OK, you told me so...

[outlawmws]

My recent Pioneer SX 2000 tube acquisition was playing perfectly for days, then this morning (I'm using it as an alarm unit, plugged into a timer....) it goes POP! real loud, but continues to play. I shut it off, (Had to get out of bed...) and figure either a cap popped, or one unloaded a charge arcing to something...

I open up the bottom cover after work and start looking for confetti or burned parts/wires.

Finally I see the culprit, its a .05 uf 400 V 'lyitic. (no tolerance shown) With a confetti steamer all inside the little power switch compartment. At first it looked like someone has stuck a foil gum wrapper or two in there all rolled up. Then I realize what I'm looking at. I tell SWMBO to bring her camera, I want some pics (She's the photographer in the house, its her main hobby...) She immediately want pics of the plate of spaghetti circuitry

OK after the photo session, I clip it out and have a pic made of it. Shouldn’t be too big a deal to replace.

I have 2 different .05 uf 'lyitic caps in my discrete’s collection. Of these 2 caps would you guy's recommend? A 200V Sprague 10%, or an Aerovox 400v of unknown tolerance?

Also there are at least 24 other 'lytics in there, some pretty small and in difficult to reach positions. I have no idea which are in the tuner section as I have no schematic diagram. (I'm assuming that is the mot sensitive part of the circuits in there) Are the bigger ones more prone to blowing, or should I bite the bullet and replace them all? (Not looking forward to that...)

I have a fair collection of discrete parts, including many caps. Some are NOS but I know some of them to be 15-20 years old or more. Are they any good, or should I buy new?

TIA!

 

[EchoWars]

If that's an electrolytic. it's the smallest I've ever heard of. Normally, about the smallest I know of is a .47µf.

Check the value again. And as for voltage rating, don't go below what the original was, unless you know for a fact that the voltage applied to the cap is acceptable to the new part.

 

[outlawmws]

Well, It is a can type and had a band on one end, So I assumed...

That will always get you in trouble!


Here is a pic of the blown cap and the potential replacements. It went across the 120V AC input at the power switch.

And the part in place...

And the plate if Spagett!! LOL

Do the bands mean nothing then?

 

[Bauhausler]

Does that cap say "Suzuki" on it? I think I know that part. If so, you're in for a lot more of the same problems. In my experience, and that of others I've talked to, Suzuki oil caps do not have good reliability after so long in service. They get leaky and eventually fail. If that was mine I'd invest in decent film caps of equivalent capacitance and equal of greater voltage to replace all of those little grey bombs.
Note; Some people claim not to have had problems, yet, with those caps.
Remember that if you decide to wait until one fails it could cause a lot more damage than one dead cap. A coupling cap from a driver to a power tube could short, applying a large positive voltage to the power tube grid. That would at the least wipe out the power tube. At worst, the output transformer heats up and fries. Not good. This might be a good opportunity to get some soldering practice inside your spaghetti alarm clock.
Nice rcvr, btw.

 

[outlawmws]

Why, Yes it does! Thanks for the input!

The soldering doesn't bother me, just when I get into RF/analog circuits that are sometimes fussy about placement, and when the part I'm working on is under other parts...

So a film cap of .05 uf at 400V or more. Any brand recommendations or stay away from's? (I'll need 7...) 3 on the tuner, and the other 3 near the tuner... :yuck: hope it doesn't goof it...

The 'lytics (Yes, these have a "+" sign on them... ) are Elna's ranging from 3uf to 500uf, mostly 10's and 20's, with WV (working voltage?) from 50 to 300, and SV (Surge Voltage?) from 40-350.

These days's use the Surge (If I got that right...) as the voltage rating?

Should I worry about the Elna's?

And what about my collection of NOS caps? Use? Or toss?

 

[EchoWars]

Modern film caps go from 0.047µf to 0.056µf, although Panasonic does have a ECWF(L) metal polypro cap in an unusual 0.051 size. Either a 0.051 or a 0.056 would be fine.

Axial will be tough to find.

I'd use either a Panny ECQP(U) straight polypro cap, or a Panny ECWF(L) metal polypro.

