Zumo User Forums

After many months of my Garmin Zumo 390LM not holding charge but only works with USB cable attached, I searched internet for a solution. It constantly tells me 'Battery is low'. It seems there are a great number of users that have this issue with some having replaced the battery but still experiencing same issue.

I then came across a user who discovered a solution to this issue by adjusting the space on each connector inside the unit which was then implemented by many others with successful results.

This solution required the back of the unit to be removed to adjust the connectors within. However, his model had a door at the back to remove it but the 390LM does not. It only has 10 tiny screws. I therefore need to know what size torx (T number) screwdriver fits the screws on the back as none of mine work? Does anyone have this information?

I can't help with the size of screws on the 390 Jenny but a full set of Torx screwdrivers are not expensive on ebay. I bought this set to use on my Z550. T6 is the one needed for 550, may be different on your 390?
https://www.ebay.co.uk/itm/Draper-9Pce- ... Swv3FZxUV0

Thank you for taking the trouble to respond. I will investigate eBay & Amazon but having had a quick look, the lower T sizes (1-5) are harder to find.

I would be very surprised if the screws are smaller than T4 which is the smallest in the set I bought--but then----life's full of surprises.

I found small ones at a sears hardware store

Just for a comparison, I just took this picture of the Z550 case screws. The head is approx 3mm Dia and the driver is a T6

Thank you for your response. I think T6 maybe a little large for the 390 but I appreciate your help as it gives me a guideline. The screws on the 390 are held in deep wells on the back so it is difficult to see actual size. It will be a case of trial & error.

jennynovak wrote: ↑Tue Sep 25, 2018 7:34 am

I then came across a user who discovered a solution to this issue by adjusting the space on each connector inside the unit <snip>

Jenny, could you please post a link to show what connectors need to be adjusted?
On my 395 the 10 screws require a T6 driver.

gv550 wrote: ↑Sun Oct 07, 2018 9:30 pm

jennynovak wrote: ↑Tue Sep 25, 2018 7:34 am

I then came across a user who discovered a solution to this issue by adjusting the space on each connector inside the unit <snip>

Jenny, could you please post a link to show what connectors need to be adjusted?
On my 395 the 10 screws require a T6 driver.

if the connector is the same as the 590 try here

viewtopic.php?f=12&t=2