Glen's 700 series II build

[NavLinear]

I would be cautious Glen. Modern electrolytic capacitor voltage ratings really should not be exceeded but sometimes you can cheat a bit. I would form them to your measured rail voltage but again you need to be careful. Jerry had one vent on him and it sounded like it created a bit of a mess. Optimally you want to have a cap like this working at 80% or less of its rated voltage. Are you using the 2k ohm resistor in series with your power source to measure leakage current?

 

[Gepetto]

So I wanted to get something done today and took on the task of conditioning the power caps.
i got an old heathkit it-28 capacitor checker of eBay and installed some new power supply caps and one other the supplies the green eye.

so after much tinkering I was willing to try it on an old cap.
first run compete at 25 volts and now completely discharged will run a 50 volt charge.

i reason in using this old unit instead of me newer sencore is it charges slower and discharging is easy, flick of the switch.

i will the go on the 100 volt cycle but not the 150. Dennis suggested charging at above rail voltage so I will configure a setup like the one Lee has posted using a bridge rectifier and a varic power supply. What do you guys think of a 115 volt conditioning voltage for this on a 100 volt cap?

i will keep track of the can temps as I go throught the process
it takes about 1 hour per charge so far.

What is the capacitor rating? If only 100V then do not go above 100V.

 

[laatsch55]

115 to 120 would be plenty...

That was for the 160 volt caps Glen...most the 100's ...

 

[grapplesaw]

Thanks everyone
the caps I have at this time are Panasonic 100volt 18000 -10+50 uf 85*c made in usa

I tested them on the sencore at 100 volts

18,240 uf .
ESR .19 ohms ,
dielectric absorption 4% ,
leakage 4.2 ma


I am going to put them on the it-28 and condition them at first 50 volts the 100 volts

 

[Gepetto]

Thanks everyone
the caps I have at this time are Panasonic 100volt 18000 -10+50 uf 85*c made in usa

I tested them on the sencore at 100 volts

18,240 uf .
ESR .19 ohms ,
dielectric absorption 4% ,
leakage 4.2 ma


I am going to put them on the it-28 and condition them at first 50 volts the 100 volts

4.2mA is deadly. Should be in the 50 microamp range.

 

[grapplesaw]

Re-did test
Esr .09 ohms
leakage 900ua
18340 uf
dielectric absorption 11%

these have not been conditioned yet

 

[Gepetto]

Re-did test
Esr .09 ohms
leakage 900ua
18340 uf
dielectric absorption 11%

these have not been conditioned yet

Better Glen but that is still high leakage. Keep an eye on them.

 

[grapplesaw]

Better Glen but that is still high leakage. Keep an eye on them.

Thanks Joe

This is the first time using this unit so I will read manual again to make sure I have it setup right, I think it is right.

ps any update on chassis Joe

 

[NavLinear]

If you have a 2k ohm 2 watt resistor you can follow Joe's procedure to use as a sanity check against your cool cap tester. If you have something close - I use 2.49k ohm 5 watt one that I had in my bench drawer - you can substitute but of course the math changes.

http://forums.phxaudiotape.com/show...y-Bulk-Capacitors?highlight=capacitor+forming

 

[Gepetto]

Thanks Joe

This is the first time using this unit so I will read manual again to make sure I have it setup right, I think it is right.

ps any update on chassis Joe

Hi Glen
I sent you an email about it.

 

[grapplesaw]

Hi Glen
I sent you an email about it.

Thanks
i will look for it

 

[grapplesaw]

If you have a 2k ohm 2 watt resistor you can follow Joe's procedure to use as a sanity check against your cool cap tester. If you have something close - I use 2.49k ohm 5 watt one that I had in my bench drawer - you can substitute but of course the math changes.

http://forums.phxaudiotape.com/show...y-Bulk-Capacitors?highlight=capacitor+forming

Thanks Dennis
I have a 2k 2 watt resistor just for this purpose. I will set up on next go around

i just put one of the caps onto the heathkit it-28
it seams to be coming up nicley

it unit is cool at 72* F 23*C

 

[grapplesaw]

First run on the heathkit at 50 volts
holding fast at 30 ua and steady volts

 

[NavLinear]

One thing to remember Glen is when forming a capacitor you don't measure the leakage current until the cap has fully formed. I bet that is what bit you in the ass with your measurement. The voltage across the resistor (see Joe's write up) will drop as the cap forms.

 

[grapplesaw]

One thing to remember Glen is when forming a capacitor you don't measure the leakage current until the cap has fully formed. I bet that is what bit you in the ass with your measurement. The voltage across the resistor (see Joe's write up) will drop as the cap forms.

Thanks Dennis
I will assemble the resistor test

 

[grapplesaw]

The heathkit has leakage and discharge on a flip switch. It is so easy. The sencore makes you hold the button down with your finger the whole time. It comes with a gissmo to hold the button on using the handle and it, a hassle for sure.
I had bought some dale 43 ohm 20 watt resistors to make a discharge setup like your's Dennis
I guess it is getting put together a little later, I am sure it will come in handy

 

[Cafe944]

We will see if she does. This is new to me. Anyway its easier to ask forgiveness than permission.

Here is the case and face plate I will put on this unit

View attachment 17616 View attachment 17617 View attachment 17618

That Really Is Going To Look Great.

 

[gadget73]

Those old cap checkers are surprisingly accurate as long as the internal multiplier caps are right. Does yours measure leakage directly, or is it the neon lamp go / no-go type thing? My old Solar has the lamp. I want to say it comes on at 2ma but that may not be right. I had it figured out at one point but now I couldn't swear to you what the value is. Its higher than you'd want to see on modern gear, but considering it was built in the 1930s for equipment of that era, its fine for it's intended purpose. I'd measure them more directly but I haven't felt motivated to brew up a ~500vdc supply to do it.

 

[grapplesaw]

Those old cap checkers are surprisingly accurate as long as the internal multiplier caps are right. Does yours measure leakage directly, or is it the neon lamp go / no-go type thing? My old Solar has the lamp. I want to say it comes on at 2ma but that may not be right. I had it figured out at one point but now I couldn't swear to you what the value is. Its higher than you'd want to see on modern gear, but considering it was built in the 1930s for equipment of that era, its fine for it's intended purpose. I'd measure them more directly but I haven't felt motivated to brew up a ~500vdc supply to do it.

You were right on Gadget it closes at 2 ma. I calibrated it using a 2 m ohm variable resister and Diald in 2 ma current and set the eye to just close there. The othe capacitor types are much lower settings, but did not set thoughs as the electrolytic aluminum cap was all want to do.
I have set this up with a volt meter and amp meter. With the output voltage set at 100 the current has dropped to 40ua at about 98 volts, which is the true output voltage.
all the tide repair sited say you need to own one .

 

[grapplesaw]

Here is a read

http://www.californiahistoricalradio.com/2012/03/a-tester-every-restorer-should-own/



And this

http://www.angelfire.com/electronic/funwithtubes/Restore_cap.html

i am still feeling my way on this but it is more simple than I first thought.