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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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1st Apr 2018, 4:04 pm | #1 |
Retired Dormant Member
Join Date: Apr 2018
Location: Surrey, UK.
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Telequipment D1011 blows mains side fuse
Hi all,
I picked up a telequipment D1011 o-scope and it blows the 400ma fuse before the toloidal transformer. Looks like the transformer T401 has packed it in as when I isolate it from the bridge rectifier, the fuse still blows. Q: What should be the output of the transformer (VAC) to provide 22vdc? I'd like to see if I can find a replacement. It's been too many years since I've had to do the maths. Otherwise, anyone have one in your junk boxes? Attached is screen shot of ps circuit. THX! Frank |
1st Apr 2018, 6:38 pm | #2 | |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
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Re: Telequipment D1011 blows mains side fuse
Quote:
For a 22V output you need a 15.5V (or so) transformer. I would guess a 15V one would be fine. But what bothers me is that tap-changing switch on the secondary side of the transformer. What is that for? I understand the series/parallel switch on the mains side for 230V or 115V mains of course. |
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1st Apr 2018, 7:16 pm | #3 |
Heptode
Join Date: Jun 2010
Location: Zurich, Switzerland
Posts: 538
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Re: Telequipment D1011 blows mains side fuse
Tony,
you corrects with S403 a little bit (+/-10%?) mains deviations from nominal values... rgds, Karl |
1st Apr 2018, 7:29 pm | #4 |
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Re: Telequipment D1011 blows mains side fuse
The switch on the secondary is marked high/low and is for high/low mains respectively.
I suspect that this is a 20Volt transformer Part crossed with Karl Cheers Mike T
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1st Apr 2018, 7:33 pm | #5 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
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Re: Telequipment D1011 blows mains side fuse
Thanks...
Yes, for a 29V output you need a 20V (or so) transformer. But the OP said 22V. Which is is really? |
1st Apr 2018, 7:55 pm | #6 |
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Re: Telequipment D1011 blows mains side fuse
22V is one of the regulated supplies, its the one you set up and adjust.
Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
1st Apr 2018, 8:18 pm | #7 |
Heptode
Join Date: Jan 2009
Location: West Lothian, UK.
Posts: 760
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Re: Telequipment D1011 blows mains side fuse
Just a quick check to confirm that the fuse is a delay type?
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George |
8th Apr 2018, 11:50 am | #8 |
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Join Date: Jun 2006
Location: Chard, South Somerset, UK.
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Re: Telequipment D1011 blows mains side fuse
There is a slim chance that the 115-v. / 230-v. switch may be faulty, effectively arranging the transformer windings (pri. and / or sec.) for 115-v.
The way to test that possibility is to temporarily wire the transformer so that the switching is no longer in the cct., with 230-v.a.c. on the pri. and with the sec. on N/L. To do that, it might be easier to completely remove the transformer completely from the chassis. If the transformer does then prove to be U/S, you've not wasted your time in so removing, since you will then know it has to be replaced anyway. Al. |