Need Help Before I Kill Myself!! (Aka: How do I connect Transformer)

[diarmaid]

Hi folks. I tried to connect up my driver board but when I tried to check the voltages I noticed that Im now only getting .38V out of my capacitor.

While trying to connect the capacitor output wires (See above question 1) I accidentally created a short between the output + and - (At least I think it was the output, it could have been between an input and an output, but suffice to say there was a spark). Why am I not getting my correct output voltage anymore. I checked everything and my input voltage to the capcitor is still ok. Did I destroy my capacitor with the short?

[Al_The_Man]

I have 24.6V Going INTO my rectifier.

58.9V Coming OUT of my rectifier INTO my capacitor (Its only a 35V capacitor.....hope thats output voltage!)

29.8V Coming OUT of my capacitor. Woohoo.

Al, thanks for that, so would I be correct in saying that I just connect my mains earth wire to that copper lug?

Your numbers/results don't seem to add up, post your hookup or go to the Plitron site, Tech section and confirm that you have the full wave rect. schematic hooked up ok.
I would hook your Ground pin of your 13amp plug to the copper lug.
The white powder is electrons escaping .
OK, no it is just French chalk or this side of the pond I belive it is soap stone, just for friction reduction when the wire flexes.
Post your hookup!
Al.

[diarmaid]

Ok, heres two pics of my hookup.

You can see the capacitor in the second one. I have realised that there are markings on the capacitor. The two terminals that I think are the outputs and are the ones that are not connected in the pic below -- The left not connected one says +, and the right one has a hatched symbol which it says on the side of the capacitor represents -.

[Al_The_Man]

From the photo, it looks like you have the ac on the notched corner? which is the DC output.
Al.

[diarmaid]

Hi all.

Thanks for so much advice already. I hope the pic below will clarify my setup as is. For some unknown reason Im now getting voltages out of my capacitor again. I think it may be my use of the ammeter. So here's an explanation of my testing and the results Im getting. Hopefully someone will tell me where Im going wrong since Im supposed to get 5VDC on my PCB testing stud, but Im getting from 24V to 0V !!!
__________________________________________________ __________________________________________________ __________________________________________________ ___

TEST A:

1) I connected my black ammeter lead into the 'COM' port.
Red ammeter lead into 'V(Ohm)mA' port.

2) I selected Volts AC 200 on ammeter.

3) I get:
25V out of transformer into diode.
66.1V out of diode into capacitor.
52.9V out of capacitor into PCB.

4) When I touch either my red or black lead off the "+5VDC" stud on my PCB and the other lead off either of the PCB + or - input terminals, I get 0V.

TEST B:

1) I left the leads into the ammeter connected as above.

2) I selected Volts AC 200 on ammeter.

3) I get:
24.5V out of transformer into diode (I dont know where the other .5V went in 30seconds!)

4) I then selected Volts DC 200 on ammeter.

5) I get:
30V out of diode into capacitor
24.4 out of capacitor into PCB

6) When I touch my black lead on PCB '-' and red on +5VDC stud I get 0V
When I touch my red lead on PCB '+' and black on +5VDC stud I get 24.4V.


So what's going wrong? Thanks for any advice folks. Even stabs in the dark are welcome at this stage. Im willing to try anything other than sticking my fingers into the wall socket!

EDIT:
Im thinking that maybe the Live and Neutral leads OUT of my transformer may be in the wrong terminals. Maybe the Live should be in terminal 8 and the Neutral in terminal 5 ??? Would this affect anything?

[Al_The_Man]

What is the deal with the 4 connections on the Cap?
For it to work properly you need a direct DC connection between Bridge DC out and the Circuit Board terminals, which implies that your 4 capacitor terminals should be electrically common between any two pairs, IOW you should not have 4 distinct terminals on your cap, if this is a double capacitor in one can, then positive pairs and neg. pairs should be paralleled up.
Al.

[diarmaid]

What is the deal with the 4 connections on the Cap?
For it to work properly you need a direct DC connection between Bridge DC out and the Circuit Board terminals, which implies that your 4 capacitor terminals should be electrically common between any two pairs, IOW you should not have 4 distinct terminals on your cap, if this is a double capacitor in one can, then positive pairs and neg. pairs should be paralleled up.
Al.

I dont know. I just bought a capacitor rated at the correct farads and voltage. Do all capacitors not look the same . How do you suggest I connect up my wires?

