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April 07, 2020, 01:56:07 AM

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11
Amplifier Discussion / Re: Ampeg Vh140c power transformer replacement
« Last post by Enzo on April 02, 2020, 12:30:01 AM »
I read it this way.  The schematic doesn't say export model transformer, it points out the export model WIRING.

It does appear to be a wiring change.
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Amplifier Discussion / Re: Ampeg Vh140c power transformer replacement
« Last post by g1 on April 01, 2020, 09:26:06 PM »
Does the power transformer have 7 wires coming out of it?
4 of them should go to a board with a fuse on it (07-315-01).
Like Phatt said, take a close up picture of that board and post it.
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Amplifier Discussion / Re: Ampeg Vh140c power transformer replacement
« Last post by phatt on April 01, 2020, 09:24:09 PM »
Wire taps won't be inside the Tx.

With power cord removed from wall, Follow the incoming Mains wiring.
the sequence will be something like this;
Fuse> switch> THEN look for a tag board or block connector with mains wires that also go to the Tx.

If the Tx primary has dual winding's then there will be at least 4 mains wires between the block con and the Tx. (not to be confused with the secondary wires)
You may even find the numbers on the schematic are also printed on the tags.

Like I said; Take a picture of that section of the amp and post it, that will speed up the answer much faster than us trying to guess it all. hint.  8|
Phil.
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Hi all,
I can't report any progress as I lent this amp to a friend and he is enjoying it like it is.
So I'll be back with more stories .. if I dont sell it to him.
I'm discovering the wonderful world of amp's so I would not be surprised if I just move to something else. (this means more amp's, not less..).
Actually Im quite interested in a vintage Peavey Studio or Bandit .. well will see,
Stray strong all and away of Corona (beer is quite refreshing tho!)
Cheers
Lex
15
Amplifier Discussion / Re: Ampeg Vh140c power transformer replacement
« Last post by Ratsapprentice on April 01, 2020, 09:08:26 AM »
Had a look inside it - it's all sealed underneath the two outside plates - no obvious way to switch it.
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Amplifier Discussion / Re: Ampeg Vh140c power transformer replacement
« Last post by phatt on April 01, 2020, 07:29:02 AM »
The transformer in the schematic specifically states "Export Model".
That is not what the OP has.
HUM :-\
Yeah maybe you are right JazzP but the OP would be wise to check before spending money only to find it was a simple wiring swap.

That schematic shows both Local and Export Tx's wound with 2 winding's.
Local TX is tapped in Parallel delivering 120v while Export is the same TX but tapped in series giving 240V. (well that's how I read it?)
The note under Export Model implies the Tx is the same you just have to reconfigure the wire taps.
I'm not familiar with that particular amp but I do know that a lot of gear was wound for both 120/240.
Some older gear came with a rear panel mechanical switch usually next to the power cord and fuse.
But some gear had to be opened to access the taps.
Maybe *Ratsapprentice* could lift the lid and take a picture of the Tx. :tu:
Phil.
17
Amplifier Discussion / Re: Ampeg Vh140c power transformer replacement
« Last post by Jazz P Bass on April 01, 2020, 01:32:25 AM »
The transformer in the schematic specifically states "Export Model".
That is not what the OP has.
18
Amplifier Discussion / Re: Ampeg Vh140c power transformer replacement
« Last post by phatt on April 01, 2020, 12:04:24 AM »
Hi,
   If the schematic is correct for your amp then it is already able to run on 120/240V.
You will need to change over the input wiring which is circled showing which taps.

WARNING;
If you do not have experience with this then don't try to swap it over yourself.
Doing so could destroy the whole transformer and blow the amp as well. i.e. smoke and flames. 8|
Get a teck to do the change over.
Cheers, Phil.
19
Amplifier Discussion / Re: Rickenbacker TR25 Noise
« Last post by aruption on March 31, 2020, 06:40:40 PM »
I ended up tracing the noise to the transistors near the inputs, replaced them with new ones, and the squealing noises seem to be gone. i might end up replacing the rest of the transistors anyway just to keep everything fresh. As far as the distortion from the speaker, I took the speaker out and manipulated the cone a bit until the distortion went away. Seems to be holding up, but I think I will look into getting a new speaker anyway.
20
Amplifier Discussion / Re: Ampeg Vh140c power transformer replacement
« Last post by Ratsapprentice on March 31, 2020, 11:29:40 AM »
There are a couple of reasons:

1) I'd rather not have to use two switches to turn the amp on/off
2) Size - the S/D is quite bulky
3) Heat

I've not been able to find a step-down transformer small enough to reasonably fit into the cabinet.

What specs do I need? - luckily Ampeg have made both the manual and the schematics available for free.

I need a 3a 240VAC 50hz transformer.

Manual: https://ampeg.com/pdf/VH140C.pdf
Schematic: https://ampeg.com/support/files/Schematics/V%20Series/VH-140C/VH-140C%20Schematics.pdf

The transformer wiring is found on the bottom left hand side of page 7 of the schematic.
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