An occasional vinegar & chips instead of mayo would be a nice change.
Ay, provided it's not Leeds, Liverpool, or Llandudno, gov.
Do Panamese fruit gondolas count ?
Apologies, meant the mounting studs for those nice big Rifa's.
I used some second hand Rifa's that didn't come with the insulating washers and discovered their necessity after some heat and confusion. Luckily no harm done, they're tough buggers.
FLG's right.
You keep referring to the bleeder resistor as another "R" in your power supply filter circuit. It's not. It's there to run from your power rail to the ground, and to discharge (....."bleed" the voltage from.....) your capacitors once mains power is removed. It's there for your safety.
Place this resistor (the BLEEDER resistor) across the last set of capacitors in your power supply (the ones "furthest" from the rectifier--again, one from your + rail to ground, and another from your - rail to ground.
You keep referring to the bleeder resistor as another "R" in your power supply filter circuit. It's not. It's there to run from your power rail to the ground, and to discharge (....."bleed" the voltage from.....) your capacitors once mains power is removed. It's there for your safety.
Place this resistor (the BLEEDER resistor) across the last set of capacitors in your power supply (the ones "furthest" from the rectifier--again, one from your + rail to ground, and another from your - rail to ground.
why on the last caps
not that I know much about it, but I would have placed the bleeder somewhere between CRC resistor and trafo
but does it matter where the bleeder is placed ?
well, I see now that F5 supply schematic have the bleeder on the first caps, close to bridge
Firework
Oh Sh..
See what happend to my first rectifier start up. It was a loud bang with lighting...everything a real good firework needs I've done it seperately.
The picture shows the 2nd channel, 1st one was ok. I only changed the
ground connection from - of the cap to + of the caps.
Of course all four diodes a dead now. Luckily I have a good source of it
But I guess i made some soldering error... assuming that can be the onle reason for such a bang, right?
Cheers,
Mallard
Oh Sh..
See what happend to my first rectifier start up. It was a loud bang with lighting...everything a real good firework needs
I've done it seperately.The picture shows the 2nd channel, 1st one was ok. I only changed the
ground connection from - of the cap to + of the caps.
Of course all four diodes a dead now. Luckily I have a good source of it
But I guess i made some soldering error... assuming that can be the onle reason for such a bang, right?
Cheers,
Mallard
why on the last caps
Tinitus, actually, it doesn't matter that much on a relatively low voltage supply. This is particularly true when the "R" in the CRC network is relatively low resistance--in this case, both capacitor banks (the first and second "C) will discharge about the same, at the same time.
I put the bleeder on the last set of capacitors, from force of (construction0 habit. In large tube systems (like transmitters), the "R" value may be pretty high (and there may be several CRCRC stages). In addition, many well-designed tube transmitter power supplies are self-contained, and only the final DC voltages exist outside the power supply "cage". For such a design, it's best to quickly discharge the final set of caps (i.e., typically the final power amp's plate voltage) as it exits the power supply. For this reason, that's where I put my bleeders--on the final set of caps, so that any cap-stored HV external to the power supply is reduced relatively quickly. Again, this is more of an accepted practice on HV systems.
Having said that about HV and transmitters and bleeders, I still work with "one hand in my pocket", and I still use a "shorting wand" when working on HV transmitters. (One of our transmitters puts out 32 MEGAWATTS of RF.....and you only need to screw up one time, to get your obituary published!)
Mallard, you state "The picture shows the 2nd channel, 1st one was ok".
I'm confused. Do you actually mean "rails" when you say "channel"? You have two rails in your power supply--one ~+24 VDC and the second at ~-24 VDC.
....or do you actaully mean "channel", as in the left and/or right channel of your amp? (And are you actually doing your initial tests, with your amp boards connected? Please say no....)
And yep--to crack a power semiconductor's case with accompanying smoke/fire, I'd say you have a direct short in your power supply. Time to drag out the DMM and start taking some resistance readings.
I'm confused. Do you actually mean "rails" when you say "channel"? You have two rails in your power supply--one ~+24 VDC and the second at ~-24 VDC.
....or do you actaully mean "channel", as in the left and/or right channel of your amp? (And are you actually doing your initial tests, with your amp boards connected? Please say no....)
And yep--to crack a power semiconductor's case with accompanying smoke/fire, I'd say you have a direct short in your power supply. Time to drag out the DMM and start taking some resistance readings.
Sorry for confusing, I mean by channel the left and the right side! And I say NO - my amps are not connected, I'm not crazy.
Yeah try and error can cost a lot of money and nerves.
Did you use a fuse at all when you plugged in the PS? That could have saved your diodes.
Anyways, two suggestions : check that ALL your caps are connected correctly : ie + to + and -Ve to -ve.
Also Check that you REVERSED the polarity on your bridge. As well as the caps. on the -ve side.
I screwed it up in the beginning as well, but I had a fuse and it just kept blowing the fuse.
Anyways, two suggestions : check that ALL your caps are connected correctly : ie + to + and -Ve to -ve.
Also Check that you REVERSED the polarity on your bridge. As well as the caps. on the -ve side.
I screwed it up in the beginning as well, but I had a fuse and it just kept blowing the fuse.
Yep.... a bleeder resistor with a higher resistance would drain the caps at a slower rate.
Other factors not considered, the drain rate over time would look very much like an RC "decay curve", with the voltage on the cap impacted by (1) initial voltage applied (2) size (mfd) of the filter capacitor, and (3) size (ohms) of the bleeder resistor.
Ken
Hmm... I had a fuse but with 4Amps... I changed to 1.25A.
Regarding your 2nd suggestion: till now I thought the + pol on a bridge is always the same. So I connected the + from the bridge to + of the cap and the - pol of the bridge the - of the cap. For the positive side of the PSU the - of the caps goes to gnd. For the negative side the + goes to gnd. Thats the only difference i see.
Sorry, it's my 1st PSU
Cheers,
Mallard