Nikko Graphic Equalizer EQ 20 repair

This equalizer was headed to E-waste before I got my hands on it. I wanted to try to fix it.
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Thank You!

[@RustOnTime]

Old fashioned electronic detective work and fixing. Really enjoyed watching this

[@st.clairworrell8758]

I wish I had a technician in my neighborhood like you are, since I have a Marantz EQ for about 40 years and it just recently started humming just as I turn the EQ button on, and I can't find a technician. I truly love the simplicity of this EQ and it also has become a souvenir.

[@1959Berre]

That trick with the magnet for testing reed switches is so obvious. And yet I have never tried it. Thanks for that tip.

[@1pcfred]

It does not really test the relay so much as trip it. The coil could still be burnt out. I wonder if you could hyper extend the reeds and damage the relay doing it too? Maybe not. They're in little glass capsules.

[@THOMMGB]

Hi John, I really enjoyed watching you troubleshoot and repair this Nikko equalizer. I really learned something. I just picked up a Nikko EQ-1 equalizer that looks very similar to the EQ-20 you repaired. Mine powers up, but I haven't tried it out yet. I'm cleaning off all the gross nicotine covering it now. I'm starting to learn that a lot of problems with older gear seems to be bad capacitors and cracked solder joints. It hurts my soul to see such good gear being thrown out when a lot of the time all it needs is a solder repair or some capacitors replaced.

[@JohnAudioTech]

It's always good to save old gear from the scrap heap!

[@TheTrueVoiceOfReason]

Truly, "what we have here is, failure, to communicate."

[@johnsonlam]

Thanks John, your voice sounds tired, wish you're OK.

[@PileOfEmptyTapes]

Most consumer EQs I've seen tend to have a single 4558 running the show and no reed relay anywhere in sight, so yours seems to be way above average. Good catch, and excellent diagnosis btw. As mentioned, Nikko (pronounced like the Nikkei index, I presume) was a good brand back in the day and made some high quality gear.

[@briangoldberg4439]

Thanks John! Great video. I love the repair stuff!

[@TrevorsBench]

Good job on the repair John

[@jp040759]

Good job. Enjoyed your journey

[@saarike]

Excellent repair and nice vid! It was a joy. 👍

[@davidahmad6090]

Another great and informative video, please keep it up.

[@rleeAZ]

Nikko made some nice stuff back in the day. Going to keep a magnet on the bench, great idea.

[@Fardeenfarwest]

Good work. Well you are also a good detective. Whats new for me here I learn the trick of magnet on the relay.

[@andymouse]

Great a JAT upload ! nice diagnostics tutorial...cheers.

[@garygranato9164]

hi john great vid . please could you make a video on "amplifier probe" that you made, which allowed you to safely check the signal through the EQ.

[@jaymahaffey4133]

I would like to see that too.

[@Stelios.Posantzis]

Nice job! That was a good rescue. I bet there's a Nikko collector out there looking for one of those! Btw I'm surprised to find to much so much circuitry inside an equalizer. The filters all seem to have been constructed with good quality parts and lots of op-amps. No hifi here!

[@EngineeringEssentials]

Good work 😍👍

[@GnuMovies]

Awesome video! thanks alot for making it :D

[@mrb.5610]

Nothing like the feeling you get when you've 'got the b@st@rd' and fixed it ! I repaired a Bruel & Kjaer sound level meter a few weeks ago - 2 dead capacitors - and it put me in a good mood for a fortnight !!

[@listerine-pr5lt]

Great signal tracing technic.

[@youwilldisobey]

Nice One Mang"

[@beamer.electronics]

Interesting video, thank you. Just a thought: It might be worth squirting in some switch cleaner into those slide switches before buttoning up. It'll lubricate and flush out any dirt that might cause ongoing issues. All the best, Beamer.

[@paulb4661]

That's a quick fix only; there's a fundamental difference between level of cleanliness, appearance, life expectation and, most importantly, measured contact resistance between switches pumped full of cleaner and ones disassembled and serviced properly.

[@beamer.electronics]

​@@paulb4661 Hmm, having earned my living for decades doing this I can assure you a quality cleaner correctly applied helps maintain a switch's integrity for many years. Even if a switch is failing it can be rejuvenated for many extra years of use - guaranteed. Please see my video: kzbin.info/www/bejne/g4SWY3mOm7aUgJI Naturally, nothing lasts forever and if a switch is so far gone (and you'll know it) - it'll need replacing. The process of switch disassembly can introduce mechanical and electrical intermittency issues.

[@paulb4661]

@@beamer.electronics Our experiences differ then substantially, having seen the insides of throughly sprayed switches on serviced equipment multiple times through the years. Broke a few, fixed many more - time consuming and demanding in the dexterity department, but no intermittent contact issues, no oxidation, no patina and no comparison to still dirty, but well oiled spray jobs. Jewellery cleaning agent and a liittle contact grease does it.

