Last summer, after replacing the LMS-520c on the bow of my boat with a HDS-7, I began to experience interference on the sonar screen when the MotorGuide Tour TM was on. This occurred both in 2D mode and Structure Scan mode.

The problem persisted even though I tried all of the normal "fixes" discussed through the many boating/fishing-related forums on the Internet.

My first contact was with Lowrance. After a few days, I received a telephone call from a Lowrance tech. representative. After discussing my situation, he told me that he was sending an SD card with a test version of the HDS update software that is currently being developed (in part) to help with interference issues. A few day later, I received the SD card and promptly installed the software.

On the next trip to the lake, I found that the interference was still present, but much improved, eg., much less severe.

My next contact was with MotorGuide. After several days, I received a telephone call from a MotorGuide representative. We discussed my situation and he then told me that they would authorize the replacement of my entire lower unit/motor assembly with their latest version which is Lowrance compatible. This even though my MotorGuide Tour by then was a couple of months out of warranty.

There were some hiccups with getting the necessary parts, but on Tuesday I picked up my TM from the shop with the work MG had authorized completed.

Yesterday I went to the lake and found that the 2D interference was completely gone.

Initially the Structure Scan interference remained, but I discovered that connecting a jumper between the sonar power (negative) and the TM shaft/case removed that problem also.

So - to my immense relief - the perplexing interference problem is now history!

I decided to post this and give both Lowrance and MotorGuide some public credit for stepping up to help eliminate the problem!

C.

Good Deal..

very good to hear stories like this! good deal!