Dodge1965 Posted March 20 Share Posted March 20 So my 22/17 Hornby Elite had died.. I called Hornby Technical and they will not now repair the older Elite's like mine, only the newer ones. Does anyone know a place that would repair one? I took it apart and i can see a chip that is burnt/black on left side of pic. Not sure other anything has gone. Thanks Link to comment Share on other sites More sharing options...
96RAF Posted March 20 Share Posted March 20 Clean off the soot and tell me the Q number and I will tell you the component ID and likely you can swap it out. Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 20 Author Share Posted March 20 7 minutes ago, 96RAF said: Clean off the soot and tell me the Q number and I will tell you the component ID and likely you can swap it out. The top of the chip has melted. All i can see is either Q7 or O7 on the printed circuit board, by the side of the chip Link to comment Share on other sites More sharing options...
96RAF Posted March 20 Share Posted March 20 Q7 is the motor drive H-bridge part number IRF7303. An obsolete part so you may have to source a superseding item. Edit - correction - this is a dual mosfet in the Railcom circuit - see later post. 1 Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 20 Author Share Posted March 20 Just now, 96RAF said: Q7 is the motor drive H-bridge part number IRF7303. An obsolete part so you may have to source a superseeding item. Sorry Rob, No idea how to do that? Thanks for the help. Link to comment Share on other sites More sharing options...
96RAF Posted March 20 Share Posted March 20 Just now, Dodge1965 said: Sorry Rob, No idea how to do that? Thanks for the help. You look up the part number on electronics suppliers and see what they suggest - comparing datasheet specs. 1 Link to comment Share on other sites More sharing options...
Rog RJ Posted March 20 Share Posted March 20 What happened that caused the chip to fail? Link to comment Share on other sites More sharing options...
Going Spare Posted March 20 Share Posted March 20 Until recently, Lendons of Cardiff offered a repair service. Although they now only handle warranty repairs, they may still have the component you need as a sale item. 1 Link to comment Share on other sites More sharing options...
96RAF Posted March 20 Share Posted March 20 A tip for changing these devices. Snip the legs carefully, then unsolder each bit that is left as this minimises risk of pulling up pcb traces. Then a minute dab of superglue or epoxy to hold the new device in place before you solder it. 1 Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 20 Author Share Posted March 20 13 minutes ago, Rog RJ said: What happened that caused the chip to fail? Not 100% sure. But she sure smells bad... Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 20 Author Share Posted March 20 1 minute ago, 96RAF said: A tip for changing these devices. Snip the legs carefully, then unsolder each bit that is left as this minimises risk of pulling up pcb traces. Then a minute dab of superglue or epoxy to hold the new device in place before you solder it. Great bit of info... Thanks again Link to comment Share on other sites More sharing options...
OssieB Posted March 20 Share Posted March 20 Dodge, you may be able to find one here:- https://www.aliexpress.com/item/1005001304536364.html?spm=a2g0o.productlist.main.21.33853966c07GuQ&algo_pvid=11e37288-db40-4a68-9e05-2e7fafeab295&algo_exp_id=11e37288-db40-4a68-9e05-2e7fafeab295-10&pdp_npi=4%40dis!GBP!0.32!0.28!!!0.39!0.34!%40210384b917109519761344589e9fdf!12000015639785819!sea!UK!754451072!&curPageLogUid=GUOsz463KrtV&utparam-url=scene%3Asearch|query_from%3A 1 Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 20 Author Share Posted March 20 6 minutes ago, OssieB said: Dodge, you may be able to find one here:- https://www.aliexpress.com/item/1005001304536364.html?spm=a2g0o.productlist.main.21.33853966c07GuQ&algo_pvid=11e37288-db40-4a68-9e05-2e7fafeab295&algo_exp_id=11e37288-db40-4a68-9e05-2e7fafeab295-10&pdp_npi=4%40dis!GBP!0.32!0.28!!!0.39!0.34!%40210384b917109519761344589e9fdf!12000015639785819!sea!UK!754451072!&curPageLogUid=GUOsz463KrtV&utparam-url=scene%3Asearch|query_from%3A Thanks.. Found one on ebay and UK person.. So will give that a try, hope its just the one part thats gone... Link to comment Share on other sites More sharing options...
