Electronics! Falling into the geek rabbit hole.

I have fallen down a rabbit hole lately. It's not the first rabbit hole, and it certainly won't be the last rabbit hole. But it's a cool one!

It really got kick started from installing a subwoofer in the wife's land cruiser, and then going crazy building a stereo system on the cheap for the Porsche,

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and I've continued messing around with car stereo stuff on my BMW pretty much non stop since then. I found a really cool amp for sale, and I bought it, and I got home.... and it didn't work. I was kind of pissed, but I decided I would fix it. So lots of googling, and researching, (helps take attention away from fucked up news as well) and I learned how an AB class amplifier works, and how to troubleshoot and diagnose.

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Well, I fixed that amp. Then I fixed the old Nakamichi receiver I had laying around. Then I fixed an old Pioneer receiver display that wasn't working. Then I signed up for a college level Linear DC circuits course on Coursera so I can actually learn wtf is going on. My math skills need work.

I decided I wanted to learn to build my own amplifier. I want to design my own circuitry, and build an attractive powerful quality sounding home amplifier. So I am on the first steps. I have built a couple of different small DC to AC to DC power supply circuits. I have built a couple of small basic amplifiers using an operational amplifier chip, to learn how different components interact with the audio signal. Kids think it is fun too. They like pressing wires into the breadboard and seeing waves pop up on the oscilloscope.

https://youtu.be/2fYvDdPjHN4

I recently found the matching mono amp for the 4 channel one I already fixed, and it needs to be repaired too.... So learning about Class D amplifiers.

Stuff is pretty cool. Fun.

Any other geeks wanna share their projects? It's be cool to find a couple other geeks on here that I could learn a thing or two from.

That's badass! Have any soldering tips? That's def one of my weaknesses but I really want to get better at it. SO many things get thrown away that could be fixed but sadly electronics repair is quickly becoming a lost art. Definitely something I want to pursue more but time has been my enemy with the hobby. Good post, basin. Very motivating.

Well, for soldering, a clean tip, and an iron that gets hot enough make it much easier. I've been soldering stuff since I was a kid, mainly for rc car stuff. My cheapo one just died. So Amazon is bringing me a fancier temp adjustable one with an adjustable hot air rework station (for surface mount stuff). Stoked. Just find something broken and practice putting stuff on, taking it off, cleaning it up, etc...

sent from Utah.

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Originally Posted by basinbeater

Well, for soldering, a clean tip, and an iron that gets hot enough make it much easier. I've been soldering stuff since I was a kid, mainly for rc car stuff. My cheapo one just died. So Amazon is bringing me a fancier temp adjustable one with an adjustable hot air rework station (for surface mount stuff). Stoked. Just find something broken and practice putting stuff on, taking it off, cleaning it up, etc...

sent from Utah.

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If you're doing old and modern stuff check for pb free or pb solder on your boards. Mixing the two can create an alloy that melts at crazy low temperature, ~90C if I recall. It's pretty easy for home use to just use two different tips if you're good about organization

Ah. I was not aware. I knew there was leaded and unleaded, but didn't know they have problems when they mix. Good looking out!

Here is one project I completed....
Diamond Audio d5 600.4. was only producing sound from channels 3 and 4. So at least I had a functional side to base things off. Ended up being a blown driver transistor. And a couple resistors that also fried. After replacing them, it came back to life.


https://youtu.be/yI_8fTZE-nc

The nakamichi, I was able to tackle with the tektronix oscilloscope I recently purchased.
Seemed to function normal, good voltages at all the rails and stuff, but no sound. So I started tracking the input signal with the scope. I use a simple signal generator app on the phone to put a clean wave in, and I started tracking the signal until it got lost at the input selector switch. Clean switch, works great now.

Then the pioneer, that one was easy, I pulled the front apart and when twisting, the display would occasional light up. Sure enough, cracked solder joints.

It's funny how sometimes you just go on a roll.
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sent from Utah.

I have some old equipment that could use a little TLC too. I'd particularly like to get at least one of the old tape decks spinning at the right speed so I can hook up a way to digitise about 500 (more?) old live tapes. Winter project...

