Problems restoring Dansette Major Deluxe - UK Vintage Radio Repair and Restoration Discussion Forum

Yeatsy79 · 6th Mar 2018, 7:05 pm

Hello Everyone. I have often had a look through this Forum and find it really helpful, although to be honest I don't understand half of it.

The reason for my list is that I have gotten my hands on a Dansette Maror Delux which I have begun to try to restore.

When I first turned it on it had a very loud hum coming from the amp. Following on from advice from this forum I have replaced the can with a 33uf x2 can from cricklewood and a 47uf 25v capacitor as someone was advised in a different thread.

I'm not sure if I have done this correctly, but I have soldered the negative axial from the 47uf cap to the negative tag on the new can. I have then soldered the Two tags and other axial to the corresponding parts on the circuit board, and the negative tag on the can to the corresponding part on the circuit board.

The hum has stopped instantly, however I have no sound from the cartridge (or wires at the back when touched). In addition to this the mains transformer gets very hot quickly and starts to melt/fizzle. I've turned it off straight away and wonder if any one could help shed any light as to what to do next. I have very little scientific understanding of electronics but can follow instructions, solder, etc.

I have stripped the deck back and reassembled it after cleaning and this is working well.

Any help us greatly appreciated.

Thanks!

Yeatsy79 · 6th Mar 2018, 7:36 pm

Also forgot to mention that I have replaced the mains power cable.

Croozer · 6th Mar 2018, 9:49 pm

Those that know more than me may give better advice, but if the mains transformer was not overheating before you replaced the triple capacitor can then it sounds like one of two things may have happened:

1. When re-wiring the capacitors you have inadvertently short circuited the HT (supplied from a metal rectifier) to earth (eg via a wire touching the chassis)
Or
2.you have placed the 47mFd 25 V capacitor in the wrong place. All of the capacitors in the old can would have had a high (300?) working voltage. Two of the capacitors in the old triple can were connected across the full 240v HT supply. The third was connected across the cathode resistor of the valve and therefore only had a small (10ish) voltage across it. The single 47mFD capacitor which you used only had a voltage rating of 25V. If it was wired in either of the other positions, it could have failed owing to too high a voltage being applied across it. This could have caused it to short circuit, thus drawing a high current and causing your transformer to overheat. Trace back from where you soldered the 47mFd capacitor. One side (the positive side) should be connected to pin 3 (counting clockwise from bottom left) on the valve.

Wiser counsel may prevail from others-a pic would probably show quite quickly anything obvious. I love the simplicity of these little amplifiers and am always a little in awe of what could be got out of a single valve.

Good luck!
Rob

Yeatsy79 · 6th Mar 2018, 10:35 pm

Thanks for your reply Rob.
When I have double checked this it also appears as though there is a wire from the transformer not connected to anything which I think I may have disconnected when I was trying to reattach the printed board to the plate. Don't know where it's meant to be connected though. I'll see if I can work out how to add a photo.

'LIVEWIRE?' · 6th Mar 2018, 10:39 pm

The 47uf capacitor, as you say, would be the output valve's cathode bypass cap., which is why it only needs to be a 25v type., so, if it had been incorrectly wired to the HT line, the chances are it would blow apart in a spectacular fashion. The other two, which do need to be high voltage - at least 350v -types are the reservoir & smoothing capacitors. The positive terminal of the res. cap. is (should be) connected to the output of the metal rectifier, whilst the smoothing cap. connects to the amp. HT positive line, and via a series resistor, to the reservoir cap. positive. The triple can capacitors originally used would have 2 x 350v (or higher) and one rated at 25v or similar.

DonaldStott · 7th Mar 2018, 11:15 am

As I'm just about to embark on the identical procedure with my Dansette "Monarch" I read this Thread with some interest.

As usual some pictures or schematics would help as I am very much a visual person - thanks.

Edward Huggins · 7th Mar 2018, 11:23 am

The original triple can capacitors in most Dansettes had a very modest 275V rating for the smoother and reservior caps.

Yeatsy79 · 7th Mar 2018, 5:01 pm

Hello again everyone and thanks again for the advice.

I followed what Rob said and he was right. I had soldered negative lug of the new can directly to the board, although the can was a different size to the old one. The smaller cap was pressing against the bare wire I had used to solder one of the larger caps within the can.

I have rectified this, and (after snapping almost every other connection and re-soldering whilst refitting) we now have a working record player that doesn't overheat.

The volume is quite low but I think this is due to the cartridge. It's very loud when the cartridge connectors are touched by hand. I have a few old high output mono cartridges in some other players, including a ful-fi one so will try this out this evening. I will add some photos when I work out how to do this.

