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At site C401 of main board. Cap is some kind of polymer electrolytic, but rectangular, not cylindrical. Roughly 9/16"H x 1/2"W x 1/4"D, black plastic case,
with flat sheets of polymer/plastic inside. Markings as follows:
S 5.5V
0.1F
- 6A +
This is on the output of a 7806 regulator
(IC401). Cap was cracked, regulator ran warm but works out of circuit. Did Denon actually intend to use a 5.5V cap on a 6V rail, or is this an incorrect substitution? Solder joints on cap appear to be factory, but the silkscreen for this part is round.
Thanks,
Tony
Well, because... 1. The receiver isn't functioning yet. 2. You didn't actually ID the cap that I described. 3. You didn't specify what cap should be in that location. 4. You didn't demonstrate any familiarity with this type of circuit, or you would have questioned me about my description of the circuit (as a poster in sci.electronics.repair did) and I would have found the diode between the regulator and the capacitor (so that the rail is ~5.3V, below the 5.5V rating for the cap, though that's not much derating). The reason it's 0.1F, BTW, is that it's a supercap used as backup for the receiver presets. 4. You refer to 'Dell' in this most recent message when the question is about a Denon receiver.
Being an electrical engineer, I wouldn't have needed to ask the question if I had the schematic. I would have expected a "Master" to either be familiar enough with the circuit to not need a schematic, or to realize that (s)he didn't know enough without the schematic to draw conclusions about the part.
Think I'll stick with sci.electronics.repair...Well, because...
1. The receiver isn't functioning yet.
2. You didn't actually ID the cap that I described.
3. You didn't specify what cap should be in that location.
4. You didn't demonstrate any familiarity with this type of circuit, or you would have questioned me about my description of the circuit (as a poster in sci.electronics.repair did) and I would have found the diode between the regulator and the capacitor (so that the rail is ~5.3V, below the 5.5V rating for the cap, though that's not much derating). The reason it's 0.1F, BTW, is that it's a supercap used as backup for the receiver presets.
4. You refer to 'Dell' in this most recent message when the question is about a Denon receiver.
Being an electrical engineer, I wouldn't have needed to ask the question if I had the schematic. I would have expected a "Master" to either be familiar enough with the circuit to not need a schematic, or to realize that (s)he didn't know enough without the schematic to draw conclusions about the part.
Think I'll stick with sci.electronics.repair...
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Tony,
this is an incorrect substitution. The cap voltage should be higher. They probably ran out of the cylinder types. I'm surprised to see such high capacitance value however.
why only rating of "almost there"? I answered your question, but I cannot, nor can anyone, tell you why Dell did this.why only rating of "almost there"? I answered your question, but I cannot, nor can anyone, tell you why Dell did this.
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What kind of capacitor? all caps have the micro farad and voltage printed on the body,this information can be googled and many suppliers can be found,even e'bay will have sellers.
your local electronic hobby shop may have some.
If the cap is electrolytic and has bulged or burst check for any other caps that may look suspect ,please be careful handling the power board as the main filter cap may be holding a charge of up to 400volts
First.
By the "size" you refer to... I assume you mean the Value's of the Capacitor.
These are written on the Capacitor as Voltage and uF.
The "size" of an Electrolytic Capacitor depends on the voltage & micro farads(uF) it is storing. (Like a Battery)
You can always add more uF and the voltage rating can be more (but not less).
Does the Cap have signs of leakage around the leads or does it have a Bulge in the top of the can. If so, it's probably bad.
The Electrolytic Cap's wires are marked positive & negative. (Negative is marked down one side).
Do not swap the polarity + - of the cap or it can blow.
The Radeon Graphics Card in a computer would run on probably 5v for logic for circuit boards & 12v for hard drives etc. No more than 12v DC max. So you can replace with a 16v replacement electrolytic Cap. But would be easy to check across the Cap with a voltmeter to find out.
Always buy a Cap with slightly higher voltage rating than the circuit it is going in to.
If it's large and attached to the main power input then it will probably be around 1000uf to 2000uf. The voltage and uF are written on the Cap body.
You can't hurt the electronics (in a power supply circuit) by adding more Capacitance.
Large Electrolytic Cap's are used to remove noise ripple from the power supply. They smooth it out. More Capacity = less ripple.
Because Electrolytic Cap's usually fail as open circuit and loose capacitance it's easy to attach another Cap in Parallel over the bad one. If so...
