Exploded transistor. Can anyone suggest replacement?

[pnb]

Hi all,

This time I am trying to repair the power supply to a vacuum fluorescent display in an instrument cluster.

Apart from heavy heat damage and a completely wobbly resistor there is a transistor that has exploded.

Seems to have markings of D 18*5, maybe D1815 and below that S (or 5) in left corner and maybe a 64 or 614 in lower right corner.

This is a 17 year old part and I cannot seem to find a replacement for a D1815 anything, if that is what it is.

Can any of the knowledgeable posters on here suggest a replacement transistor i could use? As a Noob I dont even know where to begin a comparison. This is for a vehicle so is 12v any help?

[budm]

Re: Exploded transistor. Can anyone suggest replacement?

Japanese products? 2SD1815 (NPN)?
https://cdn.badcaps-static.com/pdfs/...51309aa0b9.pdf

[pnb]

Re: Exploded transistor. Can anyone suggest replacement?

Heres the circuit. Seems a little under-engineered to me, almost every joint is bad.

[budm]

Re: Exploded transistor. Can anyone suggest replacement?

It looks like Osciallator circuit. You can also see lots of cracked solder joints on the component's legs which is typical failure mode of Japanese made products, you can see that the solder joints are not nice and shiny. I would re-solder all the joints. It looks pretty easy to draw up the circuit.

[pnb]

Re: Exploded transistor. Can anyone suggest replacement?

budm,

Phoned up my local Jaycar and they dont have 2SB1215 or 2SD1815 available either. None on ebay.

I would have thought google could turn up a list of compatible parts, but no luck.

Could be an oscillator circuit, although I dont know how you can tell that. Seems VFD are driven by high frequency pulses..

http://hem.passagen.se/communication/vfd.html

[rievax_60]

Re: Exploded transistor. Can anyone suggest replacement?

2SD1815 can be found on Aliexpress. The minimum order quantities make it expensive though.

[pnb]

Re: Exploded transistor. Can anyone suggest replacement?

I found one for around $40 including shipping from OS, but that just seems like "F.O.P". Surely there most be something compatible available locally for under $5?

Any thoughts on the chance of success on scratching around on Gumtree for a free unwanted VCR etc and the likelihood of that being a common part in vfd display drivers?

<<<<
What about this D1815 TO252 ? Is that compatible with that suffix?

http://www.idevopen.com/index.php?ma...ducts_id=14734

Has anyone used http://www.idevopen.com for parts before? is it a legit operation?

<<<< edit - scratch above. Looks to me like a TO252 only has two legs. Cant be compatible.

[rievax_60]

Re: Exploded transistor. Can anyone suggest replacement?

The TO252 is a package type with short pins, google it.
You could try a BD139. If nothing else is wrong after the cracked solder joints are resoldered, I would expect the oscillator to start but likely to not run efficiently.
The BD139 is likely to get hot.
Its also possible that the high fault current has damaged the transformer.

[rievax_60]

Re: Exploded transistor. Can anyone suggest replacement?

There are some 2SD1815 on eBay also.

[pnb]

Re: Exploded transistor. Can anyone suggest replacement?

Ok, Think I found some of those locally at X-on... Ebay OS shipping is a rip off and long wait to boot so I was hoping for a local source..

http://www.x-on.com.au/InventoryDeta...uct=2SD1815T-E

Not sure what the extra letters mean though, so I guess I will go ahead and get one of those and try it out.

[pnb]

Re: Exploded transistor. Can anyone suggest replacement?

Thanks for the help everyone!

Will post update when project completed.

[budm]

Re: Exploded transistor. Can anyone suggest replacement?

http://www.mouser.com/ProductDetail/...JKbl9w8Vfdc%3d

http://www.onsemi.com/PowerSolutions....do?id=2SD1815

[rievax_60]

Re: Exploded transistor. Can anyone suggest replacement?

Ok, Think I found some of those locally at X-on... Ebay OS shipping is a rip off and long wait to boot so I was hoping for a local source..

http://www.x-on.com.au/InventoryDeta...uct=2SD1815T-E

Not sure what the extra letters mean though, so I guess I will go ahead and get one of those and try it out.

I have found stuff for good prices at X-on including capacitors. Have to search deep and be prepared to buy many sometimes.
I think the postage was 15 or 16 dollars.

[ben7]

Re: Exploded transistor. Can anyone suggest replacement?

You can also just get replacement transistor of a different part number, as long as it has the right specs! It might be hard to find the right replacement part number though.

[budm]

Re: Exploded transistor. Can anyone suggest replacement?

Here is the diagram based on the pictures, resistor color may not be correct to the colors I can see on the pictures so the values should be verified.

[pnb]

Re: Exploded transistor. Can anyone suggest replacement?

Thanks for the help everyone, the 2SD1815 arrived and is the correct replacement part.

I re-soldered all cracked joints and tested that all resistors were close to spec. Tested diodes, but did not bother testing the small caps, and did not know how to test the 9-leg transformer so just hoped it was still ok..

Re-soldered the main resistor in as far from the board as possible to give it more opportunity to shed heat, and drilled a few small holes in the metal cover for a bit of airflow.

The micro-board DC->AC oscillator has been re-soldered onto the cluster and hey presto - the VFD is fluorescing.

Really chuffed I got this working again after reading that these VFD's fade out and need to be fed higher voltages close to EOL, all it turned out the be in this case was the AC power supply.

Again, thanks for all the contributions.