- Schottky diode in SM PSU o/p? - 11 Updates
- WiFi out to 800 feet - 13 Updates
- Tablet Charging Port Repair - 1 Update
| T i m <news@spaced.me.uk>: Oct 09 09:51PM +0100 Hi all, I was given a 'dead' cheapo 20V Lithium drill battery, charger and wall wart to look at by a mate tonight. Plug PSU (wart) into wall socket, clip 'remote' charger interface onto battery, switch socket on ... nothing. I took the covers of the charger clip module and connected it onto the battery, measured 19 or so volts on the battery pins but nothing coming from the PSU. However, after a few minutes I felt the PSU was slightly warm so assumed it was doing something? I disconnected the PSU output leads from the PSU at the charger module and connected my bench PSU at 20 and with the current limited to the same 400mA as the PSU and the green 'Charged' LED came on constantly. I rigged up a load (a couple of 12V 60W headlights in series) onto the battery and let it run for a while and then hooked it back up to the charger, charging LED now flashing, indicating it was charging. DMM on the unloaded o/p of the PSU, nothing. After leaving it disconnected for a while ... I cracked the PSU open with my toffee hammer and gave the board a look over, nothing obviously burned and no dry joints etc. I checked the bridge rec and a couple diode over and they seemed ok, but an axial series diode (SJ220 from memory) on the output that was driving a cap that went to the remote charger module seemed to be short? I found the spec somewhere that suggested it was a 2A 1000V (?) device and I have a couple of questions please? I know Schottky diodes have fast switching times (and a low forward voltage drop but not sure if that would be relevant here?) so is a Schottky required in what I think might be part of a 'charge pump' circuit because of the frequency of the output through the SMPSU and assuming I decoded the markings correctly, why would it need a 1000V device there? Cheers, T i m |
| "ohg...@gmail.com" <ohger1s@gmail.com>: Oct 09 04:21PM -0700 On Friday, October 9, 2020 at 4:51:25 PM UTC-4, T i m wrote: > assuming I decoded the markings correctly, why would it need a 1000V > device there? > Cheers, T i m Use the Schottky diode. Sometimes a fast/soft recovery diode will work, but I've run into problems where the drive IC or transistor will run hot or fail or the secondary voltage will be lower if the Schottky diode is subbed from original spec. Also, sometimes those diodes check very leaky even when they're not - depending on your meter and the polarity of the leads, even when not using the diode scale. You can put in a fast recovery to see if the circuit works, but I wouldn't run it more than a few seconds. |
| legg <legg@nospam.magma.ca>: Oct 09 09:08PM -0400 >assuming I decoded the markings correctly, why would it need a 1000V >device there? >Cheers, T i m Output rectifiers of simple wide-range input flybacks will tend to see voltages stresses unrelated to the output voltage. At the same time, HV diodes will be relatively inefficient, due to slow speed and high Vf. If you can find real info on the part, it'll be easier to make a safe replacement. Seeing as the original part failed, it would be unwise to skimp on any of it's intended ratings. RL |
| Phil Allison <pallison49@gmail.com>: Oct 09 07:19PM -0700 T i m wrote: ============= > I found the spec somewhere that suggested it was a 2A 1000V (?) device > and I have a couple of questions please? ** That cannot be a Schottky. The highest voltage available is about 200V. Most of your facts are WRONG ! ..... Phil |
| T i m <news@spaced.me.uk>: Oct 10 10:02AM +0100 On Fri, 9 Oct 2020 16:21:38 -0700 (PDT), "ohg...