1
Remove the regulator and check for wear
- Remove the regulator: two screws (slotted in the original)
- The carbon brushes should still protrude by at least 5 mm, otherwise replace the carbon brushes or the entire regulator. Here they are 12 mm.
Bosch 70A alternator bearing, commutator contacts replacement
In order to overhaul the alternator with approx. 300,000 km mileage, it must first be dismantled.
Problem: despite a new charge regulator, less than 14 V is being supplied.
Order number for bearing
Order number for sliding contact
Charge regulator with carbon brushes (one unit)
Cold cleaner or similar is useful for cleaning the generator, which is usually very dirty.
Пошаговая инструкция
2
Disconnect contacts
- On older alternators, the screws may be rusted solid. Spray generously with rust remover or penetrating oil and allow to soak in for a while if necessary.
- Unscrew the nuts and washers (if present) on the two/four pull arms.
- Unscrew the nuts and washers on the positive contact bolt (13 mm).
- Unscrew the nuts, washers, and contact tongue from the control line (7 mm).
- Unscrew the nuts, washers, and contact tab from the control line (7 mm).
3
Belt pulley
- Unscrew the belt pulley: hold it in place with an old belt and unscrew it with a wrench or ratchet. (22 mm)
- Remove the nut and all washers as well as the fan blade, noting the order.
- Remove the crescent key.
4
Open the housing
- Mark the alternator housing for later reassembly.
- If the four tie rods (screws) are of different lengths, note or mark where each one belongs
- Unscrew the four screws (PH2).
- Note: There are versions with four screws of the same length and versions with screws of different lengths.
- Pull out the front housing part with the stator, using a plastic hammer to help if necessary.
5
Split the housing
- Remove the four countersunk screws
- Pull the rotor out of the bearing shield (housing).
- Bearing shield and screws
6
Check rotor contacts (commutator segments)
- Check: between the commutator segments 2.8 ohms +/- 10%, no contact with the housing?
- Even if the resistance is correct, the contacts are so worn that the commutator ring must be replaced.
- Wear limit: commutator ring diameter 27.8 +/- 1 mm, max. runout 0.03 mm
7
Remove bearings -1
- This step is also necessary to replace the commutator ring
- Remove the two bearings from the rotor shaft; a good bearing puller is helpful.
8
Remove the diodes and stator winding
- This step is necessary to check the diodes
- In the rear housing, remove the two screws that connect the diode plate to the housing
- Pull the diode set and stator winding out of the housing
- Do not lose the plastic bushing (or sliding ring).
9
Check stator winding
- Desolder the three stator cables.
- Do not break the cables (e.g. by bending them).
- Solder quickly (short and hot) so as not to fry the rectifier diodes.
- Check the stator windings for short circuits to ground. Target: infinite resistance
- Check continuity of the stator windings (the displayed 0.3 ohms) are inaccurate but continuity is present
- Theoretically, the resistance of the windings (always 2 phases) can also be checked: should be 0.09 ohms +/-10%. However, this is not possible with a simple multimeter; 0.3 ohms is displayed here.
10
Test rectifier diodes
- Insert translation here
Завершение
Follow the steps in reverse order to reassemble your device.
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