Electronics! Falling into the geek rabbit hole.

[basinbeater]

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.

[basinbeater]

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?

sent from Utah.

[basinbeater]

Victory... Is mine.

[basinbeater]

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


sent from Utah.

[Chugachjed]

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.

[billyk]

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.

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.

[basinbeater]

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.

[basinbeater]

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.

[basinbeater]

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

sent from Utah.

[billyk]

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.

[Viva]

Looks like I have a little project for this afternoon!

[tgapp]

Looks like I have a little project for this afternoon!

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

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[Viva]

12AU7W. Gonna upgrade my Rogue integrated with these.

[tgapp]

12AU7W. Gonna upgrade my Rogue integrated with these.

solid!! what rogue do you have?

looks like really nice kit

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[Viva]

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.

[basinbeater]

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...


sent from Utah.

[Viva]

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

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

[basinbeater]

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.

sent from Utah.

[Viva]

.....

[MTT]

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.
Attachment 303366Attachment 303367Attachment 303368Attachment 303369

sent from Utah.

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

[dfinn]

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.

[MagnificentUnicorn]

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.

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


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[dfinn]

Is there a way to test that?

[MagnificentUnicorn]

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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[dfinn]

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