@gmail.com" <ohger1s@gmail.com> wrote: <snip> >Use the Schottky diode. Yeah, I will, I was just wondering why / if they were used in that role? ;-) >Sometimes a fast/soft recovery diode will work, but I've run into problems where the drive IC or transistor will run hot or fail or the secondary voltage will be lower if the Schottky diode is subbed from original spec. Ok. >Also, sometimes those diodes check very leaky even when they're not - depending on your meter and the polarity of the leads, even when not using the diode scale. I'll check it again but I believe I measured the resistance both ways and it looked short ... and the PSU wasn't working (but warming) and everything else I could check tested out ok. >You can put in a fast recovery to see if the circuit works, but I wouldn't run it more than a few seconds. Understood. I'll wait for the right things to arrive and keep my fingers crossed it was that. ;-) Assuming the spec I looked up was correct, and it was a 2A device, and the PSU itself was rated as 400mA, I wouldn't have thought straight current would have taken it out so would there me a recommended 'safe' startup procedure that might put the least shock load on the diode? eg, Should you connected charger clip to the battery first, then switch on at the wall (and likely what it says in the instructions) ... or switch on first (allowing the PSU to get the output cap charged up) and then connect it to the battery? Wall wart / PSU <> lv Lead <> charging clip / LED status <> Battery. Cheers, T i m |
| T i m <news@spaced.me.uk>: Oct 10 10:27AM +0100 On Fri, 09 Oct 2020 21:08:30 -0400, legg <legg@nospam.magma.ca> wrote: <snip> >Output rectifiers of simple wide-range input flybacks >will tend to see voltages stresses unrelated to the >output voltage. Ah, ok. >At the same time, HV diodes will be relatively inefficient, >due to slow speed and high Vf. Check. >If you can find real info on the part, it'll be easier to make >a safe replacement. <checks diode again with better light and loupe> Ah, it's an SR2200 JF (not SJ220, that was a result of my dyslexia <g>) that looks to be a 200V 2A Schottky Barrier Diode. https://www.4project.co.il/product/210423 >Seeing as the original part failed, it >would be unwise to skimp on any of it's intended ratings. Understood, I'll get the right thing ordered now. Cheers T i m |
| T i m <news@spaced.me.uk>: Oct 10 10:37AM +0100 On Fri, 9 Oct 2020 19:19:34 -0700 (PDT), Phil Allison >> I found the spec somewhere that suggested it was a 2A 1000V (?) device >> and I have a couple of questions please? >** That cannot be a Schottky. Oh? >The highest voltage available is about 200V. The eBay listing suggested it was a 'Axial Lead Schottky Diode HER208 Ultra-fast Recovery Diode MIC 2A1000V DO-15' so maybe it was wrong / misleading? >Most of your facts are WRONG ! Most of my facts were questions but as I have mentioned since and with a better / closer look, it's an SR2200 (not an SJ220) and that is indeed a 200V, 2A device so will order one now. Cheers, T i m |
| Phil Allison <pallison49@gmail.com>: Oct 10 03:31AM -0700 T i m wrote: ---------------- > The eBay listing suggested it was a 'Axial Lead Schottky Diode HER208 > Ultra-fast Recovery Diode MIC 2A1000V DO-15' so maybe it was wrong / > misleading? ** The HER208 is a fast recovery silicon diode, not a Schottky. ... Phil |
| "ohg...@gmail.com" <ohger1s@gmail.com>: Oct 10 03:49AM -0700 On Saturday, October 10, 2020 at 5:03:02 AM UTC-4, T i m wrote: > the PSU itself was rated as 400mA, I wouldn't have thought straight > current would have taken it out so would there me a recommended 'safe' > startup procedure that might put the least shock load on the diode? 400ma is the maximum continuous duty design output, but during the first few cycles, it's essentially feeding a short circuit until the filter caps charge. Most modern smps circuits ramp up the drive in a controlled manner using a slow or soft start strategy to mitigate that. Still, sometimes diodes just short, and I've seen more random Schottky failures than other types. > ... or switch on first (allowing the PSU to get the output cap charged > up) and then connect it to the battery? > Wall wart / PSU <> lv Lead <> charging clip / LED status <> Battery. I wouldn't worry about the start up procedure unless there are specific instructions to the contrary. Consumer electronics are generally designed to be plug and play regardless of the sequence. |
