Can someone help me with this board to identify the burned IC component? - Page 1
Forum section: electronics / repair

author: lfostano
author_rank: Newbie
timestamp: December 14, 2016, 03:03:33 pm
content: This is a circuit board out of a vintage van that I was told had to do with operating the fan circuit. Most of the board is easily identified ,only issue is the IC at this moment. I will try to attach a few pis, tried a few times before but was not able to get them to upload. Thanks, this is out of a 1977 family van I am told.

author: SvanGool
author_rank: Regular Contributor
timestamp: December 14, 2016, 04:13:06 pm
content: Hi, you will have to supply some more information to help people to help you:Where was the board located?Do you know its function?To which other devices was the board connected to?Can't you upload the complete picture of the component side, in stead of a part?What is the battery voltage of your van?First guess would be that it is some diy custom made board, maybe a regulator, that got a voltage spike on its guts. Just a guess, can give it another try, when you supply the above information.

author: SeanB
author_rank: Super Contributor
timestamp: December 14, 2016, 08:19:25 pm
content: Well, 3 leads, and 2 are attached to the connector, so likely it is a power switch of sorts. Being a van, and running a DC fan motor kind of rules out a SCR, and being 1977 rules out a MOSFET as well, leaving the likely candidate to be a darlington transistor, in a custom casing. Something like a TIP142, just in a custom case and with a very poor heatsink ability.

author: Gyro
author_rank: Super Contributor
timestamp: December 14, 2016, 08:40:21 pm
content: Just trying to decypher the bottom of the board, it looks to me as if two of the pins are tied together, so diode or Zener?It looks as if a couple of the nearest component have been cooked too.What doesn't it do with the board removed? [Edit:] It looks like a home-made board so it possibly isn'tneededfor the functioning of the van.

author: Twoflower
author_rank: Frequent Contributor
timestamp: December 14, 2016, 09:05:29 pm
content: No, I don't think they're tied together. It seems to be able to put a TO-18 style of device in there as alternate to the given package.I don't really think that's home made. At least the design/routing seems to be commercial. There is a part number on the PCB: PD-1025?8 (probably the unreadable digit is a 0). Also the mouse-teeth left and right might indicate it was cut out from a bigger board. But I don't think that's original as the design does not look 'automotive' (e.g. no coating). Maybe it's some add on to improve the fan' functionality (speed control?).Without having more information I think that's very hard to identify the device. Eventually a full picture from the front side might help to reverse the schematic. And or the information what is attached to the connector.

author: dan3460
author_rank: Frequent Contributor
timestamp: December 14, 2016, 09:14:41 pm
content: Also the van make and model. I remember seeing in popular mechanics of the time all sort of home made add on to improve the functionality of different parts of cars; from battery monitors, wiper blades controls, etc.

author: voltz
author_rank: Frequent Contributor
timestamp: December 14, 2016, 09:47:20 pm
content: The board is marked with "pvt312pbf". Did you write that or was it already there?The device pvt312pbf is a mosfet with 6 pins, 3 either side. Can you see if some redundant pins have been snipped off?

author: KhronX
author_rank: Frequent Contributor
timestamp: December 15, 2016, 11:07:58 am
content: That component looks a lot like a DPAK package to me, with a leg soldered onto the tab. The ones to its right look like some sort of diodes, perhaps?Have you tried cleaning off some of the soot? A q-tip and some (rubbing / isporopyl) alcohol should do the trick.

author: lfostano
author_rank: Newbie
timestamp: December 15, 2016, 07:00:26 pm
content: Ok , thanks to all that has looked at this, sorry for not having too much information on this board. This board was as I am told , stuck behind a panel box in the van, Also I have included a picture of the front of this board above. If I try to get too much definition the site will not allow more than 100 mb I believe. What I can tell you at this point:The PVB part # is what I once thought it was but I was wrong,There are 4 leads to this device,one side has a wide lead ,and it is manufactured at least it appears to be that way but is a single lead through the board, the other edge has 3 leads, center is clipped.I am told that this board controls a fan, i suspect it has to do with going between 100v ac and 12vdc ,seeing how it will control the fan circuit.Again I am just guessing,will try to contact the person I was trying to help with this for more information.His van is at a camp site that he rarely goes to.The single lead goes to what appears to me 137 ohm resistor which amazingly enough still read on 200 ohm scale my ohm meter.I have tried to clean component but alas nothing left to see.I will include another shot of this board backlit ,maybe you can get a clue this way.Thanks to all

