Blowing your fuses probably means you've got something wired wrong. However, somewhere in the Pearl thread there was someone who was blowing fuses because of the high inrush current. He solved that by adding 2 CL60 thermistors in series with the live AC connection. I did the same, and am still on my first fuse up until now ("stock" PSU but with the two thermistors and discrete rectifiers).
it turns out that i had used fast/rapid blow fuses, which might explain it. (Im hoping) so if I'm lucky it might just be a little nuisance tripping. Last thing i want is to disassemble the box and resolder everything. it all looked good going in. the caps are wired to,a blank insulating pcb so there was no pcb notation to reference as everything was soldered in place.
What values do you use? 500mA 250v ?
Im ordering a variety to keep personal stock of varieties and may try a slightly higher value.
the led worked and still is. all the diodes are still functioning from what i can tell and the capacitors must be in correct as voltage slowly trickled down across the bleeders as they drained.
I ran all over town today trying to find someone who sold 6mmx20mm fuses... No one had them, and half of the people didn't seem to even know what a fuse was. Darn big box stores putting the little guys out of business.
I have some photos on my phone from the build process and ill try and post them on the weekend. In the meantimemlooks likemill have to order fuses from digikey
What values do you use? 500mA 250v ?
Im ordering a variety to keep personal stock of varieties and may try a slightly higher value.
the led worked and still is. all the diodes are still functioning from what i can tell and the capacitors must be in correct as voltage slowly trickled down across the bleeders as they drained.
I ran all over town today trying to find someone who sold 6mmx20mm fuses... No one had them, and half of the people didn't seem to even know what a fuse was. Darn big box stores putting the little guys out of business.
I have some photos on my phone from the build process and ill try and post them on the weekend. In the meantimemlooks likemill have to order fuses from digikey
I have 30va r-core and 4X10000uF filter caps within unregulated dual PS. It's good idea to keep plenty at hand. I am using same value 500mA for 230V. I buy box of 20 pieces.
This is good news.
let's see what is on the schematic -
Yep. 1/2A
A good idea. You will always be able to use fuses.
Found the problem...
Sorry i didn't post the photos, 6L6.. During the tear down process (to take the photos and show the bottom of the layout) i thought about how my dim bulb tester was glowing a bit more than id like before the fuses went. it suggested there was a short even-though i just couldn't find one in the wiring.
So i pulled the caps out and checked the resistance and wow! It was over 200k on 3 of 4! You could say, Thats a 'little' too much esr! Haha. Turns out Id cooked a couple caps with the 350deg iron. (Typical mistake for the inexperienced i hope.)
Tore down the board and rebuilt with a couple spare 10,000uf nichicon kw (m) gold tune caps i Had. Im pleased to say I'm generating 39v. Im going to throw in a 3300 and series resistor to keep the crc layout in the psu. Hopefully i can get volts down a bit with what i have here, to make for some breathing room.
Thanks for the help guys!
Sorry i didn't post the photos, 6L6.. During the tear down process (to take the photos and show the bottom of the layout) i thought about how my dim bulb tester was glowing a bit more than id like before the fuses went. it suggested there was a short even-though i just couldn't find one in the wiring.
So i pulled the caps out and checked the resistance and wow! It was over 200k on 3 of 4! You could say, Thats a 'little' too much esr! Haha. Turns out Id cooked a couple caps with the 350deg iron. (Typical mistake for the inexperienced i hope.)
Tore down the board and rebuilt with a couple spare 10,000uf nichicon kw (m) gold tune caps i Had. Im pleased to say I'm generating 39v. Im going to throw in a 3300 and series resistor to keep the crc layout in the psu. Hopefully i can get volts down a bit with what i have here, to make for some breathing room.
Thanks for the help guys!
Isn't that 2K2 is more? I used that 2.2K for bleeder resistance and CRC made of 10,000uF - 1R - 10,000uF for each rail. Off course all were unmatched except noted values.
Yeah i had some left over 2.2k resistors that i bought for bleeders. They were the highest value resistor i had, so i put them between the extra 10,000 and 3300's i had ... They arent dropping the voltage much. The rails are stabilizing at 40.2 volts. A little too much.
Going to need to find stronger resistors to drop it down to something closer to 34v or so..
I lack experience, can anyone recomend values to drop around 5 or 6 volts?
Going to need to find stronger resistors to drop it down to something closer to 34v or so..
I lack experience, can anyone recomend values to drop around 5 or 6 volts?
Rather than resistances use 10 number of 1N4001 diodes in series for each rail. They should drop that much voltage. Resistance drop is current dependant, is your voltage reading is while current consumed by pearl boards?
Hmmmmm. I usually keep my iron set a almost double that, havent fried a cap while installing yet...
Russellc
Regulator Heatsinks?
I'm building a Pearl 2 to replace a FET 9 that I sold and had been using as a phono preamp. I am in the process of stuffing the boards and was wondering what you all are using for a heat sink on the 7824 and 7924???
As an aside, I was talking with Kent at Pass Labs when I ordered the boards and FETs. I mentioned that several years ago I'd sold my AlephOno and really missed it. He said that I will be very pleasantly surprised when I finish the Pearl 2!
6L6, Thank you so much for the BOM! That made it so easy to order the parts!!
I'm building a Pearl 2 to replace a FET 9 that I sold and had been using as a phono preamp. I am in the process of stuffing the boards and was wondering what you all are using for a heat sink on the 7824 and 7924???
As an aside, I was talking with Kent at Pass Labs when I ordered the boards and FETs. I mentioned that several years ago I'd sold my AlephOno and really missed it. He said that I will be very pleasantly surprised when I finish the Pearl 2!
6L6, Thank you so much for the BOM! That made it so easy to order the parts!!
Hi bnorrish,
Thanks so much for the info!
I was also thinking about the instructions on the PCB to adjust the DC offset to zero with P1. I bought Nichicon Muse BiPolars for the output electrolytic but I wonder if a polarized audio grade electrolytic that was biased correctly wouldn't have better sound?
That may be a good test after I get the unit built and burned in.
Thanks again
Thanks so much for the info!
I was also thinking about the instructions on the PCB to adjust the DC offset to zero with P1. I bought Nichicon Muse BiPolars for the output electrolytic but I wonder if a polarized audio grade electrolytic that was biased correctly wouldn't have better sound?
That may be a good test after I get the unit built and burned in.Thanks again
I went with the Elna Silmic II. Not sure how other caps would sound - worth experimenting for short money. I agree - get it running and experiment after. The Pearl 2 sounds fantastic - definitely not the weak link in my setup! Once I got it running, I was more than happy with it and ready to move on to other parts of my system and buy a lot of records. It took a few months but well worth it!
I have my boards stuffed except for the big caps, heat sinks, and regulators. Waiting on heat sinks. I'm also working on recycling a nice 2U rack-mount chassis that once held a Crestron Control System. I also ordered a couple Panasonic Low Signal relays designed for switching uVolt signals. My main TT has two tone arms and I'd like to be able to switch between them easily. When I had an AlephOno I put a toggle switch through the power LED hole which controlled two relays mounted to the underside of the PCB where the MC/MM selection DIP switches were. (Nelson's idea) That was easy. Now I'll have to switch between two sets of input jacks and also switch between gain setting resistors on the PCB. Years ago I was spoiled by the Threshold NS-10. Remember when all of the nice preamps had multiple phono inputs? Oh it would be nice to have a Pass X-25!