Electronics! Falling into the geek rabbit hole.

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Originally Posted by unitofstuff

I used to tinker with all sorts of random crap. Now I work as an engineer and hardly tinker at all in my off time, so maybe you made the better choice than I did. I definitely think there's something to the concept of not ruining your hobbies by turning it into a job.

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I can certainly relate to this, although I don’t regret the choices I made. I was working a blue collar job in a machine shop when I started tinkering around with Radio Shack projects. I wanted to understand how they worked so I studied up on the resistors, capacitors, and inductors, to the point where that all made sense.

But then there were the transistors. So I got to one level of understanding of them as being switches, but there were some complicated equations and explanations about how they worked that got more and more complicated the further I dug into it.

Eventually I went back to school to try to understand this stuff better, and I did - to a point. But there was always another layer of abstraction that proved difficult to penetrate. But in the meantime, I got my EE degree and a job, and there was no more time for tinkering anymore.

Yeah, I don't regret my choices, but a career in engineering would have been fun. I just got a raise today, so that is good.

So, billy k, Mr. EE. Want to help me reverse engineer an unobtainium chip? I have an old Yamaha r2000 receiver that has a blown voltage amp chip an stk3156. These are now impossible to find, except for cheap ass chinese fakes. I tried one of those already and it let the magic smoke out after about 10 mins. I have a schematic for the chip. It should be doable to rebuild it as discrete on a proto board.
This project has been shelved for awhile as I got into the amp building.

sent from Utah.

After you get it on a proto board I could lay it out and give you files to buy it from osh park so it's a bit cleaner

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Originally Posted by basinbeater

Yeah, I don't regret my choices, but a career in engineering would have been fun. I just got a raise today, so that is good.

So, billy k, Mr. EE. Want to help me reverse engineer an unobtainium chip? I have an old Yamaha r2000 receiver that has a blown voltage amp chip an stk3156. These are now impossible to find, except for cheap ass chinese fakes. I tried one of those already and it let the magic smoke out after about 10 mins. I have a schematic for the chip. It should be doable to rebuild it as discrete on a proto board.
This project has been shelved for awhile as I got into the amp building.

sent from Utah.

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How DO they fit all that magic smoke in such a small space???

Beats the hell out of me, but the shit sure don't work when it gets out.

sent from Utah.

Abraham. Now we are talking. I've come close to pulling the trigger for custom pcbs for amp boards, but not done it yet. I got more shit to do before I get to that but, it is starting to come back on the radar. Need to improve some math skills and get ltspuce going again see if I can figure out how to actually run a basic sim.

sent from Utah.

Also, broke a me tap. I had two holes to go, was getting excited to be done drilling and tapping, when snap, the tab breaks off in the hole in the heatsink. FUCK. Somehow through brute force of a big hammer and a skinny punch, I got it out. And somehow salvaged the threads. And then threw a dremel stone in the vice and reshaped the end of the busted tape so I could tap that last hole. And surprisingly, it worked. Putting amp boards on the heat sink now.

Kind of a funny progression of feelings. Fuck! Feeling pissed for 30 mins getting it out, then, victory is mine! You fucking thing are out! Yes! Ok, now what to do about the buggered hole? Shit. Hmmm. Aha! I'll try this, fuck yeah! It works! Wahoo. Ok what's next?Attachment 342511Attachment 342512Attachment 342513

sent from Utah.

Victory... Is mine.

Test in the case tomorrow night after the kiddos go to bed.
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sent from Utah.

That’s awesome. I’m still in the 1950s as far as electronic tinkering goes. I’ve built a couple tube guitar amps and a couple effects pedals. I haven’t really gotten into the transistor era. This has my interest piqued though. Maybe I’ll build a solid state micro head.

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Originally Posted by basinbeater

Yeah, I don't regret my choices, but a career in engineering would have been fun. I just got a raise today, so that is good.

So, billy k, Mr. EE. Want to help me reverse engineer an unobtainium chip? I have an old Yamaha r2000 receiver that has a blown voltage amp chip an stk3156. These are now impossible to find, except for cheap ass chinese fakes. I tried one of those already and it let the magic smoke out after about 10 mins. I have a schematic for the chip. It should be doable to rebuild it as discrete on a proto board.
This project has been shelved for awhile as I got into the amp building.

sent from Utah.

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Hah! I just watched “Back To The Future III”. Reminds me of the time travel circuitry Doc made on the hood of the Delorean out of 19th century electrical components.

The only suggestion I have is that when an IC like that goes poof, the problem is often outside the chip. A short, blown cap, improper voltage supply, etc. I don’t know the specifics of that particular chip, but if replacement chips are blowing up, I’d suspect that even more. And just because a chip is cheap and from China doesn’t mean it’s crap.

