The caps I got with the kit has an ESR of nearly 2 ohms and while I don't have enough knowledge about the values of caps in these positions, it sounds a bit high. Will they work?
I also only got four for five positions. Obviously. Can anyone be changed for a close value?
I also only got four for five positions. Obviously. Can anyone be changed for a close value?
The two closest to the top of the picture look to be power rail bypass caps. Pretty much any value above the 4.7uF specified is fine, to around 100uF. Did you get a schematic with the kit?
It's also a good idea to source your own op amps and transistors - many of these kits come with counterfeit parts, depending on the seller. The needed parts are still really cheap from a trustworthy supplier like RS or Mouser etc. If you end up ordering genuine parts you may as well get quality capacitors (Panasonic, Nichicon) while you're at it.
It's also a good idea to source your own op amps and transistors - many of these kits come with counterfeit parts, depending on the seller. The needed parts are still really cheap from a trustworthy supplier like RS or Mouser etc. If you end up ordering genuine parts you may as well get quality capacitors (Panasonic, Nichicon) while you're at it.
A 4.7uF/50V Panasonic FC (which is "low-ish" ESR) has a data sheet ESR of 1.3 ohms. So, the value it itself isn't scary, but I agree that caps (especially electrolytics) in cheap kits should be treated with suspicion. They may well be genuine but they can still be of questionable origin i.e. very old, rejects from manufacturing etc. and you never know how they have been stored and handled.
No schematic, unfortunately. I found some Panasonic FC 10uf's and put where you suggested. Hopefully those will suffice.
Yeah, that was the first thing I did, the kit had some 'elite' branded caps and some Samwha, and although the latter is probably okay, I got Nichicon's in their place. The reason I didn't do it with the 4.7 ones is they already were Nichicon's. In fact, apart from those above mentioned caps, all parts were surprisingly of nice quality given that the kit cost $16.
For the OP amps, I tried the rubbing with a cotton bud trick, first with IPA and when nothing came off, with acetone, still with no result. If those are fake, they're good ones. The thing is, those are $5 a piece, nearly the entire price of the kit. Yeah, I don't know.
By the way, if anyone have a suggestion what value pot to get for HD650, I'd appreciate it. The kit says 50k to 100k. I'm leaning towards a Blue Velvet 50k.
Awesome information. Thanks.
There are not any "low-ESR" 'lytics below 100uF. And even the best 100uF ones (Panasonic, Rubycon, etc.) are around 50mOhms.
I generally replace all the lytics on kits from China except maybe the largest ones (say 2200uF and up).
I generally replace all the lytics on kits from China except maybe the largest ones (say 2200uF and up).
From the pics I'd say those op amps are counterfeit. The ejector pin marking (the little circle on the top) should be smooth, not textured.
For the pot, 10k or 20k would be fine. 50k also okay.