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Old 20th Aug 2009, 9:07 pm   #21
geofy
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Post Re: Dansette Electrolytic Capacitors

Fairly sure the negative can side all taken to the same negative line, but a continuity checker (Ohms range on multimeter) on all three points will show if they are joined.

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Old 20th Aug 2009, 9:46 pm   #22
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Default Re: Dansette Electrolytic Capacitors

It's quite clear from the picture that the negatives are all connected to the can. If the three pins go to different lands on the PCB, then these lands need to be joined with wire to give the necessary continuity.
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Old 20th Aug 2009, 11:09 pm   #23
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Default Re: Dansette Electrolytic Capacitors

Thanks; here's a photo of the PCB. I have marked in where each cap goes (+ and -) should be correct, only query now is if any of the negs need to be joined with wire? I'm hoping to have a go at this tomorrow. John
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Old 20th Aug 2009, 11:27 pm   #24
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Default Re: Dansette Electrolytic Capacitors

I suspect much of this faffing is my fault. Earlier in the thread I suggested obtaining axial replacement caps. It hadn't twigged that the original can was PCB mounted and 'can negative', in which case radials may have been much easier. I apologise for that.

In trying to visualise the new caps on the PCB, I imagine it isn't physically possible to twist all negative leads together and solder the combine to a single land?
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Old 20th Aug 2009, 11:49 pm   #25
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Default Re: Dansette Electrolytic Capacitors

From what I can make out, originally the three negatives were all placed on different tracks of the PCB with one negative on an isolated piece of track. Is it therefore necessary to need to join the negs up with wire? As I would have thought if I placed the 3 new positives and the 3 new negatives in the same places as the originals that would have been correct? Thanks. John
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Old 21st Aug 2009, 12:04 am   #26
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Default Re: Dansette Electrolytic Capacitors

This looks very much like the Dansette I repaired for someone earlier in the year.

When I replaced the capacitors I used Radials. Use some insulated wire for safety to bridge all three negative leads. That should solve the problem, but if you like, post pictures of each stage that you go through and we can check and verify that you've done it correctly.

Darren,

I used Radials when I repaired the Dansette, they are perfectly alright to use and I had no trouble fitting them. I think your advice was spot on and very helpful.
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Old 21st Aug 2009, 12:08 am   #27
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Default Re: Dansette Electrolytic Capacitors

Quote:
Originally Posted by john600601
From what I can make out, originally the three negatives were all placed on different tracks of the PCB with one negative on an isolated piece of track. Is it therefore necessary to need to join the negs up with wire? As I would have thought if I placed the 3 new positives and the 3 new negatives in the same places as the originals that would have been correct? Thanks. John
Yes indeed, that was what I was partly trying to say. If it's physically possible to get the negative leads to reach the original points then that's a neat and simple way to do it.

Do a dry run first. Insert the positive leads in their respective places, then see if you can get the negative leads to reach their respective locations. The 25v cap should give no problems, but the size of the two 450v jobs may be tricky - depends how long their leads are. Remember the lands for each cap's +ve and -ve leads will be only millimetres apart and to reach the lands the leads need to be long enough to get around the physical size of the cap itself.

Have that dry run, you'll soon see what I'm trying to say.
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Old 21st Aug 2009, 10:55 am   #28
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Default Re: Dansette Electrolytic Capacitors

Looking at the printed circuit board, it seems to be relying on the capacitor can to connect some of the tracks together.

What you've labelled as "15µF neg" doesn't seem to go anywhere (unless you unsoldered a wire from the nearby hole), but what you've labelled as "22µF neg" and "33µF neg" do need to be joined together.

(PS, Anyone else notice the extra set of holes in the bottom right hand corner, and the wire link between pins 4 and 5? That same PCB was designed to be used for either an EL84 with semiconductor rectifier as here, or the usual UL84 / UY85 lineup!)
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Old 21st Aug 2009, 11:05 am   #29
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Default Re: Dansette Electrolytic Capacitors

It would be pointless having the negative side of the 15uF going nowhere, even though it appears to do so. I suppose it's possible that a standard can capacitor was used with the 15uF being redundant.

It really doen't matter. Just join all three negative lands together with wire and you'll have one less thing to check if the set doesn't work after the caps have been replaced.

