When spudgers won't work - Page 1
Forum section: electronics / repair

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 14, 2025, 11:56:35 pm
content: A friend has asked me to look at a 20+ year old device which is sealed against weather. Namely a Cateye Cordless 2 Cyclocomputer Model CC-CL200.As far as I can tell this device is either glued or welded therefore spudgers won't work.Fortunately he also has another one which has been smashed so I have one to experiment with.Whilst my suspicion is that I'm on a hiding to nowhere I thought that someone might have an idea of solvents that I may be able to try to use to loosen any glue.I'm guessing that heat is not an option.Any ideas?RegardsDave

author: thm_w
author_rank: Super Contributor
timestamp: March 15, 2025, 01:13:48 am
content: https://www.eevblog.com/forum/repair/how-to-break-ultrasonic-welding/If you show a photo of the smashed one it should be possible to tell if there is glue on the seam or not.Either way very high chance it will be damaged. Probably easier to buy either a replacement or a newer device.

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 15, 2025, 01:42:19 am
content: In the freezer now. I'll let you know the result.Thanks for the suggestion.

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 15, 2025, 01:55:04 am
content: My friend, who is a passionate (nutter) cyclist has later versions of the device which he considers to be inferior.The smashed version is the worst of three bought in the 90s and thus available for destructive experimentation.However the point of this post is to find a non destructive way of opening it if at all possible.

author: Haenk
author_rank: Super Contributor
timestamp: March 15, 2025, 07:01:49 am
content: Glue is the worst method to combine two plastic parts.There are several superior methods, which create molecular bonds, like solvents, hot melt and ultrasonic (melting). The bond might be weaker than the parts themselves in some cases (then you can crack them apart), the bond might even be tougher in many cases (then you can't crack them apart). You can't open this device without desctruction, IMHO.

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 15, 2025, 09:01:47 am
content: Thank you. That is what I suspect. However if there is a way then this forum is probably the best place to find an answer.

author: benj38
author_rank: Frequent Contributor
timestamp: March 15, 2025, 11:37:19 am
content: A thin hacksaw is the way to go.Just cut along the seam, and when it is time to put it back together just put a thin bead of hot glue into the gap created by the saw. Works perfect.For small enclosures, and opening up things like Dallas NVRAM chips (in order to replace the internal battery) I use the following excellent little saw:https://www.tamiya.com/english/products/74111

author: jpanhalt
author_rank: Super Contributor
timestamp: March 15, 2025, 11:59:44 am
content: @benj38I second the idea of a saw, but suggest a "razor" saw, rather than hacksaw. (That's probably what you meant.) The former has a much thinner and finer pitched blade usually. Hobby versions will be about as thick as a safety razor blade. They are also pull saws rather than push saws and a bit easier to control.For reassembly, I would use a permanent/high bond strength tape with adhesive that doesn't turn to goo. Second choice would be solvent weld. For that, you might need to know what type of plastic.EDIT: Here's the type of saw I use and almost always without a handle. I hold it by the stiffener.

author: GLouie
author_rank: Regular Contributor
timestamp: March 15, 2025, 04:18:22 pm
content: One technique I have used on similar product, such as plastic power supply boxes, is to take a chisel and place it in the seam where it looks like it was glued or ultrasonically welded. Then I tap the chisel with a small - or large hammer and attempt to break the weld, which is often weak right at the weld. Often it takes a surprising hammer blow, so this can be largely an experiment if you have nothing to lose. However, it often breaks the seam nicely enough to open the case, which can be replaced with a bit of sealing glue.I might be careful about the window on the cyclocomputer. Is there a battery cover that might offer insight to the construction? Something else to try is some mild pressure to the case with a vise, and look for any seam distortion.

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 15, 2025, 05:01:21 pm
content: Yes there is a battery compartment with a seal. However whilst you get glimpses of the circuit board there isn't isn't anything else of use.I'll try the suggestions to see if I can get anywhere. There is no time pressure on this so it may take some time to get aroundtuit.