Developing a Capacitor Inventory

[BmacSWA]

Not sure if this is the right spot for this post, but here’s my question. I’ve successfully recapped my es10 with much advisement from our community, thank you all. Now I’m interested in having these most common caps on hand to get similar repairs underway without having to place single orders of random individual caps and waiting for them to arrive. Can anyone point me to a series of kits with common uF and voltage ratings that will be a good start to have available? I thought after I had this setup, if I needed something out of the ordinary, I’d just order 3-5 at that time Ang continue to build the inventory. Any help and thoughts would be appreciated.

Bmac

[Subtitles]

Check out components distributers like Mouser and Digikey. They have all kind of components including capacitors.
I wouldn't recommend having a stock of capacitors because they have expiry date (date code) and you will have a dead stock over time unless you are using the stock all the time for repairs. You will be much better off making new orders for specific capacitors that you really need.
https://www.mouser.com/
https://www.digikey.com/en/products

[johnmeyer]

I've replaced a LOT of caps, and am about to fix a cheap VCR whose SMPS died. I was able to determine which components died, and there was one cap that failed. It may or may not have caused the other components to fail which included the main transistor on the hot side, and the fuse. So, to fix this VCR, I needed those two parts, in addition to the capacitor.

Thus, having a stock of capacitors on hand would not have helped.

Another story that supports what Subtitles said is that I am trying to resurrect my ancient (1980s) Heathkit weather station. Just prior to doing this work, an elderly neighbor who was in the wireless business, gifted me all of his parts, along with a lab-grade Tek oscilloscope, and a top-of-the-line HP spectrum analyzer (yeah, wow!). The parts included a box of standard electrolytic capacitors along with boxes of resistors, inductors, and transistors. To fix the weather station, I tested all the caps on both the PS and the main board and immediately found one that was totally dead. I looked in this box and actually found the right capacitor. Eureka!

Well, that's what I initially thought until I started testing the other 50 caps and found that, while none of them were totally dead, they were all testing way below nominal. While some of that could have been from testing in-circuit, my instincts told me otherwise and, since I have a de-soldering station, I lifted a few of the leads and verified that the out-of-circuit measurement showed that they were indeed about 1/2 of nominal.

So having a box of capacitors was not sufficient and once again I had to place a large order with DigiKey. I also use Mouser, but I've been ordering from DigiKey since the 1970s, back when they sold surplus and kits, so I have a certain emotional attachment.

The reason I still had to do the ordering is that there are thousands of capacitor specification combinations; its not just capacitance, but working voltage, temperature, ESR, size (try repairing a camcorder!), leads, etc.

Finally, when I do get around to fixing the VCR, I am going to make a video and post it. I'm going to do this because I was able to find the service manual, and it shows that to pull out the single circuit board (it's so cheap that everything is on one board), I will have to disassemble absolutely everything which will take hours, each way. Instead, I'm going to use a trick that I discovered when fixing a broken roller on an HP inkjet printer. That was going to be even more impossible to fix. I had to design and then 3D print a gear to replace the broken gear, and then split it in half and glue the halves together over the driveshaft that feeds the paper. I'm pretty sure I would never have been able to disassemble it without breaking parts, given that everything is snap fit and given that the entire printer must be taken apart, so I took the soldering iron that I've dedicated to welding plastic and used it to cut a hole in the bottom of the printer. That took three minutes. I then performed "laparoscopic surgery" and did the repair through the hole I created. I wasn't sure the glue would hold, but it's been working since last December.

I am planning to do the same thing with the VCR. By using the soldering iron, I don't create any dust or shards. For the printer, I never bothered to cover the hole because it was under where the paper sits. For this repair, I'll have to cover the hole back up, since there are deadly voltages.

Back to the main thread: just get used to making an order and waiting a few days.

Oh yeah, one more thing. Whenever I do a repair I ALWAYS test the new component before inserting it, and double and triple check that it is inserted in the proper orientation. More to the point of this thread, I then always test the "bad" component after I've taken it out, and if it passes the capacitance and ESR tests, I put it in a junk box and if I need to get something up and running in a hurry and am not replacing ALL the caps, I sometimes will use the old part. Since these are often taken from power supplies, they are more likely to match the specs I need when repairing another PS, something that you probably won't get if you just by a generic capacitor assortment.

I am NOT a fan of "re-capping" power supplies because, except for the 1999-2003 era when we were flooded with defective capacitors, and also the lesser problem that developed from about 1988-1992, most capacitors, even in SMPS, work pretty well, and most failures are usually limited to those where the cap was either under-specified, or just experienced a random failure. If you are willing to test all the caps in circuit, you can save a ton of time and money.

[BmacSWA]

Thanks for the input