Re: [MBZ] 1985 300SD new problem
I'll second that thought. Would that also manifest itself as a measurable AC waveform on top of the expected DC voltage? (I would also expect that it would kill batteries) -- John W Reames jwrea...@comcast.net Home: +14106646986 Mobile: +14437915905 On Nov 29, 2010, at 11:02, Jim Cathey j...@windwireless.net wrote: Something new, at least for me, when I turn the key to the off position and remove the key, the battery light comes on and stays on until battery is dead. One or more bad diodes in the alternator? -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
I'll second that thought. Would that also manifest itself as a measurable AC waveform on top of the expected DC voltage? (I would also expect that it would kill batteries) If you had a o`scope, you would be able to see the ac and dc waveforms, but a multimeter will just average the readings. A small amount of AC (ripple) is normal and hurts nothing. Larger amounts indicate bad diodes. There are a lot of large diodes in a altenator. Just one shorted out can cause a battery drain. AC is only present when alternator is rotating. When rotating AC is converted to DC by the diode bank. The voltage regulator then clips the high voltage down to aroud 14 volts. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
Would that also manifest itself as a measurable AC waveform on top of the expected DC voltage? I'd expect so, but I've never had a scope available at the same time as a bad alternator to prove this out. In theory the AC ripple voltage would be higher too so that you could use a decent multimeter (like a Fluke) to diagnose this, but I've no proof, nor an idea of the magnitude of difference. The frequency of the ripple ought to measure differently, too. (Again, on a Fluke.) Be the first to document a case, and win our undying gratitude! -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
Umm I thought that most VOM/DVM's had a capacitor in series with the input... This ensures that only the ac component is measured. -- John W Reames jwrea...@comcast.net Home: +14106646986 Mobile: +14437915905 On Nov 30, 2010, at 8:57, Mike Gildea mikgi...@verizon.net wrote: I'll second that thought. Would that also manifest itself as a measurable AC waveform on top of the expected DC voltage? (I would also expect that it would kill batteries) If you had a o`scope, you would be able to see the ac and dc waveforms, but a multimeter will just average the readings. A small amount of AC (ripple) is normal and hurts nothing. Larger amounts indicate bad diodes. There are a lot of large diodes in a altenator. Just one shorted out can cause a battery drain. AC is only present when alternator is rotating. When rotating AC is converted to DC by the diode bank. The voltage regulator then clips the high voltage down to aroud 14 volts. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
Umm I thought that most VOM/DVM's had a capacitor in series with the input... This ensures that only the ac component is measured. True, to a point. Don`t expect much from a Harbor Freight type of meter. Depends on the quality (price) of the multimeter (DVM/VOM). More expensive meters do a better job. But for automotive use, were are primarly stuck with the cheaper units. Very little AC involved. Cheaper and older units use averaging counting methods as opposed to the more sophisticated sampling methods. They average highs and lows without displaying the deviation. You don`t know when there has been a dip or a spike . Peak/hold meters (higher end more expensive meters) capture and hold and then display the highest/lowest reading, instead of averaging. They can be programmed for specific hi and low variations. Some even have print outs over a specified time period. (ie power line monitors) This works well for capturing digital pulses, spikes, circuit loading. Fluke, as you are probably aware of, makes both high quality and mid quality units. A few low end units. One of their models is made for auto technicians. Most of their models are designed for touchy computer circuits. They also have one sweet digital display unit that gives digital readouts and also shows waveforms in a compact handheld device. Kind of like a handheld digital o`scope. Nice, but very very pricey. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
One of the MB manual CDs includes o'scope shots of various wave forms that let you differentiate between the two diode sets - peaks up or down - to isolate which ones are bad. I think I saw it in the 124 set. On Tue, Nov 30, 2010 at 8:11 AM, Jim Cathey j...@windwireless.net wrote: Would that also manifest itself as a measurable AC waveform on top of the expected DC voltage? I'd expect so, but I've never had a scope available at the same time as a bad alternator to prove this out. In theory the AC ripple voltage would be higher too so that you could use a decent multimeter (like a Fluke) to diagnose this, but I've no proof, nor an idea of the magnitude of difference. The frequency of the ripple ought to measure differently, too. (Again, on a Fluke.) Be the first to document a case, and win our undying gratitude! -- Jim-- OK Don 2001 ML320 1992 300D 2.5T 1990 300D 2.5T 1997 Plymouth Grand Voyager ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