With that amount of wires, circuits, soldering and remotes, I think DHS will contact you soon for...job opportunities?

Quote:

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Originally Posted by basinbeater

I have fallen down a rabbit hole lately. It's not the first rabbit hole, and it certainly won't be the last rabbit hole. But it's a cool one!

It really got kick started from installing a subwoofer in the wife's land cruiser, and then going crazy building a stereo system on the cheap for the Porsche,

Attachment 303354

and I've continued messing around with car stereo stuff on my BMW pretty much non stop since then. I found a really cool amp for sale, and I bought it, and I got home.... and it didn't work. I was kind of pissed, but I decided I would fix it. So lots of googling, and researching, (helps take attention away from fucked up news as well) and I learned how an AB class amplifier works, and how to troubleshoot and diagnose.

Attachment 303352

Well, I fixed that amp. Then I fixed the old Nakamichi receiver I had laying around. Then I fixed an old Pioneer receiver display that wasn't working. Then I signed up for a college level Linear DC circuits course on Coursera so I can actually learn wtf is going on. My math skills need work.

I decided I wanted to learn to build my own amplifier. I want to design my own circuitry, and build an attractive powerful quality sounding home amplifier. So I am on the first steps. I have built a couple of different small DC to AC to DC power supply circuits. I have built a couple of small basic amplifiers using an operational amplifier chip, to learn how different components interact with the audio signal. Kids think it is fun too. They like pressing wires into the breadboard and seeing waves pop up on the oscilloscope.

https://youtu.be/2fYvDdPjHN4

I recently found the matching mono amp for the 4 channel one I already fixed, and it needs to be repaired too.... So learning about Class D amplifiers.

Stuff is pretty cool. Fun.

Any other geeks wanna share their projects? It's be cool to find a couple other geeks on here that I could learn a thing or two from.

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Multiple hour long convos with the Radio Shack virgins? It's pretty cool what a few inexpensive components can be made to do.

Are you lost?

OP, I am in awe of your ability. I have a multimeter and the only function I know how use is a continuity check. I could accomplish that with a battery, some wire and a light bulb from my Christmas tree.

Got back into it tonight. I fixed my nakamichi sr4a, (kick ass reciever/amp by the way) and fixed all my other electronic shit, so the other day I went by the local hoarders garage and bough a bunch of stuff.
I got a nakamichi sr2a reciever, same basic stasis circuit as the sr-4a, fewer features, less power. It was inoperative and showed zero signs of life.
I fixed it tonight. Initial diagnosis showed power making it to the lower power rails on the main board, but not to the main power rails for amplification, so no sound. Blown fuses on the power supply board, and a bad bridge rectifier. Replaced them tonight, and voila! Sound! It seems to be fixed. I couldn't figure out why all these wires and diodes were on the bottom of the main board, but according to the diagram, they all seem to be going to the right places, and it all checked out. I think I'm done with that one.
The hoarder also had a nakamichi oms7 top of the line CD player, he said didn't work, seems to work fine. I'll use that with my sr4a. Sounds so gooooood.
He also had a band and Olufsen beomaster 3000 system, complete, reciever, turntable, and speakers. It does not work. Next project I guess after turkey day.Attachment 303638Attachment 303639Attachment 303640

sent from Utah.

Spidey senses are tingling...

A good soldering setup will make your life way better. I have a Hakko FX-951 and a Quick 861DW. Hot air is very much necessary for big surface mount stuff. Scope is an MSO 2024, which has some pretty powerful tools for finding glitches in digital comms.

Audio stuff is a ton of fun. While I was learning about power electronis in college, I had an old seeburg select-o-matic 100 jukebox that I rebuilt in my dorm. It had a full class-A tube amp, and all of the mechanical stuff was controlled by mechanical contacts. Oh, and the death-trap ancient florescent light ballast along with a shaded-pole motor to turn the candy cane things. I'll have to go find some pictures.

These days, I do mostly mixed-signal stuff for mechatronic devices. Traveling with electronics is entertaining to say the least. I had the terminal at Jackson Hole airport evacuated a few years ago.

