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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 81
Registered: 2-2016
Posted on Friday, 12 May, 2017 - 11:57 pm:   Edit PostDelete PostView Post/Check IP

So, tonite I had by first FTP.

I was out to dinner, in horrible traffic, and just as I was waiting for a park (after essentially idling/crawling for 20mins), she cut out.

Got it started, and it cut out after a few seconds again. Luckily I was waiting for someone to leave a parking space, so I pushed it into the space and started poking around.

No backfire, no splutter, just cut out. Engine happy to crank all night long, just not fire. Not even a cough.

Fuel pumps are good, they were rebuilt 3 weeks ago, and sprayed fuel all over the floor when I disconnected the outlet hose.

Coil is luke-warm to touch, nothing out of the ordinary.

Waited 10 mins while I did some quick troubleshooting on the spot, and she started back up and revved cleanly, so I went off to dinner.

30min later, car started right up, and drove fine under various loads for about 10mins until it died again, this time at a 40mph cruise.

Again, it started, but died within a 15 seconds.

Suspecting ignition, I tried the old 'screwdriver in the coil lead', with no spark from the coil. Explains how it just died without dropping individual cylinders.

The 30 min tow truck ride home cooled it enough to back it into the garage. For kicks, I just let it idle; and it lasted 20mins before shutting off.

A few facts:
- When it runs, it runs fine, from idle to high load.
- The coil (likely original Lucas) is hot, but not burningly hot, and no hotter than the dizzy housing or any other engine bay part
- The coil reads 2.5ohm resistance between the +/-, and 5000ohm between the + and HT.
- With Ign ON/engine OFF, the coil is getting 12v.
- The Opus module looks fine, with no visible cracks from looking at it (I haven't pulled the foam off).
- Water temp and oil pressure (senders) are fine; the pressure light doesn't illuminate until the engine dies.

It was serviced 3 weeks ago, where:
- Plugs were replaced
- HT leads were tested, 2 replaced
- Tuned by oscilloscope and exhaust sniffer

One other odd thing I noticed thought.
About half the time when I crank it and it doesn't fire, turning the key from ON to OFF makes the engine kick lightly. Almost like there is a single spark triggered by turning the key to OFF.

Where to from here?

I think a new coil is in order anyway, but how to I check if it's 9v or 12v?

Can the ballast resistor fail once hot?
Same with the Opus unit?
Or the coil? (all at once, not a weak spark?)
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1812
Registered: 6-2006
Posted on Saturday, 13 May, 2017 - 12:08 am:   Edit PostDelete PostView Post/Check IP

Ignition module.

Wish the 1 kick as you turn the key off was at the beginning.

sure fire tell take that the ignition module is switched to earth and not pulsing.
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 82
Registered: 2-2016
Posted on Saturday, 13 May, 2017 - 12:15 am:   Edit PostDelete PostView Post/Check IP

"sure fire tell take that the ignition module is switched to earth and not pulsing

Sorry Paul, not quite following you there.

I'm assuming you're talking about the Opus module?
Are there any simple multimeter/lamp tests I can run to confirm failure?
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1702
Registered: 5-2012
Posted on Saturday, 13 May, 2017 - 12:50 am:   Edit PostDelete PostView Post/Check IP

Hi Jeff

Brian had a similar fault on his car. Turned out to be the Opus unit. The thread is well worth reading through, although it does go off topic in parts.

I can't get the link to work. The subject title of the thread is called "A Christmas FTP!!"

Geoff
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 83
Registered: 2-2016
Posted on Saturday, 13 May, 2017 - 01:21 am:   Edit PostDelete PostView Post/Check IP

"The subject title of the thread is called "A Christmas FTP!!"

Thanks Geoff,

Funny; I acutally had a quick skim over of that thread when I was stuck waiting for the tow truck.

My FTP seems to be slightly different in that there were no backfires, and she starts up 'normally' just fine, choke dependent on temp as usual (no tricky throttle play required).

So initially I'm thinking of replacing:
- Ignition module
- Coil
- Dist. cap & rotor

I know the leads and plugs are all good, so if that doesn't fix it, there's only really the ballast resistor left that might be temperature related, right?

