I'm new to electronics. I can only afford used right now.

What should I inquire about when purchasing a used unit?

- are hours running important? (how many hours is too many)?

- will the transducer wear with time and use? Should I ask for pics of the transducer?

- what about the internal electronics and connectors / cables?

I have no idea how to find a good used unit!

(if it means anything - I'm looking for a cheap sonar + map for mounting on trolling motor of an old small aluminum sea nymph)

What's your price range? You can get some pretty nice electronics with maps for very affordable prices anymore. Buying electronics used electronics is a gamble that I just can't get myself to take. 

Buying used can be good and bad.  You might get a good deal, but you may end up with issues.

 

#1 If you do buy used, you need to see it work before buying which isn't easy.  Then it would have to be installed in the boat and then removed.  When the owner removes it, he may damage it.

 

#2 You have no warranty to cover your investment.  The money you save on a used unit may be wasted if it craps out early.

 

Bottom line, save up, get the biggest display you can afford.  Look on ebay and see what you can find.  But your risk may outweight your reward.

Hours are important, transducers will wear out.

 

What's your budget? New sonar/gps combos aren't horribly expensive and are cheaper at some reputable online dealers than they are in the retail stores. Pricing really jumps when you get Imaging technology 

Under $500. But if I ever scrape up more, I still want to ask the right questions no matter the price.

600 hrs approximate to how long in use?

Oh yeah, I'd be buying new for sure if you have that much to play with. Quite a few options for you to choose from in that range. 

Buying used online means testing it is out of the question... The best I could do would be to check his reputation by seeing if he's sold other items to users who back up his listings

I'm either going to buy new or used. There's a million articles about buying a new unit - I need info about buying used. Obviously people buy used electronics. Some first hand information would be helpful.

Under $500. But if I ever scrape up more, I still want to ask the right questions no matter the price.

600 hrs approximate to how long in use?

If the unit you are considering has a usage timer, find out the hours and divide that by 8. That will give you an estimated days of use.

600 hours is only 75 days.

 

Look for a well cared for unit that is not left on the boat.

 

My units are not on the boat between the lake and home. At home they are still not on the boat. Actually, right now I have 4 units within reach of my computer.

I've never bought used but have sold a bunch of units both here and other web sites.  If I were buying used, I'd look for a site like this one and how many posts the seller has.  That should help you determine the reliability of the seller.

Thanks guys. That is helpful.

Is there an updated article / crash course on the typical electronic set-ups and how they function ?