Of course if you're restuffing the can will substitute the wire.
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Old 21st Aug 2009, 11:44 am   #30
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Default Re: Dansette Electrolytic Capacitors

Well, the positive side of the 15µF goes to pin 9 of the EL84, which is the second (screen) grid. So that section isn't doing nothing: it's the screen decoupling capacitor. The 22µF is connected to pin 3, so it must be the cathode bypass (and need only be rated for a few tens of volts). The 33µF is the smoothing capacitor (and is connected to pin 3 of the unused valve position; which would be the cathode of a UY85).
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Old 21st Aug 2009, 11:55 am   #31
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Default Re: Dansette Electrolytic Capacitors

Quote:
Originally Posted by ajs derby
What you've labelled as "15µF neg" doesn't seem to go anywhere (unless you unsoldered a wire from the nearby hole), but what you've labelled as "22µF neg" and "33µF neg" do need to be joined together.
So the neg side of the 15uF needs to be joined to the other two neg lands then?
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Old 21st Aug 2009, 12:23 pm   #32
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Default Re: Dansette Electrolytic Capacitors

Yes, sorry. I was thinking he'd already joined up the negative leads and was looking to put them into one hole. But even if you do that, two of the holes will still need to be joined together.

If that makes sense!
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Old 21st Aug 2009, 2:58 pm   #33
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Default Re: Dansette Electrolytic Capacitors

I see what your'e getting at now. If the neg leads are twisted together and put into the neg land for the 22uF or 33uF cap, then only these two lands need joining.
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Old 21st Aug 2009, 5:21 pm   #34
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Smile Re: Dansette Electrolytic Capacitors

Hello everyone. I have done it and it is working perfectly!!! Joined the negs together on the 22uf track, switched it on and waited for the bang(!) and it is perfect, very quiet running! Thanks for all your help; this is an excellent forum and I will print this thread off for future reference. John
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Old 21st Aug 2009, 10:23 pm   #35
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Default Re: Dansette Electrolytic Capacitors

I know that I will echo the sentiments of all who have contributed to this thread in saying a hearty Well done!

It is rally satisfying to know that in some small way you have helped a fellow member repair his or her piece of equipment.

For future reference, if you or anyone else ever have to do a similar job, and you use axial capacitors instead of radial capacitors, fit the positive end nearest the board, connect up all three negatives and have one or two wires going to the negative print lands. That way you wont get a jolt if you accidentally touch one of the wires.
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Old 22nd Aug 2009, 11:50 am   #36
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Default Re: Dansette Electrolytic Capacitors

Well done!

I haven't had much to post about of late so have been mostly lurking. I have followed this thread with interest though! Congratulations and enjoy the Dansette!

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Old 29th Sep 2009, 10:42 am   #37
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Default Re: Dansette Electrolytic Capacitors

right i'm sorry to bring this thread back up. i was directed back here from a recent thread on the same subject. i've been through the information on here and its amazing how in depth all of you are.

i intend to aquire a capacitor for a dansette popular then get someone a little more qualitifed in electronics to fit it for me.

so the origional poster used axial capacitors which ment buying 3 seperate ones to do the job of te 3 in 1 now obsolete capacitor from the dansette. but later in the tread the revelation came that it would have been easyer to use a radial capacitor which would have been easyer? the poster michael maurice used this method, i was wondering if you could recall where you got this one from and which exact model capacitor it was?

many thanks

sam

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Old 29th Sep 2009, 12:49 pm   #38
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Default Re: Dansette Electrolytic Capacitors

Once you've received a response from Michael, we think it'd simplify things if you adhere thenceforth to the other thread (as linked to above). We assume that is your intention though, so this post is merely to underline that assumption.
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Old 29th Sep 2009, 2:27 pm   #39
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Default Re: Dansette Electrolytic Capacitors

I get a lot of my components from RS http://uk.rs-online.com/web though you might need an account to do so.

I also buy from Cricklewood electronics, www.cricklewoodelectonics.co.uk

I see that you are in Melton Mowbray, in which case SEME are there www.seme.co.uk There website is not the easiest to use, but will stock some capacitors. There is also a phone number and I believe they have a trade/retail counter.

I hope you find what you're looking for.

Michael

Last edited by Michael Maurice; 29th Sep 2009 at 2:29 pm. Reason: to make sure the rs web address is correct
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Old 29th Sep 2009, 4:23 pm   #40
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Default Re: Dansette Electrolytic Capacitors

With reference to post #38 above, as Michael has now given a helpful response we'll close this thread and you (Sam) can continue if necessary in the other thread as linked to in post #37.
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