[Oldmanandhistoy]

Hi,

Please be aware that an electrolytic capacitor could and probably will explode quit violently if connected the wrong way around.

John

[diarmaid]

Hi,

Please be aware that an electrolytic could and probably will explode quit violently if connected the wrong way around.

John

That's not good news. So what exactly would be the 'right way round' ?

Im completely lost here folks.

[Oldmanandhistoy]

I am not qualified to give you the advice you need; I would advice that you do not use trial and error.

The capacitors I have used for power supplies have had only two connections a + and a - . The + must be connected correctly or big bang.

John

[diarmaid]

Please forgive my ineptitude, but I dont understand. If the capacitor was to have only two connections, then how do you connect 4 wires to it? There are two input wires ( + and - from the rectifier) and two outputs (+ and - to the PCB) ?
If in series, then does the '-' wire go back from the PCB to the capacitor, and then simply end there?

[Oldmanandhistoy]

As I have said I am not qualified to help so cannot; please read up on capacitors before continuing .

John

[Al_The_Man]

First establish that the capacitor is in fact a 'single' unit IOW they can sometimes come with two or more capacitors in the same Can, when they come this way, it is generally the custom to make one common with independant + terminals.
So look on the side of the cap. and see if it indicates one unit.
A capacitor like this has two terminals and the DC IN and DC OUT are the SAME terminals, IOW only two terminals per cap + & -.
If you vist a site like the Plitron I mentioned the schematic is there for a power supply.
The four terminals you show on the cap, may be in fact be commoned up in pairs, but you have to establish just what you have before proceeding.
A capacitor is connected ACROSS the DC to act as a resevoir for the DC
Al.

[Mariss Freimanis]

diarmaid,

Maybe I can help. Take the rectifier + to cap +, then rectifier - to cap -. Connect your power supply + lead to cap + as well, use a red wire. Connect your power supply - lead to cap - too, use a black wire.

Red and black will make sure the polarity does not get mixed-up at the far ends of your wires.

Mariss

[Oldmanandhistoy]

diarmaid,

Maybe I can help. Take the rectifier + to cap +, then rectifier - to cap -. Connect your power supply + lead to cap + as well, use a red wire. Connect your power supply - lead to cap - too, use a black wire.

Red and black will make sure the polarity does not get mixed-up at the far ends of your wires.

Mariss

Is this presuming the cap has only two connections?

His cap has 4 connections.

John

[Al_The_Man]

Sorry, I just went to the Plitron site and they have taken their schematics off now.
But this is a representative of how the cap is placed across the supply.
http://www.kpsec.freeuk.com/powersup.htm
Al.

[diarmaid]

Ok EXACTLY what it says on my capacitor is:

Panasonic
CE THA
(+) 35V 27000uF (M)
(#) NEGATIVE
( ) DO NOT CONNECT
+105oC 5320C3

Mariss:
Im not sure if Im interpreting you right. Why would I also connect my transformer outputs directly to the capacitor + and -. I thought it had to be DC going into my capacitor, and hence only through the rectifier first?

[diarmaid]

Al I've had a look at that site. Thanks.

Heres my theory:

I think maybe I attach my rectifier dc + to my capacitor +, and my capacitor - to my PCB +, then my PCB - to my rectifier -, and that ends the circuit.

What does everyone think?

[Al_The_Man]

Im not sure if Im interpreting you right. Why would I also connect my transformer outputs directly to the capacitor + and -. I thought it had to be DC going into my capacitor, and hence only through the rectifier first?

I think you mis-interpreted, he did not say transformer outputs but the output of the rectifier!
we are talking DC only. The link I just posted for the FW bridge shows it exactly how it should be connected.
Your Capacitor appears to be a single unit so all you use is the + and - for both the + wires coming from the bridge and going to the amp, same with the - wire from bridge to the - amp.
Think of it wired electrically as direct from bridge to amplifier and the capacitor placed ACROSS this DC supply line.
AL.

[Oldmanandhistoy]

Using a capacitor with only two terminals. You would connect as follows.

+ side of rectifier to + terminal on cap
from the same + terminal on the cap connect a wire to your pcb + terminal.

From the – side of your rectifier to the – terminal on the cap then connect a wire from the same terminal on the cap to the – terminal on your pcb.

As for your capacitor with 4 connection points I can not help.

Maybe you could pop into a local electronic supplier and ask for advice on your capacitor?

John