Need cap replacementt advice Chang CD288H / HE

[nfadel]

COBY TFTV4025 40" TV, stobing / flashing fluorescent tubes, found 4 bulging caps in the power supply:

Chang CD288H 220uF 35V
Chang CD288H 1000uF 16V
Chang CD288HE 1000uF 35V (2 of these)
all rated -40C 105C

I was all ready to go to digikey and order some Panasonic FC like I have in the past to fix Dell monitors and then I read in the forums here that matching the ESR and ripple current is important.

I looked through the specs list available here and couldn't find this Chang series, and google and yandex result sites only yielded "low ESR, high ripple current" for CD288H.

Any advice? I suspect that some good Panasonic FC/FK/FM will work but I would like to be certain to get the best match, hoping for a decent lifespan.

[mockingbird]

Re: Need cap replacementt advice Chang CD288H / HE

COBY TFTV4025 40" TV, stobing / flashing fluorescent tubes, found 4 bulging caps in the power supply:

Chang CD288H 220uF 35V
Chang CD288H 1000uF 16V
Chang CD288HE 1000uF 35V (2 of these)
all rated -40C 105C

I was all ready to go to digikey and order some Panasonic FC like I have in the past to fix Dell monitors and then I read in the forums here that matching the ESR and ripple current is important.

I looked through the specs list available here and couldn't find this Chang series, and google and yandex result sites only yielded "low ESR, high ripple current" for CD288H.

Any advice? I suspect that some good Panasonic FC/FK/FM will work but I would like to be certain to get the best match, hoping for a decent lifespan.

CD288H is LF Series (dead link) and 288HE is GF Series.

For the 35V 1000uF:

Chang GF
12.5 x 20 - 0.035 1950
Panasonic FC
12.5 x 25 - 0.030 1945

It'll work, if you can fit the taller cap in. But GF has a better spec than Panasonic FC in general.

[kc8adu]

Re: Need cap replacementt advice Chang CD288H / HE

a better advertised spec that is.
if you want some margin go fm,fr.
fc will outlast the rest of that set.

[nfadel]

Re: Need cap replacementt advice Chang CD288H / HE

My uninterruptible power supply battery died. So, I go to the auto scrapyard to get a $20 car battery sized deep cycle battery to replace the puny $15 3 Ah UPS battery. All they had this time though were 4 huge $30 deep cycle batteries, and I didn't want to spend the $30 they wanted for one of those. But then I noticed a pallet of dead batteries destined to be scrapped for the lead, and wandered over to look at it. On top of the pallet were numerous rows of 7 Ah and 8 Ah UPS batteries. I took out my meter, and found a large number of them that tested 14.75 volts, and bought 4 of them for $1.50 each. All test near new for amp hours. I'll be going back for more, since I can sell them for $10 each, $35 new for these. I also found a $15 stainless steel 1.5 gallon stock pot for 50 cents, almost like new. Then I saw a large box full of circuit boards and decided to investigate.

I found a CRT TV mainboard, and not only did it have 3 of the 4 capacitors I need, there were all in perfect condition, and all the caps on this board are high quality Nichicons. Paid 45 cents for it. And I can get that back by scrapping the copper and aluminum from the board and flyback transformer.

The scrapyard can be a great source of parts, never underestimate its potential.

[momaka]

Re: Need cap replacementt advice Chang CD288H / HE

The scrapyard can be a great source of parts, never underestimate its potential.

If you have one near you, that is. There are none around here and within 50 miles radius. Most electronics go to the e-recycles, and those never let you take anything. Same with large chain stores that collect e-waste (i.e. Best Buy, Micro Center, etc.).

The Nichicon caps you got from that CRT TV board are probably VR series (and if that is the case, then this would also tell me it was from a Sony TV. ) They are good caps buy probably only rated for 85C. Not sure how long they will last in a hot LCD TV. Still probably better than the Changs, though.
And for a darn 45 cents, I guess it's worth it - at least if your time isn't too valuable, of course.

[Behemot]

Re: Need cap replacementt advice Chang CD288H / HE

Check the newer Chemi-Con series (KYB, KZN, KZH), you should be able to find D12.5x20 caps with the same or higher capacity.

[nfadel]

Re: Need cap replacementt advice Chang CD288H / HE

I searched those links for Chang and elsewhere for CD288HE and the specs only say high frequency, low ESR. But no values are given.

I understand the value of ESR being low, but what is ripple current, and how important is it? If I cannot find the original ripple current specs, what is the best shot in the dark here for use in this TV power supply (all on the cold side)?

I decided to move the 2 taller 1000uF 35V caps off the power supply board to a vented location because the board had heat discoloration underneath both of them, so the extra 5mm of height going with the Panasonic FC isn't going to be a factor.

I was thinking this for the 1000 35V caps However, there is no ESR value listed and it doesn't say low ESR.

Would this be a good ripple current value for this TV usage (1.459A)? Is higher generally better in this type of power supply application? Is a lower impedance value better? How critical are these values?

[Behemot]

Re: Need cap replacementt advice Chang CD288H / HE

Well I got datasheet for FOAI CD288H. I also know these caps beng sold as ChengX. Would say they are all the same…

[nfadel]

Re: Need cap replacementt advice Chang CD288H / HE

Found what I was looking for, at wikipedia of all places! Very detailed descriptions of aluminum electrolytics.

