this post was submitted on 12 Jan 2025
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BudgetAudiophile

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WARNING: In this post I talk about working on HIGH POWER electrical circuits. DO NOT DO THIS UNLESS YOU HAVE BEEN TRAINED... PERIOD! The capacitor in the final photo is quite easily capable of KILLING YOU if you discharge it through yourself. The amp uses TWO of those in its power supply.

As a hobby, I pick up distressed amplifiers, receivers, and other audio equipment and attempt to bring them back to life. This has netted me some spectacularly great pieces for pennies on the dollar, to outright free.

This photo is a receiver I picked up locally for free. Both main channels were "out". It wasn't the internal amplifier that was the problem though, rather the input board had some dry solder joints. About 3 hours of soldering netted me a perfectly working receiver, which has been in my living room for the past two years working perfectly. If you want photos of when I took it apart, just let me know.

Below is an 8 channel McIntosh MC7108 that I bought off of eBay listed "for parts". While what I paid for it probably doesn't fit the definition for "budget", it was less than a quarter what the amp is worth... So maybe budgetish? It's works great, but I ended up not really fixing it. It actually worked for about a week after I bought it. I thought I had really scored, until it started up with a horrendous buzzing noise that came from inside the cabinet. The protection circuits also kicked in and the amplifier would not power up. Some investigation, again photos are available if you want to see them, revealed that buzzing came from a bad capacitor and relay in the on/off switch circuit. As I didn't care about the on/off switch, I simply bypassed it. Now, if the amp is plugged in, it turns on. I control it using a Zwave outlet (look at the power outlet and you'll see it) and that is what I use to turn on and off the entire stack you see.

Below the McIntosh is a Carver TFM-15B that needed the input pots cleaned and new meter lights. It's not a well built amp, but I've always loved Bob Carver's work and it sounds very warm. Bob was known for is ability to copy the sound of much more expensive amplifiers in his design, which he called "Transfer Function." In the case of the TFM-15B is copies the sound of a Classe amp, although I don't remember which one.

Below that is my wife's old Soundcraftsman amplifier that I put new power supply capacitors in. The caps in that thing are the size of coke cans.. Don't believe me? See the last photo...

At the very bottom is an old HTPC I built many years ago. It is retired as an HTPC and is currently serving as a low power server for my house.

Big honking Capacitor:

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[–] masterspace@lemmy.ca 1 points 1 day ago* (last edited 1 day ago) (1 children)

I just started getting into proper stereo gear and speakers and now have a small collection of broken stuff that I suspect is fixable...

Any recommendations on tutorials / videos / learning resources? Also do you find you need an oscilloscope for this or will a multimeter do?

I've currently got a receiver that works in analog but just hisses in surround sound and gets no signals from digital inputs, and I've got a set of speakers that make no noise from the tweeters for some reason.

[–] Canopyflyer@lemmy.world 1 points 3 hours ago

I am, for the most part, self taught. I worked for Radio Shack in the late 80's to mid 90's and read through every book on electronics they had. That is how I got my start on low power circuits. I had several breadboards and components and would build circuit after circuit. I was in college at the time, so I took a couple of electronics classes. Also had a friend who was an electronics repairman and he helped me to learn high power circuits, such as power supplies for high powered amplifiers. That is how I learned to work with capacitors the size of Coke cans.

Low powered circuits you can learn on your own. Read to learn the theory, there are a lot of Youtube channels to watch now as well, which I didn't have when I was starting up. When you get to high powered electronics I would highly recommend either taking classes, or learning directly from someone. The risk is just not worth it.

The blue capacitor below is one of 2 in my wife's amplifier, which is a 240w/channel Soundcraftsman from the late 80's. That cap, charged, will kill you many times over.

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](https://example.com/)

[–] clickyello@lemmy.world 6 points 4 months ago

I don't know much about any of this and as such will not be messing with coke can sized capacitors but I do have one thing to say:

neat!