Solid State Voltage Regulator Conversion

[Surfcuda]

I would like to convert my 1970 barracuda Voltage Regulator (3Wire) to a Solid State VR (2Wire). Is this a complicated task?

Also I currently have a RTE Internal VR installed for my instruments. I don’t know it this would interfere with a conversion.

Any help much appreciated. Please provide any guidance using the KISS (Keep it Simple) method because I’m electronically challenged.

 

[Surfcuda]

After pulling the VR wires, I see that it is a 2 Wire connection rather than 3. I have attached a photo of my VR and one of my Alternator. I know Photos always help.

 

[Vaanth]

I would like to convert my 1970 barracuda Voltage Regulator (3Wire) to a Solid State VR (2Wire). Is this a complicated task?

Also I currently have a RTE Internal VR installed for my instruments. I don’t know it this would interfere with a conversion.

Any help much appreciated. Please provide any guidance using the KISS (Keep it Simple) method because I’m electronically challenged.

After pulling the VR wires, I see that it is a 2 Wire connection rather than 3. I have attached a photo of my VR and one of my Alternator. I know Photos always help.

View attachment 158232

View attachment 158233

The 1970 Barracuda was originally equipped with a two terminal electronic, or solid state, voltage regulator. The pictured regulator is an aftermarket electronic, or solid state, voltage regulator.

The pictured alternator is a 1972 - 1977 "Square Back", isolated field alternator. The 1970 Barracuda was originally equipped with a "Round Back" isolated field alternator. The two alternator versions have two field connection terminals and are used with the 1970 and later electronic voltage regulator. The two versions are interchangeable. The following image shows the two versions:

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[Surfcuda]

Thanks Vaanth

The 1970 Barracuda was originally equipped with a two terminal electronic, or solid state, voltage regulator. The pictured regulator is an aftermarket electronic, or solid state, voltage regulator.

The pictured alternator is a 1972 - 1977 "Square Back", isolated field alternator. The 1970 Barracuda was originally equipped with a "Round Back" isolated field alternator. The two alternator versions have two field connection terminals and are used with the 1970 and later electronic voltage regulator. The two versions are interchangeable. The following image shows the two versions:
View attachment 158234

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Thanks Vaanth, great info on both VR & Alt. Appears my set up is already a Solid State VR. Would you agree?

My Alt instrument has been bouncing up to +C when I rev the motor. I believe it may be a bad VR. Any input would be welcomed

 

[Vaanth]

Thanks Vaanth

Thanks Vaanth, great info on both VR & Alt. Appears my set up is already a Solid State VR. Would you agree?

My Alt instrument has been bouncing up to +C when I rev the motor. I believe it may be a bad VR. Any input would be welcomed

Yes, it is already a solid state voltage regulator.

The needle moving a small amount to the charge (+) side on the alternator gauge (ammeter) is not necessarily a bad indicator. If it is doing it too much, some measurements, checks, and possible tests are in order. The factory service manual provides detailed testing of the charging system including the alternator and voltage regulator, but the following is a short list of items to check or consider:

• The gauge shows a charge, so basic health of the alternator is okay.
• The varying charge with engine speed but without load changes indicates a possible regulation issue.
  • The regulator is powered by, and senses voltage at, the Ignition RUN circuit (blue wire).
  • If the sense voltage is too low, the regulator can drive the alternator field more resulting in over charge.
  • If the sense voltage varies too much, too much variability in the charge can occur.
• Measure the voltage at the battery, at the alternator output, at the blue wire connected to the alternator field terminal, and at the regulator input (blue wire - easier to tap into it at the ballast resistor ignition switch side).
  • The voltages should be within one volt of each other at least; ideally around 0.2 volts difference is better. If the voltages do not check, high resistance is in the circuit(s). All wiring at junction points should be checked for good connections, including the following:
    • Battery post terminals to battery.
    • Battery post terminals to cables (internal).
    • Negative battery lead to engine ground, and body ground if present.
    • Positive battery lead to starter relay
    • Positive lead from starter relay to bulkhead, including dusible link and fusible link connecrions.
    • Bulkhead connections into and out of interior.
    • Ammeter connections.
    • Ignition switch and ignition switch connections, including connectors at the steering column.
    • Ignition RUN wiring from bulkhead to voltage regulator and alternator.
    • Ground connection through voltage regulator mounting screws.
    • Auxiliary ground lead from engine to body (firewall).
• The green wire from the regulator to the alternator should have good continuity.
• Field resistance of the alternator (between the two terminals) should be ~4-6 ohms. If higher, brushes may be worn or dirty. Worn or dirty brushes usually cause low charge though.
• Ensure the battery is healthy. Fully charged without load, a healthy battery measures ~12.7 volts. However a specific gravity check of the electrolyte (if possible), is a more direct indicator. Specific gravity specification will vary depending on temperature and can vary depending on battery chemistry type. A battery that is beginning to get weak can cause more charge variation.
• Quick check the charge capability by running the engine at idle. Monitor the voltage at the battery and the ammeter. Turn on the head lights on high beam and the heater blower motor on high. The voltage should initially dip, and the ammeter show a slight discharge. The voltage should recover as the engine runs. The ammeter should also move back to the center, fully or mostly. A carbon pile load is better, but this is a decent quick check. If it does not recover, a weakness in the system is indicated. If it over charges, a likely high resistance issue exists.

The foregoing are a few quick and basic things to consider. More in depth testing or checks as outlined in the service manual will provide more information if needed.

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