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In Reply to: RE: II. Power Supply posted by Paul Joppa on December 16, 2014 at 14:45:42
Gotcha, no worries.
I made some Styrofoam stunt doubles of the Panasonic DC Link caps today.
Tentative locations have been determined, they will fit within the chassis, just need to make up some sort of bracket to support them.
A bracket of sorts will also support the potentiometers under the chassis as well.
Cheers
Follow Ups:
I though maybe I would toss up a few pictures.
The 2A3 is there, but the other tubes are stand-ins.I appreciate your patience.
I have tentative locations for the DC Link caps as per the blue foam replicas. I have some aluminum stock that I will run across the tops of those capacitors to secure them.
The choke can go in that general area as shown (156), I will see if I can find a null before I attach them.
The two pots will be located at the front near their respective sockets. These will also be secured underneath with some aluminum angle stock.
The grounds and 25W resistor will go in the center area.
So the layout is more or less finished, I can now run my B+, although some joints may remained un-soldered until I get the film caps etc.
I didn't wire my AC as I think I will need most of my black solid core for ground returns. I have some flex wire for this I could use if needed, I could use clear, as to distinguish the live AC from the grounds.
It doesn't really matter but I thought it would be nice to have the wires coded.
Here is the 8 colour code I came up with, omitting the 120VAC to PT.
Red - B+
Orange - HV secondaries
Brown - 5v heater
Green - 6v heater, speaker +
Blue - Plates
Black - Grounds, grounded elements, returns
Yellow - Cathode
White - 2.5v heaters
Edits: 12/20/14
nt
A really clever hardware hack with chassis construction !
Thanks!
The rest of the tubes ordered last night. I decided against used ST glass 6J5s and ordered a pair of military spec Sylvania's.
The price of NOS 5AR4's are a hundred dollars and up so got some new production Sovtek instead.
It's apparent that I won't be putting the panel meters on these, just a little to tight for space, one model from Partsconnection may fit, but resolution wasn't there, I went ahead with the assembly without putting a big hole in for it.
I might yet build a larger cage around my chassis and mount a suitable panel meter there.
I guess I just leave the 267K and 178K resistors in place, but it is unclear if I need to put a jumper resistor where the panel meter was or not.
Hey Garg0yle,
Nice pics. It's looking good.
It seems that good analog panel meters aren't cheap. I wonder if putting in test jacks wouldn't work better. Just plug in your DMM, and adjust the bias from the deck.
I'm interested to hear how the adjustible cathode resistor works out for you, and if you use it to tweak the voltage.
Jamie
Big speakers and little amps blew my mind!
Thanks you.
"It seems that good analog panel meters aren't cheap. I wonder if putting in test jacks wouldn't work better. Just plug in your DMM, and adjust the bias from the deck."
It's looking that way, other then I will probably keep everything below deck.
Have a good new year.
OK so some parts have started to roll in.Tubes, electrolytics, the 390Ohm Rs and the bleeder resistors that have the ratio to read the 180V point for the meter/DVM terminal.
I got 270K and 180K instead of 267K/178K, hopefully that gets me close enough, maybe I will have to read 179V instead of 180VThe 6J5s look nice.
The 5AR4's are a little chincy, when I hold them to my ear and tap, they make a clanging sound similar to bumping the reverb tank on a guitar amp.
Drlomu and the Tube Wrangler would not like these! :P lol.They sound like this @ 0:20
https://www.youtube.com/watch?v=N5maWd6gm2E
Edits: 01/03/15
Thought I would post a bit of an update.
I'm just waiting on the chokes and terminal posts to arrive.
I have had a bit of design paralysis with regards to locating particular parts like the pots and large resistors. It feels like a chess match at times without having all of the parts in hand.
My overkill hum-pot is a little large, the Bournes pot for the 6J5 is shockingly smaller then I expected. To somewhat complicate matters, I want to have them underneath the chassis. so I need to accommodate room for a bit of L stock.
I more or less have my grounding scheme planed out. I debated having the chassis shield connected only at the input, as I had never tried that.
Ultimately I decided that I will connect it at the power supply caps.
The electrostatic shields are connected to the mains Earth, I wasn't sure if it mattered, just thought it might be a little quieter ground is all.
Overall I am reasonably happy with what is installed. I might move the B+ wire a little farther away from the PT though.
The last of the parts have arrived.
My power transformer does not have a center tap on the heater windings. (it has 0-5V-6.3V)
So I was wondering if I should make an artificial center-tap with some 100 ohm resistors that grounds at the 6J5 cathode pin? or on my ground buss close to the HT center-tap?
OK I guess I am going to elevate the 6J5 heaters at the cathode pin.
I was doing some grounds last night and wanted to accommodate a heater return in a certain order.
Thanks anyways.
OK chokes turret posts and RCA jacks are ordered.
I wussed out and I am going to use Electrolytic caps.
As it is I dropped almost $500 on odds and ends, also I found it next to impossible to buy film caps with paypal that would fit.
So now I just hurry up and wait.
Everything except for one package is coming from Canada, so everything should arrive in a reasonable amount of time without customs roulette.
Happy new year.
Happy Holidays.
I finally got a few parts ordered.
-390 ohm 10 watt wire wound ceramic type. (Only need 5 watt, but it was close etc)
-3K ohm 25 watt resistors. I got the adjustable kind and will just leave the wiper off. Fairly compact.
-25 ohm 25 watt ceramic potentiometers for the hum pots. Probably overkill, but it looks sturdy enough.
-1K ohm 2 watt Cermet potentiometers. Now these I was trying to get in a little higher wattage, but they were huge.
Hopefully the 2 watt pots would be OK on the 6J5 cathodes?
Going back to eBay now to find some tubes.
I have a couple 6J5 book marked.
It's a little unfortunate I need the 5AR4 in my specific application, as some of the other rectifiers are a little cheaper and available NOS in a ST jug.
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