The SMS Spot server will be down till further notice 'coz the disk in the server is playing silly blighters Itās been on continuously for 53months so I canāt complain as it only had a 36 month warranty. I hope to liberate a suitable replacement this weekend if not I have an old 200GB disk that will do. Iāve a lot of other committments this weekend so it could be midweek before everything is up and running again.
It will be missed Andy! Iāve enjoyed not having to go running and dancing around summits to get a WAP signal. If I donāt get one immediately, I just sack it and send a text to that nice friendly SMS SOTA Spot Bot instead! Like I did today.
Iāll try and get it on ASAP as I miss the server for itās other uses. Iāve got a wedding tomorrow night and Jethro Tull on Monday plus other stuff over weekend. But at least the mains is back on and everything is running again (except the server with the poorly disk) :-o !
Thatāll teach me not to use any old IEC (Wlat knows what they are now) mains lead in the 'scope. So Iām trying to fix the busted PSU from my SI/NS expedition and with the 'scope earthed (as it has the wrong IEC mains lead in it) when I put the 'scope probe earth on the -ve of the bridge capacitor there was a mighty flash bang crack and the lights went out. āOh dearā I said and remembered the floating earth 'scope lead did a vanishing trick hence the wrong lead in the scope. Iāve just pushed 330VDC up the earth lead of the 'scope probe and into the earth circuit. The ELCB in the consumer unit didnāt like that and off went the mains.
No lights and my hand very close to the capacitors charged to 330VDC, move hands slowly whilst everyone in the house started moaning about no power. Of course the big torch was nowhere to be felt. Hrmph!
The PSU is a Lascar PSU130, a 0-30V 1A adjustable bench supply. I rang Lascar and asked for a circuit and they said āwe donāt supply themā. I told the dude that my employers wont be buying their products in future then. Anyway, after puzzling for a while I can see there are 2 switched mode controllers in it. Oh the complexity to save on a big transformer and shunt regulator. It looks like thereās an SG6840 driving the main chopper FET producing the raw DC plus the volts for the LCD board. Then thereās a TL494 (the one in every PC PSU ever made) driving another chopper to produce the variable 0-30V. Apart from the opto feedback, everything is DC coupled meaning the fault could be anywhere.
Argh! I hate analogue stuff!
Anyway the mini DMM is fixed (blown fuse in mA circuit), the super lightweight BNC extension lead is next to be fixed. Then thereās the vacuum cleaner and then when I find some T2.5A fuses this nasty Lascar PSU.
One piece of advice I got from the great Harry Leeming G3LLL many moons ago was to avoid Switched mode power supplies for anything requiring decent current at 13.8 Volts DC.
Of course they come in handy for small current devices like mobile phone chargers & even some computer PSUās are half decent, but for pure high current DC, equivalnt to a bank of battieries I will only use something with a big transformer & capacitors.
I am very sorry to hear about your power problems Andy, but at least you are still here to talk about it, so just chalk it down to experience
And be thankful it wasnāt something really big that went bang & took you with it!
We live & learn
Hope to work you again soon.
P.S. I havenāt used it yet, but I have seen quite a few of the SMS generated spots & the server did seem to be working very well. Best of luck getting it going again.
If I had a pound for everytime Iād popped the breakers in the lab Iād be a rich, rich man. Itās more of an annoyance at home when you do it as so many things need reseting! This time there were complaints from the non-technical residents too. Iāve found some F2A fuses so Iāll have a brew and another bash at leaving everyone in the dark.
Switchers are wonderful till you have to fix them. Normally you can see which component has released its āwhite smokeā and hence needs replacing. But this one just went off and everything looks kosher. It wasnāt even being stressed much. Worse, I know I wont get it running till itās ābittenā me, thatās what usually happens!
Have a look at the waveform - itās digital (sorry, forgot, the scope is also probably bust - now that is analogue!!!).
If it switches on and off it is digital, if the waveform has wiggly bits itās analogue (I am simplistic - and hate digital!)
Scope is working FB! No progress on the PSU as I need some slow blow fuses, the inrush current pops a fast blow. However, a colleague at work has just given me a 250GB disk so I can get the server running again sometime this weekend given a following wind.
In reply to MM0FMF:
Hi Andy.Sometimes when I have no fuse I have put a bulb in its place.One that draws the same current as the fuse.If there is a dead short the bulb is full brightness ATB Geoff.
In times of desparation Iāve resorted to such tricks but Iād like to fix this wrecking anything else along the way.
Iām just about to start reinstalling the server with the ānewā disk. The bloke who gave it to me said āthereās some music stuff from my iPod on there you might want to copy before you format it.ā Some music stuff? 215GB of mp3 files! If only I had somewhere to save them
The server is back up and running again with all the correct lights flashing away. Everything should be working as before.
It turns out the problem was not disk related at all but a PSU issue. The computer is very small and has a small PSU. The actual problem was the PSU not being quiet big enough to handle the transmit current peaks the GSM dongle draws and run the PC at high load at the same time. If the PC was idle then there was no problem. An increase in things it does plus my SMS server software was just enough to push the system over randomly. The fix is not to connect the GSM dongle to the PC but to connect it via a powered hub.
Of course I figured this out after spending all afternoon moving files about and then swapping disks left, right and centre. It takes a long time to copy 198GB from the original disk to another one
The upshot is that I have 4 more LEDS on in the shack (on the hub), the replacement disk has about 13000 less hours on the clock and runs 3C cooler than the original. The original disk is still in tip-top condition and I have a much more uptodate backup. Also I banged the serial number into the website and the disk is still under warranty!