The frequency of the ripple should be calculably related to engine rpm (consider pulley diameters...) iirc some manufacturers used an AC output from an alternator as a tach sensor... -- John W Reames jwrea...@comcast.net Home: +14106646986 Mobile: +14437915905 On Nov 30, 2010, at 9:11, Jim Cathey j...@windwireless.net wrote: Would that also manifest itself as a measurable AC waveform on top of the expected DC voltage? I'd expect so, but I've never had a scope available at the same time as a bad alternator to prove this out. In theory the AC ripple voltage would be higher too so that you could use a decent multimeter (like a Fluke) to diagnose this, but I've no proof, nor an idea of the magnitude of difference. The frequency of the ripple ought to measure differently, too. (Again, on a Fluke.) Be the first to document a case, and win our undying gratitude! -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
Yeah the scopemeters are neat. The 87/89 and (slightly upgraded) renumbered brethren (189) can simultaneously display an ac voltage and it's measured dc offset. It can also do duty cycle... -- John W Reames jwrea...@comcast.net Home: +14106646986 Mobile: +14437915905 On Nov 30, 2010, at 11:27, Mike Gildea mikgi...@verizon.net wrote: Umm I thought that most VOM/DVM's had a capacitor in series with the input... This ensures that only the ac component is measured. True, to a point. Don`t expect much from a Harbor Freight type of meter. Depends on the quality (price) of the multimeter (DVM/VOM). More expensive meters do a better job. But for automotive use, were are primarly stuck with the cheaper units. Very little AC involved. Cheaper and older units use averaging counting methods as opposed to the more sophisticated sampling methods. They average highs and lows without displaying the deviation. You don`t know when there has been a dip or a spike . Peak/hold meters (higher end more expensive meters) capture and hold and then display the highest/lowest reading, instead of averaging. They can be programmed for specific hi and low variations. Some even have print outs over a specified time period. (ie power line monitors) This works well for capturing digital pulses, spikes, circuit loading. Fluke, as you are probably aware of, makes both high quality and mid quality units. A few low end units. One of their models is made for auto technicians. Most of their models are designed for touchy computer circuits. They also have one sweet digital display unit that gives digital readouts and also shows waveforms in a compact handheld device. Kind of like a handheld digital o`scope. Nice, but very very pricey. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
- Original Message - From: OK Don okd...@gmail.com One of the MB manual CDs includes o'scope shots of various wave forms that let you differentiate between the two diode sets - peaks up or down - to isolate which ones are bad. I think I saw it in the 124 set. _okiebenz.com Years ago there was a article in the star magazine about adapting a old suplus CRT type O scope for use on the Benzes electrical and ignition, It was intresting reading. Old analog scopes can be found cheap now days. I`ve played with my vintage Heathkit Auto analyzer scope on old delco alternators but never on the benzes. But alternators are very much alike in principle and theory. Not much use on a D or SD. Now i just use it on the old Beemer motorcycle or boat engine. No more cars with ignition systems. My heathkit manuals have a lot of photos of the wave froms and explain them in great detail (point ignition systems prior to Hall Effect and HEI ignitions). ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
[MBZ] 1985 300SD new problem
Something new, at least for me, when I turn the key to the off position and remove the key, the battery light comes on and stays on until battery is dead. If any of you guys or dolls have any thoughts as to what might be causing this situation, your thoughts would be most appreciated. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
I really don't have a clue - but I would start by disconecting the Alt and seeing if the light goes out. How long does it take to kill the battery? Peter On Mon, Nov 29, 2010 at 9:09 AM, John P. English johnpengl...@hotmail.comwrote: Something new, at least for me, when I turn the key to the off position and remove the key, the battery light comes on and stays on until battery is dead. If any of you guys or dolls have any thoughts as to what might be causing this situation, your thoughts would be most appreciated. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
Peter, I takes about 24 hrs. -- From: Peter Hertzing phertz...@gmail.com Sent: Monday, November 29, 2010 9:12 AM To: Mercedes Discussion List mercedes@okiebenz.com Subject: Re: [MBZ] 1985 300SD new problem I really don't have a clue - but I would start by disconecting the Alt and seeing if the light goes out. How long does it take to kill the battery? Peter On Mon, Nov 29, 2010 at 9:09 AM, John P. English johnpengl...@hotmail.comwrote: Something new, at least for me, when I turn the key to the off position and remove the key, the battery light comes on and stays on until battery is dead. If any of you guys or dolls have any thoughts as to what might be causing this situation, your thoughts would be most appreciated. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
Something new, at least for me, when I turn the key to the off position and remove the key, the battery light comes on and stays on until battery is dead. If any of you guys or dolls have any thoughts as to what might be causing this situation, your thoughts would be most appreciated. Check altenator diodes, windings, brushes, alt wiring harness ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 1985 300SD new problem
Something new, at least for me, when I turn the key to the off position and remove the key, the battery light comes on and stays on until battery is dead. One or more bad diodes in the alternator? -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
