18-03-2023, 07:08 PM
Having tried and failed to get a consistently reliable 12v charging system to work with a two brush C35 and RB106 regulator I have always fancied the idea of a Dynamator. I have managed to do my A7 driving with no charging, setting off and getting all day on the 12v battery charge (e.g. the arduous Beamish Run) without issue, just that red light shining at you unblinkenly. YES; I do know about the Dynamator gear problems with the angst that has caused but that's easily avoided and I don’t recall anyone saying there had been similar widespread bearing or internal electrical problems so it seemed a good technical step forward. Stuart Giles had had a similar go at a defective Dynamator, posted here, with helpful photos (thank you), that had an open circuit rotor. Accuspark don’t make them anymore and after enquiring about them I get the impression after what happened and what was said that they want to distance themselves from the A7 variety. My opportunity came a couple of months back when a ‘spares or repair’ unit came up on that well known on-line auction site. Once secured, I immediately started a strip down to determine what was ailing it, hoping it would be something easily fixed. It was obvious someone had had it in bits before and not found the fault(s).
It comes apart in a similar way to a C35, go in from the distributor end removing the circlip and disc to slacken the drive gear nuts at both ends. Remove the distributor drive worm (not losing the tiny key) by drawing off the end housing. The regulator and brushgear can be removed from the opened end and the internal body terminals similarly from the ugly external block (take a photo of the connections on your phone and make a sketch of the wiring arrangement!). Remove the four body screws and unthread the rotor. Testing at this point revealed that the rotor winding was open circuit (was this the same Dynamator that Stuart had a go at?). Oh poo. The fault wasn’t visible so I was determined to press on and perhaps rewind the rotor. That necessitated removing the bearing and sliprings. A simple puller got both off though the bearing was very tight on the spindle. But despite a valiant attempt I could not get the rotor claws off the spindle, they were V tight. Having the coil now unsoldered from the slipring I noticed that one tail end wobbled about and with a bit of poking about with a pick I found the winding was broken just where it exited the coil towards the sliprings. Eureka!!! Happy days all round! Further probing released the first turn of the winding and I was able to pull it through and re-establish the winding testing out at 4 Ohms so there was fortunately only the one fault. The body coil and rectifier tested out OK with no more open circuits or earth faults. Reassembly is the reverse of the above. You can get the gear end bearing out by removing the three internal screws and sliding everything off the spindle.
My mission didn’t finish at this point. I didn’t like the four cross head screws retaining the body and replaced them with more aesthetic M5 hex heads. Similarly, the rubberised terminal block looks decidedly non-vintage and I thought the way the connections were made with a soft insulating spacer inside tempted a poor connection. I extended the two outgoing cables and grommeted the body adding a Lucas type ‘brushgear’ coverband and connecting box. The wiring loom also needed reconfiguring. Be careful with the RB106 wiring diagram on the Accuspark site. It implies that the D terminal of the Dynamator should be connected to the ‘power’ side of the electrical system whereas it should be connected through the ignition light loop and the heavy cable from the rectifier should go into the power system. I found by gutting my RB106 regulator that the cabling and terminals could remain as they were with a shorting loop between the F and A terminal making the right connections.
I write this hoping it will help someone else in the future, and encourage them to have a go. Other bits of info that may be helpful are that the gear end bearing is a 6202RS, the same as the C35 and the distributor end bearing is a 6201RS, both being sealed bearings. The rotor claw is tiny compared to most modern alternators at 69mm diameter. The only rotor that I could find on the informative Wood Auto site this size was a Denso for a Kuboto lawnmower! The brush assembly and sliprings look very similar to many advertised on that well known on-line auction site. As Stuart pointed out, the regulator could be replaced by another if you have a problem. BTW, the brushgear is very fiddly to get back into place, compressing the spring loaded brushes while aligning the two screws, wires and plastic spacers is difficult. I put in some slightly longer screws and filed them to a point to help them find the holes.
Mine sprang into life generating over 10 amps initially then settling down with a steady 14.6v. The red light is no longer my constant driving companion! I hope it continues to do so and this helps you too.
Dave
It comes apart in a similar way to a C35, go in from the distributor end removing the circlip and disc to slacken the drive gear nuts at both ends. Remove the distributor drive worm (not losing the tiny key) by drawing off the end housing. The regulator and brushgear can be removed from the opened end and the internal body terminals similarly from the ugly external block (take a photo of the connections on your phone and make a sketch of the wiring arrangement!). Remove the four body screws and unthread the rotor. Testing at this point revealed that the rotor winding was open circuit (was this the same Dynamator that Stuart had a go at?). Oh poo. The fault wasn’t visible so I was determined to press on and perhaps rewind the rotor. That necessitated removing the bearing and sliprings. A simple puller got both off though the bearing was very tight on the spindle. But despite a valiant attempt I could not get the rotor claws off the spindle, they were V tight. Having the coil now unsoldered from the slipring I noticed that one tail end wobbled about and with a bit of poking about with a pick I found the winding was broken just where it exited the coil towards the sliprings. Eureka!!! Happy days all round! Further probing released the first turn of the winding and I was able to pull it through and re-establish the winding testing out at 4 Ohms so there was fortunately only the one fault. The body coil and rectifier tested out OK with no more open circuits or earth faults. Reassembly is the reverse of the above. You can get the gear end bearing out by removing the three internal screws and sliding everything off the spindle.
My mission didn’t finish at this point. I didn’t like the four cross head screws retaining the body and replaced them with more aesthetic M5 hex heads. Similarly, the rubberised terminal block looks decidedly non-vintage and I thought the way the connections were made with a soft insulating spacer inside tempted a poor connection. I extended the two outgoing cables and grommeted the body adding a Lucas type ‘brushgear’ coverband and connecting box. The wiring loom also needed reconfiguring. Be careful with the RB106 wiring diagram on the Accuspark site. It implies that the D terminal of the Dynamator should be connected to the ‘power’ side of the electrical system whereas it should be connected through the ignition light loop and the heavy cable from the rectifier should go into the power system. I found by gutting my RB106 regulator that the cabling and terminals could remain as they were with a shorting loop between the F and A terminal making the right connections.
I write this hoping it will help someone else in the future, and encourage them to have a go. Other bits of info that may be helpful are that the gear end bearing is a 6202RS, the same as the C35 and the distributor end bearing is a 6201RS, both being sealed bearings. The rotor claw is tiny compared to most modern alternators at 69mm diameter. The only rotor that I could find on the informative Wood Auto site this size was a Denso for a Kuboto lawnmower! The brush assembly and sliprings look very similar to many advertised on that well known on-line auction site. As Stuart pointed out, the regulator could be replaced by another if you have a problem. BTW, the brushgear is very fiddly to get back into place, compressing the spring loaded brushes while aligning the two screws, wires and plastic spacers is difficult. I put in some slightly longer screws and filed them to a point to help them find the holes.
Mine sprang into life generating over 10 amps initially then settling down with a steady 14.6v. The red light is no longer my constant driving companion! I hope it continues to do so and this helps you too.
Dave