The ignition module, being a big(ger) dollar item, should last another few decades, so throwing money at that isn't AS bad when I think about it that way
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1336
Registered: 9-2004
Posted on Saturday, 13 May, 2017 - 01:38 am:   Edit PostDelete PostView Post/Check IP

IMO the start of the breakdown of the pickup module however worth a short term fix is the closing of the air gap between the "E" shaped core and the timing rotor, mine carried on working till the cold winter weather. Check gap should be about 0.020" but 0.018" will get you going hot or cold.
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 84
Registered: 2-2016
Posted on Saturday, 13 May, 2017 - 01:49 am:   Edit PostDelete PostView Post/Check IP

Thanks Patrick,
I will have a poke around tomorrow and report back on the rotor/sensor gap.

Do these ignition modules have a history of heat related failure modes?

I read somewhere of replacing the coil with a test light, then lining up a ferrite rod with the sensor and heating the lot with a hairdryer to see if there are any effects from heat.
Worthwhile test in your opinion?
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John Beech
Grand Master
Username: jbeech

Post Number: 382
Registered: 10-2016
Posted on Saturday, 13 May, 2017 - 01:49 am:   Edit PostDelete PostView Post/Check IP

Jeff, if you're determined to throw parts at it, I'd begin with the coil because it's cheap, fits the facts, and it's old. If it were the cap and rotor I believe you'd have an engine subject to misfires instead of cutting out dead. And if it turns out to be the Opus, an inexpensive coil purchase only to discover it's the module is lunch money in the equation.
--
John, who is interested in what you learn.
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 85
Registered: 2-2016
Posted on Saturday, 13 May, 2017 - 02:04 am:   Edit PostDelete PostView Post/Check IP

John, you are correct in that the price of a new coil is a fraction of that of the module. It's also probably the only item that I can get locally tomorrow from the parts store, so I will report back after testing with a new coil.

I also agree that a rotor/cap issue would lead to poor running rather than cutting out dead. There's something killing the spark from the coil when things get hot... Just gotta figure out what.

Now, what 'type' of coil should I get? The +ve feed into the coil is 12v with ign ON, so I should get a 12v coil? Just a generic Bosch GT40R red coil?
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 108
Registered: 1-2014
Posted on Saturday, 13 May, 2017 - 03:16 am:   Edit PostDelete PostView Post/Check IP

I agree with Paul, it is the Opus module. I have replaced dozens of them over the years, the symptom of kicking once when the key is turned off is the classic tell tale. Not to say your coil is likely poor too if it's the original. Paul previously posted the test light check on the coil terminals which you should review to check for firing signal from the Opus. Brian also previously posted a link to a site with instructions to repair the Opus module. Search function should find them quickly.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Patrick Francis
Prolific User
Username: jackpot

Post Number: 115
Registered: 11-2016
Posted on Saturday, 13 May, 2017 - 04:12 am:   Edit PostDelete PostView Post/Check IP

Hi Jeff

I have had a coil fail when it gets hot before - quite a common fault?

If you have a ballast resistor, it means that you have a 9v coil that only works on 12v whilst cranking.

If the ballast resistor is faulty the the engine will run whilst cranking only since the ballast resistor is bypassed whilst cranking.

All this is true for a normal non electronic ignition. I have no idea how the Opus system works, or if it even has a ballast resistor as you suggest?

Hope some of this helps....
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Martin Taylor
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Username: martin_taylor

Post Number: 75
Registered: 7-2013
Posted on Saturday, 13 May, 2017 - 09:49 am:   Edit PostDelete PostView Post/Check IP

Don't waste your time on the coil, the opus transistor is getting stuck in the on position, the coil works by creating a spark when the magnetic field collapses or when it is turned off, hence your spark is being generated when you turn the ign off.
With a few small modifications a modern electronic unit can be fitted, they are so cheap I carry a complete spare module in the battery compartment of the car although I doubt I will ever need it. The opus units were rubbish when they were made and gave Rover and Jaguar cars a bad name for failing so often.
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 1532
Registered: 4-2016
Posted on Saturday, 13 May, 2017 - 11:05 am:   Edit PostDelete PostView Post/Check IP

Hi Jeff.

