why doesn't the IEC transfer current?

fajimr · « **on:** 19 May 2006, 03:40 pm »

o.k. hugh you said it was quiet.. I am in the last stages of constructing/testing and have more questions...

here is the latest:

I was trying to test quiescent current and noticed I wasn't getting any change in voltage... through a series of tests- I found out the fuse was blown on the IEC and therefore no power was getting to the PS board (and it took me a long time to figure this one out

.. in any case, I replaced the fuse and still have problems with current getting to the PS board. When I hardwire the transfo wires (straight to a plug) everything is o.k. and get +/- 40v at each of the DC spades.

Two questions:

Any ideas why the IEC is not transferring current? It is rated 10A 250V which has no meaning to me. I did buy the 3A fuses that Hugh suggested (the second fuse I put in has not blown yet). I double checked that I had it wired correctly (L=hot, N=neutral, E= ground to chassis).... could it be related to the fuse? or should I just order another IEC?

Also would testing at this point with a straight connected (i.e. not fused) pose any dangers? (I'm at the point where the main fuses are in each of the boards). Everything up to this point has been fine (all the earlier testing was performed like this running through the safety lightbulb box peter suggested). From the plug, I have black wire to the hot, wire to neutral, and the ground wire unattached. It might take a while to find another IEC...

patiently waiting to continue...

Geoff-AU · « **Reply #1 on:** 20 May 2006, 12:21 am »

sounds like your inrush is too high for the fuse. Are you using the recommended transformer/filter combination or did you increase the capacity of either?

Also, if your hot wire is black it sounds like you're at a 120V system - you need a 6A fuse for 120V systems and a 3A fuse for 240V systems.

I would not rely on the PCB fuses to protect the amp during testing. If you have a bridge rectifier failure or there's a problem with your wiring you'll get a large fault current flowing until your main breaker trips.

AKSA · « **Reply #2 on:** 20 May 2006, 12:51 am »

Jim,

Geoff is right; thanks Geoff! 6A for the IEC is correct for 115Vac mains, and during amp testing, leave off the pcb module fuses and rely only on the 100R fuse resistors to limit current should there be a trauma.

The IEC has three terminations. Looking at the back of it, with fuse compartment facing down, the tab at the top in the center is EARTH. This connects to chassis. Next tab down is directly connected to one of the internal power pins for the plug; that's NEUTRAL. The bottom termination is connected VIA the fuse, so this one is ACTIVE. This goes to the brown (preferably but not critical) wires of the primary on the trafos, while blue is connected to NEUTRAL. I would stress this connection order to active or neutral to the trafos is not too important since the trafo primary is not polarised.

Aside from that, just follow the procedure in the instructions.

Hope this is helpful!!

Cheers,

Hugh

fajimr · « **Reply #3 on:** 20 May 2006, 11:42 am »

Quote from: Geoff-AU

Are you using the recommended transformer/filter combination .

thanks geoff

I am not sure of the filter combination that you are speaking of here. I just have the transfo connections running straight into the iec. I've read other posts of people doing john risch filters (among others?) but wouldn't know how to do one myself.

When you say recommended.. are you saying recommened by the MAN (hugh

) I didn't see anything in the instructions about a filter but would certainly be interested.

yes, I am on a 120v system so I will change the fuse value.

rabbitz · « **Reply #4 on:** 20 May 2006, 01:10 pm »

If it has toroidal transformers make sure the fuse at the IEC socket is a slow blow and not a fast blow.

Geoff-AU · « **Reply #5 on:** 21 May 2006, 06:21 am »

Quote from: fajimr

I am not sure of the filter combination that you are speaking of here. I just have the transfo connections running straight into the iec.

I didn't make it clear, sorry, I was talking about the filter caps after the bridge rectifiers. If you increased those the startup surge would last for longer.

AKSA · « **Reply #6 on:** 21 May 2006, 11:07 pm »

Hi Jim,

Is this resolved now?

Let us know if you need more help, either here or by email!

Cheers,

Hugh

fajimr · « **Reply #7 on:** 23 May 2006, 04:43 pm »

Quote from: AKSA

Is this resolved now?

should be... as long as there is no other filter network to install outside what is part of the kit....

thanks geoff and rabbitz for the info- 6 amp slo blow it is