Page 8 of 9
Re: 1972 Kawasaki 500 H1B
Posted: Tue Jul 15, 2025 2:59 pm
by Skub
Taipan wrote: Tue Jul 15, 2025 2:02 pm
Those two connectors look messy and like someone's played around with them before? I cant see them too clearly, but could have a dry joint there? You can stick a soldering iron on soldered joints until they suddenly shine (solder reaches melt point) and that cures a lot of dry joints. We often used to turn PCBs upside down and
shine all the joints on the underside when encountering a board fault.
Not part of the Accent ignition. That's the brushes for the stator. Believe it or not that's them pretty tidy,the ones on the H1a are well hairy arsed.
Re: 1972 Kawasaki 500 H1B
Posted: Tue Jul 15, 2025 8:57 pm
by Ian
Check the blue black and green wires next to the thyristors for cracks in the solder. They are soldered flat onto the PCB and solder is very prone to cracking. You could check resistance from the PCB to the coil connector
The circuit will be pretty simple there's an oscillator that's common to all 3, charging a capacitor the the hall effect switch under the rotor triggers the thyristor to dump the charge into the coil. Thyristors are tough they'll be either good or dead. The hall effect switches sometimes get mechanical damage but they don't handle high voltages so unlikely to fail.
Get a multimeter and check the resistance end to end
Re: 1972 Kawasaki 500 H1B
Posted: Tue Jul 15, 2025 9:33 pm
by Skub
Ian wrote: Tue Jul 15, 2025 8:57 pm
Check the blue black and green wires next to the thyristors for cracks in the solder. They are soldered flat onto the PCB and solder is very prone to cracking. You could check resistance from the PCB to the coil connector
The circuit will be pretty simple there's an oscillator that's common to all 3, charging a capacitor the the hall effect switch under the rotor triggers the thyristor to dump the charge into the coil. Thyristors are tough they'll be either good or dead. The hall effect switches sometimes get mechanical damage but they don't handle high voltages so unlikely to fail.
Get a multimeter and check the resistance end to end
No resistance between the blue,black and green wires on the pcb and the coil connector.
Re: 1972 Kawasaki 500 H1B
Posted: Tue Jul 15, 2025 10:43 pm
by Ian
Any signs of mechanical damage to the hall effect switches?
I was going to say if you're handy with a soldering iron swap the thyristor for the centre pot but it looks like some twat has rubbed the numbers off. FFS That really pisses me off.
Re: 1972 Kawasaki 500 H1B
Posted: Tue Jul 15, 2025 11:19 pm
by Skub
Ian wrote: Tue Jul 15, 2025 10:43 pm
Any signs of mechanical damage to the hall effect switches?
I was going to say if you're handy with a soldering iron swap the thyristor for the centre pot but it looks like some twat has rubbed the numbers off. FFS That really pisses me off.
Where are they Ian,I'm not familiar with the term 'hall effect'?
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 7:04 am
by Mr. Dazzle
Don't need to worry particularly about what the hall effect is, it's just sufficient to know it's a physical phenomenon you can use to detect the presence of something by using a wire and a magnet.
Same effect is used in laptops and phone cases to tell when you've shut the lid.
In this case, it's being using to detect when a thing goes past a sensor. They're the sensors which actually 'read' the position of the crank.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 9:22 am
by Skub
Mr. Dazzle wrote: Wed Jul 16, 2025 7:04 am
Don't need to worry particularly about what the hall effect is, it's just sufficient to know it's a physical phenomenon you can use to detect the presence of something by using a wire and a magnet.
Same effect is used in laptops and phone cases to tell when you've shut the lid.
In this case, it's being using to detect when a thing goes past a sensor. They're the sensors which actually 'read' the position of the crank.
Ah yes. The alloy wheel under the rotor bolt has little magnets/sensors which trigger the ignition,it's fitted on with two grub screws and moveable to set the correct timing.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 9:44 am
by Mr. Dazzle
I'd say Ian is definitely on to something though.
Solid State electronics are super robust. "Chips" don't tend to break all that much and when they do they just don't work, there doesn't tend to be much of a middle ground. You probably wouldn't get a weak spark if the switches were bust, you'd just get nothing.
Solder on the other hand frequently fails. As Pietin says, just making the joints shiny again would be a big help.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 9:48 am
by Skub
Maybe nothing to lose at this point. Pointing anything hot at a pcb with my rudimentary soldering skills,is definitely a last resort.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 9:52 am
by Mr. Dazzle
How much is a new Accent?
As Ian says, you can also check the resistance between where the blue/black/green wires touch the PCB and the other end of said wire where it plugs into the coil. Might find the dodgy one just doing that. You'd have to take the PCB out and check between the copper track the wire is connected to and the other end of said wire - but you'll have to take it out to solder anyway.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 9:54 am
by Count Steer
Skub wrote: Wed Jul 16, 2025 9:48 am
Maybe nothing to lose at this point. Pointing anything hot at a pcb with my rudimentary soldering skills,is definitely a last resort.
