China tach doesnt work

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It may do if it is in circuit turn the unit on & measure the voltage across the zener it should be around 5 vdc. Also check the emitter the leg next to the base leg with the resistor to the other l6 emitters they all could be common it is possible the via next to l6 is open circuit & not connecting the 2sides of the pcb together
 
Its in the trash. I kinda destroyed the case opening it as my curiosity got the better of me. I sent a 12v square wave in and probed the path and I got it all the way down to the NPN collector and then out the base. IT still didnt pick up the pulse off the coil negative so I bypassed all the protection (caps, diodes and resistors) and sent the coil trigger to the base an let the smoke out of the chip. Lesson learned. If it dont work, just send it back to Amazon.
 
$16 shipped? And how many stand in line to get a piece of the $16 pie?
Maker, seller, shipper.....?
That cheap price should have been a code red alert....
 
Ill just make one out of spare parts.....just feed rectifier to one of my analog Triplett 310 VOM

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pishta said:
it even had the Autotecnica logo in the face but it didnt light up when operating. I think it was a QC reject that got rebranded.
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I bet its a knock-off copy...............
 
sireland67 said:
I bet its a knock-off copy...............
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100% it's a knock off copy. If it's $80 on the manufacturers website and you bought it on Amazon for $16 it is a counterfeit. I have had my share of buying counterfeit product on Amazon. Their shelves are full of it, and the third party sellers make a killing doing it. Amazon also does not care and they have previously removed some of my reviews of counterfeit product I have received before. It is literally impossible to tell what you are going to get when you order from Amazon because of how Amazon works. Amazon has ONE ad per product and every seller has to "attach" themselves to that ad. So, if you are selling that tach for $80 on Amazon and it has sold hundreds or thousands of real pieces and has good reviews, a counterfeiter literally uses the exact same ad, with the same reviews, attaches themselves to it and lowers the price. Since they have the lowest price they are the ones that will sell the product. So, if they lower the price to $16, that is what you see, the product at $16 with good reviews. So, you buy it and get the counterfeit. Since a lot of buyers have no idea what they are buying most will not notice that it is a counterfeit, or if they do its either too late or they never say anything. By the time Amazon gets enough complaints on it and kicks off the counterfeiter, dozens or hundreds of these may have been sold.

Even the prime stuff that they have in their warehouses is full of counterfeits.
 
So do you think a genuine Autotecnica would have worked? This one literally sensed the RPMs then it dropped to zero when the motor was still running. Curiously, my dwell meter does the same thing, it senses the RPMs then drops, then pickes them up again in very short spurts but is not stable. My timing light picks the coil strikes 100% and timing is dead on.... ?
 
HSDemon said:
100% it's a knock off copy. If it's $80 on the manufacturers website and you bought it on Amazon for $16 it is a counterfeit. I have had my share of buying counterfeit product on Amazon. Their shelves are full of it, and the third party sellers make a killing doing it. Amazon also does not care and they have previously removed some of my reviews of counterfeit product I have received before. It is literally impossible to tell what you are going to get when you order from Amazon because of how Amazon works. Amazon has ONE ad per product and every seller has to "attach" themselves to that ad. So, if you are selling that tach for $80 on Amazon and it has sold hundreds or thousands of real pieces and has good reviews, a counterfeiter literally uses the exact same ad, with the same reviews, attaches themselves to it and lowers the price. Since they have the lowest price they are the ones that will sell the product. So, if they lower the price to $16, that is what you see, the product at $16 with good reviews. So, you buy it and get the counterfeit. Since a lot of buyers have no idea what they are buying most will not notice that it is a counterfeit, or if they do its either too late or they never say anything. By the time Amazon gets enough complaints on it and kicks off the counterfeiter, dozens or hundreds of these may have been sold.

Even the prime stuff that they have in their warehouses is full of counterfeits.
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Probably has a GPS chip in it so it can upload your cars coordinates to the nearest satellite
 
Having a hard time measuring the frequency of my distributor lead to coil negative using a digital o-scope. Rigol 5120 ish 2 channel 1GHz rated scope. I hook up the lead to the negative side coil expecting to see a 40 Hz 12v square wave of the distributor sending the 12v to ground but I just see garbage on the screen even when I set it to "auto test" with no clear frequency defined. Any pointers? Maybe wrap a wire around the coil wire as a 20kv pickup? I have this digital Rigol and a tradutional vacuum tube HP scope. Any scope doctors here?
 
"I ain't there", obviously, but I'd think this is a trigger issue. First thing is, I would ramp the v/ cm setting WAY up towards the higher voltage end. There is a high voltage spike in that wave form and you may be over-driving the input. Then play with sync/ trigger. You may do better using external sync/ trigger if that scope has one.

Are you using a 10:1 probe?

Those are a fairly slow waveform, so once you get the trigger/ sync right, almost any scope should work. The old ignition scopes were often electromagnetic deflection--like a TV CRT, so the bandwidth was VERY low frequency.

I have only had my own digi scope (an now old Tektronix TDS-220) for a few years, and have never used it for ignition. Previously, everything I had was analog. Old Tek 475 which now has capacitor and other problems
 
Thanks! I got the specs all wrong off memory as I wrote this at work. Its actually a 100MHz (200MHz firmware update) Hantek DSO5102 with 1GSa/s sampling and 200MHz 1-10X probes.
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This Hantek has an 'auto set' that seems to get about any wave form to show up on screen in a decent spread out waveform. My probes are 1x-10x switcheable and were on 1x during testing. I didnt realize this when setting it up outside. And I didnt think to alter the trigger level as I was kinda in a hurry to see if it would even work. How would I use the external trigger on this? I did see a waveform that looked like a huge spike with a trailing 'ring' but the frequency counter never gave me an accurate figure, it was all over the place. My other scope is a 60MHz HP 54603B using the same probes. Maybe the anolog style CRT would give me an easier waveform to analyze?
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