Ricardus

Question about unobtanium transformer
« on: February 24, 2020, 03:08:19 PM »
I have a friend with a VTL home HiFi preamp, model TL 2.5 PH. He thinks the transformer is bad, and the manufacturer says it was custom wound and won't give him any specs. Just wondering if any of you magnetics guys have any ideas that would help him, or is he completely SOL?

Here is a pic of the traffo.
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Ricardus

Re: Question about unobtanium transformer
« Reply #1 on: February 24, 2020, 03:09:20 PM »
More pics.
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Ricardus

Re: Question about unobtanium transformer
« Reply #2 on: February 24, 2020, 03:09:57 PM »
One more pic.
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ruffrecords

Re: Question about unobtanium transformer
« Reply #3 on: February 24, 2020, 03:51:25 PM »
Is this the power transformer?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Ricardus

Re: Question about unobtanium transformer
« Reply #4 on: February 24, 2020, 05:23:18 PM »
Is this the power transformer?

Cheers

Ian

Pretty sure.
Audio mastering for hire..

moamps

Re: Question about unobtanium transformer
« Reply #5 on: February 25, 2020, 05:08:09 AM »
You should first find out is power transformer really dead. You can test it with an ohmmeter. Usually the primary winding is open, sometimes just installed thermal fuse goes off, it is covered with layers of insulation material.
It is unusual that this preamp with installed MC/MM board doesn't have a second "helper" power transformer.

IMO, red wires are HT (about 250V or so), green are heater voltage (you should check which type is reg on the heatsink), most probably 12V. Blue wires are secondary voltage for logic; if the reg on front board is 5V, then it is about 6V or so.


scott2000

Re: Question about unobtanium transformer
« Reply #6 on: February 25, 2020, 06:33:44 AM »
I wonder if David Manley's book has the info... ??

I've never seen one so wouldn't know...

Ricardus

Re: Question about unobtanium transformer
« Reply #7 on: February 25, 2020, 10:13:08 AM »
You should first find out is power transformer really dead. You can test it with an ohmmeter. Usually the primary winding is open, sometimes just installed thermal fuse goes off, it is covered with layers of insulation material.
It is unusual that this preamp with installed MC/MM board doesn't have a second "helper" power transformer.

IMO, red wires are HT (about 250V or so), green are heater voltage (you should check which type is reg on the heatsink), most probably 12V. Blue wires are secondary voltage for logic; if the reg on front board is 5V, then it is about 6V or so.

 Thanks. I'll have him do some more digging.
Audio mastering for hire..

Ricardus

Re: Question about unobtanium transformer
« Reply #8 on: February 25, 2020, 10:30:10 AM »
He said he thinks it's shot because it gets really hot. He believes there may be an internal short.
Audio mastering for hire..

moamps

Re: Question about unobtanium transformer
« Reply #9 on: February 25, 2020, 10:45:18 AM »
He said he thinks it's shot because it gets really hot. He believes there may be an internal short.

But there may be an overload with, for example, faulty rectifier diode or a capacitor. Hi should disconnect all secondaries and test all secondaries voltages without load.


ruffrecords

Re: Question about unobtanium transformer
« Reply #10 on: February 25, 2020, 03:57:57 PM »
I wonder if David Manley's book has the info... ??

I've never seen one so wouldn't know...
I did not know David Manley wrote a book. Google was not much help - do you have a title?

Cheers

ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

scott2000

Re: Question about unobtanium transformer
« Reply #11 on: February 25, 2020, 04:19:11 PM »
https://www.worthpoint.com/worthopedia/vtl-vacuum-tube-logic-book-david-247799935

It's a lot of audiophile jargon and such but, it has a bunch of tube data and some drawings of some of his circuits afaik.... I'll try to find a snippet but there are some examples scattered out there...

like this person seems to have a copy with a drawing shown in his listing of one of the pres

https://www.stereo.net.au/forums/topic/248051-withdrawn-or-relisted-fs-vtl-the-ultimate-preamplifier/

 I found  this weird site.....

https://library.foi.hr/knjige/knjiga1.aspx?B=1&C=X01580

....you have to know how to navigate to the text but it does in fact give you text of the book,,, just nothing else...at least I can't figure it out.....