Have a read of this thread I started.
Symptoms sound the same.

It's pretty common in these cars.

http://au.rrforums.net/forum/messages/17001/23452.html?1491048976
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Nick Adlam
Frequent User
Username: crewes_control

Post Number: 100
Registered: 12-2015
Posted on Saturday, 13 May, 2017 - 12:01 pm:   Edit PostDelete PostView Post/Check IP

Hi Jeff

When the engine stops dead, confirm you're still getting 12V to the ballast resistor, if fitted, and the coil. From memory, even OPUS systems used a ballast?.

When working on my Shadow, I found bad connections at the wiring connector blocks at the firewall. The ign circuit passes through the driver's side group, under the fan motor. These are sometimes disturbed when people change plugs, leads, etc- as yours has recently.

Wishful thinking, I know, but it does sound like the dreaded module.
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2291
Registered: 6-2009
Posted on Saturday, 13 May, 2017 - 01:09 pm:   Edit PostDelete PostView Post/Check IP

Jeff,

Just because you haven't experienced a backfire doesn't mean you mightn't if the conditions were right.

I've just hopped on the forum for the first time in a couple of days and I instantly said, "He's got a failed/failing Lucas Opus ignition module!!" Mine is still in my garage and there is no obvious sign that anything is amiss. It's definitely at the electronics level.

Even though you've read it, I'll still post the link to the thread, A Christmas FTP!! . . ., in case future readers are curious.

Not that I did this, as I transplanted the distributor from my SWII into SRH33576, but have a look at, Repairing and Modifying the Lucas Opus Ignition 35DE8 Module, to see if it's of interest to you.

And the Lucas Opus system definitely uses the 9BR ballast resistor block. See this diagram I made regarding the 9BR and its relationship to the other ignition system components. I have still never gone back to confirm wire colors on the incoming connector to the ballast resistor block.

Brian
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 86
Registered: 2-2016
Posted on Saturday, 13 May, 2017 - 01:29 pm:   Edit PostDelete PostView Post/Check IP

Thanks for all the advice and suggestions.

Since I'm doing some yard work today, I'm idling the car (30mins now), hoping I can get it to die and not fire.

I have test leads with a globe ready to tag onto the coil's + & - terminals; and if it then cranks and the light doesn't flash, the problem is BEFORE the coil, right?
I've done the same test cold, and the globe flashes as the ferrite rods come into and out of the sensor's range.

Is there a way to bench test the Opus unit? Could be difficult since the problem only presents when hot.

I hate troubleshooting intermittent issues at home... better than getting stranded though...
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1703
Registered: 5-2012
Posted on Saturday, 13 May, 2017 - 02:39 pm:   Edit PostDelete PostView Post/Check IP

I thought I'd add my thoughts on this, having been in a similar situation myself.

Replace the lot. Less than 200 bucks will buy a new ignition module, a coil, leads, distributor cap and rotor arm. The Opus unit is nearly forty years old and should be replaced anyway. A new ignition module will drive a high output 12v coil and deliver 40kV to the spark plugs. How much better is that. You can also throw away the ballast resister - one less thing to go wrong in the future. This is so much better than buying a new 9v coil to test the Opus unit. If the Opus unit is faulty then the coil will have to be thrown out with it. In my view it is so much better to replace the lot rather than wasting time fault finding a system that is so old it should be replaced anyway.
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 87
Registered: 2-2016
Posted on Saturday, 13 May, 2017 - 03:37 pm:   Edit PostDelete PostView Post/Check IP

The plot thickens...

So the last thing I did last night was to pull out the Opus module to inspect for obvious damage. Not finding any, I just put it back together.

Today, trying to replicate the fault (in order):
- Idle for 60mins (in garage, to get it hot)
- The drive for 60min (30 miles) varying load and speed
- 10min break
- Drive another 15miles on 60mph freeway back home

Not once did the car falter.

Could removing and refitting the Opus module have tightened an intermittent loose connection? Ignition faults never fix themselves...