Agreed, stuff usually fails for a reason, but... In this case, the amp in the Yamaha uses dual voltage rails, and the high voltage one is +-86v. Failure of the stk voltage amp chip is very common and these were known to be unreliable units. The genuine chip on the initial design was so failure prone that they specced another chip within a few months, but it also was operating on the ragged edge it's whole life, and were known to run very hot. A common mod is to attach a large heat sink to the chip. The Chinese fake replacements are known to be junk, and the real thing cannot be found anymore. So .. discrete replacement time with larger SOA.

sent from Utah.

Before I installed the Chinese fake, I tested all supply voltages, and signal paths, and everything checks out. When the chip failed for the previous owner, it took out the current amp section as well. I have the pieces to repair that, just haven't gotten around to it. I'll have to bust it out when I finish this rotel/gb150d.

I have a Sony es amp with an stk chip in it that I am pretty sure is a Chinese fake, it works fine and sounds good. The original ones are also known to fail in the Sony, and run hot, so people put heat sinks on them.

sent from Utah.

We just finished watching back to he furture 1 and 2. Good stuff.

sent from Utah.

86V is a little outside my area of expertise. We get nervous anytime voltages get much above 1.2V on the stuff I work on. But if you have enough cooling, you can push the boundaries some.

Make sure you have sufficient heat sinks, and good thermal grease. That applies if you are making the circuit out of discrete components as well.

Another thought, often circuits burn up because they go into a condition called “latch up”, caused by unexpected voyage supply differentials in different parts of the circuit, or floating grounds, etc. it can be tough to debug.

Good luck with your tinkering.

Looks like I have a little project for this afternoon!

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Originally Posted by Viva

Looks like I have a little project for this afternoon!

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Nice Viva, what tubes are those and what are you up to?

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12AU7W. Gonna upgrade my Rogue integrated with these.

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Originally Posted by Viva

12AU7W. Gonna upgrade my Rogue integrated with these.

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solid!! what rogue do you have?

looks like really nice kit

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Sphinx v1. The v2s and v3s have much better phono and headphone stages, but I don't need those.

I also ordered a set of NOS RCA clear tops. Gonna play around with tubes to figure out which gives me the sound I want.

Love it. I haven't messed around with tubes. I should. I'm going tomorrow to give a listen to one of these...
Jbl paragon...
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sent from Utah.

Whoa... Is this gonna be the powered version?

https://en.wikipedia.org/wiki/JBL_Paragon

Well, another amp. Just wrapped this one up and trying it out in the basement with some Sweet Thistle Pie.
Gb150d amplifier pcbs, ebay speaker protection, arcam power supply capacitors, and the case, heatsink, transformer, and soft start are all Rotel.
Next step is putting an arduino to give it a pushbutton turn on from the front, power indicator led, maybe an lcd screen that can readout rail voltages, or digital vu meter. This one was quite the mashup. Seems to work pretty well though. Sounds good. Vocals are great, bass is powerful. Not as bright in the highs as the honey badger. Not sure if that is good or bad yet.
Oh, and I snagged a free Krell showcase 5 power amplifier today. Not sure if it works properly yet or not. It has the biggest transformer I have ever seen in an amplifier. Next project. Attachment 343433Attachment 343434Attachment 343435Attachment 343436Attachment 343437

sent from Utah.

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Originally Posted by basinbeater

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.

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Be sure to use heat sync's when soldering. The heat from the iron will take out other components. wearing a ground strap when your in the guts of a board is also a good idea. Better safe than sorry

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Recently picked up this early 70s Pioneer SX-1000 for some tunes in the garage. Paired it with some ADS L500s from the same vintage.

Sounds great but I’m getting some intermittent crackling and popping from the left channel. It comes and goes but is quite annoying. Got some deoxit on the way, hoping a good cleaning will do it but my guess is I’m going to have to take it to someone who knows what they are doing.

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Originally Posted by dfinn

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Recently picked up this early 70s Pioneer SX-1000 for some tunes in the garage. Paired it with some ADS L500s from the same vintage.

Sounds great but I’m getting some intermittent crackling and popping from the left channel. It comes and goes but is quite annoying. Got some deoxit on the way, hoping a good cleaning will do it but my guess is I’m going to have to take it to someone who knows what they are doing.

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It needs new output capacitors most likely. Most amplifiers and receivers will need a re cap.


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Is there a way to test that?

I’m not sure how, but if you look at the capacitors inside, big cylinder looking things, the tops should be completely flat. I would just take it to an electronics tech and have them replaced. Vintage electronics all need new capacitors at some point. They go bad with age.


