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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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29th Jun 2017, 8:48 am | #21 |
Rest in Peace
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
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Re: Dansette Major Restore
It is possible to get triple can electrolytics, though whether a 32+32+ 22uf is available I know not. Check www.askjanfirst.de as they list a wide range of can capacitors. If the right triple can isn't available, fit a 32 + 32uf Can (350v or higher) and replace the cathode bypass cap. (the third one in the can) with a 22 or 33uf 25v axial leaded capacitor wired directly between the appropriate pin on the valveholder and chassis. 32+32uf cans may also be available from Cricklewood Electronics or the BVWS. One of these should fit in the space vacated by the original. The cans of most modern Dual Electrolytics are Insulated so be sure to connect a wire from the negative terminal to the earth pointa as mentioned by PJL. Another component which may need replacing, especially if the HT is low, will be the metal rectifier (The rectangular silver item to the right of the valve in picture 1)
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29th Jun 2017, 10:16 am | #22 |
Octode
Join Date: Mar 2015
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Re: Dansette Major Restore
Hi Mick, welcome to the forum! I've recently refurbished a Dansette Conquest so I've got lots of photos and notes. I'm not far from you so let me know if you want to meet or talk about anything.
The photo shows the replacement capacitors.
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29th Jun 2017, 6:29 pm | #23 |
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Re: Dansette Major Restore
Hi yes your just over the hill almost. I may take you up on that. All the help so far has been amazing.
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29th Jun 2017, 9:45 pm | #24 |
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Re: Dansette Major Restore
So this is what i have . can someone shout if I'm completely wrong. This is where the capacitor is soldered in. The blue circles would be a negative side of the capacitor and would all be linked together? Is the yellow the positive side of each capasitor? if so how I determine what capacitor each of the yellow
circles are, 32uf or the 22uf? Will i only find out by stripping it out and looking inside the cap? also are the valves normally this black. Do they go at all and what will it do if its not working? |
29th Jun 2017, 10:10 pm | #25 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
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Re: Dansette Major Restore
Yes, the blues are the capacitors -ve, no matter what you replace the existing with the top blue and middle right blue connections must be electrically connected together, the bottom blue can be ignored.
The three yellows are the three capacitors +ve connections, the top yellow is the 32uF which is the HT reservoir capacitor, the middle left yellow is the 25uF which is the cathode bypass capacitor, the bottom yellow is the 16uF which is the HT filter capacitor. Yes, black inside the valve is normal, yes the valve can fail but it can be replaced. If replacing with individually then use 33uF for the 32uF, 22uF for the 16uf, both at 400VDC (min) 22uF for the 25uF at 25VDC, all can be found here: https://www.cricklewoodelectronics.c...re-values.html Other suppliers are available. Lawrence. Last edited by ms660; 29th Jun 2017 at 10:40 pm. |
29th Jun 2017, 10:13 pm | #26 |
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Re: Dansette Major Restore
The easiest way to determine which section of the capacitor is which, is by checking the pinouts of the valve used, which, I think, is an EL84. If so, Pin 3 is the Cathode, and the 22uf is connected to that. The 32uf is connected to pin 9, the Screen Grid (referred to in Valve data as g2). Valve bases are numbered clockwise(when viewed from underneath) from the gap, so, in the case of the EL84 the reevant pins are pin 2 g1(Control Grid) pin 3 Cathode pins 4 & 5 Heater, pin7 anode, pin 9, as mentioned g2. The other pins have internal connections, so nothing is connected to those. Be aware that when the amplifier is powered there will be HT (maybe 250 volts DC) on pins 7 & 9 & 6.3vAC on pin 5 (pin 4 is earthed) Electrolytic Capacitors can take some time to discharge after the power is disconnected, too.
Regarding valves, they ususually appear much as in your picture, but seldom fail. edit; Crossed with Lawrence's post. |
29th Jun 2017, 10:58 pm | #27 |
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Re: Dansette Major Restore
All very useful information. I must thank you all for your input, it has been more than helpful. I will get the new caps ordered this weekend. Iv ordered some motor grommets that i hope will work with the old motor. If not ill nip to Maplins and see what they have.
Thanks for all the help this would not be posable with out forums like this one |
30th Jun 2017, 12:57 am | #28 |
Hexode
Join Date: Mar 2012
Location: Liverpool, Merseyside, UK.
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Re: Dansette Major Restore
Also if you look at the can (as in the 4th picture of the original post) you will see each capacitor in the can is marked with a symbol, apart from one which says plain. When you remove the can and look at the tags on the bottom you should see these symbols which will identify which tag is which.