The only mechatronic thing I have ever heard of was the mechatronic cable sleeve into a BMW transmission. I was like, and they leak. fuck that noise. Sild that car and sticking with the manual 6 speeds.

More research is needed. I've been studying up on DC power supply circuits quite a bit. I've made a couple of mini power supplies from a power supply on my bread board. They take the 14vdc or so from the power supply and first produce a square wave ac voltage, then through a bridge rectifier, that spits it out into straight DC positive and negative rails.

Fun stuff.
I need a hot air setup, I bought a cheapo Amazon China special, and it arrived DOA. Cheap Chinese shit. I'll look at the ones you have.

sent from Utah.

If you're not going to use it a ton, look at the Aoyue units. They're loud and will fail with heavy use, but they'll last long enough for you to develop preferences and learn about settings with different solders and components. The quick is a fantastic heavy use unit. It's pretty quiet, though it's got a nasty power converter on the input that'll cause the lights in the room to flicker. I'd also recommend getting a good set of tweezers (Hakko CHP3 and CHP7 from amazon are my two workhorses) and a wire-type tip cleaner. Try a couple different fluxes and see what you like, though try not to breathe it.

Power converters are a ton of fun. They really combine everything you learn in school - everything has to be carefully chosen to make it perform well in the application, and building controllers to keep them stable across a wide range of loads can be obnoxious, especially when you get into something like a switched-cap or SEPIC converter.

Another question. What is the best app (that doesn't cost am arm and a leg for android, and pc, for simulating circuits, so I can play digitally and figure out what I want to try to build for real?

sent from Utah.

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Originally Posted by basinbeater

Another question. What is the best app (that doesn't cost am arm and a leg for android, and pc, for simulating circuits, so I can play digitally and figure out what I want to try to build for real?

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I don't know. I would imagine that there are plenty of freeware things that'll keep you entertained. I typically use simulink in matlab (definitely not cheap) and used to use Cadence a long time ago. Several of the microcontroller manufacturers (Microchip in particular) have things like that, but I can't speak to them.

But I can recommend Paul Sherz, Practical Electronics for Inventors. It does assume some math and basic electronics background.

Quote:

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Originally Posted by basinbeater

Another question. What is the best app (that doesn't cost am arm and a leg for android, and pc, for simulating circuits, so I can play digitally and figure out what I want to try to build for real?

sent from Utah.

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I don't do much of this stuff because I mostly touch the digital design and use working designs for power. I'll have to do more of it soon though and I've been occasionally looking at tools.

Circuitlab.com

Qucs was a thing. Not sure about it now?

Linear's LTspice

Here's a blog post that might be helpful
https://hackaday.com/2018/08/10/circ...lifier-design/

That was a good link. Thanks for that.

These need to go in the car. Fixed em both.
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sent from Utah.

Hats off to ya, basinbeater. I dabbled in car audio installs in the teenage years. At the time it was all about the boom for the subwoof and was primary focus was on maxing out the decibels. Managed to cobble together a pretty decent system that eventually presented a pretty good balance of sq and dbs. MB Quart components for the front end and rear fill. Tuned a nice ported enclosure for a single JL Audio 12w6 sub that pumped out 138 dbs at 40 hertz...gotta love the cabin gain for sub bass in vehicles.

I've got a boneyard of old home audio amps and receivers stacked in the basement...this post has given me hope to bring them back from the dead.

One particular favorite/pretty nice sounding Yamaha receiver started exhibiting a background constant buzz/hum. Furthest I got with troubleshooting was removing all the wires, rca plugs, changed speakers/speaker wire, tried different power plug ins...still there, thought it was hooped. Any off the cuff guesses as what it could be?

I hadn't even considered it up to this point...besides basic googling, do you have any specific websites/links/chat forums that were useful in your process?

I was in Toronto on a HW course and we toured the Toronto IBM repair facility back in the day, they wanted to show us what they did with the parts we sent back for repair , they would set up to fix a float of boards all at once, i assume the parts would often fail the same way so they could get good at a specific part, they would heat stuff up in a small oven to simulate the computer overheating, I remember the hot air soldering.

