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irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251
Posted: 05:52pm 10 Jul 2016
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i have the strip board disconnected from power and resistors and transistors, so cant check that right now till tomorrow.
i checked solder bridges and all fine
I also used multi meter and done a continuity test pin 1&2 2&3 and so on.
not a problem that way
thank you.
ronEdited by irishron40 2016-07-12
VK2MCT Senior Member Joined: 30/03/2012 Location: AustraliaPosts: 120
Posted: 05:55pm 10 Jul 2016
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Did you check for solder bridges or check for no solder bridges. How?
John
irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251
Posted: 06:00pm 10 Jul 2016
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I also used multi meter and done a continuity test pin 1&2 2&3 and so on
I also checked all other tracks with tester
I had the board disconnected from power resistors tranistor and pot meters when i done thatEdited by irishron40 2016-07-12
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 12:01am 11 Jul 2016
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A couple of tips about working on strip boards (vero boards).
1. do all your checking with a good magnifying glass, I use one of these illuminated ones on a stand. They are well worth the little money they cost.
2. Especially check where you used a drill or that special tool (I'd recommend that)to cut the tracks. It is remarkable easy to leave a tiny sliver of copper still bridging the cut track. Often not seen by naked eye.
Oh, an extra tip: do not use the strips for any higher power (>1-2A), they are too small for that. If you must carry high power on a strip track do solder a piece of tinned wire along it after you soldered on the components.Klaus
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 03:39am 11 Jul 2016
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I can not see any errors in your hookup, althought your colourful drawing is not easy on the eyes.
May i suggest next time put the colour pencils away and draw your schematic in black and white, and use simple symbols like almost all schematics are constructed by.
I still thing you have a short somewhere like several others have also indicated.
It may not be a dead short and just a resistive short that the meter wont detect, but big enough to cause problems.
Have you checked the large resistors have one of them became faulty.
Pete.Sometimes it just works
irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251
Posted: 05:51am 11 Jul 2016
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Hi Pete. the 0.1 resistors all show 0.7 ohm on my meter. i compared that with a new one I have and its the same
The 2 0R47 resistors i had to check while the 2 outputs are soldered together
thanks . combined they showed 0.8 ohm.
is that ok Pete?
thank you.
I`ve just put a lot of time in trying make it neath, and am a bit frustrated as I cant see anything wrong.
I just received 4 tip3055 transistors as they might be better then the small tip41c I used before
here they are John
I did not connect the input and output wires when i done the test
VK2MCT Senior Member Joined: 30/03/2012 Location: AustraliaPosts: 120
Posted: 12:11pm 11 Jul 2016
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Hi Ron,
Thanks for the readings between pins.
However I'm not sure whether a reading of 0 is 0ohms (zero) or is it high resistance (open circuit)
Also are the other readings ohms, kilo ohms or mega ohms ?
Does the board you are using have metal strips on the top surface. I can't tell from the photo.
John.
irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251
Posted: 01:06pm 11 Jul 2016
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k ohms John
I am after re building it.
the hint i was given with a light under the vero board is brilliant. not sure who told me , but you can see the tinyest bridges
im greatfull for the patience , but I will learn more each day.
ron
rustyrod Senior Member Joined: 08/11/2014 Location: AustraliaPosts: 121
Posted: 01:41pm 11 Jul 2016
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Ron, Before you hook up your new transistors can you put a fuse between the positive of the filter capacitor and the transistors?
Even if you use just one strand of very fine wire, it may save those transistors.
Another way is to have a bulb in there.
I would start with a 12 volt power firstly.
Get it regulating away at say 9 volts into another bulb as the load, then try your motor.
Perhaps use a car battery and a headlight bulb as the safety between the battery and your circuit. This should save the parts and brilliantly show up any fault.Always Thinking
irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251
Posted: 02:39pm 11 Jul 2016
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Hi Rustyrod
I dont understand about the bulb , so fuse be easyer for now if thats ok.
1)Is the filter capacitors the ones after the Bridge Rectifier?
2) what size fuse should I use?
3)Im not sure where this fuse should go if it isnt after the main cap
Insted of those 7 1000uf caps I used a 50 volt 10.000 uf capacitor
BTW, after using a light under that veroboard and magnifying class There was a very very tiny solderbridge
I am now nearly finished rebuilding it.
just waiting on the lm723 supplies to arive. lolol
Thanks Rusty
ron
Edited by irishron40 2016-07-13
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 01:13am 12 Jul 2016
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What Rusty is suggesting with using a bulb is to use it in the place of a fuse.
A bulb can be used as a cheap visual resistor that also limits the current during testing.
No current, no glow, small current filiment glows red, lots of load (short) full blinding bright glow.
The bulb current is limited to ohms law. with 12v input a 21w brake light bulb would be .. 21 / 12 = 1.75 amps.
low beam headlight or house low voltage downlight
50w / 12 = 4.2 amps.
It is a good trick to use as i too used when learning.
PeteSometimes it just works
irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251
Posted: 03:15am 12 Jul 2016
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ok I try that.
but where on the diagram should i put the bulb. is it after my 10000uf cap?
thanks Pete.
ron
irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251
Posted: 02:28pm 12 Jul 2016
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i see where to connect it now,
pete could you please tell me how to connect digital amp meter?
am i right that 1 cable goes to neg. 1 to output and 1 to output terminal?
thanks appreciate the help.
ron
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 01:33am 13 Jul 2016
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A digital amp meter often requires a voltage regulated power supply to power it (12v+/-)then it depends if its a high side (+) or low side (-) connected meter.
The basic answer is the meter goes in series with either one of the outputs (V+ or V-) (just like you would add a fuse to the output)
My personal thoughts is Gnd should be 100% Gnd and no resistance added to the output in any way, so i would put the meter in the V+ output, although most cheap meters are designed for a negative connection.
my choice is an analog meter. You can connect it either way prefered.
Firstly you need to get the circuit working before the need for meters.
Pete.
Sometimes it just works
irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251
Posted: 01:40am 13 Jul 2016
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i am waiting for new lm723 to arive and I installed 4 tip 3055 now.
I am confident it will work now, as the torch and magnifying glass did show up 1 or 2 solder bridges. very very tiny but like I was told the tinyest is all it takes to cause problems
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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