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142 Guy · Mar 31st, 2021, 16:46

Response to your questions in red.

So, if I'm not getting reading from the DF terminal where the green wire from the regulator fits, it sounds like my regulator is toast. - That is the most likely cause of the problem.

As far as the 1.5v I'm getting on the yellow indicator light side of the circuit, youk that's an issue within re regulator itself? Connections seem to be sound. - Again, the most likely cause of the problem. If the charging light is glowing brightly when the engine is running that suggests that the yellow wire from the charge light to D+ on the alternator and regulator is intact and you are getting your field flashing current. As a test, disconnect the yellow D+ wire from both the alternator and the voltage regulator. Switch the key to the run position. If the charge light does not illuminate then the wiring is OK. If the charge light still illuminates you have a short circuit to ground on the yellow wire which is preventing the alternator from starting up.

Blueosprey90's comments about the light measuring the voltage difference between the battery and the alternator are correct. Normally, the light comes on when you have 12v from the battery and 0 (or 1.5) volts at the alternator D+ terminal indicating a dead alternator/ regulator. However, if there is a short circuit to ground on the yellow wire that will cause 0 volts on the alternator 'side' causing the light to illuminate and the alternator to fail to start up. However, your next comment about the disintegrated ground wire makes me think that the yellow wire is not the problem.

I have the later three pin regulator and my excitement level raised when the spade connector for the earth lead disintegrated in my fingers, but alas a new connector didn't cure the problem. - Did it disintegrate because it looked like it had been overheated? Overheating can be caused because the spade connection was poor causing the connection to heat up. This overheating would have been accompanied by voltage drop which would cause the regulator to supply additional current which may have exceeded the current rating of the internal pass transistor.

Interesting what you say about getting the right regulator. My Bosch alternator is 55amp. Brookhouse only seem to supply one type of regulator. As I said, mine is quite new. The previous one was only giving 13 amp charge and looked pretty manky. Wish I'd kept it! I wonder if the new one is only designed to handle 35amp? I'll take a look inside tomorrow. Also have emailed Brookhouse. - I would follow up with Brookhouse. My comments were based upon the fact that Skandix show separate part numbers for the voltage regulator for the 35 amp and 55 amp Bosch alternators. It may be possible that the 55 amp regulator will work on the 35 amp alternator. I have the solid state regulator that Dave Barton sells on my 35 amp Bosch.

https://www.prancingmoose.com/AdjustableVoltage.html

The information on his webpage indicates that his one regulator works for all the Bosch external regulator alternators so the Skandix listing may smell of fish.

Mar 31st, 2021, 16:46	#10
142 Guy Master Member Last Online: Yesterday 18:11 Join Date: Jul 2020 Location: Saskatchewan, Canada	Response to your questions in red. So, if I'm not getting reading from the DF terminal where the green wire from the regulator fits, it sounds like my regulator is toast. - That is the most likely cause of the problem. As far as the 1.5v I'm getting on the yellow indicator light side of the circuit, youk that's an issue within re regulator itself? Connections seem to be sound. - Again, the most likely cause of the problem. If the charging light is glowing brightly when the engine is running that suggests that the yellow wire from the charge light to D+ on the alternator and regulator is intact and you are getting your field flashing current. As a test, disconnect the yellow D+ wire from both the alternator and the voltage regulator. Switch the key to the run position. If the charge light does not illuminate then the wiring is OK. If the charge light still illuminates you have a short circuit to ground on the yellow wire which is preventing the alternator from starting up. Blueosprey90's comments about the light measuring the voltage difference between the battery and the alternator are correct. Normally, the light comes on when you have 12v from the battery and 0 (or 1.5) volts at the alternator D+ terminal indicating a dead alternator/ regulator. However, if there is a short circuit to ground on the yellow wire that will cause 0 volts on the alternator 'side' causing the light to illuminate and the alternator to fail to start up. However, your next comment about the disintegrated ground wire makes me think that the yellow wire is not the problem. I have the later three pin regulator and my excitement level raised when the spade connector for the earth lead disintegrated in my fingers, but alas a new connector didn't cure the problem. - Did it disintegrate because it looked like it had been overheated? Overheating can be caused because the spade connection was poor causing the connection to heat up. This overheating would have been accompanied by voltage drop which would cause the regulator to supply additional current which may have exceeded the current rating of the internal pass transistor. Interesting what you say about getting the right regulator. My Bosch alternator is 55amp. Brookhouse only seem to supply one type of regulator. As I said, mine is quite new. The previous one was only giving 13 amp charge and looked pretty manky. Wish I'd kept it! I wonder if the new one is only designed to handle 35amp? I'll take a look inside tomorrow. Also have emailed Brookhouse. - I would follow up with Brookhouse. My comments were based upon the fact that Skandix show separate part numbers for the voltage regulator for the 35 amp and 55 amp Bosch alternators. It may be possible that the 55 amp regulator will work on the 35 amp alternator. I have the solid state regulator that Dave Barton sells on my 35 amp Bosch. https://www.prancingmoose.com/AdjustableVoltage.html The information on his webpage indicates that his one regulator works for all the Bosch external regulator alternators so the Skandix listing may smell of fish. Last edited by 142 Guy; Mar 31st, 2021 at 16:54.