They used to fix something once only and trash it the second time, all the boards were bar coded so they could track each one and how it failed

I might solder the odd wiring harness but otherwise we never did any component level fixing in the field ... too slow and too unreliable

Thar be tunes in that trunk! My 7 year old is making pirate jokes. But anyway, hooked it up, also put in a new headunit in that is fully active capable. Just a quick and dirty to test it and get it sounding good before I decide if this is worth doing a complete install.
Initial thoughts with just a quick setup, is powerful clean bass, and lots of power available up front. This is by far the most powerful amp I have ever run a subwoofer with. Did I say power yet? Power! Arrrrr!
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sent from Utah.

I have been working on some home stereo stuff in these times of covid quarantine.
I rebuilt a set of bang and olufsen ms150 speakers. They were bang and olufsens largest passive loud speaker in the early 80s and they are gorgeous. Sound pretty good too!
I recapped the crossovers, refoamed the 8" mid woofer, and replaced the 10" woofer with peerless units. One of the 3" mid-range driver's had the voice coil separate from the done, so I fixed that as well. I did not have the original stands, so I designed and built some out of 80/20 t slot railing.

Here they are.
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sent from Utah.

More home stereo stuff. I got a old school early model dsp preamp from Sony the other day. It really is very cool, but needed some work. I'll test it out today to see how it sounds post work.
It is a Sony ta-e1000esd preamplifier. I opened her up and removed the video board, put sockets in for the opamps so I can swap opamps easily and figure out which one I like. I also recapped the entire analog board with high grade nichicon fine gold and muse capacitors. Signal line caps are now Elna silmic ii capacitors. I also went through and reflowed solder on all rca connection (many were dried out and cracked) and reflowed all transistor joints.

Need to hook it up today and give it a go. I was rather surprised to get it back together and see that it worked again.
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sent from Utah.

Oh, and the car amps have increased to 3 and a dsp. The railing I was going to use to build the rack got pilfered and used for those speaker stands and a rack for some jbl amps I have laying around.
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sent from Utah.

Cool to see this stuff. Thanks.

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Originally Posted by basinbeater

I have been working on some home stereo stuff in these times of covid quarantine.
I rebuilt a set of bang and olufsen ms150 speakers. They were bang and olufsens largest passive loud speaker in the early 80s and they are gorgeous. Sound pretty good too!
I recapped the crossovers, refoamed the 8" mid woofer, and replaced the 10" woofer with peerless units. One of the 3" mid-range driver's had the voice coil separate from the done, so I fixed that as well. I did not have the original stands, so I designed and built some out of 80/20 t slot railing.

Here they are.
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sent from Utah.

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Wow..great work!

Quote:

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Originally Posted by basinbeater

Oh, and the car amps have increased to 3 and a dsp. The railing I was going to use to build the rack got pilfered and used for those speaker stands and a rack for some jbl amps I have laying around.
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sent from Utah.

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You didn't increase the volume level available to 11??? ..(face palm)

Hehe, always to 11.

I just hooked up the refreshed Sony. Initial test with the kids going bonkers reveals much much much improved detail, power, and general liveliness to the music. Then I did some A b testing.

I used a Sony ES CD player with The Black Crowds playing jealous again. Amplifier is a hafler dh200. CD player sends a digital optical signal out to the Yamaha receiver and Sony preamplifier, and an analog signal out to the hafler preamplifier. All units then send their signal to the hafler amplifier and out to the big b and o speakers.

First up, the Yamaha htr 5960 and the Sony. The Yamaha has been doing the tv audio duty for the last while, and is heads and shoulders above the soundbar that I unilaterally dismounted and sold on ksl. The Sony now blows the Yamaha out of the water. Much more dynamic and lively, better bass, better treble, more clarity and detail. Better everything. I had spent considerable time fiddling with the Yamaha settings to get it to where it sounded decent, so this is not without taking proper settings into account. Keep in mind with the Sony, this is without any settings changed. After all the work I did, it had a full memory reset. So that was easy.

