Jacked up ESR Meter

[NxB]

I have a blue esr meter and its screwed up. Q1 overheats and the display partially turns on for a second then dims and shows only certain segments.

[Toasty]

Re: Jacked up ESR Meter

It was working then died? Did you try and measure a charged cap?

If he doesn't come in shortly, PM Bob Parker.

Toast

Edit: Which model/brand meter is this??

[NxB]

Re: Jacked up ESR Meter

Anatech. It was assembled but didn't work.

[Toasty]

Re: Jacked up ESR Meter

Hmmm. Perhaps IC1 is bad, or in backwards, or you've a short in you're soldering. Check all of that.

You should have +5v at Leg 1 of IC1.

Desolder just Pin 1 of IC1 and see if Q1 stops overheating. See if you have +5v on Leg 1 then.

Toast

[NxB]

Re: Jacked up ESR Meter

I think they overheat in the order of Q1 then IC1 then Q1 again. I don't have another exact 5v regulator, I tried to substitute but IC1 and the new regulator started overheating. With the new regulator display was bright for a few seconds then segments started getting dim and nothing would light until the battery was reconnected.

I've changed the caps, the PNP and NPN transistors and still it does the same thing. I don't see any shorts but the bipolar cap or the tiny caps could be bad, no way to test. Its as if the circuit is oscillating. Maybe some resistors went. I got this kit mostly completed, I don't think it ever worked some resistors were flipped, 100k where 10k should be but I put them in the correct spots.

Will try running with the regulator disconnected and probably order another one tomorrow.

[Toasty]

Re: Jacked up ESR Meter



IC1 is the 5v regulator - 3 pin
IC2 is the microcontroller Z86E0412 - 18 pin
IC3 is the CMOS shift register/display driver 4094 / MC14094 - 16 pin

This was someone else's unfinished unit? Then I would go from A-Z with a component list sheet and schematic and make sure every last component is installed correctly. Mark them with a marker or something to make sure you've verified every last one. The resistors can be especially confusing as you're dealing with both 4 & 5 band coding. Confirm that the IC sockets were installed correctly with the pin 1 markings.

I doubt any caps or resistors are bad, but the electrolytic caps could be in backwards. Double check C1 & C3-100uF, C2-10uF.

Resistors from 100-1K ohms, if they failed, would be obvious as a burn, overheat mark on board, or blistered paint. Above the 1K ohm value here, there's not enough voltage to damage them.

Verify that the regulator is putting out 5v. If it's shorted from input to output, it would pass the 9v from the battery, and that could take out many items -> Primarily the microcontroller and LED driver IC's.

If you don't have the assembly manual PDF, let me know you email where I can send it as it's too large to attach here.

Good Hunting!
Toast

[NxB]

Re: Jacked up ESR Meter

I checked it for oddball stuff like backwards caps. The caps it came with were swollen but not in backwards. It turns on right away when a battery is plugged in, is that normal?

[NxB]

Re: Jacked up ESR Meter

Regulator is passing 2-3 volts and it keeps jumping around as Q1 heats up.

[Toasty]

Re: Jacked up ESR Meter

Sounds like Q1 is bad then. Unit should not turn on immediately when batt is connected. Q1 is the "electronic switch" to power the unit.

Input to IC1 should be batt voltage. Output MUST be 5 volts.

>>The caps it came with were swollen but not in backwards.<<

WHAT !! Replace them all. Not possible unless reversed.

Toast

[NxB]

Re: Jacked up ESR Meter

Replaced them when I got it. I've been replacing IC1 and the unit still does the same thing. But I didn't have any spare regulators except a big 5v one that doesn't fit and is rather generic. I'll order the regulator and put it in with a new IC1 and see what happens.

[Toasty]

Re: Jacked up ESR Meter

IC1 IS the regulator as I said before.

>>Regulator is passing 2-3 volts and it keeps jumping around as Q1 heats up.<<

That was with Pin/Leg 1 lifted?

Do you have the schematic & manual?

Toast

[NxB]

Re: Jacked up ESR Meter

[I've been replacing IC1] = [I've been replacing Q1]

I have the schematic/manual from the site. I didn't lift the output leg. I did it in circuit from negative battery to output leg. I can try that tomorrow.

[Toasty]

Re: Jacked up ESR Meter

>>[I've been replacing IC1] = [I've been replacing Q1]<<

Okay. LOL

If you lift the regulator leg, get 5v, AND Q1 stops heating up, there's likely a problem with either IC2 or IC3.

Toast

[Bob Parker]

Re: Jacked up ESR Meter

There's something seriously wrong with that meter. When it's just sitting there idle with only "- " showing, it should only pull around 10mA which isn't enough to heat up any components at all.

What you're describing is a major overload on the +5V rail. I bet it's pulling 100mA or more from the poor little 9V battery. Are you really sure that none of the electrolytic caps on the board are installed backwards?

If you can't find some component mis-installed, you should be able to find the cause of the overload by feeling around with your fingertip because whatever it is will get very warm from dissipating a lot of power.

[NxB]

Re: Jacked up ESR Meter

Nothing gets warm besides the IC and eventually the regulator. After the regulator comes I'll try again and see what happens.

[Toasty]

Re: Jacked up ESR Meter



Any progress on this NxB?