Computers & Electronics

Ever changed components in an audio unit?

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  • Sep 1st, 2019 12:33 am
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Ever changed components in an audio unit?

Just wondering if anyone has ever changed electronic components on audio equipment? Not the whole piece but electronic board-level components (and something other than tuning chips and tubes if you use tubes).

I did it a couple of times in the past year with an old entry-level pre-amplifier. I had sent it in for an upgrade over 25 years ago but due to career direction, it went into storage and wasn't used until ~16 years ago when it promptly crapped out after a very few minutes of operation. Didn't think much about it until I opened it up last year. A quick look at the circuit board revealed that one of the electrolytic capacitors (IC / Illinois Capacitors, who some say made sub-standard and unreliable products in that era) was leaking. Replacing it with a Mundorf capacitor - a 5 minute job because I couldn't easily get the circuit board out of the chassis - got the amp working again.

Working but not great sound (just not very good). Having a look at the circuit board again, I got new around to replacing the 4 other power capacitors (all also IC) with Jensen units (couldn't get Mundorf in the same capacitance values) yesterday. Couldn't get the board out even with medium difficulty so I had to do the same hash job (cut old capacitors out and solder the wires together). What a difference it made however: Trebles higher and more dynamic, more and tighter bass. Clear and livelier sound with more detail overall. I'd like to replace the low-voltage signal capacitors but those will prove much harder without getting the board out. FWIW, electrolytic capacitors apparently wear out over time and especially when not used.

Some would question the value as the 5 capacitors came up to around $150.
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alot of 90s and early 2000s electronics had knock off capacitors in them that would leak all over the board.
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I heard about bad caps but not fake ones. The caps may have been original from the mid '80s. Lack of use may have hurt.
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Counterintuitively, you want to add solder to remove components from a board. Ideally, you want your soldering iron not to touch the board or components (though it's obviously not easy), but be submerged in a molten solder ball. The increased amount of solder holds more heat (so stays liquid longer), is less hot than the tip of the soldering iron (so will not lift traces or scorch the board, also "cools" the traces), and has better heat transfer from the tip into the solder (essentially, ensures everything is at approximately the same temperature, instead of the leg of the capacitor being 450°C and the solder "only" being 200°C).

Once the component is out, you can remove the excess solder however you want (wick, solder sucker, etc, etc), and re-add a new component with new solder.

This is extremely useful when you're removing a large item (IC with dozens of pins) or a hardwired daugtherboard with many pins in a row.

Edit: Also, all capacitors of the same specification essentially perform identical when new; issues arise in the future where cheaper capacitors tend to dry out, explode, or leak. You don't need to worry much about the manufacturer if you're willing to get in there and replace these things again one day.
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thriftshopper wrote: I heard about bad caps but not fake ones. The caps may have been original from the mid '80s. Lack of use may have hurt.
https://en.wikipedia.org/wiki/Capacitor_plague u can read about it here.

newer Capacitors are also better now a days then old ones. as they get smaller produce less heat and can withstand more heat older ones only could do upto 85c now can get ones that can take u to 105 and some even 125c. just gotta buy quality ones like nichicon and panasonic ect. and only buy from reputable suppliers like digikey mouser.
Last edited by aaron158 on Sep 1st, 2019 12:36 am, edited 1 time in total.
[OP]
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Thanks. My equipment was factory modified a few years before that happened and the 5 power capacitors that I replaced were Illinois Capacitor units so that wasn't the problem. Age and lack of use, perhaps.
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