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Low ESR (effective series resistance) when the cap is supplying current to maintain a power supply, you don't want any internal volt drop due to cheap materials/construction
Its a measure of quality for the job. The Nichicons are 150mOhms so only 150mV drop for a 1A draw
I am installing bucket seats so already all of the hard work to get access to the unit was done so replaced the caps earlier this week. Was an easy job if you know how to solder with a pencil iron on an electrical board.
In terms of performance, I think there is about 5-10 feet more range and what is noticeable is that now that I point the fob at the car it will lock or unlock with one button click on the fob. I used to have a click a few times on the fob pointing the fob at different angles or walk closer. I know this is a subjective comment... seems to "work" better.
Samurai -thanks for trying this and the feed back. A couple questions....
- You said improvement was 5-10 feet but what is the range now compared to before? (I went from ~5 to ~50ft)
- Was the improvement due solely to the cap change or did you also change FOB battery?
- Did you use the recommended Digikey parts?
- Did you use any board cleaner on the radio circuit after the swap?
BTW, I also notice the "only takes one button click" improvement.
Looks like we have the same board. I recently got a set of schematics from a fellow Rennlister and noticed schematic (sheet 2) shows 31 connections going to this device, whereas our boards only have 24 pins. The schematic set I'm using is titled "911 Carerra (993) Model 95". Do you know if there are updated ones covering our 97's?
Samurai - Do you remember what the connector(s) looked like going to the back of the box? Was it 1 or 2? I can't recall on mine. Below is a snippet of the page 2 "95" schematic I'm using which clearly shows 2 connectors going to the box: Plug 1 (15 pin) and Plug 2 (26 pin), which obviously doesn't jive with our hardware. Anyone have the correct schematic for 97's?
My original range was about 30-35 feet. I could only get a measurement from the front of the car as my car was on jack stands in the garage and it was raining outside so I measured between the car and inside the hallway of my house with line of sight of the front head light and driver door through my garage door. I did not have the driver seat installed in the car when I measured.
I did not change the FOB battery.
I used the Digikey parts.
I did not clean the board as the board is enclosed in a plastic housing that sealed enough and looked clean to me. It was not like an audio amp where venting would cause dust to enter the unit.
My unit had one connector going into it. There is another female interface that was not used.
Overall, range increased slightly, but as I mentioned earlier it just now "works". Now I have to find someone with a hammer to activate the headlight flash on lock/unlock as I don't have that turned on my car.
You are confused.... The portion of the wiring diagram that you are referencing shows the connectors on the alarm module, which is located under the passenger seat. The immobilizer (which contains the receiver) only has one connector, and it is located under the drivers seat (as you already know).
The immobilizer is shown on sheet 17 of the wiring diagram. There is very little information about the interface with the immobilizer, as one would expect. The main signals are the "Prime" and "Unprime", which are connected to the Alarm module.
FWIW, I find it hard to believe that using a lower ESR cap in the receiver could cause such a dramatic improvement, unless the original cap had essentially failed.
Edited to add: The flashing of the lights is controlled by the Alarm module, not the immobilizer...
Originally Posted by Jay777
Samurai - Do you remember what the connector(s) looked like going to the back of the box? Was it 1 or 2? I can't recall on mine. Below is a snippet of the page 2 "95" schematic I'm using which clearly shows 2 connectors going to the box: Plug 1 (15 pin) and Plug 2 (26 pin), which obviously doesn't jive with our hardware. Anyone have the correct schematic for 97's?
You are confused.... The portion of the wiring diagram that you are referencing shows the connectors on the alarm module, which is located under the passenger seat. The immobilizer (which contains the receiver) only has one connector, and it is located under the drivers seat (as you already know). The flashing of the lights is controlled by the Alarm module, not the immobilizer...
Correct
Originally Posted by Ivan J
FWIW, I find it hard to believe that using a lower ESR cap in the receiver could cause such a dramatic improvement, unless the original cap had essentially failed.
Valid point
Hopefully, no one damages their immobilizer attempting the mod.
You are confused.... The portion of the wiring diagram that you are referencing shows the connectors on the alarm module, which is located under the passenger seat. The immobilizer (which contains the receiver) only has one connector, and it is located under the drivers seat (as you already know).
The immobilizer is shown on sheet 17 of the wiring diagram. There is very little information about the interface with the immobilizer, as one would expect. The main signals are the "Prime" and "Unprime", which are connected to the Alarm module.
FWIW, I find it hard to believe that using a lower ESR cap in the receiver could cause such a dramatic improvement, unless the original cap had essentially failed.
Edited to add: The flashing of the lights is controlled by the Alarm module, not the immobilizer...
Ahh Haa! That clears up both the pin-count mismatch and what the mysterious Page 17 schematic was. I saw 993 schematics for the first time yesterday and not seeing an "immobilizer", assumed the box with the "prime" and "unprime" signals was it.
It makes sense that they'd hide the details. Thanks for the clarification.
Re: ESR. I think the original cap failed. IMHO, any compatible cap would have improved performance. The replacement parts were chosen based only value, voltage and physical size.
My original range was about 30-35 feet. I could only get a measurement from the front of the car as my car was on jack stands in the garage and it was raining outside so I measured between the car and inside the hallway of my house with line of sight of the front head light and driver door through my garage door. I did not have the driver seat installed in the car when I measured.
I did not change the FOB battery.
I used the Digikey parts.
I did not clean the board as the board is enclosed in a plastic housing that sealed enough and looked clean to me. It was not like an audio amp where venting would cause dust to enter the unit.
My unit had one connector going into it. There is another female interface that was not used.
Overall, range increased slightly, but as I mentioned earlier it just now "works". Now I have to find someone with a hammer to activate the headlight flash on lock/unlock as I don't have that turned on my car.
Good. The only thing that changed was the caps. Your higher starting range and smaller improvement is consistent with caps that weren't as bad as mine. In any case, we both ended up ~ 50 ft which I suspect is going to be the best that can be achieved.
Be interesting to see what others get....
Thanks for the exterior pic. It's the same as mine.
Well, it has been tagging along in my pants pocket every day for the last 10 years or so. Maybe I should spray it out with electronic cleaner. Maybe it could improve its range, ya' think?
Andy
It's purely academic at this point, but if anyone wants to send me the caps they remove, I'll hook 'em up and make some measurements. Curious to see what they turned into after 20+ years.
One other thing...
When I did my range tests a few weeks ago I did about 50 quick lock/unlock cycles in a row. Don't do that. My driver's side door handle stopped working right afterwards. I was able to get in with the key, but only once. The FOB still fired the locks ok so it was purely mechanical. It was cold when I did the test so I let the car sit a few days until it got up to the 40's and all was well.
03-14-2019, 12:20 PM
