Om het verhaal compact te houden heb ik niet alle details erin opgenomen.
In de link hieronder lees ik dat de symptomen die ik ervaar kunnen horen bij een defecte EML (deze printplaten dus). Andere mechanische oorzaken heb ik grotendeels al uit kunnen sluiten. Kijk en lees gerust met mij mee;
Kritische vragen zijn altijd goed
En nog een stuk tekst wat ik had gevonden hierover;
I'd look at his EML I finally got around to it. He reported the throttle plates were acting funny and one bank wasn't running. There was no obvious damage, but one of the aluminum electrolytic caps didn't look great. We decided to proceed and replace the capacitors.
There were a few general purpose caps in there, but there were also a few 'special' ones, including a Tantalum capacitor, a Philips aluminum can, a Fraco 100uF 10V, and some Roederstein EK sealed/baked capacitors commonly used in the Audio industry.
(There is also about 50 ceramic capacitors and about 100 early surface mount resistors in there too!). I replaced 8 capacitors altogether, cleaned and coated the board, and dropped it in my 1991 850i. It started right up and I took it out for a spin. Everything seems to work fine, cruise, idle, etc. I didn't do any kind of programming or throttle calibration, just took it for a spin. Upon return, I measured the resistance of the old capacitors, (the meter in front of me doesn't measure capacitance) and most floated up to 6M-ohm, except the Fraco, which measured a short circuit, 0.1ohm, perhaps it was the problem?
I replaced most with Panasonic FC series, which were 105C operating temp and low impedance. Interestingly, capacitors have changed enough in 25 years that many were actually smaller that the originals, though no heroic measures needed to be made.
2x Generic 220uF 63V 105C (Replaced with Panasonic FC Series, Newark #49W7101, $0.585/ea)
2x Generic 100uF 25V 105C (Replaced with Panasonic FC Series, Newark #96K9155 $0.147/ea)
ROE 220uF 40V (Popular on Audio forums, Replaced with Panasonic FC Series,220uF 50V, Newark #49W7044 $1.03/ea)
Fraco 1000uF 10V (Replaced with Panasonic FC Series, Newark #25M9148 $0.73/ea)
(EDIT/NOTE: In my diagram lower-right, I labeled the Fraco one 100uF when it's actually a 1000uF; Thanks for noticing Albert850i!)
Philips 220uF 10V Low ESR 105C (Replaced with Panasonic 220uF 16V, OS-CON Series, Low ESR, 0.013ohm, Newark #98W0174 $1.23/ea)
Unknown 200uF 10V Tantalum (Replaced with Vishay 100uF 10V, 150D Series, Axial, Newark #65F2330 $4.57/ea, I also had ordered a KEMET Tantalum #70K8848 @$4.00/ea)
Disclosure: I don't know what's so special about the ROE or Fraco capacitors, but I used pretty decent Panasonic caps that I hope are suitable quality. I also used them in place of the generic caps which is probably overkill.
Also, The Tantalum cap I used is rated 2000hrs@85C and derated to 1000Hrs@125C. The higher temp mil-spec ones were $5-6/ea, out of stock, and had 20pc minimum. Regardless, Assuming 60MPH, that's 120K miles if the capacitor is operating near boiling temperatures. In short, some of these capacitors might not last another 25 years, but should last at least 10!
[Bericht gewijzigd door
op 8 december 2021 13:46:13