 Cs. For testing purposes thats okay just be sure to not forget to replace them with the proper temperature rating later.