author: lfostano
author_rank: Newbie
timestamp: December 15, 2016, 07:37:21 pm
content: Ok so got more information on this board, it is from a camper the brand is Fan Camper , 1977 Luxury Fan Liner. The board is located behind the panel box in the camper, without this board the furnace does not work, from what I understand it has to do with the blower circuit also. I will try to get some info on the web site but so far I have not had any luck there.Thanks.

author: KhronX
author_rank: Frequent Contributor
timestamp: December 15, 2016, 07:48:57 pm
content: I don't suppose there's any chance you can lift the schematic, is there?PS:http://www.diodes.com/_files/zetex_files/pack/DPAK.pdf

author: lfostano
author_rank: Newbie
timestamp: December 15, 2016, 08:17:17 pm
content: Looking at the Dpak , looks like the component, but this is not surface mount This is about 7.7mm X 8.5 mm rectangle and approx 5.3 mm thickness. The picture on that DPAK looks like the same configuration except that this is a dip package. As far as a schematic , I don't have one not sure if I could accurately draw one, don,t have a spice program to build one either.Thanks

author: voltz
author_rank: Frequent Contributor
timestamp: December 15, 2016, 08:36:42 pm
content: Presumably this board can turn a fan on and off dependant on a thermal sensor. That being true, the device needs to be able to turn on and off within a DC circuit. That rules out SCRs or Triacs which wont turn off. My best guess is its a power Darlington transistor. And if the fan went fault at some point, it would explain why the device burnt out.

author: KhronX
author_rank: Frequent Contributor
timestamp: December 15, 2016, 08:54:17 pm
content: Ehrm... You might need a bit of brushing-up on your terminologyDIP =https://en.wikipedia.org/wiki/Dual_in-line_packageJust because a package is meant to be surface-mounted, doesn't necessarily mean it mandatorily WILL be used in that mannerEspecially since this doesn't 100% look like a factory board.In fact, that DPAK-looking component looks a bit bodged-in, especially with that piece of what looks like solder-wick along a trace that seems to run beneith that component.That leg that connects to the tab looks way too dodgy to have been factory-assembled.If the component is indeed that large, i might've misjudged the scale of it. In that case, that would most likely be a D2PAK package:http://www.vishay.com/docs/95046/d2pak.pdfAlthough looking at the specs, that's too large (10mm wide, 9mm "long" plus the tab). The DPAK is closer to what you measured (~6.5mm wide, 6mm long plus tab), apart from the thickness. Is it sitting flush with the board? Or maybe it's sitting on top of that former-component-leg that the tab is soldered to?Quote from: lfostano on December 15, 2016, 08:17:17 pm

author: lfostano
author_rank: Newbie
timestamp: December 15, 2016, 09:26:08 pm
content: Agreed, just to me it looked like a typical sized ic like that of a 555 timer more that a surface mount device.I am reasonable sure that it is not stacked on another component but I can desolder it. The solder wick is a trace repair of sort,not great but it probably will be ok.Most of the components here definitely heated up , still able to read resistance in circuit but at this point have not disassembled anything to check each device. I appreciate your input,I am no technician by any means just trying to help a fellow out,I am capable of making some measurements and replacing them but that is my extent,so any and all help would be greatly appreciated.

author: lfostano
author_rank: Newbie
timestamp: December 17, 2016, 03:15:21 pm
content: Thanks for your help, I did identify this board with your help. It is indeed a charge board. The component is an SCR ,its part number is C106y4 the Y i think has to the year and the 4 has to do with the package type.It has a peak forward blocking voltage of 30 volts and a peak reverse voltage of 30 volts.It will take a 20 amp surge and a peak forward current of 75 amps.All this is according to some of the spec sheets I have researched. Thanks again for everyones help and input.