Diagnose My 788 HD DI GPS Problem

[Wiskers]

OK here we go. You'll have to forgive me cause I a little P.O.'d!

I have a Humminbird 788 HD DI. I have had "GPS" problems with it from the start. It has already been sent in to be repaired once (cost me $18 to ship it). I thought when I got it back the problem had been resolved but after looking at my network setting I realized that it was using the 998's GPS antenna instead if it's own internal antenna. I switched it back to the internal antenna and it went to crap from there! It's doing the very same thing it was doing before.

The speed & direction is jumping all over the place! First I'm pointed this way... Then I'm pointed that way! The speed jumps from 0 to 2.2 or more MPH! How the heck can I troll & keep my speed around .5 mph or even find a waypoint?!!!

I have provided 2 screen shots.

The first is of the 788 while it's using the 998's antenna via Ethernet connection. The second is the 788 using its internal antenna.

The shots were taken setting still, in the middle of my yard, with nothing but air between the units and the Satellites. Both units had been on for about 30 minutes. The shots were taken about 30 seconds apart (notice the time).

I took the shot of the internal antenna first and then switched to the 998's antenna.

I NEVER have gotten an Enhanced reading on the 788 internal antenna!

I talked to HB Customer Service and she said to send it back in for the Techs to check it out. Very nice lady by the way.

It goes out of warranty in June. If I keep sending this thing in, I'm gonna have more money tied up in postage than I've got in the unit!

OK fella's... What's the problem?

[Humminbird_Greg]

The problem is that the internal GPS Receiver is not tracking as many satellite, especially to the south. Neither WAAS satellite is being tracked. Those that it is tracking do not have as strong of a signal as with the external GPS Receiver. Now what is causing that would be either a blockage of the satellite signals or a poorly performing internal GPS antennae.
Can you post a picture of how it is mounted on your boat?
Make sure that when you send it in that you send a printout of those two GPS Diagnostic views along with it.

[Wiskers]

The problem is that the internal GPS Receiver is not tracking as many satellite, especially to the south. Neither WAAS satellite is being tracked. Those that it is tracking do not have as strong of a signal as with the external GPS Receiver. Now what is causing that would be either a blockage of the satellite signals or a poorly performing internal GPS antennae.
Can you post a picture of how it is mounted on your boat?
Make sure that when you send it in that you send a printout of those two GPS Diagnostic views along with it.

Greg the Top of the unit is about 2' off the deck & is in clear sight of the open sky when I'm fishing. Couldn't ask for a much better setup.

[rnvinc]

Terry... Have you tried hooking the external antenna up to the 788 .....??

I've read several posts on different forums indicating these internal antennas are just not as satisfactory as the external...

(Remember to go into the menu to "Override GPS" and set it to "External"...)

Rickie

[Wiskers]

Terry... Have you tried hooking the external antenna up to the 788 .....??

I've read several posts on different forums indicating these internal antennas are just not as satisfactory as the external...

(Remember to go into the menu to "Override GPS" and set it to "External"...)

Rickie

Rickie, I don't have an extra 50 channel GPS module. I have hooked it to the 998 GPS Module via the Ethernet connection. I works great. Only problem is that antenna is at the other end of the boat. That creates an 18' error right off the bat.

I paid for an antenna when I bought this thing & by golly the 1 in it should work. This is the second unit I've had with this problem. Cajun Fryer's unit does the exact same thing as mine does. He was given the run around until his unit went outta warranty. Mark's way too easy go'n and he just accepted it, when they told him it was fine! That ain't right! That's the first GPS unit he's ever owned and he didn't know any better. I do! I have another friend that had issues with his internal GPS. They finally had to send him an external antenna to make his work right.

It's just frustrating to me to recommend these units to friends (and you know several of'um) and have them have these issues with the units. Kind destroys your credibility.

Can ya tell I spent another day on the water with this thing yesterday?

I want this thing to work right. I don't want to have to drop another $150 in an external antenna to get it where it should be. This 788 HD DI only comes with an internal antenna but I almost bought an external antenna the other day. Then I thought. You know what? If I buy another antenna, HB will profit from a defective piece of equipment. I ain't do'n that!

I've been in the boat with guys using other brands and they never missed a bed all day. I go out & I spend half a day doing donuts, trying to hit mine!

