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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 04 Jul 2017, 12:46 
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Joined: 06 Apr 2009, 10:08
Posts: 1486
Location: US Pacific Northwest
john55 wrote:
I've just received two XPWR009-240 power transformers from Edcor. One replacement and one for the next Lacewood V.2 build for a friend. I thought I'd check these straight out of the box, on the bench, direct connection to the 225V mains with no loads. I'm reading 250V-0V-250V instead of 275V-0V-275V......5.4V instead of 6.3V and 4.4V instead of 5V.
John;

I am beginning to think that this problem is with your mains supply and not the Edcor transformers. It is EXTREMELY unlikely that you received three bum transformers in a row for Edcor. My suspicion is that there is a power factor problem on your mains circuit. If there are heavy industrial loads in your area or lots of HVAC equipment in your distribution area, then the harmonic content on your mains could be wreaking havoc with the operation of the power transformers. What you may actually need is a mains side power conditioner to clean up your mains power.

The problem is that what you are measuring is not a complete picture of the power situation. Just changing voltage levels may make the readings look ok, but the presence of excessive harmonics and odd power factor will still cause problems with the transforms such as excessive core heating, poor conversion efficiency, and potentially premature failure.

Given what I've heard to date, I strongly recommend you investigate the condition of your mains power and possible mitigation strategies.

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It's all about the Glass!
http://www.CascadeTubes.com
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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 04 Jul 2017, 18:24 
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Joined: 06 Jun 2008, 18:23
Posts: 4977
Location: Australia
What about a higher than normal DC on mains. This could produce similar results. Easy enough to make a DC blocker. And cheap.

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Projects: "Grace" - Psvane 6SN7-SE Globe preamp | | "VoXUno" - Single driver MarkAudio 12P speaker | | "Lagoon Take 2" - Single stage tube preamp | Website: retro-thermionic


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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 05 Jul 2017, 01:41 
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Joined: 13 May 2016, 02:02
Posts: 97
Location: Javea, Spain
Quote:
John; I am beginning to think that this problem is with your mains supply and not the Edcor transformers.


Hi Matt,
I live in a small Spanish town that was completely rewired approx 10 years ago. All properties are fitted with smart meters. There is no heavy industry in this area. I would agree with you that the chances of getting 3 bum transformers is ridiculously low, BUT, I bought a Hammond 370FX locally. It's the same as the 270FX shown in the power supply schematic, but has twin primaries with various taps to allow for different mains voltages. I've wired it to run off 240v mains so it is running under the same set of rules as the Edcor transformer. The 370FX wired up, stand alone on the bench, with 225v applied to the 240v windings and no load gave me readings of 260v-0v-260v exactly what I was expecting. The 6.3v winding was bang on 6.3v and the 5v winding was 4.7v (I'm not sure why the 6.3v hadn't dropped a little but an approx 6% under voltage on the primary gave an approx 6% drop on the secondaries). So, using the 370FX I'm having no problems at all. I've been listening to the amp every day now for 3 weeks and enjoying every minute.
I've just looked up a post I put on the 6EM7 thread last year. This was the first amp I built. “All valves are glowing, all voltages are low eg. 235V instead of 250V, 245V instead of 260V and 31V instead of 35V”.
Highly confused.


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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 05 Jul 2017, 02:46 
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Joined: 06 Jun 2008, 18:23
Posts: 4977
Location: Australia
john55 wrote:
Quote:
John; I am beginning to think that this problem is with your mains supply and not the Edcor transformers.


Hi Matt,
I live in a small Spanish town that was completely rewired approx 10 years ago. All properties are fitted with smart meters. There is no heavy industry in this area. I would agree with you that the chances of getting 3 bum transformers is ridiculously low, BUT, I bought a Hammond 370FX locally. It's the same as the 270FX shown in the power supply schematic, but has twin primaries with various taps to allow for different mains voltages. I've wired it to run off 240v mains so it is running under the same set of rules as the Edcor transformer. The 370FX wired up, stand alone on the bench, with 225v applied to the 240v windings and no load gave me readings of 260v-0v-260v exactly what I was expecting. The 6.3v winding was bang on 6.3v and the 5v winding was 4.7v (I'm not sure why the 6.3v hadn't dropped a little but an approx 6% under voltage on the primary gave an approx 6% drop on the secondaries). So, using the 370FX I'm having no problems at all. I've been listening to the amp every day now for 3 weeks and enjoying every minute.
I've just looked up a post I put on the 6EM7 thread last year. This was the first amp I built. “All valves are glowing, all voltages are low eg. 235V instead of 250V, 245V instead of 260V and 31V instead of 35V”.
Highly confused.

Try a DC blocker. ESP has the cct. for one. You'll make it in three hours.

