ESR meter blues

[sceva]

I purchased a blue ring tester kit about 6 months ago, and it has been working well, until... I was checking a transformer on a circuit board on a computer LCD monitor. The led's just went out and would not turn back on. I tried another battery but no luck. The only "life" I have managed to squeeze out of it is to remove the battery for awhile, and then when I connect the battery again I see led 5 and led 6 turn on (sometimes 1,2, and 3 also flash), and then back off, and then it seems dead again. I can also remove the battery, press the power button about 10 times, and then when reconnecting the battery the same led's flash once.

It is possible that a capacitor was not discharged and could that have had enough voltage to damage the tester? A component has failed, but I have no idea where to start looking. There are not visible signs of damage to the board. If you have any recommendations please let me know.

I redid all the solder joints and and put in a brand new battery, but neither helped. There were a few solder joints that did not have much solder applied, so I was hoping that would be the problem, but no such luck.

I was testing the main transformer with the power off. I had just removed the plug 15 seconds before, and since it the lcd isn't working, it may have not discharged before I applied the probes...

I removed the three transistors and they all tested ok.

I connected the battery and tested voltage at the two large ic's. Pressing the power button has an affect on the voltages at the ic's, but no led's ever appear. So I have two voltages for each pin, the first for as it was when first testing, the second after pressing the power button.

The IC nearest the probes:
1 - 9.3 - 0
2. - 0 - 9.3
3 - 0 - 0
4 - 9.3 - 0
5 - 7.7 - 7.7
6 - 0 - 0
7 - 0 - 0
8 - .2 - .2
9 - 9.1 - 9.1
10 - 9.1 - 9.1
11 - .44 - .44
12 - .44 - .44
13 - 7.3 - 7.3
14 - 9.3 - 9.3

The ic nearest the battery:
1 - 0 - 0
2 - 0 - 0
3 - 0 - 0
4 - 0 - 0
5 - 0 - 0
6 - 9.3 - 0
7 - 0 - 0
8 - 0 - 0
9 - 0 - 0
10 - 0 - 0
11 - 0 - 0
12 - 0 - 0
13 - 0 - 0
14 - 9.3 - 0
15 - 9.3 - 9.3
16 - 9.3 - 9.3

Something else a little odd. Lets call the first set of numbers "on" and the second set "off". If I was testing the "off" values and touched pin 3 of the ic near the probe wires, it had the same effect as pressing the power button. I can't remember, but I think it only turned it "on".
I did find a couple of datasheets for the ic's, but they were a bit beyond my knowledge to gain much from them.

Thanks for the help. I really use this tester and would like to have it back working again.

(I had posted this originally at anatek's forum, but they don't get a lot of traffic.)

[Krankshaft]

Re: ESR meter blues

You probably killed some semis in circuit check all of the transistors with the diode check.

If they're fine you probably fried one of the ICs that's why I put sockets in mine.

IC1 is both the oscillator and the comparator. IC2 drives the individual LEDs.

IC1 applies the oscillations to the inductive component and the comparator also part of IC1 counts the rings. It's findings are sent to IC2 which drives the LED indicators.

Killing either can cause your issue unless you have a scope to check to make sure the oscillator and comparator in IC1 is working there's no point in going further. On a circuit this small troubleshooting is a bit of a waste.

This circuit is all off the shelf components I'm sure Newark, Mouser, or Digikey will have the semis.

Here is a circuit description if you're interested:

[sceva]

Re: ESR meter blues

You probably killed some semis in circuit check all of the transistors with the diode check.

If they're fine you probably fried one of the ICs that's why I put sockets in mine.

This circuit is all off the shelf components I'm sure Newark, Mouser, or Digikey will have the semis.

Thanks for the info. After testing the transistors and resistors I thought the ic's were the most likely solution, but did not know if they were off the shelf or programmable. As the parts are less than $1 each (from Digi-Key) I have ordered 2 each of the ic's, and a few spare transistors, AND two sockets so I can easily swap them out in the future.

I really love this tester and the ESR meter from anatek, so I will be happy to get it working again.

thanks so much.

[Krankshaft]

Re: ESR meter blues

No problem.

On a side note most failures of the Blue ESR Meter not the ring tester. Are due to connecting it to a charged cap that usually ends up blowing the micro controller. The ESR meter is only protected to charged caps up to 50 volts stock this can be increased with the back to back diode mod. I find it interferes with the meter readings though so I didn't use it.

The micro is a coded proprietary part but the guys at Anatek can sell you it should you ever need it.

[sceva]

Re: ESR meter blues

It was the 7 pin IC near the probe wires. Replaced it and all is happy again. I did not realize how much I used it until it was gone...

Thanks for the info about repairing the ESR meter, as I will undoubtedly wreck it someday!

I had posted this first on the forums at Anatek without much luck, and when I just went back to update that post there was a message saying that Anatek would have provided the parts at no charge... if I had asked. So that could save someone a couple of bucks if they encounter problems.