I'm thinking to replace the lot as per Geoff's suggestion, since the parts are over 40yrs old. Then drive the crap out of it and see what happens.
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 424
Registered: 11-2015
Posted on Saturday, 13 May, 2017 - 03:41 pm:   Edit PostDelete PostView Post/Check IP

Just to be clear, the coil basically sees 9v all the time. The oem starter on a shadow drops the system to 8v on cranking. Then when running the ballast resistor keeps the coil at 9v. A 12v coil might actually throw a weaker spark as it would see 9v on start as well.

Also, I would be cautious with high voltage coils with the HT leads running parallel, touching, and probably overdue for replacement. Crossfire won't make a car FTP, but that's better than fire in the intake.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1340
Registered: 9-2004
Posted on Saturday, 13 May, 2017 - 05:52 pm:   Edit PostDelete PostView Post/Check IP

"Could removing and refitting the Opus module have tightened an intermittent loose connection? Ignition faults never fix themselves..."

Yes IMO, most common for this to happen is a dry joint or item breakdown in the pickup module assembly.
also the air gap between the timing rotor assembly and pickup may have been closed causing a short term cure.
I am not great one for just replacing this and that and not knowing what the fault really was.
Like to get to the real problem!

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Nick Adlam
Prolific User
Username: crewes_control

Post Number: 101
Registered: 12-2015
Posted on Saturday, 13 May, 2017 - 06:33 pm:   Edit PostDelete PostView Post/Check IP

Hi Jeff

Bummer, sounds like you might've inadvertently disturbed the fault and it's now "behaving"....until next time.

If you're getting power to the ballast and coil when the engine dies, then I'm with Geoff W on this one- replace the lot, or go Pertronix/equivalent. Keep the old module/ballast in the boot as a spare. Pertronix will allow you to ditch the factory ballast- another Lucas bugbear.
Nothing worse than cruising in your pride and joy while dreading another FTP, especially in the Aussie countryside. I replaced the entire system on my points-ign Shadow which gives real peace of mind.

As an ex auto-elec, I found that if a module has suffered any form of poor connection, bad earth, open circuit, arcing, etc- it's days were usually numbered. Electronic components might still function at the surface, but can be critically damaged internally- especially transistors. Much like ESD with computers- sure it might boot up afterwards, but 2 months later....
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2292
Registered: 6-2009
Posted on Sunday, 14 May, 2017 - 01:51 am:   Edit PostDelete PostView Post/Check IP

I, also, am not a "lets throw parts at it" sort of solver, but the sort of behavior described has been consistent enough over a period of years to serve as a pretty good diagnostic sign itself once other possibilities have been examined.

I take it as an additional reinforcement of this that Paul Yorke, who's probably worked on more of these cars himself than any of us will work on collectively, instantly went to "ignition module" with no hesitation.

This failure mode, starting out inconsistent sometimes but eventually becoming either consistent after driving or permanent in that the car won't even start, is now pretty well documented.

On my own cars my intention is to leave the transplanted Lucas distributor in SRH33576 and to fit a replacement Mallory optical distributor that was made for the Rolls-Royce application (and is now no longer made) in LRK37110. I still have the old distributor from SRH33576 and if any future custodian wants to fit a new electronic ignition in it and transfer the drive coupling back to it from the Mallory they can easily do so. I'll live with the bright red distributor cap and superior modern technology.

Brian
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Alan Dibley
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Username: alsdibley

Post Number: 57
Registered: 10-2009
Posted on Monday, 15 May, 2017 - 07:23 pm:   Edit PostDelete PostView Post/Check IP

Slightly relevant to this thread, here's a hint from experience elsewhere.

"If a component will not function OK at 100 degrees C it is no use in a car engine compartment."

So for items like spark coils and (particularly Citroen CX) magnetic pick-up sensors, if they go open circuit when put into boiling water they are no use. Same with condensers, but you need a capacity meter. With a bit of imagination the idea can be applied to other things.

Alan D.
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Alan Dibley
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Username: alsdibley

Post Number: 58
Registered: 10-2009
Posted on Monday, 15 May, 2017 - 08:23 pm:   Edit PostDelete PostView Post/Check IP

Perhaps I should have said in my previous post that the method of use is to connect a resistance meter across the terminals and watch the reading as the item comes up to the boil. Coils take a minute or two for the heat to soak through. If it goes infinite or varies by more than a few percent, bin it. (Anyone, what's the percentage variation for copper between room temp and 100 degrees?)

