sunday morning organ salvage comin down...

[gadget73]

wind it up until you start to get voltage across cap 26. Monitor the other spots, if its good, bump it 5-10 volts at a time until the voltage across cap 2 is about where it should be, provided the voltages on the other caps do not exceed their ratings. Possible they will be rated at less than 400-odd volts.

 

[ceylon]

wind it up until you start to get voltage across cap 26. Monitor the other spots, if its good, bump it 5-10 volts at a time until the voltage across cap 2 is about where it should be, provided the voltages on the other caps do not exceed their ratings. Possible they will be rated at less than 400-odd volts.

roger that.

btw, is a 600V multimeter suitable for this type of stuff, or shouod i go ahead and replace it with a 1000V? im still within the "free returns" period.

 

[ceylon]

round 2 of testing came to a half--can cap started smoking. tok me a long time to get there, as i couldnt get correct measurements with my 2nd set of probes. 1st set i could, but the handles were busted. second set in tip top shape but gave me 1/10-1/5 the expected ratings. voltage off the wall very low. switched probes.

took one reading, 117VAC at the wall, then saw the can cap (5a-d) smokin.
then saw current draw from receptacle at 1.15A and not movin. shut it all off.
can cap5 good n hot. transformers and choke still room temperature.

which brings me to my next questions:

did i likely do any irreperable damage?

do i just replace all the caps and start over?

ceylon

 

[Catmanboo]

I'm no seasoned expert, but depending on where in the circuit the smoker is, whatever it pulled enough juice from to overheat like that bears closer inspection. If it's right close to the HV secondary of the power xfmr, I'd check the secondary voltage. Being that you seem to have caught it before the fireworks started, yer probably good there. Maybe have a rectifier problem giving that cap a case of the ass.

 

[ceylon]

I'm no seasoned expert, but depending on where in the circuit the smoker is, whatever it pulled enough juice from to overheat like that bears closer inspection. If it's right close to the HV secondary of the power xfmr, I'd check the secondary voltage. Being that you seem to have caught it before the fireworks started, yer probably good there. Maybe have a rectifier problem giving that cap a case of the ass.

would i be able to check that without significant extending damage beyond that 5(a-d) can caps?

R to L: choke, 5U4G, 4uF cap #26 4uF cap #2, OPT, multi-cap can


multi-cap can 5a-d

 

[gadget73]

At this point the most sensible thing to do is replace the cans. Not likely you did any damage if it was shut down fairly quicky, at worst maybe the resistor feeding that section is a little unhappy but I'm about 50/50 on being able to re-use resistors mounted on the bottom of caps. Half the time the legs break when trying to remove them, and often when they do come loose they are off-value anyway.

 

[ceylon]

At this point the most sensible thing to do is replace the cans. Not likely you did any damage if it was shut down fairly quicky, at worst maybe the resistor feeding that section is a little unhappy but I'm about 50/50 on being able to re-use resistors mounted on the bottom of caps. Half the time the legs break when trying to remove them, and often when they do come loose they are off-value anyway.

all right. i think ill replace those as well.
what sort of caps do u suggest--what types/brands will do fine without goin boutique? might i go to hayseed hamfest for that multi-cap can i fried?

 

[nerdorama]

Hayseed is a fine option. Restuffing with new caps works too. I have restuffed many cans with good results. Authenticap is well regarded for their modern made can caps. CE have a bit of a rep for premature failures as the temp rating on some of their higher voltage rated caps is quite low. Have to watch the specs.

 

[nerdorama]

You might very well use discrete capacitors under the chassis. From the schematic, you only need 3 caps as two of the 20uF 450V are in parallel. Could put a 47uF there.

 

[Catmanboo]

would i be able to check that without significant extending damage beyond that 5(a-d) can caps?

