China tach doesnt work

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pishta

pishta

I know I'm right....
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Ha, no **** right? New "Autotecnica" digital tachometer with digital and lcd sweep readout. Kinda cool for $16 shipped, only to use it to set idle speed on a non tach equipped 2.0 82 Mazda from under the hood. 3 wires : hot, ground, and signal to - slide of coil. So far as good. I hooked it up while idling and the sweep registered so RPMs then returned to zero. Took sense off and touched it again and same thing. A blip then zero. F this, took it apart and it's all surface mount except 1 capacitor. I'll pull and test, maybe it went south. << The 'Autotecnica' that's in the display never illuminates , I only saw it light when I touched the display leads with my fingers and everything lit up. This tach is on the Autotecnica Australia website at $80 so maybe this is a failed QC reject that Amazon sells for $16?

17041538326393501967684451960551.jpg


17041539306626334577041459886504.jpg


17041539738447934032927657602823.jpg
 
Cute but send it back to amazon. That way they start to get better products!!!!!!!!
 
Oh and I sent it a (12.4 peak to peak ) square wave out of a signal generator and nothing at 418Hz, or 100 rpm....
 
What do you suppose J6 (L6 on component) is? I actually get a reading when I touch the signal generator to this top leg and i trace it back to a via to a 10k resistor.

20240101_163534.jpg
 
I say this every time this comes up... American companies send their specifications to China and a little tiny tiny bit of money so they can get a product. Sell it to us "at a large profit margin" and when anything is wrong blame it on china...
They get what they pay for because they don't care. They can send you four more of them and still make a profit at what they give china...
 
I'm glad some of yall know what you're lookin at.
 
You should contact tech support ask for Sum Ting Wong, he will get you straightened out..
 
67Dart273 said:
Might be this

datasheetspdf.com

2SC1623-L6 datasheet

2SC1623-L6 - MCC TM Micro Commercial Components omponents 20736 Marilla Street Chatsworth !
datasheetspdf.com datasheetspdf.com

That center terminal is the collector

Info on the larger chip, HT1621B


I am unable to read the smaller chip
Click to expand...
yes the big chip is only the LCD driver. That little L6 is a 400-600 gain NPN. I can inject a square wave into the Base and pick up a reading.
 
It's retrieving your phone data and hacking into your computer, so it's working.
 
Found a zener diode that measured 13k both ways! It's a W8 so it's a 5.1v so I'll try and replace if I can find one. Is the voltage that critical? Kinda makes sense as I injected my square wave after this diode (seems to be part of the conditioning/protection chain: 2 diodes, 3 resistors and 3 capacitors) and i got some action on the meter. Its the diode above the right hand screw lug above the resistor and I'm injecting right into the NPN.

BZT52C5V1
"W8"
5.1 max
4.8 min
5.4 nominal
 
pishta said:
Found a zener diode that measured 13k both ways! It's a W8 so it's a 5.1v so I'll try and replace if I can find one. Is the voltage that critical? Kinda makes sense as I injected my square wave after this diode (seems to be part of the conditioning/protection chain: 2 diodes, 3 resistors and 3 capacitors) and i got some action on the meter. Its the diode above the right hand screw lug above the resistor and I'm injecting right into the NPN.

BZT52C5V1
"W8"
5.1 max
4.8 min
5.4 nominal
Click to expand...
Doubt it is that critical. Too bad you don't have a diagram
 
Products from China are not supposed to work
 
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