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Discussion Starter #1
Could any one help me where I can find ignition condenser for 1973 450SL.
The old one Bosch # is 1 237 330 203.
The wire from condenser to connecter is broken off and is missing. I was wandering if I could solder a wire to condenser. However, i am not sure if that may damage it or how I can test it if is functioning condenser.
If is just a larger resistor than what is the resistance?
 

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A condenser is not a resistor... think of it more as a shock absorber for electricity.
You can do a pretty good test of the capacitor using an ohm meter. Place the meter scale on 1x or 10x and measure the resistance. It doesn't really matter what resisteance you read (as long as it isn't dead short), now reverse the leads... you should see the meter swing from zero and then slowly rise to full scale. What you are actually seeing is the capacitor charging up. Each time you reverse the leads you should see the same result... the meter swings from zero ohms to infinity ohms (on a low scale) as the condenser charges. If you see that then the condenser is very likely good. I should have said up front that this test works much better on a meter with a needle scale and not so good on a DVM (digital volt meter).

It will not harm the capacitor to solder a new lead onto it unless you get it ridiculously hot in the process. A normal solder job will be fine.

Good luck.

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Discussion Starter #4
A condenser is not a resistor... think of it more as a shock absorber for electricity.
You can do a pretty good test of the capacitor using an ohm meter. Place the meter scale on 1x or 10x and measure the resistance. It doesn't really matter what resisteance you read (as long as it isn't dead short), now reverse the leads... you should see the meter swing from zero and then slowly rise to full scale. What you are actually seeing is the capacitor charging up. Each time you reverse the leads you should see the same result... the meter swings from zero ohms to infinity ohms (on a low scale) as the condenser charges. If you see that then the condenser is very likely good. I should have said up front that this test works much better on a meter with a needle scale and not so good on a DVM (digital volt meter).

It will not harm the capacitor to solder a new lead onto it unless you get it ridiculously hot in the process. A normal solder job will be fine.

Good luck.

.
Thank you. So it is Capacitor.
 

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Discussion Starter #5
I thought MB said you can leave it disconnected. I have same year and mine was cut off.
It became an issue after replacing the injectors. I do not know if it was coincident or actually caused the engine run only on 4. Tested the Trigger points(pulse generator) and was ok. except one out of four points failed on bench inside the distributor but all them tested ok outside distributor. I was lucky to find a good used distributor on ebay. problem was solved.
When compared this new used with the existing, the wire from condenser did exist. It is possible existing trigger was bad and nothing to do with condenser. I guess I could swap them for verification.

I seen on youtube or heard that wire could be cut. But why? I know in all other cars, engine will not run without it.
 

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It can be removed. Most have been or have at least been disconnected by dealers or owners. The points in your car run at low voltage, Other cars run at full 12V and the condenser is there to reduced burning of the points. Not needed on your Mercedes.
 

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Discussion Starter #7
It can be removed. Most have been or have at least been disconnected by dealers or owners. The points in your car run at low voltage, Other cars run at full 12V and the condenser is there to reduced burning of the points. Not needed on your Mercedes.
Thanks. Now most probably it was the old trigger points were faulty.
 

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The condenser (capacitor, the terms are virtually interchangeable) also eliminates or greatly reduces switch bounce. I see no advantage in disconnecting it. While it's true that at lower voltages there is less strain on the points, the points still remain suseptible to switch bounce.
 

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It became an issue after replacing the injectors. I do not know if it was coincident or actually caused the engine run only on 4. Tested the Trigger points(pulse generator) and was ok. except one out of four points failed on bench inside the distributor but all them tested ok outside distributor. I was lucky to find a good used distributor on ebay. problem was solved.
When compared this new used with the existing, the wire from condenser did exist. It is possible existing trigger was bad and nothing to do with condenser. I guess I could swap them for verification.

I seen on youtube or heard that wire could be cut. But why? I know in all other cars, engine will not run without it.
So it sounds like the replacement distributor gives you good fuel but bad spark. Am I understanding correctly?

Have you adjusted the points (with a dwell meter, and then adjusted the timing)?

I doubt your problem is the condenser as everyone says, most have been cut. Even if your ignition system is not stock, the points would work for at least a while, and spark would fail equally on all cylinders, not just four of them when the points start to burn up from high voltage being run through them. Honestly I’m not sure what the condenser does. But...

Maybe we should ask if you are running a stock ignition setup or if you have some alterations? I’ve seen a lot of cars where people rip out the MB low voltage system and get the car running by using the points like a high voltage system, resulting in cooked points.


Sent from my iPhone using Tapatalk
 

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So it sounds like the replacement distributor gives you good fuel but bad spark. Am I understanding correctly?

Have you adjusted the points (with a dwell meter, and then adjusted the timing)?

I doubt your problem is the condenser as everyone says, most have been cut. Even if your ignition system is not stock, the points would work for at least a while, and spark would fail equally on all cylinders, not just four of them when the points start to burn up from high voltage being run through them. Honestly I’m not sure what the condenser does. But...