Alan D. - again
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Nick Adlam
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Username: crewes_control

Post Number: 102
Registered: 12-2015
Posted on Wednesday, 17 May, 2017 - 09:31 pm:   Edit PostDelete PostView Post/Check IP

Hi Jeff

Just wondering how you went with this issue?.

I absolutely agree on the wastage that happens with the "throw parts at it" mentality, but I'll admit to being OCD with the ign system. Breakdowns on Aussie country roads aren't fun. I replaced my Shadow's entire ign system, even the relay. I turn the key, it starts.
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Graham Griffiths
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Posted From: 146.90.162.30
Posted on Thursday, 18 May, 2017 - 12:47 am:   Edit PostDelete PostView Post/Check IP

Almost certainly the opus pickup module is faulty. Typically you hear one click/spark from the distributor when turning the ignition key off. To prove attach a spark plug to the centre distributor lead and you should see a single spark. Suggest removing the pickup module take out the earthing bolt give the solder tag a clean refit and ensure it really tight.

I had this problem so produced a web site showing how to repair and test opus 35DE8 module. Repairing and Modifying the ignition pick-up module

http://www.gbg.talktalk.net/

Hope this helps!
Graham

(Message approved by david_gore)
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2299
Registered: 6-2009
Posted on Friday, 19 May, 2017 - 12:11 am:   Edit PostDelete PostView Post/Check IP

Graham,

Great to see "the horse's mouth" drop in here!! I referenced your work back on May 13th, having saved the content of your Lucas 35DE8 repair to a PDF file in case of disappearance from the web (which has happened).

Yours has been the only source of this information that I've ever seen and it's beautifully presented. Thanks much for having taken the time to document this repair as you have.

Brian
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 88
Registered: 2-2016
Posted on Friday, 19 May, 2017 - 11:28 am:   Edit PostDelete PostView Post/Check IP

Thank you everyone for your insights and experience.

The repeated concensus that the single spark when turning the key to OFF being a sign of Opus failure gives me confidence in fixing the problem.

I have since ordered a reconditioned Opus module, coil, rotor and cap from Flying Spares and the old bits are already out of the car waiting for the new parts.

On a side note, does anyone know what that 'extra' lead on the Opus module is? (The one with the rubber boot at the end). I thought mine may have been butchered, but all the pics I find have the same 'dead' lead.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1813
Registered: 6-2006
Posted on Saturday, 20 May, 2017 - 12:45 am:   Edit PostDelete PostView Post/Check IP

A rong connector and boot to go on a condensor bolted to the distributor. A mod that came out on later cars.
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1431
Registered: 5-2015
Posted on Saturday, 20 May, 2017 - 04:27 am:   Edit PostDelete PostView Post/Check IP

I shall just nip into the garage and clean my points
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Graham Griffiths 2
Unregistered guest
Posted From: 37.152.203.87
Posted on Friday, 19 May, 2017 - 11:51 pm:   Edit PostDelete PostView Post/Check IP

The rubber boot, if it has two red/black wires inside would have covered a suppressor capacitor to prevent radio interference and be bolted to the side of the distributor. Some modules had this others did not - is doesn't seem to make any difference!

(Message approved by david_gore)
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1435
Registered: 5-2015
Posted on Monday, 22 May, 2017 - 01:02 am:   Edit PostDelete PostView Post/Check IP

modern radios are far better internally suppressed than the original equipment.

my radio works fine on a bit of copper brake pipe and plastic insulated p clips, fitted under the car.
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Jeff Cheng
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Username: makeshift

Post Number: 90
Registered: 2-2016
Posted on Saturday, 27 May, 2017 - 01:36 am:   Edit PostDelete PostView Post/Check IP

So my parts from Flying Spares came in today, and were fitted in about 45min after a quick bench test.

The old Lucas branded rotor and cap showed some pretty nasty pitting at the contacts, and the centre button was no long round at the tip; but worn flat.

The new ignition module looked good, with the only sign of it being reconditioned (rather than brand new) was the discoloration/yellowing of the plastic housing on the magnetic pickup. The wiring, terminals and solder all looked brand new, as did the PCB.