[@beamer.electronics]

​@@paulb4661 Yes, you're right: Same world different experience :) I probably have replaced more than I've squirt cleaned/repaired. That failed mains switch in my video has now lasted well over 1 year, tuner used every day, and no signs of failure. Since the early 1980s - it was probably the first time it had ever been squirt cleaned. Our polarised perspectives have been interesting, all the best Beamer.

[@Choralone422]

Nice repair! This is probably the same issue that I had with a Realistic brand EQ that I had bought in the early 90s. It stopped outputting audio sometime in the late 2000s and instead of trying to fix it I ended up taking it to e-waste as I didn't have a use for it or the knowledge at the time to be able to attempt to fix it myself.

[@bretthibbs6083]

I have a realistic brand EQ that I've had since the early 90's and it still works great and I've moved about 15 times with it. that's weird that yours quit working.

[@josephlalock8378]

@@bretthibbs6083 some models from realistic/optimus used extremely crappy electrolytic caps that become very leaky. some used tantalums in the signal path that will be out of spec by now and some used the very corrosive glue. it's not really weird that his stopped working, it's weird that your's hasn't. i can guarantee you that a recap will be a huge improvement in your sound and getting any glue off the board will prevent it from dying. i like nichicon UKL 10% in the filter networks. anywhere in the signal path and a good cleaning of the sliders using proper chemicals depending if they are carbon or copper traces inside with a couple hundred mini eye makeup swabs will make an even bigger difference. (i have alot of eqs come across my bench. i've done a/b testing before and after service with like models and the difference is huge)

[@PeterMilanovski]

John buddy, it appears that you have one of those cheap eBay component testers, they are available in a few different types but the type that you seem to have is the real basic one that doesn't give you a Vloss reading! I heard you say that you checked the capacitor ESR value but I didn't hear you mention the leakage value! The only place that high ESR capacitors will be a problem is in the power supply filter capacitors! High ESR capacitors won't cause problems anywhere else, but capacitors that leak DC will! As you have seen in the delay circuit! Do yourself a favour and get yourself a component tester which displays capacity, ESR and Vloss especially if you are going to be making repairs or want to know if another capacitor that has been pulled out of another circuit is actually any good! To many people focus on ESR to determine if a capacitor is good or bad, it's really bad practice and it should be stopped! This isn't about whether anyone should always leave the original capacitors or replace them all with new! It's about knowing the real condition of the capacitor! I always say that if you value your equipment, replace all the capacitors but always go up in voltage wherever possible! Your equipment will last much longer than what it did with it's original capacitors! Did you know in the old days, RCA used to test the capacitors that they were using in their TV's at twice their rated voltage! In other words, they were actually putting 400V across (t) a 200V capacitor! Try that with a modern capacitor, it won't end well lol. The point is that, the old paper wax capacitors weren't as good as what we have today so they were always underrated! Which is why they lasted so long, with the new modern capacitors, because they are so much more reliable, manufacturers tend to stick too close to voltage tolerances and that doesn't leave a lot of headroom for capacitor deterioration, in fact I believe that the larger manufacturers are most likely aware of this problem and allow it because it means repeat customers sooner! So basically the golden rule is, always go up in voltage on replacement capacitors, especially if it's next to a heat source of any kind! If you have been following Mr Carlson's Lab, you would have seen the videos where he tested leaky capacitors on his Heathkit high voltage capacitor tester, you would have seen that while he was testing a high voltage capacitor, at low voltage it tests perfectly fine but as he climbed up in voltage, it came to a point where it started to leak DC! They always begin leaking from top down, so if you go up in voltage, you won't have to replace any capacitors for a very long time to come! I really hope that I didn't come acrosst (LoL I don't know why Americans say it like that along with soder and bat tree) like a smartass, I'm just trying to bring awareness to the industry in a hope that we can understand what the real problem is and that it's better to repair it, and repair it properly rather than replacing it with a new one that is not going to last and possibly harder to repair due to everything getting smaller and surface mounted! Not to mention proprietary ic's that are not available one year later! That's why we need to keep all these old equipment out of the landfill because that's basically what we have left to purchase today! But please look into getting a better component tester, on eBay, you can see in the images where they showed a capacitor being tested and you can see the screen showing all the details! That's the one you want! I purchased a dedicated ESR meter age's ago thinking that now I have the tool that can find all the bad capacitors in circuit! And yet I was still having problems! Once I worked out that ESR is not the first thing that I should be looking for, I got the right tools, first I got the cheap Chinese eBay component tester! It was great but it didn't have a case so then I got an LCR Bridge Meter which provided even more information and I have never looked back since! I would love a vintage Heathkit capacitor tester to apply full rated voltage across it but those things are unobtainium here in Australia! Both that and a signal tracer! Either a Heathkit or an Eiko! You could have used your scope to trace out the signal but I believe that you made the right and best decision to signal trace it! Maybe you can design and build your own signal tracer? Perhaps one with adjustable and enough gain to pick up even weak signals? Carlson built his own and it's non contact using RF pickup so that you can hear bad resistors that are arching over inside! It's an indispensable tool for the bench! Anyway, I apologize for the lengthy post! I just hope that I have been of any help! Thanks for your patience.

