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-   -   OVP Relay (http://www.peachparts.com/shopforum/diesel-discussion/239578-ovp-relay.html)

BioDieseLandon 12-05-2008 07:26 PM

OVP Relay
 
So the deal is my tach and abs light are working and going on and off intermittently...with the great help and advice of others on the forum i traced it to the OVP Relay (1985 300SD located in fusebox). The fuse on the top of the cube is fine so i took the cube apart. Now i am just wondering if anyone knows which solder joints generally go bad and the best way to resolder them. much appreciated -Landon

Oracle12345 12-05-2008 07:28 PM

you can test them. I can send you document telling you how.

BioDieseLandon 12-05-2008 07:30 PM

that would be great. if you need to send it to my email it is landon@1rnorman.com i know that if you apply 12 volts to different prongs the relay contact should close but i dont know which ones.

whunter 12-05-2008 10:40 PM

Here is the link you need
 
OVP relay, Over Voltage Protection Links
http://www.peachparts.com/shopforum/diy-links-parts-category/209638-ovp-relay-over-voltage-protection-links.html








Have a great day.:D

pmckechnie 12-06-2008 10:12 AM

If you look at the printed circuit very carefully and look at the solder joints you will see a small circle in the solder around the bad pin, or it will be dull gray instead of bright and shinny. Look especially close to any big pins that go to the plug or heavy componets such as relays. Use a magnifying glass unless you are young and good eye site. I have to use a magnifying glass but my grandson can see them without any aid and in the dark. Oh to be young again. Resolder any pins that look funny.

Paul

babymog 12-06-2008 11:22 AM

You might be successful, but might not. Often times a dry-contact relay such as these are don't do well with low-amperage loads, a very light corrosion will cause high-resistance contact and thus problems with the voltage output. Cleaning these contacts is also a mixed-success story as you don't want to leave any scratches in the surfaces, nor uneven contact or they will quickly fail again. Some are plated, once the plating is worn through, sanded through, etc. the relay will not be viable. Last, using pretty much any commercial sandpaper can leave deposits from the sandpaper (often an oxide such as aluminum oxide) which will create high-resistance and be a seed for a fresh round of electro-galvanic corrosion on the contact surface.

I hate to say it as I've "repaired" so many low-current dry-contact switches and relays with so many methods and materials, but I've never been successful in making it reliable and long-lasting. I just "bite the bullet" and order new. The OVP is such a common failure item in the '80s and '90s Mercedes with several intermittant symptoms, it is prudent IMO to just buy a new one even if your repair seems to be working.

Jeremy5848 12-06-2008 01:17 PM

Babymog is probably right. The part is 201 540 08 45, under $100 from the dealer or about half that from one or another of the Internet sellers such as FastLane (click on Buy Parts at the top of this page).

Jeremy

BioDieseLandon 12-06-2008 06:01 PM

ya i am probably just going to order a new one but i did take it apart and reflow some of the solders and it helped with the tach but still no ABS


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