| T i m <news@spaced.me.uk>: Oct 10 01:17PM +0100 On Sat, 10 Oct 2020 03:49:20 -0700 (PDT), "ohg...@gmail.com" <ohger1s@gmail.com> wrote: <snip> >> current would have taken it out so would there me a recommended 'safe' >> startup procedure that might put the least shock load on the diode? >400ma is the maximum continuous duty design output, but during the first few cycles, it's essentially feeding a short circuit until the filter caps charge. Understood. >Most modern smps circuits ramp up the drive in a controlled manner using a slow or soft start strategy to mitigate that. This is the PSU OOI: https://ibb.co/VtBY4Rt The IC is a CR6338T. >Still, sometimes diodes just short, and I've seen more random Schottky failures than other types. Oh, ok. <snip> >I wouldn't worry about the start up procedure unless there are specific instructions to the contrary. Consumer electronics are generally designed to be plug and play regardless of the sequence. Agreed, I was just thinking that this being a 'cheap and cheerful' example of this sort of thing, if they may have cut more corners than more expensive brands might, making them slightly less 'durable' under some circumstances ... how they handle the 'what if' situation? But as you say, it could have just been one of those things and if it works it could be fine till it's worn out. ;-) Cheers, T i m |
| T i m <news@spaced.me.uk>: Oct 10 01:21PM +0100 On Sat, 10 Oct 2020 03:31:22 -0700 (PDT), Phil Allison >> Ultra-fast Recovery Diode MIC 2A1000V DO-15' so maybe it was wrong / >> misleading? >** The HER208 is a fast recovery silicon diode, not a Schottky. As I was looking back into it that's what I surmised Phil. I've ordered the right thing now that should be here soon and I'll let the group know how I get on. If it's not that there isn't much else outside the CR6338T. ;-) Initially I was just going to look for a generic 20V, 400mA PSU but thought I'd open this one up just to see if there was anything obvious. Cheers, T i m |
| Fox's Mercantile <jdangus@att.net>: Oct 09 11:43AM -0500 On 10/9/20 11:23 AM, Jim Jackson wrote: > point proved:-) > Why don't you do something USEFUL with your time and energy? > Just asking. Because he really doesn't have anything better to do with his time. All his posturing around and wild assed claims means nothing. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Arlen Holder <arlen_holder@newmachines.com>: Oct 09 06:35PM On Fri, 9 Oct 2020 16:23:30 -0000 (UTC), Jim Jackson wrote: > point proved :-) > Why don't you do something USEFUL with your time and energy? > Just asking. Hi Jim Jackson, Pernicious trolls like Fox's Mercantile are those who ruin Usenet for all. o Hence it's important that _all_ of us discourage their despicable actions Thank you for being an adult above - so we didn't waste time on obvious facts. o As you observed, it's trivial to prove what Fox's Mercantile always does (as he did in this very thread - & always does - because he's a troll) Literally every time I post, I have Fox's Mercantile infantile responses to deal with, but what's worse is he attempts to troll derail _every_ thread. Others... more so than just me... need to help put a stop to this o Otherwise this newsgroup, like many others, is handed to these trolls. All Fox's Mercantile did in response to the request for help - was troll. It's what worthless pieces of shit trolls do, as you & I are aware... o But, like Snit, this Fox's Mercantile is particularly pernicious about it In summary, while yours is a great question, you're asking it of the wrong person, since you should be asking Fox's Mercantile why he does what he does. I would be happy if this infantile troll would just stop sniffing my ass o I repeat: If Fox's Mercantile ignores me - I'm happy to ignore him. He's a worthless piece of shit troll anyway... o So he can't possibly ever add any adult value to any thread topic. The problem is that if I don't make it obvious to all here what he does... o These cowardly infantile bullies will never stop ruining this newsgroup. -- Pernicious trolls like Fox's Mercantile are those who ruin Usenet for all. |
| Fox's Mercantile <jdangus@att.net>: Oct 09 01:55PM -0500 On 10/9/20 1:35 PM, Arlen Holder wrote: [ As usual, the normal dribbling of shit out of his mouth. ] Like I said, you're worthless. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Arlen Holder <arlen_holder@newmachines.com>: Oct 09 06:59PM On Fri, 9 Oct 2020 13:55:36 -0500, Fox's Mercantile wrote: > Like I said, you're worthless. I only need to point to exactly what Fox's Mercantile writes... o In order to prove the veracity of my claims about him. Instead of asking me why I defend myself against his unilateral attacks o Others should be asking Fox's Mercantile why he incessantly trolls us. -- Pernicious trolls like Fox's Mercantile are who ruin Usenet for all of us. |