 

[Tom Bavis]

I'll throw in a dissent... if this cap was connected from the power line to chassis, I'd leave it out and install a three wire (grounded) power cord. If I DID replace it, I would use a .015 uF, safety approved (UL) 'Y' capacitor, which is approved for liine-to-ground usage. .05 is too much (and 400V is too low) for power line connection.

If it's connected line-to-line, a .047 'X' rated cap, also UL approved, would be my choice. 'X' and 'Y' caps are tested at 2000V and more, so they will handle line surges safely.

Now that you know what the caps are like in this box, you might think about the rest of 'em... at least check that the right fuse is installed before you plug it in again!

 

[Thatch_Ear]

I vote for the IEC plug too. You will need to "float" the earth ground using a .1 or larger with a good 400V parralleled with a 5 watt 100 ohm resister. Only a filter to keep the chassis potential fron causing an effect that can be heard.

Do a search in tubes for a thread by me titled Bang!. A Susuki oil on the AC input did exactly the same thing a few months back. Probably a power surge and remember the voltages today are already higher than when your unit was made.

I plan on replacing all the Suzukis but just haven't decided on the right caps yet. I recently picked up an Orange Drop with a magnet and plan on looking for something else.

 

[outlawmws]

Thanks for the suggestions guys, but I don't think it applies here.

This cap was connected across the power the main power switch, So I’m guessing it was to minimize arcing across the contacts. It did not blow on switch contact, it blew about 15-20 min after a timer turned it on, and the power switch wasn't touched.

Power feed like this:

Line in, over to a fuse, (3A yes its the right rating)
over to a 120/240 selector switch,
over to the power switch,
back to the power transformer and a multitude of other things.

The other line in hits what I'd guess to be the other end of the power transformer wire.

Any suggestions on the 'Lytics? Is Elna any good, or replace anyway?

BTW only 2 of my collection of caps are a right size for my needs so its go buy new...

 

[EchoWars]

If I DID replace it, I would use a .015 uF, safety approved (UL) 'Y' capacitor, which is approved for liine-to-ground usage.

I missed that...it is indeed a safety cap. 0.047 is a pretty common size, and IMHO isn't too big (I use 0.1µf safety caps across the line all the time).

 

[outlawmws]

Thatch_Ear ,

On the grounded plug and floating the ground you mentioned, the cap and resistor are run in series from chassis groun to the ground wire, right?


EW,

This cap didn't come near ground and didn't run between the lines. It was across the poles of the main front panel power switch,

So I'm assuming, (there I go again...) that is is there to prevent arcing on the switch contacts?

Thanks again for all the advise!

 

[NOSValves]

Yup I'd recap that entire unit. Your going to have more surprises and carnage pictures to take if you don't.


Craig

 

[Bauhausler]

Originally posted by NOSValves
Yup I'd recap that entire unit. Your going to have more surprises and carnage pictures to take if you don't.


Craig

Craig;
Any opinion on the Suzuki oil caps in particular, or just old caps in general?

 

[Thatch_Ear]

On floating the ground the cap and resister are in parrallel.

Although in a different place physically on the chassis, the cap that blew sounds like it was doing the exact same thing, acting as a small filter on the AC going in. Mine just wasn't at the switch.

I do think it blew because of power surges.

It is the only Suzuki cap that has exploded in any gear I have owned.

I consider Elna lytic caps to be exellent.

 

[outlawmws]

Sorry Thatch_Ear, I didn't ask that very clearly.

The cap and resistor (that are wired in paralell to each other) run in series from chassis gnd to the cord ground wire.

Correct?

So these Elna's even though old, should be good to go? or should be replaced due to age?


Also If I have NOS (new old stock) Caps hsould those be discarded? or OK to go?

 

[EchoWars]

This cap didn't come near ground and didn't run between the lines. It was across the poles of the main front panel power switch

In which case it needs to be a saftey cap...anything that's on the AC line is spec'd to be there...regardless of which line it runs to or from or across.

So I'm assuming, (there I go again...) that is is there to prevent arcing on the switch contacts?

Yep...but that doesn't mean any ol' cap can be used.