Jaycar Valve Amp

Re. the Jaycar Valve amp that was mentioned on here a few weeks back.
http://www.jaycar.com.au/productView.asp?ID=AA0474

In this months SC ad Jaycar have printed an appology about the product being
deceptive and are offering a refund to anyone who bought it. They are even
offering a $30 gift voucher to people who still want to keep it.

Dave.

 

Why is it deceptive?

 

the advertising blurb nowhere says that the output stage is solid state.
'hybrid' has many interpretations.

Bye.
Jasen

 

Apparently because they didn't adequately tell people it used a solid state
output stage. At least one aus.electronics member got duped and posted a
rant here about it a few weeks back.
At the time though the web page for the product is as you see it now, it
clearly says it's solid state, so not deceptive at all as far as the web
page goes.
I don't know what the box or any other in-store or print advertising said
though.

Dave.

 

Here you go, here is the full story:
http://www.geocities.com/cablehack/jaycar/jaycar.html
The original flyer ad was deceptive as it did not say it was solid state
output.

Dave.

 

From that story:

"They're using the 16V transformer winding in series with a diode to
function as a dropper. Here is a 19V peak half wave rectified sine
wave to feed the heaters. The idea is that by chopping off half the
sine wave is that you feed half power into the load (valve heater).
...

This is the waveform showing 5.72V DC on the DMM. The RMS value is
closer to 8.5V. "

I'm not sure where that peak value of 19V came from. I also don't know
why I need to know the peak voltage, so perhaps it is not surprising
that I don't know how to come up with a value of 8.5V for the RMS
value.

The diode halves the power. That is equivalent to reducing the voltage
to 11.3V ( 16V divided by SQRT(2) ). The voltage drop across the
diode is not going to make that much of a difference, is it?

Andy Wood

 

Oh well, if you are dumb enough to buy a valve amp for anything other
than the eye candy value then you deserve what you get.

 

on the back of the amp reads tube or valve amp
never ses hybrid or with solid state output.
yes i fell into that trap.
im now making a mod to fix the heater problem
by useing a regulater to bring those heaters down
where thay sould be.
oh and theres another diode on the other side
that powers the relay for the speakers dthump
that diode has blown twise, im fixing that to.
i hate it when i have to mod things to make them
work properly.

 

Why on earth don't you take it back and get a refund?

Dave.

 

on the back of the amp reads tube or valve amp
never ses hybrid or with solid state output.
yes i fell into that trap.
im now making a mod to fix the heater problem to bring those heaters down
where thay sould be.
oh and theres another diode on the other side
that powers the relay for the speakers dthump
that diode has blown twise, im fixing that to.
i hate it when i have to mod things to make them
work properly.

 

problem solved, heaters now at
normal heat.
mod has been made