Perhaps this info can help someone else in the future: When replacing caps, try to get replacements with as high a ripple current as possible. A high ripple current rating automatically equates to low ESR and lower operating temperature. Also, for each 10 degree C increase in operating temperature, a capacitor's lifespan is cut in half, so for long life it is really better to relocate the larger (or all the) caps you are replacing to a remote location off of the power supply board. Use dual insulated wire of an appropriate gauge, and consider that the caps might get hot and melt plastic or glue and shift position, perhaps catastrophically if they short out on something, so secure them properly.

I have this TV sorted now, thanks to all that responded.

[Behemot]

Re: Need cap replacementt advice Chang CD288H / HE

This is general information and does not always correspond with the reality. Capacitors evolve and what was low-ESR in 1990s, corresponds to some GP at best today. Nowaddays, low-ESR caps are getting closer to motherboard grade ultra-low ESR caps 10 years ago. And the current is a fuction of ESR, but not only that. Some caps have high current while higher ESR still.

Some wire relocation, forget about that. It is always best to have the bulk capacity as close to the ripple source as possible. As there is often heat, some reasonable compromise must be achieved. But the circuit parameters are given and by changing the lenght of the path you introduce absolutelly unknown parasitic inductance and delay in the filtering (transporting charge takes time, electrons are quite slow actually and the further it is, the worse; transporting high charges here and there also produces excessive heat). That can result in lower filtering effect or even to oscillation.

If there is no room, than yeah, moving it 1, 2, 3 centimeters away is not a problem. But stretching wires all over the board is just nonsense.

[nfadel]

Re: Need cap replacementt advice Chang CD288H / HE

I've never encountered any problems moving them off the board, but I've always avoided routing the wires near inductors.

Sometimes you have to consider the unknown values introduced by heat roasting though, too. A carbonized board eventually equals a short circuit. My current power supply board:

[Behemot]

Re: Need cap replacementt advice Chang CD288H / HE

Don't see anything in there, too tiny.

[nfadel]

Re: Need cap replacementt advice Chang CD288H / HE

The brown area under the 2 big removed caps should be white. It is roasted brown.

[nfadel]

Re: Need cap replacementt advice Chang CD288H / HE

I see you are from Prague, CZ. I have a friend there. Do you know the guy who posted this?

My youtube page

[Behemot]

Re: Need cap replacementt advice Chang CD288H / HE

never seen that before

[momaka]

Re: Need cap replacementt advice Chang CD288H / HE

I've never encountered any problems moving them off the board, but I've always avoided routing the wires near inductors.

Sometimes you have to consider the unknown values introduced by heat roasting though, too. A carbonized board eventually equals a short circuit. My current power supply board:

If you have problems with heat, you don't simply move the caps away to keep them from roasting. Instead, a better solution would be to remove as much as the heat as possible. One way to do that in a power supply is to use bigger rectifiers with lower Vf drop... or forget about rectifiers (diodes) altogether, and use a synchronous rectification design with MOSFETs.

Better yet, to keep things simple, just install a low-RPM fan or put more holes in the case to allow for more air to come in and go out. Even a tiny bit of air movement can create a dramatic drop in temperature sometimes.

[Behemot]

Re: Need cap replacementt advice Chang CD288H / HE

In these displays, bad caps are often the cause of overheating (excessive switching). You change the caps, may stick a small passive in there too, and everything is good.

But discoloration directly under caps is strange, what's going on there?

[stj]

Re: Need cap replacementt advice Chang CD288H / HE

leaky diode cooking the caps maybe.

[nfadel]

Re: Need cap replacementt advice Chang CD288H / HE

Here is the video I took the image from. A bit higher resolution and you can full screen it.

These are some generic images of the PC220P power supply board in case you recognize it.

Going with installing a fan is a good idea, I will probably install a Pentium 3 class CPU heatsink fan along the edge of the board.

The two 1000uF 35V caps go on top of the browned area, and they are in parallel in the circuit. I wonder if running two copper bus bars out past the edge of the board (on top of the board under the caps) and installing 2 more 1000uF 35V caps on this bus, so all four are in parallel, would work to reduce the heat generation? There is enough space to do it, and the copper would also act as a heat sink.

[momaka]

Re: Need cap replacementt advice Chang CD288H / HE

Going with installing a fan is a good idea, I will probably install a Pentium 3 class CPU heatsink fan along the edge of the board.

If you have the space, then go for it. I would also advise you run it on 5V, because on 12V it might be very loud (at least most Pentium 3 -era fans are)

I wonder if running two copper bus bars out past the edge of the board (on top of the board under the caps) and installing 2 more 1000uF 35V caps on this bus, so all four are in parallel, would work to reduce the heat generation? There is enough space to do it, and the copper would also act as a heat sink.

Well, why not just solder the copper bus bars to the thickest areas of the PCB and without putting any caps on them? Then, the copper bus bars will simply serve as a heatsink and nothing else.

I've done something similar with 14 AWG solid wire - just soldered a long piece on the tabs of several TO-252 MOSFETs to act as a heatsink. And it worked well.