Jedi Series Gang Charger Successful Repair Story
Posted: Sun Apr 26, 2015 11:34 am
Just acquired an NTN1177E 6-unit gang charger on eBay for my HT1000's. Arrived DOA. Got a full refund from the seller so all is well, except my curiosity got the better of me and I decided to see if I could repair the charger.
First, a search on this site will show quite a few threads complaining about this type of charger and rightly placing blame on the Astec computer style switching power supply box inside. I only noticed these after I had already repaired this one.
The AC power input pins measured over 500K Ohms and the fuse was good. I had already assumed the supply was bad, and pulled it from the charger for inspection. After cutting open the "No user serviceable parts inside" label I had a look inside. Everything looked OK, so I powered it up and poked around with a long chopstick just for the heck of it. (Be careful with energized switching power supplies as they have high voltage and are not line isolated.) I was quickly greeted by a "pop!" from one end of the circuit board along with a small arc at that area. I was surprised to see that there were no components where the arc came from, instead it was where a vertically oriented PC board containing the AC input filtering components and a couple of toroids is mounted to the main board. That board mounts only by tabs soldered to traces on the main board, and the arc was where one tab had broken its solder joint completely, heated the solder up and melted it out, and now the pad was open circuit unless poked at. Further inspection showed that every one of the tabs had a broken solder joint! After cleaning up and redoing the solder joints on all the tabs, I was surprised to have the large main filter electrolytic capacitor fall out of the board when I flipped the board over! The solder joints on that had completely failed as well.
At that point I then resoldered every joint that looked the slightest bit questionable. Since I had the board out I also did an ESR check on the electrolytics and found one little 4.7 uf capacitor that was a bit too high in ESR, and replaced that one. The others were fine. After reassembly the charger worked flawlessly and continues to do so.
So, if you have one these with a defective Astec switching power supply, consider trying to repair the supply and check all the solder joints. There is a ferrite line filter wire-tied to the case that will need to be released to get everything apart, and sometimes the cheap glue holding assorted toroids will have broken loose from the case or boards, and you may have to glue them back.
Note that this Astec supply outputs a nominal 13.8 VDC so in a pinch or an emergency you could just hard-wire DC power directly to the power input connector on the mother board and use it that way.
First, a search on this site will show quite a few threads complaining about this type of charger and rightly placing blame on the Astec computer style switching power supply box inside. I only noticed these after I had already repaired this one.
The AC power input pins measured over 500K Ohms and the fuse was good. I had already assumed the supply was bad, and pulled it from the charger for inspection. After cutting open the "No user serviceable parts inside" label I had a look inside. Everything looked OK, so I powered it up and poked around with a long chopstick just for the heck of it. (Be careful with energized switching power supplies as they have high voltage and are not line isolated.) I was quickly greeted by a "pop!" from one end of the circuit board along with a small arc at that area. I was surprised to see that there were no components where the arc came from, instead it was where a vertically oriented PC board containing the AC input filtering components and a couple of toroids is mounted to the main board. That board mounts only by tabs soldered to traces on the main board, and the arc was where one tab had broken its solder joint completely, heated the solder up and melted it out, and now the pad was open circuit unless poked at. Further inspection showed that every one of the tabs had a broken solder joint! After cleaning up and redoing the solder joints on all the tabs, I was surprised to have the large main filter electrolytic capacitor fall out of the board when I flipped the board over! The solder joints on that had completely failed as well.
At that point I then resoldered every joint that looked the slightest bit questionable. Since I had the board out I also did an ESR check on the electrolytics and found one little 4.7 uf capacitor that was a bit too high in ESR, and replaced that one. The others were fine. After reassembly the charger worked flawlessly and continues to do so.
So, if you have one these with a defective Astec switching power supply, consider trying to repair the supply and check all the solder joints. There is a ferrite line filter wire-tied to the case that will need to be released to get everything apart, and sometimes the cheap glue holding assorted toroids will have broken loose from the case or boards, and you may have to glue them back.
Note that this Astec supply outputs a nominal 13.8 VDC so in a pinch or an emergency you could just hard-wire DC power directly to the power input connector on the mother board and use it that way.