Dual spark capacitor values

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Japi Roelofs
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Dual spark capacitor values

Post by Japi Roelofs » 24 Jan 2019 14:01

Dear Dual owners and experts

would it be possible to make a list of values for the spark suppression capacitors that prevent our beloved Dual turntables from making that horrible 'pop' sound when turning on or off?

So far I have found these values, when looking through service manuals:

1019: 0.01 uF / 700 V
1219: 0.01 uF / 700 V
1226: 0.068 uF / 250 V and 0,01 uF / 1000 V
1228: 0.068 uF / 250 V and 0,01 uF / 1000 V
1229: 0.01 uF / 700 V

In some service manuals the value is not specified. Does anyone have a list of those values? Maybe the values aren't that critical? I've seen quite a lot of recommendations for 0.047 uF.

The reason I ask is that it would be handy to have an overview — for future repairs it would be nice to have a 'go-to' thread, that has all the knowledge from the members here on the forum in one place...

dualcan
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Re: Dual spark capacitor values

Post by dualcan » 24 Jan 2019 15:58

Hi Japi,
Because of today's safety codes, all noise suppressors should be code X2 types, regardless which power switch , brand , nor type of equipment is being serviced:
http://www.kemet.com/Lists/Filestore/Ev ... andSMD.pdf
Dual in the late seventies changed all of these surge caps for all the various power switches to Rifa/Kemet which the above pdf file shows as PME271M family.
Consequently, I now regularly change all these caps, of which most of the time, the value is 10nf (.01uF):
PME271M510MR30.
This is exactly the type and brand used originally in these late seventies and on products.
The .068 and .047 values are found on the various strobe boards (1229 onward) and should also be changed.
As a lower cost variant, Peter (wacholder) on the German dualboard.de, uses these from Conrad as a substitute with success:
https://www.conrad.de/de/tru-components ... 66329.html
This brand has all the values needed as well.

There is one more capacitor value which is a good to keep on hand, also an X2, the .33uF cap.
It is used as a phase shift for the SM100 family of belt drive Duals. That motor is used up to the present 505-4, if memory serves.
When it shorts, the motor no longer "knows" which way to turn, and as a result will run backwards or forwards at will.
With the values 10nF, 47nF, 68nF and 0.33uF, all the Dual product suppression and phase shift cap needs can be safely met.
Regards,
Klaus

T68
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Re: Dual spark capacitor values

Post by T68 » 24 Jan 2019 17:44

Just ordered a 0.047 uF cap for the spark suppression on my 601. Should that have been a .01 uF and instead use 0.047 for the strobe board?

dualcan
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Re: Dual spark capacitor values

Post by dualcan » 24 Jan 2019 18:22

Hi,
I just checked with the 601 on my workbench and found:
DSC00051.JPG
(39.81 KiB) Downloaded 174 times
.01 / .068uF capacitors.
DSC00048.JPG
(41.7 KiB) Downloaded 186 times
DSC00052.JPG
(65.62 KiB) Downloaded 198 times
Neither the .01 in the power switch nor the .068 in the strobe box, are X2 safety rated, but conformed to the SEMKO rules at the time (German Text):
https://de.wikipedia.org/wiki/Entst%C3%B6rkondensator
The various power switches occasionally have both .01 and .047 listed as suppressors, if memory recalls. I presume this had to do with the various markets and their local electric/electronic governing regulatory bodies decisions.
Regards,
k

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Re: Dual spark capacitor values

Post by DSJR » 24 Jan 2019 18:46

I've got to bring my 601 back down to check. I was sure my German one had a conventional 'rectangular film' X2 cap and you advised on the correct value at the time a few years ago. I don't think I looked in the switchbox either - Gawd, some memories are terrible for me and unlike when the 701 X2 cap blew up a few years earlier, I didn't take pictures so will have to check physically what's in mine so I can get my head straight...

Sorry, bit of thread crap thinking out loud above there...

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Re: Dual spark capacitor values

Post by dualcan » 24 Jan 2019 18:49

Hi Dave,
That is entirely possible because the 601's production run could have contained the time when Dual switched to X2 caps.
Regards,
k

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Re: Dual spark capacitor values

Post by T68 » 24 Jan 2019 19:33

So, I guess I have to pop the hood and look what value the cap has on my unit and replace with the same?