For troubleshooting purposes, you can leave the current Cap in place and attache a couple of wires of say 1-2 inches. Use coloured wire to keep the polarity correct. Attach 1000uf 16v Cap to wire ends and run the device to see if it's working OK.
Hope all this Helps
Trevor
It is an indication that you have a problem on the vertical section on the main board.
The faulty parts is the electrolytic capacitor which affect the linearity of the screen that's why you encountered that kind of problem.
I've advice you to send it to repair shop or look for a qualified technician to isolate the faulty electrolytic capacitor and do re-soldering for some dry joints on the main board.Once replaced the capacitor your unit will back to normal again.
thanks for using fixya...
The pop may have been caused by a catastrophically failed power semiconductor or an electrolytic capacitor.
The main supply is often on a separate board (these are often outsourced) which will be smaller in size but have larger components on it.
Removing the back panel should let you recognize it fairly easily.
Examine this board carefully with a good light and look for components that appear damaged; this could be a three-lead transistor, a module (both often in black epoxy) or a capacitor any of which will be cylindrical and could be any size ranging upward to 2" in height and ~ 1 1/2" diameter.
If the latter has failed, it may have a burst aluminum top or have spit chemicals onto the board.
Since you have neither sound nor video, I don't think the back light inverter for the display will be a fault. This will be on an even smaller board and traceable to the fluorescent tube.
If you do not find a problem you can identify on the main power supply, check this smaller board for the same kind of visible failure since a failure on the inverter could cause a fuse in the main supply to fail which would disable the entire set.
Good luck-
If your sets also produced kind of an acrid chemical odor when they failed, it was likely an electrolytic capacitor that failed catastrophically.
If you haven't done it yet, pull the plug on your set, allow it to stand for at least hours (better overnight) remove the back panel and look for the main power supply.
It will have one or more transformers on the (probably separate) board.
Check the board carefully for cylindrical devices anywhere between 1/4" - 1.5" in diameter and 1/2" - 2" high that have distorted cases or have dumped nasty looking deposits on the board around them.
Because of the way these turkeys fail, they may have damaged other parts as well so if you choose to replace them, don't be surprised if they immediately fail again.
Depending on the manufacturing date of the sets, they may have additional capacitors waiting to fail; between ~ 2003 & 2005, millions of this kind of part were manufactured by otherwise reputable Asian companies but using (unknown to them) defective, counterfeit Chinese electrolyte that guarantees the eventual failure of the parts.
This kind of problem does not lend itself to DIY repairs.
The 0.1 microfarad can be safely replaced with a 275 VAC 0.1mF mains capacitor. You can remove the clip that held the old electrolytic capacitor by sliding the old capacitor out and squeeezing the metal clip so that it disengages with the plastic base. The load resistor is 450 Ohm 15W or 20W wirewound. There is a 56 ohm resistor in series with the capacitor which helps smooth the speed change and reduces wear on the contacts. A 2W wirewound resistor works best. (It is worth removing the contacts and removing any pitting or carbon build up with fime emery paper). I have repaired about 20 speed controls sucessfully with these components.
There should be some kind of thermostat inside of the set that goes bad, but I could never find it and I was told you would have to replace the whole main board which now a days cost more than the whole tv itself.
Electrolytic capacitor usually blown up the top only in you can still reading the value in the body of the capacitor like the voltage and micro farad example 400V/33UF that's the value of the capacitor
Well, because...
1. The receiver isn't functioning yet.
2. You didn't actually ID the cap that I described.
3. You didn't specify what cap should be in that location.
4. You didn't demonstrate any familiarity with this type of circuit, or you would have questioned me about my description of the circuit (as a poster in sci.electronics.repair did) and I would have found the diode between the regulator and the capacitor (so that the rail is ~5.3V, below the 5.5V rating for the cap, though that's not much derating). The reason it's 0.1F, BTW, is that it's a supercap used as backup for the receiver presets.
4. You refer to 'Dell' in this most recent message when the question is about a Denon receiver.
Being an electrical engineer, I wouldn't have needed to ask the question if I had the schematic. I would have expected a "Master" to either be familiar enough with the circuit to not need a schematic, or to realize that (s)he didn't know enough without the schematic to draw conclusions about the part.
Think I'll stick with sci.electronics.repair...
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