8.3.3.5. Check of diodes of the vypryamitelny block

The serviceable diode passes current only in one direction. Faulty — can or not pass current (break of a chain) at all, or to pass current in both directions (short circuit).
In case of damage of one of diodes of the vypryamitelny block it is necessary to replace entirely the vypryamitelny block.

Fig. 8-9. Schemes for check of diodes of the vypryamitelny block: and — check of at the same time "positive" and "negative" diodes; — check of "negative" diodes; in — check of "positive" diodes; 1 — the rechargeable battery; 2 — a control lamp; 3 — the generator; 4 — a conclusion of "B" of the regulator of tension; 5 — a wire of the general conclusion of additional diodes

Short circuit of diodes of the vypryamitelny block can be checked, without removing the generator from the car, previously having disconnected wires from the rechargeable battery and the generator. It is possible to check an ohmmeter or by means of a lamp (1–5 W, 12 V) and the rechargeable battery, as shown in fig. 8-9.

       NOTE
For the purpose of simplification of fastening of details of the rectifier three diodes have on the plus case of the straightened tension. These are positive diodes, and they are pressed in one plate of the vypryamitelny block. Other three diodes — "negative", have on the minus case of the straightened tension and are pressed in other plate of the vypryamitelny block or in a generator cover.


Fig. 8-4. Generator 37.3701: and — the regulator of tension and brush knot at release generators since 1996; 1 — a generator cover from contact rings; 2 — a bolt of fastening of the vypryamitelny block; 3 — contact rings; 4 – the ball bearing of a shaft of a rotor from contact rings; 5 — the condenser 2,2 мкФ ±20% for suppression of a radio noise; 6 — a rotor shaft; 7 — a wire of the general conclusion of additional diodes; 8 — a clip "30" generators for connection of consumers; 9 — the generator plug "61" (the general conclusion of additional diodes); 10 — a wire of a conclusion of "B" of the regulator of tension; 11 — the brush connected to a conclusion "In" tension regulator; 12 — tension regulator; 13 — the brush connected to conclusion "Ш" of the regulator of tension; 14 — a hairpin for fastening of the generator to the tension device; 15 — a generator cover from contact rings; 16 — a krylchatka of the fan with a generator drive pulley; 17 — a polar tip of a rotor; 18 — washers of fastening of the bearing; 19 — a remote ring; 20 — the ball bearing of a shaft of a rotor from the drive; 21 — the steel plug; 22 — a rotor winding (an excitement winding); 23 — the stator core; 24 — a stator winding; 25 — the vypryamitelny block; 26 — a coupling bolt of the generator; 27 — the buffer plug; 28 — the plug; 29 — the podzhimny plug; 30 — a conclusion "In" tension regulator; 31 — the brush holder

At the generator 37.3701 before check it is necessary to disconnect a conclusion of "B"(4 to fig. 8-9) tension regulator from the 30 plug of the generator and a wire 5 from a conclusion "In" tension regulator. At generators with the new regulator of tension (see fig. 8-4, a look "and") a conclusion of "B" is absent and at it it is necessary to disconnect only a wire from a conclusion "In".
At first check whether there is no short circuit at the same time in "positive" and "negative" diodes. For this purpose "plus" batteries through a lamp connect to a clip "30" generators, and "minus" — to the generator case (fig. 8-9, a). If the lamp burns, then some of "negative" and "positive" diodes have short circuit.
Short circuit only of "negative" diodes can be checked, having connected battery "plus" through a lamp to one of bolts of fastening of the vypryamitelny block, and "minus" — to the generator case (fig. 8-9, b). Burning of a lamp means short circuit in one or several "negative" diodes.
It is necessary to remember that in this case burning of a lamp can be also a consequence of short circuit of rounds of a winding of the stator on the generator case. However such malfunction meets considerably less than short circuit of diodes.
For check of short circuit only in "positive" plus diodes of the battery through a lamp connect to a clip "30" generators, and "minus" — to one of bolts of fastening of the vypryamitelny block (fig. 8-9, c). Burning of a lamp will indicate short circuit of one or several "positive" diodes.
The break in diodes without dismantling of the generator can be found only indirectly when checking the generator at the stand on considerable decrease (for 20–30%) sizes of the given current in comparison with nominal. If windings of the generator are serviceable, and in diodes there is no short circuit, then the break in diodes is the reason of reduction of the given current.