Need a new tach

[J D]

Another question, this RPM rating is out of wood right? Full throttle not in wood I mean, vs in wood?

Correct
The max rpm should be set no load with a bar of the recommended size & correctly tensioned chain

Technically, you could set the max rpms while cutting wood as the saw will always drop in RPMS while cutting. The extra rpms will help the saw cut through wood. But you need to be careful as if you run the saw full throttle with no load on it, you would be above the max recommended RPMS.

Do not do this!
Tuning a saw "in the wood" is a different thing altogether. If you try & set max rpm whilst loading the saw you will get inconsistent results & almost certainly end up lean which is a really good way to destroy your saw in very little time

 

[SteveSr]

I'm reading .998vdc. That seems awful low. It's soldered in so I would have to pop the solder and find a replacement.

Post a photo of the battery with the numbers on it. Odds are it is a lithium manganese coin cell with solder tabs on it. If so, these should read 2.5-3 volts.

There was no water present inside. It was dry. No corrosion anywhere. When I dis reinstall the screen it would try and display something then it would go away. Maybe it just needs a new battery?

Explain - reinstall the screen...

 

[Tothemax]

Post a photo of the battery with the numbers on it. Odds are it is a lithium manganese coin cell with solder tabs on it. If so, these should read 2.5-3 volts.


Explain - reinstall the screen...

I can't see any numbers as it's soldered in place. I'm guessing the numbers are face down.

The screen can separate from the board if you remove certain screws. When I did that and reinstalled the screws, I got a blip of screen response.

 

[Tothemax]

I can't see any numbers as it's soldered in place. I'm guessing the numbers are face down.

The screen can separate from the board if you remove certain screws. When I did that and reinstalled the screws, I got a blip of screen response.

 

[J D]

That battery should definitely have more than 1V.
Remove battery,
Remove Screen,
Rince circuit board with iso alcohol & dry thoroughly,
Reassemble with new battery.
There will be markings on the underside of the battery. It may also be 2 skinny batteries stacked together, in that case the voltage would likely be twice what the markings on the outside say. You can peel some of that yellow plastic off to confirm either way

 

[mudrat2]

Ae you good with a soldering iron? If so, carefully unsolder the 2 straps holding the battery in and the markings will be on the + side that is against the board. It may be a CR2032, which is a common 3 volt battery.

How was the screen connected to the circuit board? Can you show us a photo of the other side with the screen off?

I am an EE and work with battery powered circuits a lot.

 

[Tothemax]

Ae you good with a soldering iron? If so, carefully unsolder the 2 straps holding the battery in and the markings will be on the + side that is against the board. It may be a CR2032, which is a common 3 volt battery.

How was the screen connected to the circuit board? Can you show us a photo of the other side with the screen off?

I am an EE and work with battery powered circuits a lot.

I will try and take a picture of the screen and circuit board tomorrow. There are a bunch of contact points that run across the circuit board and they touch points on the back of the screen. The screws on the black plastic hold everything together. Without them, they are two separate parts.

 

[Ralf1e]

I hit it with compressed air but it is sitting on my bench in parts. I may put it in some rice to draw out any possible moisture.

Put it in a bag or box with a little pack of desicant. The stuff that they pack in with electric goods and other stuff damaged by moisture.

 

[trains]

I would give it a spray with some circuit board elec cleaner, and then blow off with dry air, and as others have mentioned, put it in a box of rice/ dessicant for a few days to help it dry out.
rescued many electrical items doing that, most recent were some ear buds dropped in the kitchen sink when washing dishes.
dead for 4-5 days, then came back to life.

 

[SteveSr]

The connection to the display is made with elastomeric zebra strips. I would NOT use alcohol on any of this as it may damage the zebra strips or the contacts on the circuit board.

1. Get some good nitrile gloves and use them when working on the tach. Skin oils WILL cause issues with bad connections and later corrosion.

2. Remove the battery with a soldering iron. You can probably find a replacement with solder tabs at Digi-key or Mouser. DO NOT attempt to solder directly to ANY battery.

3. Completely remove the display and the zebra strips. Make sure that you note which side of the display is up.

4. Using gloves for handling, clean all of the components with warm/hot water and dish soap using a small flux brush. What you are trying to do is to remove any plated on shorts that happened while the unit was wet and under power. Get the brush between the pins on the ICs. Inspection under high magnification may also be helpful.

5. With air, canned or compressed, blow any remaining water out from under the ICs on the PCB. These are the black squares and rectangles on the PCB.

6. let everything dry out for a couple of days.

7. Using gloves, re-assemble everything except the battery.

8. Install the new battery observing proper polarity..

 

[Tothemax]

It is a cr2032 battery.

How do I get solder to stick to it? I cannot for the life of me get the tabs soldered on.

 

[Tothemax]

For those asking about the screen

 

[Flippy caps]

You will need a battery stud welder to safely attach a tab onto the battery. Or you can order them with the tabs attached already. Google it, 20 options came up for cr2032 with solder tabs.

 

[Tothemax]

You will need a battery stud welder to safely attach a tab onto the battery. Or you can order them with the tabs attached already. Google it, 20 options came up for cr2032 with solder tabs.

Thanks. I just bought some off Amazon. Hate that I had to buy a 10pk for a single battery.

 

[singinwoodwackr]

It is a cr2032 battery.

How do I get solder to stick to it? I cannot for the life of me get the tabs soldered on.

Flux. At least it worked on a 18650

 

[J D]

It is highly unadviseable to solder directly to a lithium battery.
With the likes of a non rechargeable button cell it will almost certainly shorten its life & may ruin your device.
With the likes of an 18650, if you're unlucky, it could end up going up in an inferno at some random point in time in the future

 

[mudrat2]

Battery:
https://www.digikey.com/en/products/detail/panasonic-bsg/CR-2032-F2N/2404062

The LCD contacts are called Zebra strips. Clean very gently with lint free cloth. Clean the gold contacts on the board. Make sure there is no lint left on board or contacts. If there are any bad contacts after assembly it will show up as either blank or always black areas on the LCD. If so, take apart and re-clean, etc.

 

[J D]

A nice soft pencil eraser works well to clean contacts

 

[mudrat2]

Not a good idea on zebra strips and not on gold plated contacts. Zebra strips with carbon cores are quite fragile and gold plating on contacts is very thin. If it was solder coated then yes, I do that all the time. Nice soft Stadler-Mars white eraser works well. Just make sure to clean all the bits off after.

 

[SteveSr]

It is a cr2032 battery.

How do I get solder to stick to it? I cannot for the life of me get the tabs soldered on.

See #2 above...