Carver model M1.0T. Transformer required

andjur78 said:
Urgently requiring one mains power transformer for the Carver model m1.0t. Can anyone help by directing to an online parts store with international delivery? Thanks in advance.


IIRC that amp used a very special mains transformer in what was basically a switch-mode power supply. So, you cannot replace it with a "normal" 50/60Hz power transformer. I am afraid you would need to get that specific Carver part number.
BTW What's wrong with the one you have?

Jan Didden
 
One of the secondary windings has failed-and yes I have repaired many power amplifiers over the years... I read and understand the circuit topology.Thankyou.;)

Back to my original question:
Can anyone help by directing to an online parts store for
CARVER parts with international delivery? Thanks in advance.
 

djk

R.I.P
2001-02-04 4:23 am
USA
"Can anyone help by directing to an online parts store for
CARVER parts with international delivery? "

Carver is dead and gone.

"I have one."

You have a stateside model, 120V 60hz.

OZ needs 230V 50hz.

I would write a letter to Sunfire and ask if there are any spares.
 
Can anyone help by directing to an online parts store for
CARVER parts with international delivery?

Sunfire still operates a Carver service center. I had an M-400 repaired there. They have a flat fee for all repairs except for transformers, PS caps and other major expensive items. When I spoke with them they definately said they had M-400 transformers so they may well have them for other products.

The service may be limited to Bob Carver era products, so if your M-1.0T was introduced after his departure there could be a problem.

To find a contact go to the Sunfire website. www.sunfire.com. You may have to ask to be redirected.
 
Cal Weldon said:
Jan,

What are you doing out of bed? I thought you were supposed to be resting.

Cal


/OT on
Came home 10 days after surgery, no major problems, just tired quickly.

Major pain is that I am not allowed to drive a car. The movements when turning the wheel, especially in unforseen emergency circumstances, apparently generate strong and random forces in the rib cage and the muscles to the shoulders and arms, which can unhinge it. But my buddies take turns to drive me around.

/OT off

Jan Didden
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi andjur78,
Sorry, you gave no mention of the fault. Over the years I had sold scores of transformers to people who didn't need them - hence my question. I was factory warranty for Carver in Canada for a while - till Carver folded. I sold my business shortly after that.
Neat though. Never seen a shorted secondary on one of these. This product should be available through the normal parts channel.
-Chris
 
Thanks to those who have provided logical and friendly answers.
I have removed the transformer (completely) from the Carver M1.0t amplifier. Slowly I energize the transformer's primary (230 volt wiring setup mode as per the manual). I have an ammeter connected inline with the phase leg.When I get to about 180 volts RMS the current starts to climb very abruptly.The variac is good for sustaining 15Amps but it starts to groan at this voltage and the indication of current drawshown on the the ammeter goes up REAL fast.
I think I'm safe saying that the transformer has broken down and that one of the multi seconday windings has broken thru.Two of teh bridge diodes were shorted as well. The primary winding measures a few ohms (and this is what I see with other power transformers). I suppose I could perform impedance tests on the windings to see what one is actually breaking down(so much iron in there so the pure resistive component is always low)
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi andjur78,
I think your transformer is okay. As I posted before, mag coils draw excessive current with sine wave inputs.

This power supply pre regulates the incoming AC voltage to a lower effective value. The mag coil (not a transformer like you normally run into) operates on current more than voltage across the primary. The triac phase modulates the incoming AC, like a light dimmer. It is important that the firing angle of the triac is equal + and - or you get a DC component. They had that problem with the M-400 "cube" series.

If you apply a full sine the core will saturate before the rated mains voltage is reached. Sound familiar? That is what you found with your experiment.

I believe you have shorted diodes in the bridge - change them all. Check the triac feeding the primary as it may have shorted. While bringing up the amp, short the triac and come up to 40% of your AC supply. At this level you can check for excessive bias current, shorted commutators and filter cap condition. Check all three main filter caps for a spike on the leading edge. Also check the voltage sense resistors for incorrect value. All these will cause the supply to run improperly. Let me know how you do.

-Chris
 

djk

R.I.P
2001-02-04 4:23 am
USA
Nothing wrong with your transformer, its supposed to draw a ton of current and blow the fuses if you run a sine wave in.

Early Carver units used a light dimmer circuit complete with a diac on the gate of the triac to drive the primary of the transformer.

Later they switched to a SBS for the gate trigger, then they went to a discrete SBS to get symetrical operation.

The triacs were selected for quadrant IV operation.

Carver amps frequently blew the diodes on the two lower voltage tiers, there is a bulletin about replacing them with 6A types.

There is also a bulletin about limiting the conduction angle to prevent excess current draw on low line voltage. Stock, as the line voltage drops, the regulator circuit increases the conduction angle to keep the voltage up. If it increases too far the transformer will overheat.
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
And that is why you don't run Carver's through long extension cords. Worse yet [gasp] an gas generator :bigeyes:

Modern switchmode power supplies have the same behaviour. As the voltage drops, current consumption goes up. If you are unlucky the voltage drops some more and the current demand goes up and ..... on and on. Bang.

djk, you must have worked on these under warranty too. Good amps when used correctly. Not for my living room.

-Chris
 
Ah ha. Thanks for the informative posts.
Id' make the assumption that the Sunfire/ Carver engineers claim the"Magnetic Field" circuit operation as being centered around this unique power supply??
I will heat up the iron,fire up the scope and check those points in circuit.Then post what I find. Thanks again.
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Yup,
That's what "Magnetic Field Amplifier" was a about. Carver was great at giving wonderful names to circuits. Mind you, they had to alert technicians to the important differences in those amps.

Make sure you 'scope the filter caps at around 40% power and look carefully for large peaks on the waveform at the leading edge. You will see what I mean. There is a replacement PCB assy for the multisection caps. Replace both if one is bad.

-Chris