Re: [IC-7000] Re: Driver Board is smoked
Kjell Karlsen <la2ni@...>
Hello:toggle quoted messageShow quoted text
As I wrote around 1 week ago, I had a defective Driver board on my 7K. As I received the new boart from my ICOM dealer, I did the replaceing myself and then discowered that there was no heat compound between the copper strip on the driver board and the heatsink. Even worse is that the copper strip is not flat so only the ends are in touch with the sink. The power dissipation in the driver is 14W independent of the output level (class A). I think the problem must be the missing heat transfer from the transistor via the copper strip to the heatsink.
I would advice to make the copper strip flat before installing it by fileing it with a fine file to be sure the heat transfer is as good as possible and also use heat compound.
73, es LA2NI Kjell
On Fri, 14 Sep 2007 05:35:39 +0200, John Chandler <email@example.com> wrote:
Hi Chuck - I was quite concerned to see your post on the driver board etc. Well my friend you "ain't alone" as mine has done exactly the same thing twice. The last trip back to Icom Australia from the selling dealer resulted in them contacting Japan for assistance. I heard 2nd hand that an earth loop mod corrected the problem and I have had the 7k back in use now for about a week with no drama so far. The first time it went up in flames and filled the shack with nasty smoke. In fact the dealer smelt the 7K in it'[s box as I took it through his door. The 2nd demise (after 3days back) saw no smoke and flames but a distinct phtttttt was heard. The driver FET is used for HF, VHF and UHF. Apart from those probs which were fixed under W/Ty I guess I was content with the rig!!!!!! BTW., the rig still smells slightly so I hope that may disappear. Hats off to the local dealer UHF Comms. here in Townsville for their W/Ty service on boh occasions. This 7K was one of three purchase!
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