2a3 Capacitor question

[debk]

Thanks john, I have actually seen that site before.  A lot of information.

I think what I may do is build the 2a3 paramount with the stock capacitor, and then put a temperature probe  next to the capacitor and see what I measures

Debra

[Grainger49]

Eric,

I can't take credit, it isn't mine.  But isn't that gorgeous wood?  I really like that finish on the Oak.

Debra,

Try bypassing with two pair of jumpers.  It took me quite a few swaps the first time I did it.  I decided to leave the KK Teflons in my Ack! dAck!

[InfernoSTi]

Reading my note again, I may not have been very clear. I meant that the temperature of the wire inside the transformer, and the temperature of the silicon chip inside the transistor, would be kept below 100C. Inside the chassis the air temp is of course much lower - hotter than room temperature, cooler than 100C.

We have been adding ventilation slots in the chassis plates, gradually, as products get revised. This allows thermally-driven airflow, taking it in below the wood base frame and exhausting through the slots.

Cooling air from a fan or other cause does not need to flow very fast, but it does need to flow over the heat sources and then out of the chassis. Components don't sweat, so a fan inside the closed chassis won't cool anything - you need that cross ventilation!

Thank you, Paul.  Adding additional vent holes in the right spots and/or adding a small, slow fan (such as running a silent 12v DC fan at 6v) to create greater cross ventilation is the goal, then.  If ambient is around 25C and max temp is 100C, and cap max is 55C, then it should be possible to get there, perhaps.  I just love my Mundorfs....

Best,
John

[InfernoSTi]

Well a couple of things.  First, I've drilled a few vent holes above where the parafeed cap are located.  I drilled six 7/32" holes. Since I'm painting the top plates, I think they will simply disappear to a great degree.  I'm also planning on using Herbie's Tenderfoot 1/2" feet which should allow a lot of air to get in underneath the amps.  Each of these is done with the hope that this well allow better crossflow ventilation.

Also, I realize I picked up a set of Mundorf Supremes, not the SIO (and paid appropriately and with full and proper disclosure by the seller...just misspeaking on this thread).  So I'm going to get a new set of SIO for the cap and will probably allow them to hang a bit low where they can get good air flow around them.

Best,
John

[InfernoSTi]

So I thought about this some more and added a few more holes above the parafeed capacitor (9 total). I also added some holes around where the cathode resistors mount (7 total), figuring this was where Paul said there was a significant source of heat.  I have painted with black lacquer with a clear lacquer top coat.  I'm not the best craftsman around...the flaws are obvious...but I'm happy with the result and think the extra vent holes will keep the air flowing better.  Oh, and I decided to get the 3.9uf Mundorf SIO...I bi-amp and am not worried about bass extension.

Best,
John

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.us%2Fforums%2Fdownload%2Ffile.php%3Fid%3D1552%26amp%3Bmode%3Dview&hash=0a355d269021248e09f8ae1085137d82c60c4b2b)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.us%2Fforums%2Fdownload%2Ffile.php%3Fid%3D1553%26amp%3Bmode%3Dview&hash=fee77f17caf2c829bc19f82915861a7cea2f1fbd)

[InfernoSTi]

One last post for this thread...here are the Mundorf 3.9uF Silver In Oil caps installed with a bit of an air gap to allow free flow of air to the extra vent holes above.  Remember, heat rises (which is down in the photo).

Best,
John

[InfernoSTi]

As an update to this thread, the hottest place I measured on the surface of my Paramounts was 56 degrees C. with most areas within 1/2 inch away being 53 degrees C or lower.  Underneath, the cathode resistors are at 80 degrees C.  The Mundorf SIO are measuring at 43 degrees C. maximum (they are rated at 55 degrees C max).

Remember, I mounted mine "low" and have extra vent holes drilled.  While I would like to see more than 10 degrees from max, I'm not too worried.  I'd love to see what others are measuring in their Paramounts, particularly if they are mounting the caps "high" and didn't add additional vent holes. 

Best,
John

[earwaxxer]

Those Mundorfs are a thing of beauty! Just proves it... 'cap lust' is real, although tubes are always going to be prettier.

[ranger3]

Newbie question.

I will be replacing the Solen 3.3 Para Feed caps.  I have Mundorf silver in oil and have a couple of questions.

Do I need to bleed off the Solen's before un-soldering them?  If so, what's the best way to handle this.

Any advice on safely performing this task is appreciated.

Thanks.

[Doc B.]

Any advice on safely performing this task is appreciated.

Thanks.

Simply use your voltmeter to measure across the cap and see if it has any voltage. If it does, connect a 10K ohm resistor across the leads to drain it off. You will be able to see the voltage drain off on the meter.

[ranger3]

Thanks Doc.

I'm assuming DC voltage is what I am measuring?

[Doc B.]

Yes, DC. Once it gets below 10 or so volts you should be fine.

[ranger3]

The Mundorf Silver in oil do not appear to have polarity.

Do you know if they do, or will either orientation work?

Thanks again for all your help.

[earwaxxer]

nope - dont have to worry about polarity with any film cap, unlike electrolytics. Some say that there is a inner winding side and an outerwinding side and its good to go from inner to outer. Not sure that makes a difference.

[ranger3]

I installed the Mundorf caps. and all went well.  No voltage detected on the old caps. so no need to drain them.

Thanks for everybody's help on this.