Transitor/ESR tester dead

[stj]

Re: Transitor/ESR tester dead

either - just to check the regulator wasnt damaged.

[SteveNielsen]

Re: Transitor/ESR tester dead

With or without display attached?

[stj]

Re: Transitor/ESR tester dead

good,
so if you jump the regulator you should see 5v - just to be sure.

[SteveNielsen]

Re: Transitor/ESR tester dead

Without the chip there is 1053 ohms from Gnd to Out pads where IC2 reg was, so the 2 ohm short is in the chip.

Al foil in 4 layers for a heat shield worked perfectly. The chip came off sliding sideways a bit so I cleaned up the solder pads for it with wick and iron and no solder bridges or damaged pads. This is a first for me; the first smd microchip of this type I have ever tried to remove! Yay!

[vinceroger69]

Re: Transitor/ESR tester dead

this has some good info too
http://www.cwtd.org/May7.html

[stj]

Re: Transitor/ESR tester dead

there are many schematics because it's an open evolving design and the dil chips and smd chips have different pincount.

[keeney123]

Re: Transitor/ESR tester dead

Stj I do not think the schematic matches up with the board as the large IC is 32 pins and your schematic is 28 pins. The pin out on the 32 pin makes pin 4 the VCC.

[stj]

Re: Transitor/ESR tester dead

if the chip is bad then:
http://www.ebay.co.uk/itm/141666259867

and:
http://www.ebay.co.uk/itm/261574745774

[SteveNielsen]

Re: Transitor/ESR tester dead

Hmm, I've got a copper RF shield from an old Mac backplane. If I cut off the part with holes and flatten it out it might work too. OR get soldered to the board... I think I'll pass on trying that and going with the Al foil unless I dig up something better... Alright - I've got a nice Al pie pan.

[stj]

Re: Transitor/ESR tester dead

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

i keep the covers from old tuners for that.

[keeney123]

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.

When you say downstream does that mean going to the 5 Vcc to the IC chip? If that is the case can you not lift resistors to determine where it is?

[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.

[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

I've got a dangerous heat gun.

[stj]

Re: Transitor/ESR tester dead

got hot air?

[SteveNielsen]

Re: Transitor/ESR tester dead

Without display connected.

[stj]

Re: Transitor/ESR tester dead

with or without the display fitted?

[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.

[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

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.