Alan Zoff Posted January 3, 2010 Share Posted January 3, 2010 The heating side of our chauffage has packed up. It's a 13 year old de Dietrich GT100 oil-fired boiler which has worked perfectly for the 5 years we have owned the property. The relays controlling the pumps will not kick in, or will operate then shut off or flicker wildly. Although the boiler fires up, this meant we couldn't even get hot water at first but I have disconnected the pump control and hot wired the domestic system pump to the mains for the time being so at least we can have a hot bath!Unfortunately, the village heating engineer/electrician who installed the system for the previous owner has moved to another part of France and the electronics side seems too much for the nearest plumber. I contacted de Dietrich who say they do not support this boiler any more and I would have to find a local engineer myself. This is a very rural part of France (03 North Allier) and I have drawn a blank with that so far.But I know what the problem is. A 16 pin chip next to the pump relays on the control panel PCB has a blackened terminal and, more dramatically, a burn hole through the top of its casing. (Whether something else on the board is faulty and has caused the chip to burn is another matter but all the other components look fine from an admittedly inconclusive visual inspection.)My problem now is that the burnt area is right through the chip identification number! I am left with "ULN", then a hole where I think 2 digits would have been, possibly beginning with "2", and the number ends "03A". So it would initially have read ULN **03A. Below that is a separate number 9003. I had hoped that de Dietrich would be able to give me the full number but they say they can't help. They confirmed though that it would be a case of someone repairing the circuit board, as it is no longer possible to order a replacement board.I have tried surfing the net to try to identify the chip, but without knowing the first 2 numbers I am getting nowhere. I am therefore posting the information here in case anyone has any bright ideas. I hope to fix the boiler rather than replace it as, although the price of oil is frightening, the system is otherwise in good condition and normally makes a super job of heating the house.All suggestions gratefully received, both as to how to identify the component and where I might buy a replacement. (Ebay looks promising if I can identify the part accurately.) AlPs. It's damned cold.... Link to comment Share on other sites More sharing options...
Théière Posted January 3, 2010 Share Posted January 3, 2010 Only ever happens in the depth of winter [:@]only suggestion is back to manufacturer, although not supported any more maybe a drawing with component list exists in their archive files, fingers crossed Link to comment Share on other sites More sharing options...
AnOther Posted January 4, 2010 Share Posted January 4, 2010 Could help if you posted a photo of the burn chip, someone might recognise it.EDIT: There are companies who specialise on obsolete spares, THIS being one. Link to comment Share on other sites More sharing options...
Charriols Posted January 4, 2010 Share Posted January 4, 2010 How about this?ULN2003A, ULQ2003AHigh Voltage, High CurrentDarlington Transistor ArraysYoy can find it by Google seach.Could be a short circuit has fried it.Ray Link to comment Share on other sites More sharing options...
Anton Redman Posted January 4, 2010 Share Posted January 4, 2010 Bricodepot site is down at the moment but they stock Brueleur fioul. Which are € 268 and € 329 . When I checked hole spacings and gaskets they would fit our oil fired central heating. I susepct the relay has gone because it is they board or sender for temperature is not telling the system that the boiler has reached operating temperature. Link to comment Share on other sites More sharing options...
Northender Posted January 4, 2010 Share Posted January 4, 2010 [quote user="Charriols"]How about this?ULN2003A, ULQ2003AHigh Voltage, High CurrentDarlington Transistor ArraysYoy can find it by Google seach.Could be a short circuit has fried it.Ray[/quote]If you read the description of what they are used for , Charriols suggestion sounds likely. http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXtyyvx.pdf Link to comment Share on other sites More sharing options...
Alan Zoff Posted January 4, 2010 Author Share Posted January 4, 2010 Thank you for the suggestions so far.I will be able to get hold of a digi camera this evening so will see if I can upload a photo later.I am also about to fax de Dietrich to see if I can get past their first line of defence with the "Sorry we can't help with this" line. It seems to me (as Theiere has implied) that even if the model is no longer "supported", they should still have access to the detailed spec if I can just persuade someone to look hard enough. Link to comment Share on other sites More sharing options...
Charriols Posted January 4, 2010 Share Posted January 4, 2010 Ebay UK have the ULN2003A-N for 99p + P&P.It'a an obsolete chip but there are newer (and better, more robust) alternatives.Find the cause before replacing the chip!Ray Link to comment Share on other sites More sharing options...
Alan Zoff Posted January 4, 2010 Author Share Posted January 4, 2010 Ok, here's the picture. It's the chip nearest to the row of relays. (The board will have a good clean before it goes back in.) Ignore the rubber band - that's just there to hold the board while taking the photo.When you say there are newer and better alternatives, how do I establish what is the current equivalent? Link to comment Share on other sites More sharing options...
