Caps in parallel and series in PSU, experiences?

[gingertube]

utervo,
The 20% tolerance is insignificant - don't worry about it.

Your calacualtions are correct. Now its time to check your basic assumptions.

You calaculated for 2 x 66uF in series to give 33uF total and said it was for a Super Reverb Plate Section. I'm not sure what you mean by plate section but if this is the main power supply node feeding the output transformer primary centre tap then 33uF sounds way too low. If it is the feed to the preamp section node then its probably OK.

Cheers,
Ian

[utervo]

The first filter cap section, the original has 70uF in series, so 35uF total.

[utervo]

I am convinced there is something wrong with my calculation, I am not sure I should use the capacitance of the capacitor but half the total voltage?

[Reeltarded]

series 1/2 the capacitance x2 the voltage.

(100u/500v x2 = 50u/1000v)

para x2 the capacitance but the voltage of the lowest capacitor's rating.

(25u/500v paralleled with 25u/450v = 50u/450v)

[utervo]

Yes but I mean for the leakage current of caps?

[utervo]

Anyways the load will be around 1.5-3mA of total current strain on the B+ line.

Classictone Deluxe Reverb PT is rated at 120mA and their Super Reverb PT at 200mA. It is not too much strain on the PT?

PS. The transformers have finally arrived and are waiting in the post, yes!

[utervo]

Deleted some posts as I wasn't sure about my calculations.

Anyways, I asked someone at F+T what I should use, and I was told 47K/1W.

Illinois advises a R=10/C, capacitance in uF and resistance in MOhm. so 10/33=0.303M=303K etc...

Illinois paper also has another technique:

"To calculate the Balancing resistor value more accurately do the following:
1. Determine the leakage current of the capacitor.
2. Calculate the DC resistance value of the capacitor using the formula
3. Balancing resistor value will be 10% of the calculated DC resistance value.
RDC= Rated voltage/Leakage current
4. Balancing resistor wattage rating is calculated by determining the amount of current
flowing through the balancing resistor multiplied by the voltage across the resistor.
When a series- parallel combination is utilized it is recommended that each capacitor have
a balancing resistor placed across it. "

[utervo]

Here's how I do the first cap bank, here's two 80uf caps.

https://tubeamparchive.com/download/file.php?id=24406

You have a wire under board from - of right side cap to + of left side cap? Very neat. What amp is this build?

[ToneMerc]

Here's how I do the first cap bank, here's two 80uf caps.

https://tubeamparchive.com/download/file.php?id=24406

You have a wire under board from - of right side cap to + of left side cap? Very neat. What amp is this build?

Bottom left > top right, 6G6B clone

TM

[utervo]

I have most of the parts here. Did a sketch of the power supply board. Can anyone check if it looks ok?

[gingertube]

Checked you have the caps around the right way and voltage share resistors correct - all looks OK.
You have effectyively 33uF , 16.5uF, 16.5uF, 16.5uF
Is that what you were wanting?
Cheers,
Ian

[gingertube]

Checked you have the caps around the right way and voltage share resistors correct - all looks OK.
You have effectyively 33uF , 16.5uF, 16.5uF, 16.5uF
Is that what you were wanting?
Cheers,
Ian

Sorry about the double post - the forum gave me an error message (something about emailer.php) so in good "Engineers Method" I hit the button again. I did'nt need to go to the next step (reach for the percussive maintainance tool).

[utervo]

Checked you have the caps around the right way and voltage share resistors correct - all looks OK.
You have effectyively 33uF , 16.5uF, 16.5uF, 16.5uF
Is that what you were wanting?
Cheers,
Ian

Thank you a lot. Its good to have another pair of eyes to take a look.

Those are the capacitances I planned. I will try to measure higher capacitance ones for Super Reverb and the lower ones for the Deluxes.

USPS has by 6PS caps that I am waiting for fine tuning the main board layout.

[utervo]

Double post. Has some email error showing.