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Re: Dual spark capacitor values

Post by dualcan » 24 Jan 2019 19:56

..... pop the
hoods
and look what value the cap has on my unit and replace with the same?
yes, but x2 compliant!
k

Japi Roelofs
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Re: Dual spark capacitor values

Post by Japi Roelofs » 24 Jan 2019 20:16

I just finished work on a 1226. I replaced the cap with the 0.01 uF that you linked to (from Conrad) and I would still hear a pop. Well it was actually a loud kaboom.

Now I switched it out with a 0.068 uF one and the pop is gone. But I did notice quite a bit of black crud on the switch contacts. Cleaning that off might have helped too.

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Re: Dual spark capacitor values

Post by T68 » 24 Jan 2019 21:36

dualcan wrote:
24 Jan 2019 19:56
..... pop the
hoods
and look what value the cap has on my unit and replace with the same?
yes, but x2 compliant!
k
Of course :-)!

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Re: Dual spark capacitor values

Post by T68 » 28 Jan 2019 18:41

Well, I looked under the hood on my 601 today and the cap looked a bit old. Worried that it might blow I replaced the 0.01 uF with the 0.047 I just got from Conrad, just too keep spinning. But should I get a 0.01 to replace with the same value or can the 0.047 work in the long run?
Still getting pops but not as loud as with the old 0.01 uF.
Haven't gotten to the strobe cap yet. Can this one cause pops too?
The new X2 cap in place:
IMG_20190128_190151.jpg
(141.2 KiB) Downloaded 143 times
Just a note: Conrad really likes big boxes for small stuff:
IMG_20190128_183729.jpg
(100.1 KiB) Downloaded 118 times

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Re: Dual spark capacitor values

Post by dualcan » 28 Jan 2019 19:24

Hi,
The strobe cap can create problems in the audio via a poor working neon bulb, besides the possibility of exploding if it is a Rifa and has cracks in the body. These cracks allow humidity to creep into the cap. It is this humidity which, over time, shorts out the cap and the resulting explosion of same.
Better to change as a preventative measure.
Regards,
k

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Re: Dual spark capacitor values

Post by Nolperi » 23 May 2019 09:16

Hi guys,
my first post here btw.

So, I've got a Dual 1216 Turntable in a "Salora Stereo 2001" setup. It was sold as such - the dual 1216 with Salora's amplifier.
Anyways, all the mechanisms were pretty much stuck and the motor was constant ON. I disassembled all, cleaned out all gummed up lubricants and re-lubricated. Just like that the ON/OFF switch for the turntable motor started working.

Well, kind of - there was an audible crackle sound every time the motor switched state (ON-->OFF or OFF-ON). I found that an open loop spark suppressor capacitor would do this. Inside I found an old german capacitor, roederstein P1872 0.01uF. Dual being a german brand, I'd say this capacitor is of the right era and area to be ORIGINAL.
So it's 10nF cap, and it is NOT BUSTED. I put it on a professional LCR meter and it measures out at 11nF. It's got 250V~FMF stamped on front and below is 1000V-400V~ DIN41159. I'd say this is the closest modern replacement: https://www.mouser.fi/datasheet/2/427/f ... 239776.pdf

Anyways, the 1216 service manual says I should replace this capacitor with 0.1uF/700V capacitor - that is 100nF - 10x the capacitance of the original roederstein. I put in an epcos X2 rated capacitor: B32922H3104M, which is 100nF.
Now it makes no sound at all! Completely fixed!

But I also cleaned up the switch contacts using 1000 grit sandpaper. Now I wonder. Is there a mistake in service manual asking for 10x the capacitance? Should it be 0.01uF (10nF) like the one I pulled out? Did the original capacitor do its job, and cleaning up the contacts fixed it? Or did they put 0.01uF into it in the factory, then learned that it should have been 0.1uF instead?
What do you guys think? I may have to solder the original capacitor back in there just to test it out :D

Bottom line: Dual 1216 spark suppressor capacitor value is:
a. 0.01uF/250V~ (1000V - 400~ DIN41159) - as found inside the device a ROE P1872
b. 0.1uF/700V - as stated in service manual

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