| Fox's Mercantile <jdangus@att.net>: Oct 09 02:43PM -0500 On 10/9/20 1:59 PM, Arlen Holder wrote: > Instead of asking me why I defend myself against his unilateral attacks > o Others should be asking Fox's Mercantile why he incessantly trolls us. Because it's funny watch you run around in circles pissing yourself. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Arlen Holder <arlen_holder@newmachines.com>: Oct 09 08:02PM On Fri, 9 Oct 2020 14:43:54 -0500, Fox's Mercantile wrote: > Because it's funny watch you run around in circles pissing yourself. You prove the veracity of my claim you post not to be helpful... o ...but only for your infantile trollish amusement, Fox's Mercantile. -- People like Fox's Mercantile are they who ruin Usenet for the rest of us. |
| Fox's Mercantile <jdangus@att.net>: Oct 09 04:01PM -0500 On 10/9/20 3:02 PM, Arlen Holder wrote: >> Because it's funny watch you run around in circles pissing yourself. > You prove the veracity of my claim you post not to be helpful... > o ...but only for your infantile trollish amusement, Fox's Mercantile. Hands you a wet wipe. You've done it again. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Arlen Holder <arlen_holder@newmachines.com>: Oct 09 09:04PM On Fri, 9 Oct 2020 16:01:08 -0500, Fox's Mercantile wrote: > Hands you a wet wipe. Snit and Diesel are the worthless pieces of shit trolls... o Who can't stop acting like Fox's Mercantile is right now... Fox's Mercantile can't stop proving he's incapable of _not_ being a troll. -- People like Fox's Mercantile are those who ruin Usenet for all of us. |
| Fox's Mercantile <jdangus@att.net>: Oct 09 05:34PM -0500 On 10/9/20 4:04 PM, Arlen Holder wrote: [ usual whiny shit ] Fuck you. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Arlen Holder <arlen_holder@newmachines.com>: Oct 10 01:39AM On Fri, 9 Oct 2020 17:34:21 -0500, Fox's Mercantile wrote: > Fuck you. Fox's Mercantile can't stop proving he's incapable of _not_ being a troll. o Just like Snit. -- People like Fox's Mercantile are those who ruin Usenet for all of us. |
| Fox's Mercantile <jdangus@att.net>: Oct 09 08:59PM -0500 On 10/9/20 8:39 PM, Arlen Holder wrote: > Fox's Mercantile can't stop proving he's incapable of_not_ being a troll. In case you missed it, go fuck yourself. You could have just as easily ignored me the first time around, but no, you had to keep going on and on and on. You're fun to play with, you just keep insisting on getting kicked in the face. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Arlen Holder <arlen_holder@newmachines.com>: Oct 10 05:15AM On Fri, 9 Oct 2020 20:59:33 -0500, Fox's Mercantile wrote: > In case you missed it, go fuck yourself. What's interesting is you prove to be infantile in _everything_ you say. o Interestingly, like Snit, you have no capacity to NOT prove to be a troll. -- Fox's Mercantile, just like Snit, can't NOT prove he's an infantile troll. |
| Fox's Mercantile <jdangus@att.net>: Oct 10 04:10AM -0500 On 10/4/20 7:59 PM, Arlen Holder wrote: [ nothing of value as usual ] Let me know when you get tired of proving how useless you are. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| whit3rd <whit3rd@gmail.com>: Oct 09 12:56PM -0700 On Thursday, October 8, 2020 at 3:53:16 AM UTC-7, J.B. Wood wrote: > A10-70F models that seem notorious for the mini-USB charging port > acquiring broken solder connection(s) to the motherboard. Probably due > to stressing/bumping the AC adapter plug while attached to the tablet. Yeah, surface mount is tricky, and finding an exact part to do a connector replace is trickier. First, check the warranty; if it's covered, you might lose data (backup or full cloud-service registration can make that less painful) but it gets a professional workover. Second, find out if the manufacturer's out-of-warranty service is reasonable. Usually, that'll be a flat-fee mailin, but sometimes the common problems get a free repair; you'll have to ask about that. Some breaks (rips in the copper traces) are almost impossible to repair, because the mechanical bond to the logic board is bad (a glob of adhesive MIGHT hold it...). I've been known to solder tinned steel wire for reattaching a loose connector... |
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