......of course it's not helpful in this topic..this is primary side........but there is mention of  12v heaters....the 260v b+ ... maybe not helpful at all but it's interesting.... sorry for the derail.....

Power Requirements

All equipment is designed to operate on the various AC voltages around the world. The mains transformers in our units have multi-tapped dual primary windings (for series or parallel connection) that use the following color coding:

Power Transformer Color Code

Volts PRIMARY 1 PRIMARY 2
0 BLACK ORANGE
100 BROWN YELLOW
120 RED/WHITE BLUE/WHITE or YELLOW/WHITE
127 RED BLUE

Hence any line voltage from 100 to 254 volts can be configured; some examples: black and orange are joined together as 0 volts, with red/white joined with blue/white as 120 volts to form the standard U.S. mains/power input, putting the two transformer primary windings in parallel. For 240 volt operation, the primaries would be connected in series, with black alone being
0 volts, red/white (120 volts) connected to orange (0 volts of the second primary) with suitable insulation, and blue/white being the 240 volt termination.

From these examples, it can be seen how 100 volt operation (Japan) is connected in parallel, and how 220 volt operation (most of Europe) is achieved with the primaries in series. Of course, we do not classify this oper-ation as a modification provided it is undertaken by a qualified technician or a competent dealer.

However, we stress that the equipment should not be opened for any reason by anyone other than experienced, qualified technical personnel. Tube equipment contains extremely high voltages400 to 600 volts Direct Currentwhich can cause a nasty or even lethal shock long after the unit has been switched off and disconnected from the mains supply. This is due to the

70 General Operation of VTL Equipment
« Last Edit: February 25, 2020, 04:57:53 PM by scott2000 »

abbey road d enfer

Re: Question about unobtanium transformer
« Reply #12 on: February 26, 2020, 02:00:24 AM »
I have a friend with a VTL home HiFi preamp, model TL 2.5 PH. He thinks the transformer is bad, and the manufacturer says it was custom wound and won't give him any specs.
Did not they offer a solution?
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

EmRR

Re: Question about unobtanium transformer
« Reply #13 on: February 26, 2020, 08:16:54 AM »
I did not know David Manley wrote a book. Google was not much help - do you have a title?

Cheers

ian

The book is an interesting read, someone lifted my copy years ago unfortunately, I've never tried to replace it. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

Ricardus

Re: Question about unobtanium transformer
« Reply #14 on: February 26, 2020, 04:23:04 PM »
Did not they offer a solution?

They wanted him to buy their latest model.
Audio mastering for hire..

abbey road d enfer

Re: Question about unobtanium transformer
« Reply #15 on: February 26, 2020, 04:38:29 PM »
They wanted him to buy their latest model.
Ooh, the gall!
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

ruffrecords

Re: Question about unobtanium transformer
« Reply #16 on: February 26, 2020, 05:35:50 PM »
They wanted him to buy their latest model.

How to piss people off and lose customers 101.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

scott2000

Re: Question about unobtanium transformer
« Reply #17 on: February 26, 2020, 06:34:15 PM »
Quote
How to piss people off and lose customers 101.


Stay out of this.....

Fall in line or we may have to remove your posts..... :D

scott2000

Re: Question about unobtanium transformer
« Reply #18 on: March 08, 2020, 12:02:44 PM »
Looks like it's not limited to just audio.. A bit OT but relevant...


Farmers Fight John Deere Over Who Gets to Fix an $800,000 Tractor
The right-to-repair movement has come to the heartland, where some farmers are demanding access to the software that runs their equipment.


https://www.bloomberg.com/news/features/2020-03-05/farmers-fight-john-deere-over-who-gets-to-fix-an-800-000-tractor?utm_source=pocket-newtab

Ricardus

Re: Question about unobtanium transformer
« Reply #19 on: March 09, 2020, 10:52:57 AM »
It looks like my friend found a local tech who is going to try to find him an off-the-shelf solution.
Audio mastering for hire..


 

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