Dansette conquest output transformer - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Station X · 23rd Nov 2019, 6:46 pm

With the wire disconnected is there any voltage between the secondary winding and the chassis?

simonbridge · 23rd Nov 2019, 7:06 pm

Station X good thinking.

300VDC that's with the primary connected and the secondary wire disconnected.

Looks like a short between windings yet multimeter doesn't seem to show this.

John10b · 23rd Nov 2019, 7:11 pm

It’s useful to have a “megger” to check for insulation break down, but the test you have carried out, as suggested by station x, seems to prove the point.
Cheers
John

Station X · 23rd Nov 2019, 7:13 pm

That's because the voltage supplied by your meter isn't enough to "break down" the fault. I wouldn't give up on the transformer yet. It's insulation breakdown, not a hard short. Keep it in a warm place for a few days.

simonbridge · 23rd Nov 2019, 7:14 pm

suppose dunking it in water didn't help.
the guy switching it on didn't do it any favours either.
suppose the 300VDC was doing what the megger would..

New O/P Transformer it is then..

its been a good way of introducing me to valve amps so thanks to eveyone..

crackle · 23rd Nov 2019, 7:19 pm

What resistance range did you use when you checked the windings to laminations and between the primary and secondary windings.
Mike

simonbridge · 23rd Nov 2019, 7:28 pm

auto its a fluke so usually quite good.

simonbridge · 23rd Nov 2019, 7:29 pm

From the first photo of the transformer it looks as though its got some damage to the windings its just difficult to tell because its so old.

electrogram · 23rd Nov 2019, 7:49 pm

If drying it out doesn't cure it , assuming the secondary is on the outside you could unwind it,put some insulating tape over the primary, the assumption being that the existing insulation is punctured due to physical damage, then rewind the secondary back on, it is probably only one or possibly two layers of windings. Before going to that trouble check the underside of the tagstrip on the transformer for any problem !

simonbridge · 23rd Nov 2019, 7:56 pm

Its had two weeks of drying out.
I will get a replacement

thanks

simonbridge · 1st Dec 2019, 4:34 pm

Fitted a replacement output transformer and it's back to its old self sounding good

Station X · 1st Dec 2019, 4:45 pm

That's good. Which transformer did you use as a replacement?

simonbridge · 1st Dec 2019, 11:26 pm

Got another old conquest swapped it out of that one

Edward Huggins · 2nd Dec 2019, 9:50 am

Was it from the same type of amplifier? The 2 versions of the Mk1 Conquest used different output valves.

23rd Nov 2019, 6:46 pm	#41
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Dansette conquest output transformer With the wire disconnected is there any voltage between the secondary winding and the chassis? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

23rd Nov 2019, 7:06 pm	#42
simonbridge Triode Join Date: Oct 2019 Location: Wakefield, West Yorkshire, UK. Posts: 28	Re: Dansette conquest output transformer Station X good thinking. 300VDC that's with the primary connected and the secondary wire disconnected. Looks like a short between windings yet multimeter doesn't seem to show this.

23rd Nov 2019, 7:11 pm	#43
John10b Nonode Join Date: Nov 2016 Location: Aberaeron, Ceredigion, Wales, UK. Posts: 2,887	Re: Dansette conquest output transformer It’s useful to have a “megger” to check for insulation break down, but the test you have carried out, as suggested by station x, seems to prove the point. Cheers John

23rd Nov 2019, 7:13 pm	#44
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Dansette conquest output transformer That's because the voltage supplied by your meter isn't enough to "break down" the fault. I wouldn't give up on the transformer yet. It's insulation breakdown, not a hard short. Keep it in a warm place for a few days. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

23rd Nov 2019, 7:14 pm	#45
simonbridge Triode Join Date: Oct 2019 Location: Wakefield, West Yorkshire, UK. Posts: 28	Re: Dansette conquest output transformer suppose dunking it in water didn't help. the guy switching it on didn't do it any favours either. suppose the 300VDC was doing what the megger would.. New O/P Transformer it is then.. its been a good way of introducing me to valve amps so thanks to eveyone..

23rd Nov 2019, 7:19 pm	#46
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Dansette conquest output transformer What resistance range did you use when you checked the windings to laminations and between the primary and secondary windings. Mike

23rd Nov 2019, 7:28 pm	#47
simonbridge Triode Join Date: Oct 2019 Location: Wakefield, West Yorkshire, UK. Posts: 28	Re: Dansette conquest output transformer auto its a fluke so usually quite good.

23rd Nov 2019, 7:29 pm	#48
simonbridge Triode Join Date: Oct 2019 Location: Wakefield, West Yorkshire, UK. Posts: 28	Re: Dansette conquest output transformer From the first photo of the transformer it looks as though its got some damage to the windings its just difficult to tell because its so old.

23rd Nov 2019, 7:49 pm	#49
electrogram Heptode Join Date: Jul 2008 Location: Hereford, UK. Posts: 719	Re: Dansette conquest output transformer If drying it out doesn't cure it , assuming the secondary is on the outside you could unwind it,put some insulating tape over the primary, the assumption being that the existing insulation is punctured due to physical damage, then rewind the secondary back on, it is probably only one or possibly two layers of windings. Before going to that trouble check the underside of the tagstrip on the transformer for any problem !

23rd Nov 2019, 7:56 pm	#50
simonbridge Triode Join Date: Oct 2019 Location: Wakefield, West Yorkshire, UK. Posts: 28	Re: Dansette conquest output transformer Its had two weeks of drying out. I will get a replacement thanks

1st Dec 2019, 4:34 pm	#51
simonbridge Triode Join Date: Oct 2019 Location: Wakefield, West Yorkshire, UK. Posts: 28	Re: Dansette conquest output transformer Fitted a replacement output transformer and it's back to its old self sounding good

1st Dec 2019, 4:45 pm	#52
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Dansette conquest output transformer That's good. Which transformer did you use as a replacement? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

1st Dec 2019, 11:26 pm	#53
simonbridge Triode Join Date: Oct 2019 Location: Wakefield, West Yorkshire, UK. Posts: 28	Re: Dansette conquest output transformer Got another old conquest swapped it out of that one

2nd Dec 2019, 9:50 am	#54
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,336	Re: Dansette conquest output transformer Was it from the same type of amplifier? The 2 versions of the Mk1 Conquest used different output valves. __________________ Edward.