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ok, that is my plan if giving it a good cleaning and some deoxit doesn't fix it.

Ha dfinn, I'm looking at getting new cells for a thinkbook convertible I bought from you in the snowbird parking lot a long time ago. Planning on setting it up as a music box for the basement workshop.

That's sweet! I definitely have no memory of that but that doesn't surprise me. :)

I've still got those old blue house skis I bought from you back in the day banging around in the garage. I should turn them into a shelf to put broken stereo equipment on.

You may solve your crackling issue with deoxit, and it may sound ok, but if it hasn't been recapped, some new caps will bring it to life. Also, the old ads speakers probably have electrolytic capacitors in the crossovers, and surely those could stand to be replaced as well. I had a pair of old bang and olufsen speakers that sounded 'ok', but new caps in the crossovers made a huge improvement.

sent from Utah.

I forget where I read it but something I came across said the speakers use a film type cap that doesn't need to be replaced. They also used rubber surrounds which seem to be holding up really well.

Were those BH skis the District?

Anyone have recommendations on places I might be able to ship this old Pioneer to to get some lovin? Looks like we have a local place here in SLC that is highly recommended but they are 9 months out. I'm looking at Just Audio in Baltimore.

So my remote control for my very low end but newish Yamaha home theatre receiver doesn't seem to have any affect suddenly. Assuming it's the remote, obviously first thing I did was change the batteries. No luck with new ones. Tested the batteries voltage and they're good. Disconnected the unit from power, reconnected, no change.

Then I noticed when I press buttons on this otherwise not working remote, one of the LEDs on my iptv box flashes, indicating to me that the remote is putting out some sort of signal, but the receiver isn't 'reading' that signal.

Contacted Yamaha with this info and their response was literally "this is the part number for a new remote, call us with credit card to order a new one". I was hoping for some trouble shooting since the remote seems to be doing something but no.

Next I found my old Harmony 1 programmable remote from Logitech. Set it up for the receiver and still nothing.

Tried downloading their app that interfaces with the receiver but my model is one unit too low to support that feature.

Is it common for a receiver to lose the capacity to receive the signal from the remote?

Your Pioneer could be suffering from a speaker relay going out. My Pioneer 1010 was doing the same stuff, one channel popped & crackled, then would drop out only to re-appear later. Local tech. guy fixed that & a few resistors he didn't like for around a hundred bucks. Some capacitors are likely not in spec but unless they're distorting (shape) leaking, or tops starting to bulge, they're probably acceptable. Would certainly improve it to recap and it's a beautiful piece to invest in if it's a keeper.

I'm pretty sure I'll be sending it out somewhere for repair. I wouldn't say it's in pristine condition but it's pretty damn clean for being 50 years old. The guy I bought it from was cool about it, he gave me back half what I paid for it so I'm only into it for about $80. I'm ok with investing that $100 and maybe a little more back into it to get it working.

I dig into my krell today. It was free, so can't complain. Guy said it had some distortion in the highs. One channel is blown, and has super high offset. The other 4 channels play ok, but pass a weird looking signal. There is econd order harmonic distortion in there signal, which is apparently a desireable feature of some amps. There is a bit of disgortion that shows up at higher frequencies, and is a known problem with this showcase series amplifier. There are 3 electrolytic caps that apparently suffer from heat and cause this. So I ordered up a bunch of caps. I've not done much with surface mount soldering, so this will be an interesting challenge. Krell will not release the schematic, and there are a bazillion little surface mount diodes and transistor on the driver board for each amp module, so repairing the broken amp may be beyond my capacity. But fixing up the other four should be doable. Transformer is fucking huge. Case is beautifully made. We'll see if she sounds any good, or if I need to rip the amps out and build something custom.
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sent from Utah.

It’s actually pretty awesome how well documented this owners manual is for this 50 year old Pioneer. Full wiring diagrams and also a break down by circuit board of the components on each board.

Those service manuals are super handy. I found one for an old bang and olufsen in a proper enveloped taped to the inside of a wooden case.

I wish I could find one for this krell. But they sit pretty tight on their stuff. Don't like to let it out.
That said, I did fix and adjust 4 of the 5 amplifier modules in my Krell Showcase amplifier. I reached e capacitors per amp module that suffer from the heat generated by this unit. I popped one open, and it was dry as a bone. There was severe crossover distortion. Replacing these caps on all 4 boards fixed the issue on each case. Adjust bias, and close it up. It now has 4 good channels. The 5th channel has very high dc at the output. So... Something is wrong. But I can't find a circuit diagram. I may try to draw it up. Should be feasible with the power board, but the driver board is so damn small and has a shitload of small diodes and transistors.
The waveform pics below are before and after repair.
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sent from Utah.