Rog RJ Posted March 20 Share Posted March 20 "So will give that a try, hope its just the one part thats gone..." That's why I asked what happened. Was there a short circuit before it failed or perhaps it had been powered up for a long time. Other parts may also have failed that caused that particular part to burn up. Perhaps RAF knows if there are any power transistors between the track connectors and the H bridge chip. 1 Link to comment Share on other sites More sharing options...
96RAF Posted March 21 Share Posted March 21 17 hours ago, Rog RJ said: "So will give that a try, hope its just the one part thats gone..." That's why I asked what happened. Was there a short circuit before it failed or perhaps it had been powered up for a long time. Other parts may also have failed that caused that particular part to burn up. Perhaps RAF knows if there are any power transistors between the track connectors and the H bridge chip. Nothing downstream, and only a pair of common mode chokes (off to the left side of the diagram below) upstream of the Q7 dual mosfet. As seen only a resistor and a pair of diodes in circuit. Having looked at it again it looks more like a Railcom driver than a motor H-bridge (earlier post amended). 1 Link to comment Share on other sites More sharing options...
Pendragon Sailing Posted March 21 Share Posted March 21 All clever stuff….and utterly beyond me ! 😵💫 thank goodness we have some clever chaps on this forum 👏👏👏 1 Link to comment Share on other sites More sharing options...
Rog RJ Posted March 21 Share Posted March 21 Thanks Rob. Link to comment Share on other sites More sharing options...
Rog RJ Posted March 21 Share Posted March 21 Having had a look inside mine, build code 11/07, it looks like the track output is fed by some kind of transistors/mosfets under the black heatsink (mine has different, plain aluminium heatsinks) then to the chokes and finally the track connectors. It may be that one or more of the output transistors has blown, causing Dodge's chip to burn out. 1 Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 21 Author Share Posted March 21 8 minutes ago, Rog RJ said: Having had a look inside mine, build code 11/07, it looks like the track output is fed by some kind of transistors/mosfets under the black heatsink (mine has different, plain aluminium heatsinks) then to the chokes and finally the track connectors. It may be that one or more of the output transistors has blown, causing Dodge's chip to burn out. How would i test that? Link to comment Share on other sites More sharing options...
Rog RJ Posted March 21 Share Posted March 21 Not sure, I would try with my multimeter after removing the parts and checking the data sheets for pinouts and specs. If anything looked a bit odd I'd get new parts, test and compare and replace if necessary. If you haven't done this sort of work before it can be quite daunting. Sometimes you need to replace a who;e bunch of components at the same time. I worked in an electronic repair workshop for a while and had training prior to that in electronics. we had access to all kinds of test equipment that ordinary folk don't have. We also had full circuit diagrams to work from. Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 21 Author Share Posted March 21 11 minutes ago, Rog RJ said: Not sure, I would try with my multimeter after removing the parts and checking the data sheets for pinouts and specs. If anything looked a bit odd I'd get new parts, test and compare and replace if necessary. If you haven't done this sort of work before it can be quite daunting. Sometimes you need to replace a who;e bunch of components at the same time. I worked in an electronic repair workshop for a while and had training prior to that in electronics. we had access to all kinds of test equipment that ordinary folk don't have. We also had full circuit diagrams to work from. Will try changing the chip and then see. If still bad, will try and find a place to send it to.. Thanks for info.. 1 Link to comment Share on other sites More sharing options...
96RAF Posted March 21 Share Posted March 21 It is worth taking those heat sinks off, cleaning up the hear sink gunge and reapplying, making sure the heat sinks are secure else this can happen... These are the Q2 and Q4 motor drive components adjacent to Q7. The other pair Q1 and Q3 are under the other heat sink near the chokes. Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 22 Author Share Posted March 22 17 hours ago, 96RAF said: It is worth taking those heat sinks off, cleaning up the hear sink gunge and reapplying, making sure the heat sinks are secure else this can happen... These are the Q2 and Q4 motor drive components adjacent to Q7. The other pair Q1 and Q3 are under the other heat sink near the chokes. Thanks Rob.. I've posted it to you house ...🤣🤣 Link to comment Share on other sites More sharing options...
96RAF Posted March 22 Share Posted March 22 1 minute ago, Dodge1965 said: Thanks Rob.. I've posted it to you house ...🤣🤣 ??? Link to comment Share on other sites More sharing options...
Dodge1965 Posted March 22 Author Share Posted March 22 Just now, 96RAF said: ??? Joking 1 Link to comment Share on other sites More sharing options...
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