Transitor/ESR tester dead

[SteveNielsen]

Starting a new thread about this that began in my Korg Polysix synthesizer thread in Audio forum...

That's what I'm in the process of doing. Unfortunately I will have to spend money so it's going to wait a little while. My Chinese transistor/etc tester just died too. At least I can still measure capacitance on my DMM.

seriously? there's hardly anything to die on them!
you did discharge the caps you wanted to test i hope - the testers are 3.3v

I am very good about discharging caps before measuring them. I may have missed doing so to the last one. It's usually my habit to discharge but I don't know. However, it failed right after I had re-soldered a test lead to it that the strands were breaking on. It's soldered to a length of solid wire that is soldered to a PCB pad, so I didn't overheat anything or that bit of solid wire would have come loose. Regardless, the little guy won't fire up. Oh well. I've gotten a lot of use out of it. I'll get another when I am able to.

Edit: it was also running on a regulated DC power supply not a battery, so I suppose a momentary power fluctuation or spike that didn't get filtered out could have killed it but I've been using it that way for months. *shrug*

post a foto of the parts-side so i can see the design.
it may just be a voltage regulator.

btw, i just ordered this model.
i chose it because it has a 3pin connector and flyleads.
http://www.ebay.co.uk/itm/181861030068

I like that one. I think I want one too.

That thing looks like it has no input protection, you could well have blown the uC with a charged capacitor.

see if that regulator near the battery wires has 9v going in and 5v coming out.
btw.

Nope, input on the reg is only 2.4v, output is about 1v.

Yes, it's a known fact that a charged cap can damage the chip. The manual warns of it.

i think your dead tester is just a transistor.
look at the pdf i linked - page11

I did look and have questions but I think I ought to start a new thread about this.

Ok, back to the present.

Stj page 11 appears to show a mod for the board but not what's there on my board. If I'm mistaken let me know. If you meant the basic schematic then what transistor are you referring to?

[vinceroger69]

Re: Transitor/ESR tester dead

hi i have the same tester here any measurements you need just ask on the regulator i have 9.37 in 4.99 out im running off a 9volt battery is your dc power supply still giving the correct output voltage you have probably already checked this though.

[stj]

Re: Transitor/ESR tester dead

battery power goes through the transistor top-right.
it's similar to the schematic but the diode is missing.

[keeney123]

Re: Transitor/ESR tester dead

Where is the Schematic?

[SteveNielsen]

Re: Transitor/ESR tester dead

The schematic is in the PDF file.

Stj, you mean the transistor to the left of the regulator?

[stj]

Re: Transitor/ESR tester dead

yes, just follow the track from the red wire.

you could run a fine wire from the red cable to the input on the regulator for a quick test.

[keeney123]

Re: Transitor/ESR tester dead

Thank Steve. So you have a plug in "worts" if I spelled that right and a 9 volt battery. I imagine when its plug in it disconnects the battery. What are the symptoms? Does it not have a test button?

[stj]

Re: Transitor/ESR tester dead

this is probably it.

[keeney123]

Re: Transitor/ESR tester dead

So pin7 and pin1 of the big chip should be at +5 volt. ISP pin5 is also connected.

[stj]

Re: Transitor/ESR tester dead

the regulator should have 5v coming out - start with that!

[keeney123]

Re: Transitor/ESR tester dead

the regulator should have 5v coming out - start with that!

Right I agree.

[SteveNielsen]

Re: Transitor/ESR tester dead

link the red battery wire to the regulator input and see if it turns on when you connect the battery.

Just did it except I've got no battery, using a regulated PSU. Nope, it does not come on. Nothing at the output of the regulator IC, which in circuit measures a short between Out and Gnd. I'll pull the reg test it and check the ckt for a short.

[vinceroger69]

Re: Transitor/ESR tester dead

if your testing ic2 on 2k setting i get .772 ohms between ground and out

[SteveNielsen]

Re: Transitor/ESR tester dead

This 78L05 reg (IC2 on my board) reads 3.2K ohms between Gnd and Out leads. It's not shorted. I've got a 2 ohm short downstream on the board.

[stj]

Re: Transitor/ESR tester dead

with or without the display fitted?

[SteveNielsen]

Re: Transitor/ESR tester dead

Without display connected.

[stj]

Re: Transitor/ESR tester dead

got hot air?

[SteveNielsen]

Re: Transitor/ESR tester dead

I've got a dangerous heat gun.

[stj]

Re: Transitor/ESR tester dead

lift the atmel chip & re-check the short.

btw, what part number is it?

[SteveNielsen]

Re: Transitor/ESR tester dead

ATMEGA168V 10AU 0812

I can try to lift the chip but I'm afraid of getting everything else too hot with this heat gun, no nozzles to focus the hot air.

I'll try making an aluminium shield over the board.