I took the car for a run into town for dinner; and to be honest; it ran fine, but no different from before, which I guess is a good sign in itself that not much else was wrong in the first place (fingers crossed).

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Brian Vogel
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Username: guyslp

Post Number: 2318
Registered: 6-2009
Posted on Saturday, 27 May, 2017 - 06:24 am:   Edit PostDelete PostView Post/Check IP

Note to those who may be doing what Jeff did in the future: Please photo document the parts that you receive both top side and underside.

At some point I'd love to try overhauling my Lucas distributor based on the guide from Mr. Griffiths but it would also be interesting to see what one shipped out from Flying Spares looks like and to have that on record.

Brian
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Robert Noel Reddington
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Username: bob_uk

Post Number: 1443
Registered: 5-2015
Posted on Saturday, 27 May, 2017 - 07:37 am:   Edit PostDelete PostView Post/Check IP

I guess as electronic systems age they fail eventually.
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Jeff Cheng
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Username: makeshift

Post Number: 91
Registered: 2-2016
Posted on Saturday, 27 May, 2017 - 09:23 pm:   Edit PostDelete PostView Post/Check IP

Since Brian mentioned documenting parts, here are some pics I snapped of the new (and old) bits.

New/reconditioned from Flying Spares (left) vs old Lucas module. All the wiring, components, terminals and PCB were clearly new. All solder joints looked new as expected. The only signs of it not being a NOS unit is the discoloration on the plastic pickup housing. There were no reused components, and if you cover up the pickup housing and it could pass as new.

lucas front

lucas back

Here are some of the close up solder joints on my old unit. I'm not surprised it caused issues in the end.

lucas old1

lucas old 2

N.B. if the 640x480 forum sizing makes the details tricky to make out, I've been keeping similar updates of my Shadow ownership on another forum, with bigger images, if anyone is interested. A lot more general than this forum though.
http://forums.vwvortex.com/showthread.php?8402705-An-average-guy-s-76-Rolls-Royce-ownership-experience-thread


On a brighter note; the Minister of War & Finance, her folks and I went for a nice cruise a few towns over today.
Aside from a longer shakedown, it was a good chance to squeeze some last drives before the crappy weather, and take in the pretty autumn colors.

60 smooth freeway miles today, and I think I can say with confidence that the old module was the cause of my issues, and would like to thank everyone here for sharing their wealth of knowledge for a quick diagnosis and solution.

autumn
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Jeff Young
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Username: jeyjey

Post Number: 353
Registered: 10-2010
Posted on Saturday, 27 May, 2017 - 11:18 pm:   Edit PostDelete PostView Post/Check IP

It's surprising they didn't clean the flux off those solder joints, but I'd still bet the culprit is that big transistor having seen one too many temperature cycles.

Cheers,
Jeff.
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Jeff Cheng
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Username: makeshift

Post Number: 92
Registered: 2-2016
Posted on Sunday, 28 May, 2017 - 01:05 am:   Edit PostDelete PostView Post/Check IP

Jeff,
You are most likely correct about the transistor heat cycling.

Electronics are not my strong point, so I just jump to conclusions based on what I can see in front of me. I can trace wiring diagrams, but anything resembling to a chip/transistor may as well be voodoo magic to me.

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Brian Vogel
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Username: guyslp

Post Number: 2319
Registered: 6-2009
Posted on Sunday, 28 May, 2017 - 11:05 am:   Edit PostDelete PostView Post/Check IP

Now the question is what did they use to replace that transistor. The new cases look extremely similar, so if you can't see the markings (and I think they're face down) it's hard to know what it is.

I'll have to look at what's on my Lucas unit and see what it cross-references to.

Thanks Mr. Cheng!

Brian
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Alan Dibley
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Username: alsdibley

Post Number: 59
Registered: 10-2009
Posted on Sunday, 28 May, 2017 - 05:23 pm:   Edit PostDelete PostView Post/Check IP

Brian, the markings are not face-down - the other side is a metal heat-sink face. The markings are on the black face but either very dim (not unusual) or deliberately obliterated (also not unusual). It could be any one of scores of suitable components costing a few shillings.

