Dremel 876 charger for 875 battery / Bosch BC330 charger PCB - Page 1
Forum section: electronics / repair

author: uski
author_rank: Frequent Contributor
timestamp: October 30, 2014, 10:13:47 pm
content: Hi,If by any chance any of you has a Li-Ion powered handheld Dremel cutting tool (such as the 8200) with a 875 battery, or a Dremel with a 876 charger, or a Bosch BC330 charger (seems to be the same but rebranded),PLEASEhelp my by opening it !Please check attached pictures.I had the European version (230V input) and stupidly connected it to 120V in North America and it blew up (I know I'm stupid - but the point is now to try to repair it). I'd like to find the values from an European charger, but it's possible that the values are in fact the same for the US charger and that the failure is unrelated, so I'm also interested in the internals of a US charger.Components are blown and I can no longer see the values (chg_damage.pcb - a resistor melted !)... so if you can open up your charger and look at the values it'd help a lot !I need the values for :- The small TO92 transistor (it's a 2N.......)- The big TO220 transistor (reads ....K8BZ ....02E V3)- The 3 resistors (or similar ?) in between (including the one that melted)Thank you very muchuski

author: nowlan
author_rank: Frequent Contributor
timestamp: October 30, 2014, 11:24:12 pm
content: I have a BC430, which is a US 110v bosch 10.2v charger.Layout is different unfortunately.Not what you want, but since I went to the trouble of opening mine up.I originally wanted to convert mine to 220v, but the big cap is rated 200v, so isnt universal.More BC430 talk athttp://www.hkepc.com/forum/viewthread.php?action=printable&tid=1951769---update fromhttp://www.hkepc.com/forum/viewthread.php?tid=1930517&rpid=29523444&ordertype=0&page=1#pid29523444

author: uski
author_rank: Frequent Contributor
timestamp: October 31, 2014, 02:36:57 am
content: Hey thank you very much for the pictures, it is awesome, I didn't even expect to get a reply before monthsAbout converting the BC430 to 220V, this can be done as some guy is selling a kit here :http://www.ebay.com/itm/CONVERSION-KIT-for-Bosch-BC430-Charger-Convert-120V-To-220V-As-AL1130-model-/221576242465If you look at his feedback he has a negative comment of someone saying "hey this guy only shipped me some capacitors" which would seem to say that you only need to replace the caps for 400V caps (including the big one and I'm not sure what else - maybe a varistor or something like that).So I'm pretty sure you can convert your charger.If you own a FLIR E4 (hmm not sure why you would), make sure to check the temperature of the components after the modification (I did convert a Roomba charger from 120V to 220V by changing the caps but components were getting too hot).Many thanks ! I'll try a fix tomorrow if I have the parts !

author: simingx
author_rank: Contributor
timestamp: November 01, 2014, 01:57:04 pm
content: Here you go, mine is a native 220V unit.Let me know if you need any other specifics

author: nukie
author_rank: Frequent Contributor
timestamp: November 03, 2014, 09:34:58 am
content: This is awesome about time I convert my 120v to 240v thanks for the pictures guys.

author: kamcm
author_rank: Regular Contributor
timestamp: November 17, 2014, 12:56:23 am
content: Any update?Is it work by merely changing the TVR, big Caps & Mosfet ?Will the transformer output arise from 20V to 33V and therefore exceed the PWM IC limit ?!

author: TheBay
author_rank: Unknown
timestamp: November 17, 2014, 01:59:28 pm
content: If i'm reading this right you plugged a 230v device in to a 120v socket and it blew up? I'm shocked that happened, unless it really did not like 60hz!

author: edugimeno
author_rank: Newbie
timestamp: August 02, 2015, 12:30:37 pm
content: Hi! I just moved from the US to Spain and brought with me my dremel tool and charger. Fortunately I checked the input voltage specs on the bottom of the charger before plugging it in and realized it was not capable of 220v input as expected from a switching power supply.I found this entry but I am a little confused with all the conclussions and links.Is changing the FET, ceramic and electrolytic capacitor enought for the mod?Has anyone here actually managed to have this mod working.Any feedback will be much appreciated, my dremel is at this time used as a paper weight...Thank you!

author: THoward
author_rank: Newbie
timestamp: January 06, 2016, 11:45:58 am
content: I have one of these chargers in UK 230 voltage, but mine is popping fuses.At the top, it's a fusible resistor rather than the glass fuse. The resistor popped with an impressive bang when I turned it on at the wall one day, so I opened it up and changed the resistor, but it just immediately pops again.No other components are showing any sign of damage or overheating and it's not had heavy use (lives in it's case rather than being used regularly, would expect it's not had more than 10-15 charges over its lifetime)Does anyone have any pointers about what I might look at changing to repair or diagnose further? The large transistor seems like an obvious one?

author: THoward
author_rank: Newbie
timestamp: January 06, 2016, 12:25:13 pm
content: Picture of PCB attached with the fuse on the left. any help appreciated

author: SeanB
author_rank: Super Contributor
timestamp: January 06, 2016, 01:06:41 pm
content: I would guess all 4 bridge rectifier diodes are now short circuit, and the power mosfet on the heatsink along with the current sense resistors, and probably the 1M start up resistor as well.