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30th Jun 2017, 2:46 am | #29 |
Dekatron
Join Date: May 2008
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Re: Dansette Major Restore
Modern capacitors usually come in values which are multiples of 10, 15, 22, 33, 47 or 68μF. The values of these capacitors in this circuit are not actually critical; they are all being used as energy storage devices, with the specific property that the voltage across a capacitor cannot change suddenly, but must increase or decrease gradually as the capacitor charges or discharges. Here, the charge / discharge time is not really critical as long as it would takes much longer than 10 ms. (i.e, half a mains cycle) to discharge altogether. The idea is to maintain the supply voltage during the trough of the wave, while the rectifier diode is not conducting. The reservoir and smoothing capacitors need to be rated for at least 400V. You could replace 32μF with 33μF or even 47μF (any more than 47, though, will not be doing the rectifier any good) and 16μF with 15μF or 22μF. The cathode decoupling capacitor (25 μF, connected to pin 3 of the valve) only needs to be rated for 25V and in fact, anything rated over 100V is likely to misbehave due to under-running. 22μF, 33μF or even 47μF will be suitable.
The valve is unlikely to be faulty. EL84 is a very common valve type, used in small guitar amplifiers, made until recently if not still, and any musical instrument shop should be able to get hold of replacements.
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30th Jun 2017, 8:12 am | #30 |
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Re: Dansette Major Restore
May I point out that dual (& triple) can capacitors are still made in 'traditional' values, such as 8 + 8, 16 + 16, & 32 + 32uf. As Julie points out, though, the values are not critical
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30th Jun 2017, 8:58 am | #31 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
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Re: Dansette Major Restore
Your photos have been a great help. Now, looking at your 1st photo, you will need to source a platter mat. It is unlikely you will find an original, but a 12" disco slipmat can be cut down to size. You could use a 9.5" plate as a template. I also notice what looks like a brown cartridge body in the left of the photo. It may be be a BSR "Fulfi" TC8M. If so, this will not be suitable for your Dansette as it will definately need a high output type. Whilst this may be a task for later, we can advise as to options when the time comes.
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30th Jun 2017, 7:22 pm | #32 |
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Re: Dansette Major Restore
Ok iv been reading and planning as I wait on parts to turn up. My next thought turned to the cartridge. This is the one that is in there at the moment. Im i right in thinking a BSR SC12M would be a replacement for this? I also understand I will have to bridge it out to work as a mono cartridge. Or would the BSR SC12H be a better choice? If i can find a BSR SC12H
Mick |
30th Jun 2017, 7:55 pm | #33 |
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Re: Dansette Major Restore
Or is there another option as the BSR SC12 H seems very hard to find
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30th Jun 2017, 8:21 pm | #34 |
Tetrode
Join Date: Aug 2016
Location: Wakefield, West Yorkshire, UK.
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Re: Dansette Major Restore
I use cheap black and red Chinese ceramic cartridges and a preamp circuit for my refurbs. I can sort you out with these if you come over to Wakefield. 😊
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30th Jun 2017, 9:00 pm | #35 |
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Re: Dansette Major Restore
Thanks for that offer Russell i may take you up on that. im finding very hard to find a BSR SC 12H . i will PM you
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30th Jun 2017, 9:52 pm | #36 |
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Re: Dansette Major Restore
The Chinese carts are very cheap and work well, but as has been said have a low output for a single stage valve amp. However, it might be worth trying one before building preamps etc. as real world performance can vary. You will need to fabricate a mounting but that will be an easy task given your workshop facilities. You can just use a lump of blu-tack as a temporary mounting for initial test purposes.
Sort the amp out first though! I am always a bit wary of multiple electrolytics in a single can. You will be unlikely to find one that is physically and electrically identical to the original, and new old stock replacements may be decades old. I would replace the can with several modern individual caps. Modern electrolytics are very small and can be fitted unobtrusively under the chassis, with the original left in place but disconnected. |
30th Jun 2017, 9:56 pm | #37 | |
Tetrode
Join Date: Aug 2016
Location: Wakefield, West Yorkshire, UK.
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Re: Dansette Major Restore
Quote:
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30th Jun 2017, 10:36 pm | #38 |
Dekatron
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Re: Dansette Major Restore
Be aware that the BSR TC8M as in your photo - or - if you can find one, a BSR SC12M or BSR SC12H - none of these will give enough output for your amplifier when this is restored. Your Dansette "Major" was originally fitted with a high output BSR TC8H cartridge which you can buy as rebuilds in the UK or import Far Eastern copies from Australia. Thse will cost around £50-55. This will restore you player to the original 1958 specification - BUT - are only suitable for Mono records. If you wish to play stereo LPs (which form the majority of most record collections) you will need to consider fitting a pre-amplfier, as indicated in earlier posts, in combination with a modern ceramic stereo cartridge. This is an issue that confronts most people buying this type of Dansette (or similar) record player using a very simple (single-stage) amplifier.
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Edward. |
3rd Jul 2017, 6:40 pm | #39 |
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Re: Dansette Major Restore
So my plan was to recover in the original colour but I can't find any rexine the same. So i may go for a Cream and a strong prime colour. Any recommendations where to get the paper backed rexine as i understand the ebay stuff is not real
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3rd Jul 2017, 7:21 pm | #40 |
Nonode
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
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Re: Dansette Major Restore
Hi
You can get Rexine from Sid Chaplin at Retrospecialist, tel. 01206394195. I have found Sid to be most helpful, well worth giving him a ring. Regards John |