I've gotta catch the boat on the 21st & will be gone for a month. Before I leave I'm gonna send it in for the LAST time! When I get back, if it ain't RIGHT, I'm gonna start jerk'n wire and replace all of it!

Bet me!

[CrappiePappy]

Terry ... my little Elite 5 DSI unit (internal antenna) will lock on half a dozen satellites, in less than 1min after turning it on ... and that's in my APARTMENT !! It takes less than that amount of time, if I'm outside. I've pulled the TM up & run down the lake (transducer is TM mounted) with the unit still ON, dropped the TM & started fishing ... and the GPS is still dead on.

I'd tell HB to either replace the whole head unit, or you're going to raise a holy stink, as well as switch brands. I see no reason why you aren't getting a good satellite lock, from your position, when I'm getting good reception from inside my apt. .... so it must be a defective internal antenna. (or else HB's internal antennas aren't as good as Lowrance's )

Seriously, man .... if it isn't working like it's supposed to, after two tries ... IMHO it's time to


... cp

[rnvinc]

Terry ...I understand your frustration...

Testing the external antenna on your 788 (in this case) is not to determine accuracy of marking waypoints....(so it doesn't matter that the antenna is at the other end of the boat)...

The test is determine positively that the internal antenna is not performing satisfactorily ...

I would suggest unhooking all Ethernet cables and plug the external antenna into the 788 and see if the speed and direction issues disappear....

If it does, then you have ample positive results to explain your case to HB that an external antenna is the only way to fix this issue of unsatisfactory internal antenna operation...

Rickie

[Wiskers]

Terry ...I understand your frustration...

Testing the external antenna on your 788 (in this case) is not to determine accuracy of marking waypoints....(so it doesn't matter that the antenna is at the other end of the boat)...

The test is determine positively that the internal antenna is not performing satisfactorily ...

I would suggest unhooking all Ethernet cables and plug the external antenna into the 788 and see if the speed and direction issues disappear....

If it does, then you have ample positive results to explain your case to HB that an external antenna is the only way to fix this issue of unsatisfactory internal antenna operation...

Rickie

Rickie, it's GREAT have'n a friend that's a little OCD. You are very analytical and that really comes in handy.

I really didn't want to have to tear my boat apart to pull that antenna wire. Like I said I don't have a spare antenna. I did however take your advise and went out & took my wiring harness to my 998 apart and hooked my 788 into the power and gps antenna. I sat in the boat and held the 788 in my hand and had my son-in-law pull me down the road on the trailer. At dead stop it registered 0 mph and the donut. Never jumped around or anything. NOT ONCE. I told him to pull me down the road at about 5 mph. Again little to no variation of the speed and NO jumping around of the directional arrow. While pulling me down the road the course line was steady even around curves at faster & slower speeds. I am tickled to death with it when it is hooked directly to the external antenna. It does the some when hooked to it via Ethernet. There is no doubt it's an antenna problem. That's what I told them the first time they "FIXED" it. I even sent them a note telling them what I had done to test it. I did basically the same thing I just mentioned. They never did tell me what they did to it, but it ain't fixed!

My concern is I'm gonna send it back in. It will get back while I'm gone and I won't be able to check it until I get back. When I get home it will be "PRIME TIME" and I don't want to be hit in the butt with a "surprise" screwed up unit while I'm home off the boat. I'm only home 28 days and I have to maximize my time. If I had to send it back again I'd loose at least a week of fishing! Boy... Talk about be'n PO'd if that happened!

I sent it in last August & hadn't gotten to fish much since I got it back. I don't know why it took me so long to figure out that it was using the 998's antenna via Ethernet, making me think it was fixed. I was LIVID when I switched it to it's own internal antenna and it went nuts! I thought about kick'n the darn thing in the lake!

Another thing... Say I want to sell the thing and upgrade my front unit. I don't wanna pass this problem on to the next guy!

The more I think about this the madder I get!

[kyrich]

Terry i've got the same problem with mine........When i bought mine i wasn't crazy about the internal antenna, but thought if worked right it would save me some room up front, i bought the new heading sensor antenna and i should have stood my ground like you. I think they have issues with the internal antenna and are not fessing up.

[Humminbird_Greg]

Greg the Top of the unit is about 2' off the deck & is in clear sight of the open sky when I'm fishing. Couldn't ask for a much better setup.

Thanks for the pictures Wiskers, the internal GPS should certainly be in the clear mounted there.
Can you remember what software version you were running in your 788ci HD DI unit?