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Post by gavmen on Jun 30, 2009 21:17:08 GMT
So here I am sitting staring at the components board after messing with it over the past week or so and thus here is my story. I got the main board populated quite quickly doing a relatively okay job soldering everything and such, then moved onto the transformer. Here I came to my first rather fun experience where I repeatedly blew fuses; 2x fast 2amp fuses and 2x slow 2am fuses. I finally narrowed down the problem to the fact that I had inadvertently wired my IEC/FUSE/SWITCH combined socket wrongly and created a short circuit (LIVE => NEUTRAL). Which was an absolute pain in the arse, because I had done all the IEC socket wiring very nicely and heatshrinked the lot knowing the dangers of Mains. So i figured out where I had gone wrong and rewired it correctly, (can i just say how much i hate stripping wire from its plastic sheath ). Then with all that done, i hooked it up to the amp circuit board and upon powering it up, blew F1 (fuse 1) and only one LED came on. So i turned it off quickly, checked the underside of the board for any suspect soldering and finding nothing really wrong, I am currently stumped. I wish i had a bloody digital camera to show you what i've done thus far but alas i dont have one ATM. Anyone got an idea as to where I should begin my fault finding? cheers gav
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Post by Deleted on Jun 30, 2009 23:05:25 GMT
So here I am sitting staring at the components board after messing with it over the past week or so and thus here is my story. I got the main board populated quite quickly doing a relatively okay job soldering everything and such, then moved onto the transformer. Here I came to my first rather fun experience where I repeatedly blew fuses; 2x fast 2amp fuses and 2x slow 2am fuses. I finally narrowed down the problem to the fact that I had inadvertently wired my IEC/FUSE/SWITCH combined socket wrongly and created a short circuit (LIVE => NEUTRAL). Which was an absolute pain in the arse, because I had done all the IEC socket wiring very nicely and heatshrinked the lot knowing the dangers of Mains. So i figured out where I had gone wrong and rewired it correctly, (can i just say how much i hate stripping wire from its plastic sheath ). Then with all that done, i hooked it up to the amp circuit board and upon powering it up, blew F1 (fuse 1) and only one LED came on. So i turned it off quickly, checked the underside of the board for any suspect soldering and finding nothing really wrong, I am currently stumped. I wish i had a bloody digital camera to show you what i've done thus far but alas i dont have one ATM. Anyone got an idea as to where I should begin my fault finding? cheers gav Gav Do you have a Digital Meter so that you can check things lke the voltages from the Power Supply PCB before it is connected to the main board, then progress from there ? You should also check the underneath of the PCB with a magnifying glass in good lighting, making sure there are no solder bridges etc. Then do a careful comparison with the board layout posted in the "Tweaks" thread. SandyK
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Post by gavmen on Jul 2, 2009 15:00:25 GMT
Yeah i got a multimeter off a friend and i measured over my transformer and it gave me very solid 15v / grd / -15v.
So i went and bought fresh fuses for the board and checked over the board and so i plugged it in again and this time i got some nice glowy orangey fuse action before they both blew.
I think right now i have a bridge, but i've checked over my work a few times now and i dont see a bridge anywhere : (
are there any nice points i can measure across that may narrow down the possible problem area?
Cheers
gav
ps. thanks for your time mr sandyk
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Post by Deleted on Jul 2, 2009 21:28:02 GMT
gavmen If you can't see any solder bridges between components or tracks, you need to double check that all electrolytic capacitors are the correct way around, and that all transistors are in their correct location. Let the forum know when you have done that. At the moment you are most likely looking at new output transistors at least. Also check that the I.C. was inserted the correct way around.
Alex P.S. Where are you located ?
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Post by gavmen on Jul 9, 2009 6:22:28 GMT
Bah, curse the real world... do this, do that... zzzz
The caps seem to be the right way around, as do the transistors... i'll triple check them a bit later tonight.
how much are the output transistors?
and i'm in sydney as well, in winston hills (near castle hill) to be exact
Thanks again
Gav
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Post by Deleted on Jul 9, 2009 6:49:01 GMT
gavmen Which version are you building ? The original SC HA using the BD139 and BD140 and output chokes , or the main modified version? The BD139 and BD140 are available from Jaycar for $1 each. I am not sure of the price of the 2SA1930 and 2SC5171 from W.E.S. as used in the modified version. Is there some way that you can post good photos of both sides of the PCB, or send a copy via email to me as .jpegs ? If all else fails, I live in Ryde, so one way or another, it will get sorted out. Alex
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Post by gavmen on Jul 16, 2009 14:43:40 GMT
Sorry about the delay, real world again.... : ( Anyway i took some pictures, had to borrow the GF's camera, golly the sony T77 is a terrible camera. Anyway here they are www.aboutabox.com/stuff/front.jpg and www.aboutabox.com/stuff/back.jpgI have higher res ones, but i've scaled these ones down to 1600x1150 (also cropped them hence the weird resolution). If you need higher res ones, i can email them to you... if i could find your email : D. thanks again. Also it does look like theres a solder join between the legs of the transistors, but i've checked them a few times, and are not joined. Cheers Gav
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Post by Deleted on Jul 16, 2009 21:52:06 GMT
Gav PM sent. Alex
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