Northender Posted January 4, 2010 Share Posted January 4, 2010 I see the "blown" chip is soldered onto the circuit board. I hope you have a solder sucker. Link to comment Share on other sites More sharing options...
Alan Zoff Posted January 4, 2010 Author Share Posted January 4, 2010 Yes. I'm no electronics expert as you will have gathered but I have done quite a lot of fiddly resoldering over the years. Link to comment Share on other sites More sharing options...
Northender Posted January 4, 2010 Share Posted January 4, 2010 If one of the supression diodes had failed on the chip then maybe a large back-emf voltage spike from an inductive load (motor,relay etc) could have caused that sort of damage?? Link to comment Share on other sites More sharing options...
Alan Zoff Posted January 4, 2010 Author Share Posted January 4, 2010 I'll take your word for it! I had thought about changing the relay at same time in case a fault in the relay had cooked the chip. But the relays seem unusual too. Link to comment Share on other sites More sharing options...
AnOther Posted January 4, 2010 Share Posted January 4, 2010 [quote user="Northender"]I see the "blown" chip is soldered onto the circuit board. I hope you have a solder sucker.[/quote]Not best practice by any means but it might be easier to nip the old one out close to the package and solder the new one to the remaining pins, zero risk to board with desoldering [;-)] Link to comment Share on other sites More sharing options...
Alan Zoff Posted January 4, 2010 Author Share Posted January 4, 2010 In case it's relevant/of interest, the relay is a Finder 28V = DC Type 40.61 16(2.2)A 250V-AC1 - whatever all that means.I'm about to be kicked off the PC so will catch up in the morning. Thanks again for the helpful replies. Link to comment Share on other sites More sharing options...
Northender Posted January 4, 2010 Share Posted January 4, 2010 I assume that the coil of the relay will be rated at 28v dc , the current that energises it coming from the chip.The contacts of the relay will be operating some AC device ie the pump or motorised valve maybe.I doubt if the relay is faulty , but its easy enough to check the resistance of the coil to see if there is a short circuit. Link to comment Share on other sites More sharing options...
LesFlamands Posted January 5, 2010 Share Posted January 5, 2010 If the darlington pair are required to hold the relay on for an extended period whilst the boiler is in operation it could just have burnt out with no other fault. I would order 2 or 3 new ones and do as someone suggested and solder them to the legs of the existing chip so that it can be changed easily.PS. Radiospares France have them for .84€ each Link to comment Share on other sites More sharing options...
AnOther Posted January 5, 2010 Share Posted January 5, 2010 Or you could solder a 16 pin DIL socket to the pins for instant future replacement [;-)]PS: Do RS still supply outside trade, I thought they'd stopped doing that but maybe it was just in UK ? Link to comment Share on other sites More sharing options...
Chancer Posted January 5, 2010 Share Posted January 5, 2010 When I saw the text ULN 2? **3A the identifier ULN2003A immediately leapt out of my head but I couldnt fathom why.I was intrigued to read further that it was a darlington driver and slowly the memories came back.Many years ago I discovered that I could repopulate the unfilled component locations on a burglar alarm panel that I used to create the much more expensive all bells and whistles version that could comunicate to a central monitoring station, the ULN 2003 was the chip used to pull down the outputs to the modem.I am fairly sure that I still have a few of them in my stock of components in the UK if you find that RS or Conrad in France will not sell to you. I was only ferreting through the components a few days ago to find an electrolitic capacitor for my tenant to repair a BMW dashboard but as I dont have internet access in the UK I didnt get to see this posting.I have one bit of advice for you and that is to trace the soldered track in bith directins from the pin that is burnt to inspect the next componnet along for signs of burning, if it is the relay coil then you may want to desolder it and test it in case the coil windings have short circuited.Oh and one other thing make sure that you dont have any mice nesting in your boiler, their urine plays havoc with the PCB,s, I know someone who had no sooner paid the depanneur to replace his circuit board for the new one to fail the very next night with the urine still moist on it[+o(] Link to comment Share on other sites More sharing options...
Alan Zoff Posted January 5, 2010 Author Share Posted January 5, 2010 Thanks Chancer. I have sent you a PM. Link to comment Share on other sites More sharing options...
Théière Posted January 5, 2010 Share Posted January 5, 2010 And that is what is Sooooo great about this forum [:D] Link to comment Share on other sites More sharing options...
Alan Zoff Posted January 5, 2010 Author Share Posted January 5, 2010 I'll second that! Brilliant how much you can learn from others so generous with the sharing of their knowledge. Link to comment Share on other sites More sharing options...
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