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MS-2933 Monitor Shiver issue
grendelrt:
--- Quote from: lilshawn on May 18, 2024, 02:00:24 pm ---if you decide to go a cap kit, most of the cap kits are pretty decent with regards to quality... just keep an eye out for kits that has a suspiciously good price. they are often made with really inferior caps.... and while they will work just fine, their longevity can be quite short. a good quality $60 kit will contain every capacitor on the chassis and will be by good manufacturers, and will last you another 30 years. a cheap $12 kit will have the bare minimum of the most commonly replaced caps on that chassis, (sometimes only a half dozen caps) and last you till next year before having to replace them again.
if you decide to roll your own kit just ordering online... be sure you purchase high quality, high temperature, (and if applicable, for your SMPS filter caps...) low ESR caps... and order from a reputable company. (panasonic, nichicon, nippon chemicon etc. basically anything japanese or if you can find them, american companies... Kemet, Vishay, and so on.) from an equally reputable distributor (mouser, digikey etc.) you are gonna want to avoid ebay, amazon...and sometimes... local electronic suppliers. (mainly you have no idea where they sourced them from.) as they often have quality name brand caps...but have been re-sleeved china caps. (i have a post somewhere on this site with a photo example of a re-sleeve)
avoid like the plague brands like G-Luxon, suscon, capxon... and anything that looks like a smattering of letters of a china sounding manufacturer... Fuhjyyu, Ltec, Omiyo, Wangcho.
--- End quote ---
I had already bought a kit from Syracuse Semiconductors when I bought the 2933 chassis, they are labeled 105C, think these are legit? They are about 6 years old and I need to order some of the larger caps it looks like. Might start with these while I wait until I get the others.
lilshawn:
they look okay. at least they are 105c caps and not a bag of 85c caps (105c and 85c are the max temperature the caps are designed to withstand)
it's hard to tell without measuring the value of the caps with a LCR meter (or it's equivalent) if they are actually "good" or not. their tolerance SHOULD be within 20% which is really lousy... This means that an aluminum electrolytic capacitor with a nominal capacitance of 470uF is expected to have a measured value of anywhere between 376uF and 564uF if my maffs are to be trusted... but I typically like it as close as I can be if i can help it.
grendelrt:
--- Quote from: lilshawn on May 31, 2024, 03:12:40 pm ---they look okay. at least they are 105c caps and not a bag of 85c caps (105c and 85c are the max temperature the caps are designed to withstand)
it's hard to tell without measuring the value of the caps with a LCR meter (or it's equivalent) if they are actually "good" or not. their tolerance SHOULD be within 20% which is really lousy... This means that an aluminum electrolytic capacitor with a nominal capacitance of 470uF is expected to have a measured value of anywhere between 376uF and 564uF if my maffs are to be trusted... but I typically like it as close as I can be if i can help it.
--- End quote ---
I have an esr meter i was going to use before putting each one and also take a reading of the one I am removing for future knowledge :) I have to order it looks like 4 caps that werent in the kit and 3 caps are slightly higher voltage, checking digikey it looks like those caps arent really made in the older voltages.
lilshawn:
higher voltage is absolutely fine. the volt rating is the max voltage it can take before the insulation that separates the plates in the cap fail and allows an electrical short to happen.
usually when we design circuits, we double the voltage the rail that the capacitor is on then bump it up to the next highest rating to provide lots of overhead in case of power surges... for instance for a 24v rail, i would spec a 50v cap (24+24=48 and 50 volts is the next value.) or for an 15v rail i would spec a 35v capacitor (15+15=30 and 35 volts is the next value) but for simplicities sake, i may just use the same 50v cap so i only have to buy one type opposed to 2 different ones. but if all i had was 63 volt capacitors i could absolutely use those too.
the only thing you don't really want to do is go down. so even though the 24v line only has 24v...and I can get a 25v capacitor... it doesn't leave much room for overhead before the capacitor insulation degrades and it shorts out inside... and you really don't want to put a 16 volt cap on a 24volt line.
grendelrt:
--- Quote from: lilshawn on May 31, 2024, 03:39:52 pm ---higher voltage is absolutely fine. the volt rating is the max voltage it can take before the insulation that separates the plates in the cap fail and allows an electrical short to happen.
usually when we design circuits, we double the voltage the rail that the capacitor is on then bump it up to the next highest rating to provide lots of overhead in case of power surges... for instance for a 24v rail, i would spec a 50v cap (24+24=48 and 50 volts is the next value.) or for an 15v rail i would spec a 35v capacitor (15+15=30 and 35 volts is the next value) but for simplicities sake, i may just use the same 50v cap so i only have to buy one type opposed to 2 different ones. but if all i had was 63 volt capacitors i could absolutely use those too.
the only thing you don't really want to do is go down. so even though the 24v line only has 24v...and I can get a 25v capacitor... it doesn't leave much room for overhead before the capacitor insulation degrades and it shorts out inside... and you really don't want to put a 16 volt cap on a 24volt line.
--- End quote ---
Only missing one cap now, the big orange one. I found some 6.8uf 250v on digikey but I am not sure what the full range of specs I would need to appropriately replace it. Has anyone replaced this cap and have a good replacement?
6.8uf 250V (found one post where they used the following , but its 10uf instead of 6.8uf? https://www.digikey.com/en/products/detail/nichicon/UPM2E100MHD1TO/3130324)
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