VOX AC15 repair

[Phil Allison]

** Hi,

not some relic from the 1960s, but a near new looking combo called an "AC15HW1X". The HW indicates the deluxe "hand wired'" version - see pic.

http://www.planetz.com/wp-content/uploads/2011/03/2010-11-05-Vox-AC15HW1-003.jpg

Features a bright blue, 12 inch Alnico magnet speaker, 2 x EL84s, 3 x ECC83s and a 6CA4 rectifier - but no tremolo circuit and no pentodes in the preamp so not a clone of the original AC15.

Usual assortment of faults including intermittent sound, cracking noises and completely shot EL84s.

AC30 & AC15 amps of all ages run the EL84s deep into class A and way too hot - so I normally change the wire wound cathode resistor to one of double the value and bypass it with a pair of 7.5V, 5W zeners in series. This changes it to class AB, similar to using grid bias. The 84s now run much cooler and put out a tad more power too.

As you can see from the pic, the tag board is wired with mainly carbon comp resistors - for a "vintage sound" no doubt. Should be no surprise that some of them had gone high in value, one 220kohms reading 457kohms.

So, a fake vintage amp with real vintage faults !!

BTW, on the back in small print it says:

" Made in Vietnam ".

Tom Jennings must be rotating in his grave....


... Phil

[Arfa Daily]

"Phil Allison" <palli...@gmail.com> wrote in message
news:0ff17f1c-6573-4433...@googlegroups.com...

Yebbut ya gotta say it is actually quite nicely made in terms of the
soldering quality and how nicely regimented the components are on those
strips, Phil ... :-)

At least it is readily fixable, which is more than can be said for some
'modern' offerings !

Arfa

[Phil Allison]

Arfa Daily wrote:

> Yebbut ya gotta say it is actually quite nicely made in terms of the
> soldering quality and how nicely regimented the components are on those
> strips, Phil ... :-)

** Interestingly, the coloured wires used appear to be silicone coated - which makes tidy soldering easy and ought to remain flexible indefinitely.

However, when I replaced any component on that strip using regular 60/40 solder, the previously shiny joint became very dull looking. Must be some odd brew Pb free solder they have over in Vietnam.


... Phil