Maybe we should ask if you are running a stock ignition setup or if you have some alterations? I’ve seen a lot of cars where people rip out the MB low voltage system and get the car running by using the points like a high voltage system, resulting in cooked points.


Sent from my iPhone using Tapatalk
... and a tachometer that goes nuts...
 

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The condenser (capacitor, the terms are virtually interchangeable) also eliminates or greatly reduces switch bounce. I see no advantage in disconnecting it. While it's true that at lower voltages there is less strain on the points, the points still remain suseptible to switch bounce.
Jyuma,
The recommendation to eliminate the condenser comes right out of the MB shop manual 07.5 503/2. A shielded control line without condenser is used instead. Many of our early cars had that done when being serviced by dealers.

These days, a much better plan, is to replace the points with a Pertronix 1885. No points, no condenser, no shielded cable - life is good :)

Switch bounce could be of interest to us d-jetters. We often have problems when trigger point fibre rubbing blocks start to wear. The points should just open and close to form a single pulse. But in some cases we get overly rich mixtures. These could possibly be due to the ECU seeing multiple pulses. But this is a different subject so will leave it there.

Explanation of Switch bounce: https://circuitdigest.com/electronic-circuits/what-is-switch-bouncing-and-how-to-prevent-it-using-debounce-circuit
 

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Jyuma,
The recommendation to eliminate the condenser comes right out of the MB shop manual 07.5 503/2. A shielded control line without condenser is used instead. Many of our early cars had that done when being serviced by dealers.

These days, a much better plan, is to replace the points with a Pertronix 1885. No points, no condenser, no shielded cable - life is good :)

Switch bounce could be of interest to us d-jetters. We often have problems when trigger point fibre rubbing blocks start to wear. The points should just open and close to form a single pulse. But in some cases we get overly rich mixtures. These could possibly be due to the ECU seeing multiple pulses. But this is a different subject so will leave it there.

Explanation of Switch bounce: https://circuitdigest.com/electronic-circuits/what-is-switch-bouncing-and-how-to-prevent-it-using-debounce-circuit
Having been involved in the electronics industry my entire life (well, from age 12 on) I'm thoroughly familiar with switch bounce. I'm more interested in this notion that removing the capacitor from the circuit represents an improvement... of does it? Are you aware of the reason MB recommends removing the cap or is it simply superflous and of no concequence either way? :)
 

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Jyuma,
I am not privy to the thinking of Mercedes/Bosch engineers ;) All I know, is that many of the condensers were disconnected.

On conventional points ignition systems, they were there because the points were connected directly to the coil primary. This link describes why the condenser was needed.

excerpt:
"Arcing is caused by the effect of self induction in the coil as the points interrupt the flow of current. The resultant collapse of the magnetic field produces a high voltage to be generated in the primary winding which then tends to flow across the points, thus causing burning or pitting. "
There is a lot going on in points systems, so perfect square wave with no "switch bounce" probably unlikely ?

This Pagoda article gives a good description of how the transistorized ignition system on our Djets evolved. With transistorized ignition, the points are not connected directly to the coil.


It says:
"The current through the points is extremely small (thousandths of an Ampere or milli-amperes) instead of 4-5 Amperes as seen in a non-transistorized system."
The points are not connected to the coil, so the arcing described in the first link likely does not occur (to same extent)

Initially, the condensers were retained. But they must have been found unnecessary or troublesome? They didn't have to be disconnected, but it was the recommended solution. The green shielded wire was then needed. The electrical switch bounce you speak of is not mentioned. Mechanical Points bounce is ;)

As someone who understand electronics, the switchgear diagram might be of interest. Maybe it compensates for your switch bounce?

 

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Jyuma,
I am not privy to the thinking of Mercedes/Bosch engineers ;) All I know, is that many of the condensers were disconnected.

On conventional points ignition systems, they were there because the points were connected directly to the coil primary. This link describes why the condenser was needed.

excerpt: "Arcing is caused by the effect of self induction in the coil as the points interrupt the flow of current. The resultant collapse of the magnetic field produces a high voltage to be generated in the primary winding which then tends to flow across the points, thus causing burning or pitting. "

There is a lot going on in points systems, so perfect square wave with no "switch bounce" probably unlikely ?

This Pagoda article gives a good description of how the transistorized ignition system on our Djets evolved. With transistorized ignition, the points are not connected directly to the coil.


It says: "The current through the points is extremely small (thousandths of an Ampere or milli-amperes) instead of 4-5 Amperes as seen in a non-transistorized system." The points are not connected to the coil, so the arcing described in the first link does not occur.

Initially, the condensers were retained. But they must have been found unnecessary or troublesome? They didn't have to be disconnected, but it was one recommended solution. The green shielded wire was then needed. The electrical switch bounce you speak of is not mentioned. Mechanical Points bounce is ;)

As someone who understand electronics, the switchgear diagram might be of interest. Maybe it compensates for your switch bounce?