_________________
Projects: "Grace" - Psvane 6SN7-SE Globe preamp | | "VoXUno" - Single driver MarkAudio 12P speaker | | "Lagoon Take 2" - Single stage tube preamp | Website: retro-thermionic


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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 05 Jul 2017, 04:55 
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Joined: 13 May 2016, 02:02
Posts: 97
Location: Javea, Spain
Quote:
Try a DC blocker. ESP has the cct. for one. You'll make it in three hours.


Thanks for your reply, I'm finding that the Hammond transformer works fine. It's only the Edcor transformers that are giving me low voltages on the secondaries. I've just received a Hammond transformer and choke to build the 4S pre-amp this morning. I'm hoping to connect up and check the secondaries this evening. If they're good, I have to assume it's a problem unique to Edcor. I don't want to go down the road of DC blockers and cleaning up the mains for no reason. If it ain't broke don't fix it.


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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 05 Jul 2017, 08:17 
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Joined: 06 Jun 2008, 18:23
Posts: 4977
Location: Australia
john55 wrote:
Quote:
Try a DC blocker. ESP has the cct. for one. You'll make it in three hours.


Thanks for your reply, I'm finding that the Hammond transformer works fine. It's only the Edcor transformers that are giving me low voltages on the secondaries. I've just received a Hammond transformer and choke to build the 4S pre-amp this morning. I'm hoping to connect up and check the secondaries this evening. If they're good, I have to assume it's a problem unique to Edcor. I don't want to go down the road of DC blockers and cleaning up the mains for no reason. If it ain't broke don't fix it.

When it comes to DC on mains, it's always broke.

_________________
Projects: "Grace" - Psvane 6SN7-SE Globe preamp | | "VoXUno" - Single driver MarkAudio 12P speaker | | "Lagoon Take 2" - Single stage tube preamp | Website: retro-thermionic


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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 05 Jul 2017, 10:26 
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Joined: 13 May 2016, 02:02
Posts: 97
Location: Javea, Spain
Quote:
John; I am beginning to think that this problem is with your mains supply and not the Edcor transformers.



Hi Matt,
I live in a small Spanish town that was completely rewired approx 10 years ago. All properties are fitted with smart meters. There is no heavy industry in this area. I would agree with you that the chances of getting 3 bum transformers is ridiculously low, BUT, I bought a Hammond 370FX locally. It's the same as the 270FX shown in the power supply schematic, but has twin primaries with various taps to allow for different mains voltages. I've wired it to run off 240v mains so it is running under the same set of rules as the Edcor transformer. The 370FX wired up, stand alone on the bench, with 225v applied to the 240v windings and no load gave me readings of 260v-0v-260v exactly what I was expecting. The 6.3v winding was bang on 6.3v and the 5v winding was 4.7v (I'm not sure why the 6.3v hadn't dropped a little but an approx 6% under voltage on the primary gave an approx 6% drop on the secondaries). So, using the 370FX I'm having no problems at all. I've been listening to the amp every day now for 3 weeks and enjoying every minute.
I've just looked up a post I put on the 6EM7 thread last year. This was the first amp I built. “All valves are glowing, all voltages are low eg. 235V instead of 250V, 245V instead of 260V and 31V instead of 35V”.
Highly confused.
Update: I've just wired a Hammond 369EX transformer, standalone on the bench. Again I've used the 240V tappings even though my supply is 225V-230V so it is running with the same set of rules as an Edcor transformer. This is to build the 4S pre-amp. The secondaries are spot on. 190V-0V-190V HT and 6.4V for the heaters. So, as it stands..2 Hammonds working perfectly. 3, possibly 4 Edcors all giving low secondary voltages. I'm not knocking Edcor, everyone on this forum speaks very highly of them, I'm just trying to find out what is going on.


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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 05 Jul 2017, 19:29 
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Joined: 06 Apr 2009, 10:08
Posts: 1486
Location: US Pacific Northwest
John:

Is your mains frequency 50Hz or 60Hz? I know that Edcor advertises it's 240 primaries as 50/60Hz but there may be an issue. I would send an email to Brian Weston at Edcor explaining your problem and asking for his opinion.

I still think that you may have a mains issue as the Hammond transformers are rated at their voltages at load. If they are spot on with no load, then they are also running significantly low.

_________________
Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


Last edited by Suncalc on 05 Jul 2017, 19:39, edited 1 time in total.

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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 05 Jul 2017, 19:34 
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Joined: 19 May 2011, 05:38
Posts: 28
Edcor may be rated for 60cps instead of 50cps ac that you have in Spain. Maybe not THE problem but contributes to the problem.

Suncalc got in a little ahead of me.


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 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 06 Jul 2017, 01:33 
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Joined: 13 May 2016, 02:02
Posts: 97
Location: Javea, Spain
Thanks Matt and mike567,
I'll contact Brian Weston as suggested, I'm also going to run the Hammonds under load on the 220V tappings.
Can you give me any information on how I can test the mains voltage for problems.


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