Spectroniq PLTV-3250

[CraigR]

I have a Spectroniq PLTV-3250 that's dead. I did a search here and found a few threads on this power supply so before posting this I ordered a repair kit from shopjimmy that came with 6 caps and a small transistor. I also went ahead and replaced all the other caps on the board to be safe. It's still dead no light or anything. I seen in a thread a zener diode fails (ZD4) Now being kind of new at stuff I checked this diode in circuit and get 650 one way and OL the other. I also checked some other zener diodes and the have something going both ways. So my question is do I need to check these out of circuit? or do I have a bunch of bad zeners? I do have pictures of all the boards if that is needed.

[budm]

Re: Spectroniq PLTV-3250

The ZD4 when it is bad, it will show low Ohms in both direction.
So you did replace the transistor?
http://s807.photobucket.com/user/bud...?sort=3&page=1

http://s807.photobucket.com/user/bud...?sort=3&page=1

[CraigR]

Re: Spectroniq PLTV-3250

Yes I replaced the little transistor it came in the kit. on the ohms setting ZD4 gets 38.93k one way and 10.61k the other (in circuit)

[CraigR]

Re: Spectroniq PLTV-3250

I just checked ZD3 and that reads 1.6 ohms both ways. Bad I'm thinking.

[budm]

Re: Spectroniq PLTV-3250

You can take the DC voltage reading across the Zener ZD4 to see if it has about 15V on it, Diode mode or mode is not 100% accurate.

[CraigR]

Re: Spectroniq PLTV-3250

I get 80.6v on one side of ZD4

[budm]

Re: Spectroniq PLTV-3250

That cannot be. Are you using the chassis as the Ground ref points?. You are working in the PRIMARY side of the circuits, put the two probes of the meter at each ends of the Zener.

[CraigR]

Re: Spectroniq PLTV-3250

My mistake, I was using chassis as ground. Bounces between 4.4v and 5.4v and what about what I got for ZD3?

[budm]

Re: Spectroniq PLTV-3250

Did the kit come with small value cap 47uf 50V for the startup cap. Do you also have any Zener Diode to try?

[CraigR]

Re: Spectroniq PLTV-3250

The kit did not come with it but as I stated all the caps were replaced. I have some junk boards with zeners on them but how to I get the right voltage one?
Also I just looked and the only 47uF is a 25v.

[CraigR]

Re: Spectroniq PLTV-3250

Ok, took a chance and just guessing I used a zener out of another board and put that in ZD4 and it turned on! So now I know that will fix it so how do I measure these to make sure I have the right one?

[budm]

Re: Spectroniq PLTV-3250

Measure the voltage across that Zener. The original is 15V.

[CraigR]

Re: Spectroniq PLTV-3250

19.2 volts on that.

[budm]

Re: Spectroniq PLTV-3250

That is on the high side close to the limit of the IC, I would get the correct one since you now know that you do have bad Zener.

[CraigR]

Re: Spectroniq PLTV-3250

Received the Zener today and installed and back up and running! Thanks for all the help it is always greatly appreciated.

[budm]

Re: Spectroniq PLTV-3250

Glad to hear.