Vox mini 3 amp

[midibob]

Re: Vox mini 3 amp

PM sent.

[willem59]

Re: Vox mini 3 amp

Hi Midibob, I have this Amp with the same issue.* Do you still ship these boards?

[midibob]

Re: Vox mini 3 amp

Hi Leo, I'll PM you.

[Leandrom]

Re: Vox mini 3 amp

Hi Midibob, I have this Amp with the same issue. Can I take it to your home for repair? unfortunately I don't know how to fix it myself. I'm happy to pay you.

Many thanks
Leo

Hi all,

Been grappling with this one for a while and no success so far.

These little guitar amps are rated at 3W and are quite nice, good sounding busking or bedroom amps.
I have a number of these with blown output chips and thought they would be quite a simple repair!!

On inspection I found that the chips were micro smd 9 ball WLCSP types. They are 1.2mm square and you need a microscope to see them.
Trouble is the type code bears no relevance to anything I can find. No IC manufacturers I've contacted so far have been able to identify the type number 'BP27'.

There are so many of these class D amp devices available with different specs and gains that it's impossible to guess which one would be the correct replacement.
I've tried the Vox forum with no joy either. Schematics are non existent too.

Pity it's not dodgy caps, easy stuff in comparison.

Midibob

[midibob]

Re: Vox mini 3 amp

Hi Rado, I wish you luck in replacing IC3. I have done it but it's a real pain.

For removal, one tip is to use an under board pre heater at about 150C and then use the hot air gun on top. This reduces the chances of the pads coming unstuck due to too much heat. The chip can then be removed quite easily without causing any damage.

[radoslavv]

Re: Vox mini 3 amp

Hi alltogether,

Who is interested in board details before/after IC3 desoldered from VOX Mini3 board, could find details attached. I have used hot air desoldering tool.
Even this tool used, it is hard to avoid board destruction - see IMG_5288 how pads moved . Unintentionally R23 of value 10^3 was blown from it's position, so I have to solder it back using smd soldering iron (can be seen difference on IMG_5284 and IMG_5288 - value text is rotated).
So pay attention and have a good tools to do IC3 removal job.
Later I will come back with soldering of IC3 replacement (waiting for delivery).

Rado

[midibob]

Re: Vox mini 3 amp

There is a picture earlier on in this thread, I don't have a schematic as such as it's so simple.

[radoslavv]

Re: Vox mini 3 amp

Hi midibob,
I thought your daugter board.
Rado

[midibob]

Re: Vox mini 3 amp

Hi Rado,

As far as I know there are no schematics available for the Mini 3.

Midibob

[radoslavv]

Re: Vox mini 3 amp

Hi midibob,
I have same problem like nearly everybody in this forum thread - this times from Slovakia. Could you pls PM schematics and pcb layout?
Thank you,
Rado

[midibob]

Re: Vox mini 3 amp

PM sent.

[BarryP]

Re: Vox mini 3 amp

Hi MidiBob

I'm trying to fix one for a friend. can you send cost/order details of your daughter-board please.

Cheers,
Barry.

[fth]

Re: Vox mini 3 amp

Thanks a lot for the answer Midibob. I'm glad that it is not a misfunction of the trim. I'm going to make a pot at the back of this little beauty. I followed this thread bcause I was very curious to the solution of the fried amp IC and I think you did a great job to develop your daughter board. Thanks for charing this.
Kind regards Frans

[midibob]

Re: Vox mini 3 amp

If you're using a cheap condenser mic the output level will probably be too high.

The trim doesn't cut the volume completely. Most reasonable dynamic mics I've tried it with are fine.

[fth]

Re: Vox mini 3 amp

I bought this beauty second hand for my cigarbox guitar and I must say that it sounds very good. But I have a problem with the mic input. When I put a mike in the Mic jack I have feedback. Even when I turn the trim on minimum I still have feedback. It looks to me that the trim is not working as it should. Can you tell me does the sound goes to zero when you turn the trim on minimum?
Kind regards to you all
Frans

[midibob]

Re: Vox mini 3 amp

Hi,

$2, you did well there.
There are still no schematics that I'm aware of I'm afraid.
The regulator should put out 5v, I forget what type of device it is now but I do remember it's a common part.

[Ninilium]

Re: Vox mini 3 amp

Just picked up one of these amps for a Song. ($2)
Seems the power board is only passing 2v.
Are there schematics available for the Mini3 PCBs?
What is the output of the Power PCBS suppose to be?
Thanks in advance.

[midibob]

Re: Vox mini 3 amp

My pleasure.

Ciao
Bob

[Maranelloinred]

Re: Vox mini 3 amp

the envelope arrived this morning, I just finished installing it and now everything works perfectly!!!
Thanks for everything you have been very kind and helpful.

[midibob]

Re: Vox mini 3 amp

Mail sent.