6th Mar 2018, 7:05 pm	#1
Yeatsy79 Retired Dormant Member Join Date: Mar 2018 Location: Newcastle Upon Tyne, Tyne and Wear, UK. Posts: 4	Problems restoring Dansette Major Deluxe Hello Everyone. I have often had a look through this Forum and find it really helpful, although to be honest I don't understand half of it. The reason for my list is that I have gotten my hands on a Dansette Maror Delux which I have begun to try to restore. When I first turned it on it had a very loud hum coming from the amp. Following on from advice from this forum I have replaced the can with a 33uf x2 can from cricklewood and a 47uf 25v capacitor as someone was advised in a different thread. I'm not sure if I have done this correctly, but I have soldered the negative axial from the 47uf cap to the negative tag on the new can. I have then soldered the Two tags and other axial to the corresponding parts on the circuit board, and the negative tag on the can to the corresponding part on the circuit board. The hum has stopped instantly, however I have no sound from the cartridge (or wires at the back when touched). In addition to this the mains transformer gets very hot quickly and starts to melt/fizzle. I've turned it off straight away and wonder if any one could help shed any light as to what to do next. I have very little scientific understanding of electronics but can follow instructions, solder, etc. I have stripped the deck back and reassembled it after cleaning and this is working well. Any help us greatly appreciated. Thanks!

6th Mar 2018, 7:36 pm	#2
Yeatsy79 Retired Dormant Member Join Date: Mar 2018 Location: Newcastle Upon Tyne, Tyne and Wear, UK. Posts: 4	Re: Problems restoring Dansette Major Deluxe Also forgot to mention that I have replaced the mains power cable.

6th Mar 2018, 9:49 pm	#3
Croozer Pentode Join Date: Jul 2016 Location: Edinburgh, Scotland, UK. Posts: 110	Re: Problems restoring Dansette Major Deluxe Those that know more than me may give better advice, but if the mains transformer was not overheating before you replaced the triple capacitor can then it sounds like one of two things may have happened: 1. When re-wiring the capacitors you have inadvertently short circuited the HT (supplied from a metal rectifier) to earth (eg via a wire touching the chassis) Or 2.you have placed the 47mFd 25 V capacitor in the wrong place. All of the capacitors in the old can would have had a high (300?) working voltage. Two of the capacitors in the old triple can were connected across the full 240v HT supply. The third was connected across the cathode resistor of the valve and therefore only had a small (10ish) voltage across it. The single 47mFD capacitor which you used only had a voltage rating of 25V. If it was wired in either of the other positions, it could have failed owing to too high a voltage being applied across it. This could have caused it to short circuit, thus drawing a high current and causing your transformer to overheat. Trace back from where you soldered the 47mFd capacitor. One side (the positive side) should be connected to pin 3 (counting clockwise from bottom left) on the valve. Wiser counsel may prevail from others-a pic would probably show quite quickly anything obvious. I love the simplicity of these little amplifiers and am always a little in awe of what could be got out of a single valve. Good luck! Rob

6th Mar 2018, 10:35 pm	#4
Yeatsy79 Retired Dormant Member Join Date: Mar 2018 Location: Newcastle Upon Tyne, Tyne and Wear, UK. Posts: 4	Re: Problems restoring Dansette Major Deluxe Thanks for your reply Rob. When I have double checked this it also appears as though there is a wire from the transformer not connected to anything which I think I may have disconnected when I was trying to reattach the printed board to the plate. Don't know where it's meant to be connected though. I'll see if I can work out how to add a photo.

6th Mar 2018, 10:39 pm	#5
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Problems restoring Dansette Major Deluxe The 47uf capacitor, as you say, would be the output valve's cathode bypass cap., which is why it only needs to be a 25v type., so, if it had been incorrectly wired to the HT line, the chances are it would blow apart in a spectacular fashion. The other two, which do need to be high voltage - at least 350v -types are the reservoir & smoothing capacitors. The positive terminal of the res. cap. is (should be) connected to the output of the metal rectifier, whilst the smoothing cap. connects to the amp. HT positive line, and via a series resistor, to the reservoir cap. positive. The triple can capacitors originally used would have 2 x 350v (or higher) and one rated at 25v or similar.

7th Mar 2018, 11:15 am	#6
DonaldStott Octode Join Date: Aug 2015 Location: Glasgow, UK. Posts: 1,848	Re: Problems restoring Dansette Major Deluxe As I'm just about to embark on the identical procedure with my Dansette "Monarch" I read this Thread with some interest. As usual some pictures or schematics would help as I am very much a visual person - thanks. __________________ BVWS Member

7th Mar 2018, 11:23 am	#7
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,336	Re: Problems restoring Dansette Major Deluxe The original triple can capacitors in most Dansettes had a very modest 275V rating for the smoother and reservior caps. __________________ Edward.

7th Mar 2018, 5:01 pm	#8
Yeatsy79 Retired Dormant Member Join Date: Mar 2018 Location: Newcastle Upon Tyne, Tyne and Wear, UK. Posts: 4	Re: Problems restoring Dansette Major Deluxe Hello again everyone and thanks again for the advice. I followed what Rob said and he was right. I had soldered negative lug of the new can directly to the board, although the can was a different size to the old one. The smaller cap was pressing against the bare wire I had used to solder one of the larger caps within the can. I have rectified this, and (after snapping almost every other connection and re-soldering whilst refitting) we now have a working record player that doesn't overheat. The volume is quite low but I think this is due to the cartridge. It's very loud when the cartridge connectors are touched by hand. I have a few old high output mono cartridges in some other players, including a ful-fi one so will try this out this evening. I will add some photos when I work out how to do this.