Alan D.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1369
Registered: 9-2004
Posted on Sunday, 28 May, 2017 - 08:12 pm:   Edit PostDelete PostView Post/Check IP

John this is some numbers of the different units
The pixs are of the clapped 50 year old unit unless it has been replaced in the past.
Hope they help you with your quest.





Paint removed


The first letter is a W.






The printed circut seems ok the flux was still in place but no failing on the joints.
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 93
Registered: 2-2016
Posted on Sunday, 28 May, 2017 - 11:13 pm:   Edit PostDelete PostView Post/Check IP

Brian,
Here are some close-ups of my new/recon'd and old units if it helps. They are zoomed in from my original photos.

The new unit, there is no writing on the top of the square black chip.
lucas new

Notice the big round thing (at 6 o'clock on the new pic and 12 on the old) is 'filled' on the new unit, but a blank hole on the old unit.

Comparing the hand engraving on my old unit below, combined with the non-Lucas branded transistor could indicate it had also been a replacement at some point...?
lucas old

More on the reconditioned unit from Flying Spares; the only visual faults I could find were the discolored pickup housing (I guess it's just plastic) and the 'messy' application of the white insulation material, clearly hand molded and applied, with fingerprints in it. It's texture is similar to a stiff caulk/silicone.
Everything else I could find looked to be new. I removed the large circlip to make sure the pickup 'slider' for the vacuum retard was adequately lubricated, and found they had used a new spring/wave washer and fresh copper grease. The entire unit was clean of oil/grease residue, as if it were new.
Visually, I'm quite pleased with the Flying Spares unit, but at 300 before exchange, I would expect to be.
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2320
Registered: 6-2009
Posted on Monday, 29 May, 2017 - 02:21 am:   Edit PostDelete PostView Post/Check IP

I'll have to take photos and post of mine when I get a chance.

The BU931Z transistor is dirt common, and that bit helps a lot. This is almost certainly what is in the contemporary "black blade" case.

Brian
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1370
Registered: 9-2004
Posted on Monday, 29 May, 2017 - 03:38 am:   Edit PostDelete PostView Post/Check IP

Brian and this one for the transistor listed in my old unit.
"Details, datasheet, quote on part number: Part number BU323A
Category Discrete => Transistors => Bipolar => Darlington
Description NPN Silicon Power Darlington Transistor
Company Motorola Semiconductor Products"
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1371
Registered: 9-2004
Posted on Monday, 29 May, 2017 - 03:45 am:   Edit PostDelete PostView Post/Check IP

Next is the Lucas 83447----646mov or has the pick up module been up dated????????????????
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Graham Griffiths
Yet to post message
Username: cineprojectorman

Post Number: 1
Registered: 5-2017
Posted on Thursday, 01 June, 2017 - 05:09 am:   Edit PostDelete PostView Post/Check IP

The Lucas 83447 is a press fit negative package protection diode - see attached diagram. The nearest match I can find is a S2404N or Delco 1958826 or D3916
The later 5EM module did not require the diode as it is contained within the large transistor. Hence the hole! The protection diode routes any reverse voltage around the transistor, thereby protecting it.

When I refurbished my module I disconnected the diode and used a BU941ZP Darlington transistor

http://www.gbg.talktalk.net


Graham


Negative package press fit diode
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Randy Roberson
Grand Master
Username: wascator

Post Number: 731
Registered: 5-2009
Posted on Thursday, 01 June, 2017 - 05:28 am:   Edit PostDelete PostView Post/Check IP

Replaced mine with a Pertronix. Simple as pie and knowing the Lucas was probably original (1977) made me decide it was timely to replace it, throwing parts at it or preventative maintenance?
I did keep the old module and associated parts, though.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1377
Registered: 9-2004
Posted on Thursday, 01 June, 2017 - 05:54 am:   Edit PostDelete PostView Post/Check IP

Graham, many thanks for the info.
I have also kept my car original on the Opus system when the unit packed up a few years ago.
I will repair my old unit and keep as a spare in the car.

IMO problems arrive for the owners further down the line in years to come when the non original units break down, folk won't know what's what.

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