[@SuburbanDon]

I love Acrosst. And Heidth.

[@1pcfred]

Betwixt and between.

[@pralhaddongre8585]

Thanks sir.new 10band Equalizer circuit board idea sir.

[@rotaxtwin]

My kind of repair, lots of real estate on those boards - and the bottom came off!

[@ranbymonkeys2384]

John, how did you make that little probe that you used? I think that is what I need to keep the rest of my hair.

[@JohnAudioTech]

It's something I setup on a breadboard using an audio amp chip. The input has protective components so I don't blow the chip if I touch a power rail. I should make a video about it sometime.

[@ranbymonkeys2384]

@@JohnAudioTech I saw kinda sorta what you did, I just get nervous about damaging things and want to do it right. I think a more detailed video on your troubleshooting idea may help a lot of us. Look at it as your part in helping the mental health sectors of our society, haha.

[@TheTrueVoiceOfReason]

For a homebuilt overhead mount, check out Gregg's Vintage Workshop here on YT. He made one out of plywood for both the arms and swivels. But with the current prices if lumber, you might be better off just buying something from Amazon or elsewhere.

[@SHADOW47196]

CAN YOU TEST TDA 7279SA?

[@hemlocksalad5383]

Do you know anything about the KA2209 op amp? I mined one out of a dead pocket radio from the 80's and was wondering if it would be feasible as a headphone amplifier.

[@ferrumignis]

ka2209 is a stereo power amplifier rather than a basic op-amp, it will have no problems driving headphones.

[@hemlocksalad5383]

@@ferrumignis Thank you, have a good weekend !

[@ferrumignis]

@@hemlocksalad5383 You too. There are several KA2209 projects on KZbin if you search!

[@PileOfEmptyTapes]

BTW, KA2209 is equivalent to TDA2822M. You'll probably want to lower the gain externally as the default 40 dB makes things very hissy on headphones; there's actually at least one KA2209 kit allowing you to do that.

[@tdevosodense]

What about the VU meter ?? In the mittle ?

[@JohnAudioTech]

There is no meter on this unit.

[@cajuncoinhunter]

I heard some Cajun Music at the 20:07 time stamp for a minute ......

[@mintubl7166]

I want purches this equlizer

[@1pcfred]

The first thing I saw was that relay. Wouldn't it have been better to start at the output and work your way back to the input? Kind of like cheating at solving a maze.

[@jdlech]

In this case, it would have. But not always. The first thing I did was to hit the internet for a repair manual or schematic. I didn't find one, but I did find an owners manual that was dated 1981. So this unit is roughly 40 years old. Knowing this, my first guess is a bad capacitor that probably blew a semiconductor - likely the output transistor or op amp. I would have started my trace right there. Finding the output transistor working would have led me straight to the relay - the next component in the signal path. The whole unit needs to be recapped as all those electrolytics are at or near the end of their life cycle. Luckily, all those caps are just a few pennies each. But egads - he's putting 40yo caps back in.

[@1pcfred]

@@jdlech these caps are not filtering a SMPS. Let's try to not lose sight of that, OK?

[@jdlech]

@@1pcfred Doesn't matter. When a cap fails, it can easily take a transistor or chip with it. Every one of those 40yo caps are at risk of failure. Engineers don't stick random caps in a circuit for shits and giggles. They all serve a purpose. And as we saw here, a single failed cap can make the entire unit quit working. The next failure could take out irreplaceable ICs.

[@1pcfred]

@@jdlech there are no ICs in that EQ that are irreplaceable. I am not sure about no extra caps in circuits either. The whole unit is a POS. I don't know why you are so worried about it. It was literally going to the scrap heap before John got it. It was on its way to the great hi-fi junk pile in the sky. They've have burnt it in the open air for it's metals in Africa. Bog common op amps and all.

[@jdlech]

@@1pcfred Ah, and you obviously think that's the only EQ in existence. Tell you what - give me an address and I'll send you all the 40yo caps I pull for your own use, since you think they're so precious. The Chinese second hand component industry must love you.