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-   -   [HELP] Repair Arcam Alpha 2 - 240v (http://www.diyaudio.com/forums/solid-state/228993-help-repair-arcam-alpha-2-240v.html)

CrustyD3mon 30th January 2013 12:13 PM

[HELP] Repair Arcam Alpha 2 - 240v
 
Hey guys,
Just bought an Arcam Alpha 2 for some bucks that don't turn on..
When i open it i saw that somebody already solder some resistaces and chage the fuses for ones with wrong values...so they blowup...

I saw that resistances burned too...and i want to replace them all for resistances with the right values and right fuses too...

Can anyone help me getting the values of the burned materials? Anyone have schematics for this or something?

https://dl.dropbox.com/u/21378485/20...2021.34.37.jpg

https://dl.dropbox.com/u/21378485/20...2021.35.33.jpg

https://dl.dropbox.com/u/21378485/20...2002.22.48.jpg

KatieandDad 30th January 2013 12:52 PM

I'm off home shortly I'll see if I've got the schematics for this one.

CrustyD3mon 30th January 2013 01:35 PM

Quote:

Originally Posted by KatieandDad (Post 3348490)
I'm off home shortly I'll see if I've got the schematics for this one.

Ok sir...i appreciate :)

jaycee 30th January 2013 02:05 PM

Ouch. The damage is pretty bad.

Here is the service manual: http://www.darkmatter.myby.co.uk/arc...ice-manual.pdf

CrustyD3mon 30th January 2013 02:21 PM

Quote:

Originally Posted by jaycee (Post 3348564)
Ouch. The damage is pretty bad.

Here is the service manual: http://www.darkmatter.myby.co.uk/arc...ice-manual.pdf

Thanks for that...will be very usefull...yeah aparently the damage is very bad...:S i don't know if there's solution for it...but i will try.....:rolleyes:

jaycee 30th January 2013 02:26 PM

The damage suggests the amplifiers output was shorted for a time. One of the output transistors (Q114) has failed and been replaced. Really, both should be replaced.

If you find the transistors FST239/240 are damaged, they became obsolete and Arcam used Zetex ZTX653/753 as replacements.

CrustyD3mon 30th January 2013 03:09 PM

Quote:

Originally Posted by jaycee (Post 3348586)
The damage suggests the amplifiers output was shorted for a time. One of the output transistors (Q114) has failed and been replaced. Really, both should be replaced.

If you find the transistors FST239/240 are damaged, they became obsolete and Arcam used Zetex ZTX653/753 as replacements.

Ok...nice tips....i will need because i have some "electronic limitations" ;)

The output transistors i need to check them...both fuses are blown and i don't check any of them yet...
Another thing...what is RV1 and RV101 ? i think one of them are burnet too....

KatieandDad 30th January 2013 03:42 PM

Looking at the schematics, something pretty horrible has happened to fry RV1 and RV101. Still do not be disheartened, it can be repaired.

My first move would be to remove all the obviously burnt components. Then test each of the remaining semiconductors.

Due to the age of the amplifier change all the electrolytics as a matter of course.

Any lifted PCB tracks should be cut out unless you are adept at PCB repair. Photograph the artwork before you start so that you can see what you started with.

Any blackened PCB material needs to be removed too as it will have carbonised and will have become conductive.

Next job it to rebuild the PCB itself. Tissue and Araldite in thin layers is an excellent way of repairing PCBs damaged in this way. Bit like Dope and Tissue used in RC aeroplanes.

Drill the missing holes.

Replace the components and then use P to P insulated wiring to replace the missing tracks.

Do be aware that the damage may be more extensive than you originally think. It may not work after initial repair action has been taken.

CrustyD3mon 30th January 2013 04:51 PM

Woww...ok...first thing first....so i will remove every aparently burned component from the board...

regarding the sections burned on the PCB...the ones that are only burned superficially i only need to use a small drill to remove the "black" right ? or need to cutoff a big hole with the entire section? :S

I will buy the following material:
Araldite:
Araldite AB Epoxy Adhesive Glue 5 Minutes Rapid New | eBay
PCB glue for cover the repaired circuits:
100g PCB UV Curable Solder Mask Repairing Paint Blue Negative Photoresist | eBay
And silver condutive glue to repair ( what do you think about this paste?)
0 2ml New Silver Conductive Wire Glue Paste for Electronics Repair Applications | eBay

regarding the "Tissue" to use with araldite....what kind of tissue is that and where can i find some of it?

Thanks for the guide

KatieandDad 30th January 2013 04:53 PM

Repairing the PCB you don't need to drill "ruddy great holes" just remove the carbonised bits. Bit like a dentist just dremmel out the black bits.

DON'T use conductive paint its useless. Once you've got back to solid track P to P with wire.

Tissue is tissue. If you want to go posh you can buy it from RC shop but good old toilet tissue or kitchen roll will do. Kitchen roll is probably that little bit stronger.

Also no need for the solder mask repairing paint.


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