author: THoward
author_rank: Newbie
timestamp: January 06, 2016, 05:02:02 pm
content: You are not wrong, two of the 4 diodes are short circuit, so that's a startWould you be kind enough to identify the resistors you are talking about please? I can read the values but not certain which ones on the board I am looking at. Is it common for resistors to go short circuit? I thought they failed open usually but I don't know much about this kind of thing. (I'm a theatrical electrician but not electronic)

author: SeanB
author_rank: Super Contributor
timestamp: January 06, 2016, 05:14:38 pm
content: Resistors will be open circuit, basially all low value resistors ( under 10ohm) attached directly to the mosfet are suspect as to being open circuit. As a bonus they going open circuit means it is relatively easy to check in circuit after removing the mosfet. Lower than marked value probably fine, higher than marked open.

author: THoward
author_rank: Newbie
timestamp: January 06, 2016, 07:08:58 pm
content: Thanks - I've removed mosfet and don't really know what I'm testing but found a diode test online and one side reads open circuit in both directions - so assume it's doneJust the resistors connected directly to the mosfet? Do you reckon there'd be more than one per leg? The pcb is at work now but I will ordered up mosfet tonight. I have In4007 already

author: THoward
author_rank: Newbie
timestamp: January 06, 2016, 07:10:45 pm
content: What do you think would cause this? Is it the mosfet failing and everything else is just taken out by that?What's the value of the glass fuse - would I be better swapping the fusible resistor for a glass fuse, as it might go a bit less aggressively? The resistor makes a hell of a bang and it seems lucky it isn't damaging further components when it goes

author: fubar.gr
author_rank: Unknown
timestamp: May 05, 2017, 02:30:10 pm
content: I have the 230V version that blew because a small metallic object got through the vent holes.To avoid more damage, I soft started it with a variac and a lamp in series and monitored the temp with a thermal camera.The blown components so far were:- A shorted diode on the rectifier bridge-The main switching mosfet-The glass diode below the mosfet-The small NPN transistor below the mosfet-A 3 ohm and 3.3 ohm resistorsI swapped everything with new identical components, save for the two resistors. Since I didn't have the exact values, I used 10 ohm resistors instead.I've tested pretty much every other component in the high voltage side and everything appears to be OK.How critical are those resistor values? The green led flashes and there's 0.5 Volts at the output, so it is not entirely bust, but still something isn't quite right.

author: marpelto
author_rank: Contributor
timestamp: May 05, 2019, 01:13:03 am
content: Old topic..but seems to be still valid.I just converted Bosch BC330 US charger to work on 220V.On recent model the FET is P5NK50ZFP and rated for 500V so I replaced ONLY the electrolytic capacitor to 180uF 400V...nothing else. Charged the battery for 15min and no issues.

author: alinp
author_rank: Newbie
timestamp: May 17, 2019, 09:58:08 am
content: As this topic is still valid I'm going to post my insight.The charger I have is the US 120V version and according to the markings on the back it seems to be 05/2018 manufactured.I've checked the main components on the AC side, and apart from the big 100uF 200V rated capacitor that sits right after the rectifying bridge couldn't find any major limitations to why this couldn't work with 230V.The FET that's in my unit is a P5NK50Z and according to it's specs it should stand 230V.https://www.st.com/resource/en/datasheet/std5nk50zt4.pdfI guess I'll change the capacitor and give it a try. I'll post an update with the result.

author: tppc
author_rank: Regular Contributor
timestamp: May 19, 2019, 09:33:15 am
content: Well, not sure the P5NK50Z is suitable for 230V...It is rated for 500V, but it will have to stand 230 * 1.41 * 2 -> approx.650 Volts.* 2is due to voltage reversal caused by the primary side of the transformer during flyback.Regards.

author: Haiz609
author_rank: Newbie
timestamp: September 27, 2019, 10:14:21 am
content: Hi there,How are you? Please i need to know about your Bosch 110v to 220v converted charger,Is it working good? I am going to change the capacitor as well, so i need to know if it's working fine with our any issues,Thank u,

author: bigbro
author_rank: Newbie
timestamp: September 01, 2021, 06:38:08 am
content: Hi All,I have attempted to convert my 110v bosch BC330 charger to use in 240v. I am no dummy, the 200v cap is the first thing I changed (to 400v), I changed with confidence, tested, and then it was all down hill from there.that's when i found this post.I am using the pictures of the 220volt versions posted for component conversion and I am constantly failing!to convert to 220v, looking at the photos carefully, I am sure I have got all the resistor codes correctly changed. I am using 6NK90 - 5 amp 900v mosfet and 2N2222 transistor. I keep blowing these up, along with their associated resistors etc.When i get it working, green light comes on and i measure the secondary voltage on the 470uF 25v capacitor and I get 50 volts. the 300 ohm resistor gets warm! so i cut the power. what am i missing?I'd really like to know the correct values of resistors on the 220volt version, especially the resistor of the collector of the npn transistor. the pictures are not clear for me to get the colour code. especially the multiplier band. I am currently using a value of 30ohm for the npn transistor collector.I have purchased a bosch multi-volt 110v - 265v charger from China, for under $30AUD. it's just now, this charger repair is more of a personal challenge.bugger me.I am convinced that the transformers between 110 v and 220v has different amount of turns. from inspecting the transformer part numbers they are different.has anyone actually succeeded in a conversion from 110 to 220v and still has a working unit after 5 minutes of operation?

author: bigbro
author_rank: Newbie
timestamp: September 02, 2021, 06:39:18 am
content: found my problem, the two parallel fusible resistors for the battery earth were open circuit. phew. I'm happy now! everything is now working fine.