- Desoldering the old electrolytic caps from the board
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Volvo emergency switch capacitors.pdf- PDF version of the Emergency Blinker repair (illustrated)
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If you haven’t already visited his blog, it’s well worth it.
This repair involves replacing the electrolytic capacitors on the circuit board in the emergency flasher switch, which also control the turn signals. Note: my switch was working fine before I started the job – I just did the repair for the fun and learning experience of it and to avoid a potential failure down the road.
This repair is similar to the Fuel Pump Relay and Windshield Wiper Relay capacitor repairs. I wrote up a short contribution on the Fuel Pump relay here:
https://www.matthewsvolvosite.com/forums ... =1&t=33696
Overview:
A) Remove switch from dashboard
B) Remove switch circuit board
C) Remove old capacitors
D) Install new capacitors
E) Install board back in case
F) Install switch in dashboard
Tools:
Soldering iron, low Wattage with fine tip
“Helping hand” alligator clip on a stand
2-3 small flatblade screwdrivers
Small wire clippers
Awl or drill to remove solder from holes – a solder sucker bulb would work well here.
Materials and Parts:
Solder (60/40 tin/lead rosin core)
Solder wick (copper solder removal braid)
Electrolytic capacitors. The orignials are all rated 50V and 85°C. The new ones were rated 50V except for the 33uF (63V, the next closest available rounding up), with 105°C temperature rating and 20% tolerance.
3.3μF (qty 1) 50V (Digi-Key part# P13463-ND)
10μF (qty 2) 50V (P13478-ND)
33μF (qty 1) 63V (P13470-ND)
I got all the caps from Digi-Key. They are Panasonic brand. They ranged in price from 30 to 32 cents apiece. I like this series of capacitors because they have a relatively long lifetime rating of 5000 hours @ 105°C and are rated for operating temperatures of -40°C to +105°C, which should make them last a long time in this application. In reviewing the work I did before on the Fuel Pump Relay I noticed that the temp ratings there were 105°C – this relay is located under the fuse panel much closer to the heat of the engine bay.
Time: about 1 hour.
Step 1: Before removing the switch, test the operation of the bulbs in the switch – if they are burned out you will have a good opportunity to replace them when you take apart the switch housing. To remove the switch, pry it loose using a flat blade screwdriver and finger from the sides.
Step 2: Once the switch is a little loose, it can be wiggled out.
Step 3: Pull switch all the way out from dash to expose the electrical connector at the back.
Step 4: Pry the locking tabs back to release the electrical connector. There is one locking tab at each end. Both tabs have to be pried up simultaneously to free the electrical connector.
Step 5: At the workbench, use a screwdriver to rotate 90° CCW the two white bulb housings from the side of the switch. Remove the bulbs from the case before trying to slide out the circuit board in the next step. If these bulbs don’t light up, now is a good time to change them.
Step 6: Use two or three small flatblade screwdrivers to pry up the locking tabs on the back end of the case. Once pried up, the circuit board can be slid out of the case by pulling straight back on the electrical connector.
Step 7: Identifying the old capacitors. From back to front there are a 3.3μF, two 10.0μF, and a 33.0μF electrolytic capacitors.
Step 8: Remove old capacitors. I used a “helping hand” to hold the capacitor, my fingers to position and hold the board, and a soldering iron to heat up the capacitor leads until the solder melted. Once the solder melts, the capacitor will pull out, as shown below.
Step 9: After removing all four capacitors, use the soldering iron with some solder braid to wick up excess solder from the pads and through holes in the circuit board. There will still be some solder in the holes.
Step 10: Ream open the holes with an awl. There may be other ways to do this (such as with a solder sucking bulb or even a fine drill bit) but I have had good luck using an awl to open up the holes in the circuit board. The solder is soft and can easily be pierced and spread by the awl. I used the awl from both the front and back of the board. After reaming, you can remove any excess solder from the edges of the holes with a screwdriver blade or wire clippers. Shine light from behind the board to make sure you’ve got all eight holes opened up.
Step 11: Insert new capacitor in preparation for soldering. I inserted and soldered the caps one at a time. Be sure to observe the polarity markings on the circuit board and the capacitors. The capacitors have large “-“ markings on the body above the negative lead. The circuit boards are marked “+” next to the positive hole. Be sure the lead marked “-“ on the cap doesn’t go into the hold marked “+” on the board.
For the 33μF cap, the height of the part is almost as tall as the space available in the case, so either push it down flush with the board or else leave enough lead to bend it over. I chose to push it down flush and it fit in the case, but it was close.
Step 12: Solder the leads. I found that a very small amount of solder was sufficient. I used Sn/Pb 60/40 rosin core solder. I only needed to touch the tip of the iron for a few seconds to the base of the lead near the hole to get the solder to melt and wet to the hole and lead. Repeat steps 11 and 12 for each of the four capacitors.
Step 13: Clip leads. Once you’re satisfied that the solder joints are good (well wetted, no shorts), clip the leads flush with the circuit board. I cleaned up the board with a little isopropyl alcohol to remove rosin flux residues.
Step 14: Install board in case. Reinstall bulbs.
You may have to bend the 33uF capacitor over slightly to clear the side of the switch case.
Step 15: At the car, connect the switch to the electrical cable (don’t slide the switch back into the dash yet). Turn on the ignition and verify that the emergency blinkers and turn signals work normally. Verify the operation of the two light bulbs. The sliding potentiometer to the left of the steering wheel controls the brightness of the upper bulb.
After completing the repair and testing the switch we noticed that the “tick tick” sound of the switch when blinking the lights was a little louder and ‘crisper’ sounding than it was with the old capacitors.
Good luck and enjoy the job!