Next up, hafler dh110 preamplifier and the Sony. I really like the hafler. It's not much to look at, but it sounds great. I got the preamp and the amp as a package deal for $200. It is the first unit I have had that finally displaced the nakamichi SR4A from main stereo duty. It has a great phono amp, and just has great power and smooth sound. So. This is just from 30 seconds listening to the same Black Crowes track, jealous again. But I can't pick which one. Need to take more time to really sit and listen. I think the Sony is producing more powerful bass now. I did play with a little bit of bass boost on the Sony, and the bass tone knob on the hafler. Both sound very good.

More testing to be done. But I can't believe the level of improvement with the sony. It is substantial. It had sounded quite good in the basement in a smaller space, but it had been a bit flat when more power was required for larger space. It got a recap and has different opamps in it.
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sent from Utah.

The rabbit hole deepens. I decided to build my own amp from (sort of) scratch. I decided to build my own 150 watt per channel class ab amplifier. I ordered circuit boards from diyaudio.com (great site if you like this sort of thing). I made some component choices and ordered a bunch of crap from mouser. The circuit was designed and posted by a forum member, and the store made up circuit boards for it. I needed a case, heatsinks, a power supply, and a way to softly turn it on, and protect the speakers from dc if something were to go awry.
I found a dead arcam receiver (was originally $5000). It came complete with a functional power supply, big heat sinks just the right size, and a huge case that will make setting up the layout for the amp flexible, and I can even add more to it down the road.
Check it out.
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sent from Utah.

A few more pics.... I've learned a shitload, and the next step for me is figuring out the math to apply to the circuit so I can begin to design my own amplifier circuits. I understand the concepts, and what happens at each stage, but the math is tricky.

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sent from Utah.

That’s cool you do that. Crazy skill. Are you a ham?

Holy jeebus
I’m jealous

No ham. Just like playing cracker loud in the living room.

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sent from Utah.

Sounds like some folks with stereo knowledge here. I have a Kenwood car stereo that turns off after 5-10 minutes and won't come back on until the next car start. I have taken a look at the power and it seems just fine. Do car decks have some sort of thermal fuse link that can cause something like this ? I actually know my way around electronics a bit so just looking for some direction bsinc I can't seem to find any info online and would rather try repair than replace.

It may be getting hot, and some ic that is involved in the power circuitry is shutting down, or an amp piece is getting hot and triggering the power supply to shut down. Toss it and get another one. Each of my 5 cars has a $40 used pioneer deck.

sent from Utah.

My guess would be a cracked solder joint that fails after the board/part is heated enough. Could waste a ton of time troubleshooting a problem like that

My power supply on my diy amp is together and putting out the right voltage.
I've retained the arcam factory soft start circuitry, as well as the other power supplies should I want to add things like an active crossover circuit, etc... I had to trick the startup board that controls the relays for the transformers into thinking it was getting the right signal from the (removed) cpu that controlled everything in the arcam. With that trick in place, it fires up like it is supposed to, and I get +-63.3v at the rails that will power the amp. The power supply cap board also serves as the star ground for all amp related circuits. Voltages shown are with a bad LED. with that fixed I get the 63.3 value. More power!
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sent from Utah.

Quote:

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Originally Posted by abraham

My guess would be a cracked solder joint that fails after the board/part is heated enough. Could waste a ton of time troubleshooting a problem like that

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Cold solder joints are almost fun when you can see them or detect & repair them. Great solder practice. However, multilayer PCB with conductive glue are no fun at all...micro breaks that are essentially in-between layers are maddening.

So try if you want or are interest, or jsut toss if you want "results"..lol.

Solid work basin btw. I enjoy your posts here - great project.

I'm surprised at how much fun this stuff is. I'm trying to get a simulation of the amp circuit up and running. Someone else built it along with a virtual test bench, that when I get to trying to design my own stuff, will be very handy. Instead of futzing around with a breadboard and little wires, you just build it on the computer and see if it works, and tweak it there. When you like what you get, test it in real life. This stuff is all like a big puzzle.

sent from Utah.

Making progress. One side of the amp is finished being built. We'll fire it up tonight and adjust and see if the smoke stays inside. All electronics run on smoke, and when you let it out, then it won't work anymore.
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sent from Utah.

Yup. Basin got mad man-skills. Jealous.