First post, by Ozzuneoj
Okay, I'm going to try to be brief. I'm not an engineer or even a formal student when it comes to electronics and circuits. I dabble with old PCs enough that having a basic understanding of the practical aspects of circuits and components is beneficial. I like to pick up rare or useful old parts from scrap lots, so I do a fair amount of repairs with the basic knowledge I have now, but I have a lot to learn.
Being able to identify and replace swollen or leaky caps can be tedious but is a common skill for people who are into retro PCs (specifically from the early 2000s). The area where I seem to find a lot of disagreement is when to replace caps that aren't leaking or swollen. Some say that any aluminum electrolytic cap that's more than 15 years old is basically garbage and should be replaced before it causes problems. Others are more of the "if it ain't broke, don't fix it" school of thought and will leave them basically forever. I can understand both lines of reasoning, but since the cost of replacing caps (not to mention the time) probably exceeds what I spend on the components themselves many times, I needed something more concrete to work with.
I bought a DER EE DE-5000 LCR meter and started playing with it today. I have a box of caps I've "borrowed" from boards over the years. I kept these around because for a while I was finding leaking caps very frequently, so it made sense to harvest all of the intact Rubycons, Nichicons, Panasonics and Sanyos from boards that had other problems, so I'd have some on hand to do a quick patch job on a cheap old board.
Anyway, most of these caps are 5-20 years old and were harvested from old boards. Some are far far older and were found in estate sale lots.
Rather than try to copy tons of numbers and data from spec sheets that people really don't care about, I'll simply write out my results with each cap based on the reading from my DE-5000 compared to the spec sheet (if available). The meter was calibrated using the alligator clip attachment. Capacitance readings were made at 120Hz, ESR readings were made at 100KHz. Caps that were harvested from another device will be in italics. Most of the harvested caps are from Socket A, Socket 604 or Socket 478 boards from the early 2000s. The non-italic ones are unused but still purchased 5-10 years ago and probably purchased cheaply as old stock. If I have multiple caps of the same type, I'll separate their values by commas. If the readings are out of spec, I'll simply mark them with an * (like 100uF*, 1.4ohm*). If I can't find the spec, I'll mark them with a "(?)". Any unmarked readings are within the specified tolerance of the datasheet as far as I can tell. Feel free to correct me if I'm wrong.
Panasonic FJ 6.3v 3300uF = 2690uF, 2720uF / 0.004ohm, 0.007ohm
Sanyo WG 6.3v 2200uF = 2280uf, 2260uF, 2230uF / 0.007ohm, 0.012ohm, 0.011ohm
Sprague 30D 6v 150uF = 146uf, 158uf, 162uF, 165uF / 0.194ohm, 0.169ohm, 0.44ohm, 0.164ohm(?) (used, axial lead, 30+ years old, can't find spec sheet)
ELNA RJ4 6.3v 1000uf = 802uF, 790uF*, 796uF* / 0.49ohm*, 0.45ohm, 0.47ohm (datasheet says +-20% (800-1200uF) and a max of 0.47ohm are within spec when manufactured)
Rubycon MCZ 6.3v 1800uf = 1597uf, 1565uf/ 0.009ohm, 0.008ohm
Rubycon MBZ 16v 1500uf = 1414uF, 1401uF / 0.009ohm, 0.008ohm
Rubycon MBZ 10v 1000uf = 897uF, 902uF, 900uF / 0.02ohm, 0.021ohm, 0.021ohm
Rubycon YXG 10v 1000uf = 986uF, 984uF/ 0.042ohm, 0.043ohm
United Chemicon KZG 16v 1000uf = 955uF, 974uF / 0.013ohm, 0.011ohm
That's all for now. I plan to pull caps off of boards and test them soon so we can get a more accurate picture of how they have degraded with age.
All I'll say about the results is that I didn't cherry pick what to post. This is all of the caps I measured, and all (except the cheaper ELNA caps which were never low-ESR) were within the original manufactured spec for capacitance and with ESR that was far below the maximum spec, most were below half. Keep in mind that many of these were likely used for 10+ years and then also went through being desoldered and stored for 5+ years, and yet these are the measurements I'm getting.
I hope to do more eventually, but it certainly takes a lot of time. I'm just glad to finally have an ESR meter and to finally be able to test capacitors and know something about them.
Now for some blitting from the back buffer.