electronics:repairing-a-faulty-80s-power-supply-13.8v-3a-from-conrad-elektronik-germany
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— | electronics:repairing-a-faulty-80s-power-supply-13.8v-3a-from-conrad-elektronik-germany [2022-08-31 11:16] (current) – created - external edit 127.0.0.1 | ||
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+ | ====== Repairing a faulty 80s Power Supply 13.8V/3A from CONRAD Elektronik, Germany ====== | ||
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+ | CONRAD Elektronics is possibly Germanys largest and certainly the most popular Electronic Parts Reseller. Some time in the 1980s i bought a stabilized 13.8V, 3A (5A) DC Power Supply that served my needs for decades now. Lately i accidentally dropped it to the floor and after re-checking it, it seems to send out pretty much " | ||
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+ | Sadly neither CONRAD nor the Internet seems to have the Schematics online, so i started to investigate and reverse-engineered it. I put all Parts as far i was able to identify into a EAGLE Cad Schematic incl. Values and all. Those Parts i was not able to identify i unsoldered and measured manually. Like the strange looking Zener-Diodes with their ugly pretty much non-speaking Labeling. | ||
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+ | Here are the Schematics i finally hammered together in EAGLE. Click on Image to enlarge or download PDF or Schematics. | ||
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+ | {{: | ||
+ | * **Download High Resolution PDF here: {{: | ||
+ | * **Download latest EAGLE Schematics here: {{: | ||
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+ | :!: UPDATE: The Schematics now should be pretty much CORRECT. The T2 Transistor BD317 (TO3 Casing) is a NPN type. Dont get confused by some obscure DataSheet on the Internet saying it would be a PNP. The SF826D | ||
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+ | :!: UPDATE: **The Power Supply meanwhile has been fixed.** Thanks to some gentle Users on Dave Jones' | ||
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+ | ===== What is done yet? ===== | ||
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+ | - My measurements at T2 tells me that the Transistor is pretty much conducting/ | ||
+ | - I unsoldered T1 (SF826D) and tested it with my Multimeter in Diode-Testmode. It seems to be a NPN Transistor with around 0.6-0.7V voltage drop Ubc and Ube. So in " | ||
+ | - When T1 is soldered in i measure some " | ||
+ | - Ubc on T1 is around -8.2V (or 8.2V lower than rail TP1). Seems to make sense. Since Utp1-Utp2=8.4V | ||
+ | - After getting some expertise form the Users of Dave Jones' | ||
+ | - I searched the internet for some replacement Model for the old SF826D transistor which should be a BC337. Since i didnt had those, i replaced it with an old desoldered BC338 instead. The Peoples on the EEVBlog Forum dont recommented that, but i had no other handy. | ||
+ | - The replaced T1 (now a BC338) works OK. The PSU now outputs round about 14V without and load and about 13V with 2.5-3A. Thats good enough for me. | ||
+ | - Reassembled the whole box and Job is done! Old 80s Style CONRAD (Voltcraft) 13.8V DC Power Supply has been successfully repaired. | ||
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+ | ===== Some Photos of the mid 80s Power Supply (internals) ===== | ||
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+ | - pcb-top-view \\ {{: | ||
+ | - pcb-bottom-view \\ {{: | ||
+ | - inline-transistor T2 \\ {{: | ||
+ | - pcb-zener-diodes \\ {{: | ||
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+ | ===== BIG THANKS GOES OUT TO... ===== | ||
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+ | THANKS TO ALL THE USERS ON THE EEVBLOG FORUM WHO HELPED ME WITH THAT! THANKS TO ANY MAKER WHO FREELY SHARES KNOWLEDGE, VIDEOS, TUTORIALS AND OTHER FREE LEARNING MATERIAL ON THE INTERNET! Keep information free for everyone! | ||
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+ | THANKS and C U! | ||
+ | --- // | ||
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+ | {{tag> | ||
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