Interesting. But I'm left to wonder what is meant by "They didn't have to be disconnected, but it was one recommended solution". Solution to what?

Thank you for the diagram, it was very helpful, although one interesting point... the diagram shows the condenser. hehehe?

No worries... I'm the type that always needs to know "why". I have no doubrt that you an others are correct... I just don't know why. :)
 

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Interesting. But I'm left to wonder what is meant by "They didn't have to be disconnected, but it was one recommended solution". Solution to what?

Thank you for the diagram, it was very helpful, although one interesting point... the diagram shows the condenser. hehehe?

No worries... I'm the type that always needs to know "why". I have no doubrt that you an others are correct... I just don't know why. :)
Section 503 of the manual that I referred to in an earlier post explains WHY the condenser was to be removed. It is part of solution to coatings forming on the points even with transistorized ignition. I was wrong about removing the condenser being one solution. Re-reading it, I think it says install new points AND replace the condenser with a shielded cable.

The cause of the coating appears to be higher intensity arcs caused by smaller gaps and discharge of the condenser.

The diagram probably shows the condenser because there was one installed originally! hehehe?

Whatever, anyone with one of these cars should remove the condenser AND the points and install a Pertronix just as a points replacement. If the switchgear is faulty, then by-pass that (info in Sticky or Peachparts or another site that is under development :) )
 

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Discussion Starter #16
So it sounds like the replacement distributor gives you good fuel but bad spark. Am I understanding correctly?

Have you adjusted the points (with a dwell meter, and then adjusted the timing)?

I doubt your problem is the condenser as everyone says, most have been cut. Even if your ignition system is not stock, the points would work for at least a while, and spark would fail equally on all cylinders, not just four of them when the points start to burn up from high voltage being run through them. Honestly I’m not sure what the condenser does. But...

Maybe we should ask if you are running a stock ignition setup or if you have some alterations? I’ve seen a lot of cars where people rip out the MB low voltage system and get the car running by using the points like a high voltage system, resulting in cooked points.


Sent from my iPhone using Tapatalk
Sorry for late reply. It was running on 4. However, getting spark on all 8. The injectors were replaced. I narrowed it to Trigger points(Pulse generator). They were checked out ok outside of the distributor. Yet inside the distributor on the bench test, one was failing. replacement distributor came with a Trigger point. Now,It is running o.k. The replaced distributor unlike old one had a wire to pigtail. My understanding is now is the none existence of wire would not cause an issue. Problem was the old Trigger point.
 

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Discussion Starter #17
Jyuma,
The recommendation to eliminate the condenser comes right out of the MB shop manual 07.5 503/2. A shielded control line without condenser is used instead. Many of our early cars had that done when being serviced by dealers.

These days, a much better plan, is to replace the points with a Pertronix 1885. No points, no condenser, no shielded cable - life is good :)

Switch bounce could be of interest to us d-jetters. We often have problems when trigger point fibre rubbing blocks start to wear. The points should just open and close to form a single pulse. But in some cases we get overly rich mixtures. These could possibly be due to the ECU seeing multiple pulses. But this is a different subject so will leave it there.

Explanation of Switch bounce: https://circuitdigest.com/electronic-circuits/what-is-switch-bouncing-and-how-to-prevent-it-using-debounce-circuit
Thanks useful info.
 

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Discussion Starter #18
Jyuma,
I am not privy to the thinking of Mercedes/Bosch engineers ;) All I know, is that many of the condensers were disconnected.

On conventional points ignition systems, they were there because the points were connected directly to the coil primary. This link describes why the condenser was needed.

excerpt:

There is a lot going on in points systems, so perfect square wave with no "switch bounce" probably unlikely ?

This Pagoda article gives a good description of how the transistorized ignition system on our Djets evolved. With transistorized ignition, the points are not connected directly to the coil.


It says:The points are not connected to the coil, so the arcing described in the first link likely does not occur (to same extent)

Initially, the condensers were retained. But they must have been found unnecessary or troublesome? They didn't have to be disconnected, but it was the recommended solution. The green shielded wire was then needed. The electrical switch bounce you speak of is not mentioned. Mechanical Points bounce is ;)

As someone who understand electronics, the switchgear diagram might be of interest. Maybe it compensates for your switch bounce?

Should I assume this was not the issue in my case. Since the wire from condenser was missing in old distributer and replacement distributor did have shielded green wire and now all 8 is running. As I said initially, I could swap the Trigger points between the two distributors to verify that problem was the old Trigger point and existence of the condenser wire in replacement distributer was just a coincident.

When I tested original T.points with multimeter they tested o.k. However, when T.point installed into the distributer, one out of four was shorted regardless of the turning distributer shaft. I think its wire maybe shorted at the wire terminal on the side of distributer. Does anyone had a similar issue, and possible repair short of getting a replacement T.points. I would like to fix it and have it as spare. They are hard to come by and expensive.
 
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