R to L: choke, 5U4G, 4uF cap #26 4uF cap #2, OPT, multi-cap can

View attachment 3047224
multi-cap can 5a-d View attachment 3047230
View attachment 3047233
View attachment 3047231
View attachment 3047237

I'd disconnect that load from the secondary in question, check for proper voltage, reconnect. Most likely is ok. Or, check without the 5u4 in place.
Re: stuffing the cans- they're rather huge compared to modern replacements, you should have plenty of room in the shells. Probably easier to under- deck mount replacements for expediency's sake. Those things are about 70 years on, @gadget73 has good advice there.

 

[gadget73]

If you're restuffing, Nichicon makes a tall skinny one that lends itself to that better than the short fat ones, but I couldn't recall the series name if you paid me right now. I want to say they are 10mm diameter though, so 4 will fit fairly well in a standard can.

HH makes nice caps, easy to fit and not awfully expensive. They also require no time to figure out where to mount caps and all that, just pop the old out and put the new in, wire it all back up like it used to be.

wouldn't be an awful idea to replace or at least test those teal caps for leakage too. If you don't have a tester that can give them 400 volts or so, the in-circuit way is to just measure the voltage at the 6L6 side of the caps. If its not zero volts, the cap is leaking. Or spend the 2 bucks on a pair of boring yellow jobs and put them in so you don't have to worry about it. Leaky caps there will eat the output tubes, which cost a whole lot more than the caps.

 

[ceylon]

@gadget73, if i gotta replace that can cap and nearby resistors, id like to go ahead and replace all the caps.

these the ones? any opalce in particular best for shopping for basic caps?

 

[nerdorama]

If you're restuffing, Nichicon makes a tall skinny one that lends itself to that better than the short fat ones, but I couldn't recall the series name if you paid me right now. I want to say they are 10mm diameter though, so 4 will fit fairly well in a standard can.

This is a good example. 105C and 10000 hour ratings. 10mm diameter

https://www.mouser.com/ProductDetail/Nichicon/UCS2W390MND9?qs=Z9VmbLiczeu9Ze7j%252B6n3pg%3D%3D

 

[gadget73]

@gadget73, if i gotta replace that can cap and nearby resistors, id like to go ahead and replace all the caps.

these the ones? any opalce in particular best for shopping for basic caps?

View attachment 3047636

those will work fine, but Mouser and Digikey also likely have them for a bit less. Illinois MPW is another option. If you don't mind mystery brand ones, places like justradios or oldradioparts.net have them for a bit less but they are not really a brand I know. I've got some, ETR brand I think, and I haven't had any issues with them. They are listed as mylar, which is a polyester type rather than polypropylene. I don't know for sure if they are in fact polyester but polypropylene should be the better part. Audible? No clue, but oldradioparts has them for about 50 cents each, a known polypropylene from Mouser, etc is a dollar and some change last I looked.

 

[ceylon]

You might very well use discrete capacitors under the chassis. From the schematic, you only need 3 caps as two of the 20uF 450V are in parallel. Could put a 47uF there.

in stead of 3 x 20uF 450V, 2 of which are parallel i was gonna put in a 39uF 450V for the 2 in parallel, which drops the capacitance there 1mF, and a 22uF 450V for the other--does this work?

 

[trainbuftony]

Should work just fine!

 

[ceylon]

thank you so much

doing the write-in free shipping mailorder from digikey.

 

[trainbuftony]

Aluminum electrolytic capacitors are rated as +50%-20% meaning they can be as much as 20% below or as much as 50% above their stated value. Given their wide inaccuracy margin, I'd think the 1uf difference is sufficiently negated.

 

[gadget73]

yeah, broad side of a barn for tolerance in those old ones especially. 39 or 47 are both well within spec.

 

[ceylon]

doin my recap. replacing the power supply resistors, too. still have to clean the inside of the can. some black gunk still in there.


after i tie the negative leads to create a common ground, ill thread em thru a hole in the resin base; i also thread the leads thru lil holes and attach em to the solder lugs.

after, do i just mount the caps and shut the can? do i tape the caps together as a bundle with electrical tape? do i fill the space in the can with any material?