Step 1: get a
decent soldering iron.
(Depending on how much a new Accent would be).
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 10:14 am
by Skub
Count Steer wrote: Wed Jul 16, 2025 9:54 am
Skub wrote: Wed Jul 16, 2025 9:48 am
Maybe nothing to lose at this point. Pointing anything hot at a pcb with my rudimentary soldering skills,is definitely a last resort.
Step 1: get a
decent soldering iron.
(Depending on how much a new Accent would be).
I have a couple of decent ones,it's me that's the issue.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 10:35 am
by Taipan
Skub wrote: Wed Jul 16, 2025 9:48 am
Maybe nothing to lose at this point. Pointing anything hot at a pcb with my rudimentary soldering skills,is definitely a last resort.
Lightly touch the soldering iron on the blob of solder. Watch it change colour and suddenly become
shiny, think chrome like. Lift soldering iron away. Job Jobbed.
If there is a bare minimum solder on the joints, it is more difficult and you may need to add solder, which is slightly harder but trying to shine teh joint is always worth a go imo.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 10:58 am
by Mr. Dazzle
Much harder these days without good old fashioned lead solder
Fortunately my FiL had loads of it in his garage so I've got a stash.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 11:21 am
by Taipan
Mr. Dazzle wrote: Wed Jul 16, 2025 10:58 am
Much harder these days without good old fashioned lead solder
Fortunately my FiL had loads of it in his garage so I've got a stash.
I haven't used a soldering iron since before my kids were born! I wonder if the loft-of-plenty has reels of lead solder in?
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 12:25 pm
by Count Steer
Mr. Dazzle wrote: Wed Jul 16, 2025 10:58 am
Much harder these days without good old fashioned lead solder
Fortunately my FiL had loads of it in his garage so I've got a stash.
I have a bit of a stash too.
But, tbh, with a temperature controlled iron I've had pretty good results with lead free too.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 12:30 pm
by Eclipse
60/40 (leaded solder) is available pretty much everywhere including Tesco, B&Q and the usual's like Amazon & eBay etc.
I used to repair eBike hub motors for a guy and Hall effect sensors went quite often, possible due to the environment they were in.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 11:09 pm
by Ian
Skub wrote: Tue Jul 15, 2025 11:19 pm
Where are they Ian,I'm not familiar with the term 'hall effect'?
They are the three small black three legged transistor looking things closest to the central hole in the PCB. 120 Deg apart the are covered by the trigger rotor at the end of the crank.
Re: 1972 Kawasaki 500 H1B
Posted: Wed Jul 16, 2025 11:13 pm
by Ian
Skub wrote: Wed Jul 16, 2025 10:14 am
Count Steer wrote: Wed Jul 16, 2025 9:54 am
Skub wrote: Wed Jul 16, 2025 9:48 am
Maybe nothing to lose at this point. Pointing anything hot at a pcb with my rudimentary soldering skills,is definitely a last resort.
Step 1: get a
decent soldering iron.
(Depending on how much a new Accent would be).
I have a couple of decent ones,it's me that's the issue.
Accents are 245 on ZPower
If it's you not the iron, watch a few YouTube vids and practice.
Get good because if you overcook it you can boil the tracks off the PCB. But really 80 percent of people can learn to solder.
Also don't sit there pressing a dry iron against a joint waiting for it to heat up while the components cook. Add a little solder to the tip as you touch it so that the added solder conducts the heat.
Re: 1972 Kawasaki 500 H1B
Posted: Thu Jul 17, 2025 9:55 am
by Skub
Ian wrote: Wed Jul 16, 2025 11:13 pm
Skub wrote: Wed Jul 16, 2025 10:14 am
Count Steer wrote: Wed Jul 16, 2025 9:54 am
Step 1: get a
decent soldering iron.
(Depending on how much a new Accent would be).
I have a couple of decent ones,it's me that's the issue.
Accents are 245 on ZPower
If it's you not the iron, watch a few YouTube vids and practice.
Get good because if you overcook it you can boil the tracks off the PCB. But really 80 percent of people can learn to solder.
Also don't sit there pressing a dry iron against a joint waiting for it to heat up while the components cook. Add a little solder to the tip as you touch it so that the added solder conducts the heat.
I maybe over egged the pudding with the solder thing,I'm not
terrible,just not used to fine stuff,like pcbs,having worked with boys who
were good,I became lazy and left it to them.
It costs me closer to £200 with my triples club discount,so I've bought another Accent. The plan is to send the old one back to Uwe Gottwald in Germany and get him to test it. From what folk tell me,it can take a looooong time. He's currently on holiday for the next month.
It'll be a right laugh if this doesn't solve it...
