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With the best will in the world Bill964s, "OBC backlight repair" https://rennlist.com/forums/993-foru...-repair-2.html
photo bears no resemblance to the circuit board I am having problems with on my 993 cabs circuit board, i.e There is no transistor to be seen on my board.
I have renewed the bulbs to no effect any one got any ideas that will help me?
Originally Posted by gedeon25
Steerpike,
On latest 993 OBC board, no BS170 transistor.
The fault is due to a burned board track. Have a look on the left top side of your circuit board and let me know is there is a burned point ? the track that usually burn is inside the board, you can check with a light thru the board and you will see the burned cutted track.
You have to rewire with an external 5 cm long cable.
GeD (from France)
here's a photo of the boards without the standard transistor. Let me know if anyone knows anything about schematics or common faults here (no obvious burnout/cut tracks).
Last edited by ninjabones; 12-23-2022 at 02:59 PM.
I have not yet seen any faults in the backlight circuit on the late SMD version of the OBC PCB. However, I have repaired a lot of damages on these as described above. This is a three-layer PCB, and an embedded PCB track can burn off when a charger, jump starter is connected with the wrong polarity. This can also happen when a 24V charger or jump starter is connected to the car battery. The damage is most often visible on the edge of the PCB, near the large protection diode, but can also be buried and not easily spotted.
Cheers,
Tore
Thank you, Tore. I inspected the boards very carefully and didn't see any evidence of burns or track damage.
Any recs on where to send for repair? I called North Hollywood Speedometer and they said they build the boards themselves but estimate anywhere between $550 and $1,100 for the repair. That's just absurd. One of my side hobbies is restoring pinball machines, and I've had many (much larger/more complicated) PCBs repaired usually for a couple hundred bucks. I'm hoping there are other options.
Anyone have any experience with www.espeedo.com or other options? Thank you.
Last edited by ninjabones; 12-24-2022 at 11:55 AM.
Great initiative by everyone......This OBC light lis the only thing on my car that is faulty at the moment..........I have left mine alone for years and was going to tackle, but $ 1,000 is not worth it, if you can at least see it's information in the display, albeit very faint - at least during the day........tapping on the glass of the tach has not helped relight it for me at only even temporarily.......although after many years, it was fully lit a week ago after having a battery maintainer connected for a few days..........so the transistor connection must have broken on mine like many others.........
I did replace the odometer cogwheel own my own years ago, but that was just a plug and play repair......with a new cogwheel for $15......I often wonder how many 993s and 964s left that odometer issue unprepared reflecting low mileage today! and greater value for selling?
Typically an over-voltage, e.g. battery charger, causes a burned circuit track from pin 1 (#30 input) to the transient suppressor.
The burned track needs to be bypassed with a small jumper wire (#24).
__________________
Loren
Systems Consulting - Automotive Electronics
Specializing in Porsche cars http://www.systemsc.com/
12-23-2022, 02:26 PM
