Ashdown Mag 300 evo II problems

[Jimmy74]

Also I've managed to find Z1 which is on the main power board...but I can't see a Z2 anywhere not even on the preamp board

[Enzo]

Then find the break in the -15v rail.

You realize I hope that the two boards - power amp and preamp - each have a part number sequence. ie there will be a C4 on each board.

Z1 on the power amp is a +16v regulator, there is no Z2 that I know of. The preamp 15v regulators are three terminal IC regulators like 7815. SO not sure what we need a Z2 for.

The preamp ICs are in parallel for power, so if any of them have full 15v, then the regulators are not the issue.

I would be guessing you have a small burnt open bit of copper trace. It doesn't have to look all burnt and black, a narrow bit somewher can just evaporate like a blown fuse.

[Jimmy74]

Ok let's just start from scratch... I asked where I would have to test the 2 power rails to see that voltage was getting through. I was given 2 schematics for each power rail. In one of the schematics it is clearly shown that the + and - 15v come off 2 zener diodes (z1 and z2). That's why I was looking for z2. Anyways getting back to the -ve tracks on those 4 IC's, looking at the back of the circuit board, IC 14, IC 13, IC 10, IC 5 etc share the same negative rails.

IC 12, IC 11, IC 9 and IC 7 share the same negative rail but it is different from the other IC negative rails...for example pin 4 of these four IC's are connected to Pin 3 on IC 10. That would explain the absence of -ve voltage on these 4 IC's.... I doubt one would expect to see -ve voltage on pin 3 of a TL072 opamp. If only I could find the right schematic for these board versions, it would just make life so much easier!!

[Enzo]

I am sorry, I thought you already had the drawing. You have the MAG300 EVO2.

APC041
http://bmamps.com/Schematics/Ashdown...PC041schem.pdf

Preamp
Ashdown APC060 preamp EB and MAG.pdf

[Jimmy74]

thanks for that...so if I've understood correctly pins 4 on those four IC's are just grounded (as is also pin 3 on IC10) and therefore not having -ve voltage is as it should be...correct?

[Enzo]

Ah, I see those now, yes, they operate between ground and +15, so it is normal for all other pins to sit at half of 15.

[Jimmy74]

Ok great...so what's next?

[Jazz P Bass]

Does the amp pass a signal to the input of the unloaded power amplifier?

Connector P_1.

[Jimmy74]

Do you mean PL1? How do I test that?

[Jimmy74]

I tested the output supply and I'm getting + and - 72.2vDC....so at this point I'm guessing that regarding the power supply rails the amp seems to be ok...and also the opamps should be fine too...correct?

[Jazz P Bass]

Do you mean PL1? How do I test that?

Are you set up to properly test this equipment?

What do you have?

-Signal generator
- O scope

[Jimmy74]

No I don't have either of them

[Jimmy74]

I just powered it up attached to a speaker and there is no hum or weird noises, I just heard a very subtle thump when turning it on. Also plugged a guitar lead into the passive input and touching the tip after turning the input and output volumes up a bit, I'm getting that classic noise...so I think it's ok... I guess I should test the tuner\line out just in case.

[pjw]

could you help me with schematics

I am sorry, I thought you already had the drawing. You have the MAG300 EVO2.

APC041
http://bmamps.com/Schematics/Ashdown...PC041schem.pdf

Preamp
[ATTACH]41502[/ATTACH]

Hi enzo,

I'm looking for the main amp schematics PDF for the ashdown Mag 300 EVO 2 (the board says it is APC041 issue 4)
I can't find the right version anywhere, but I think you posted the right link above (which unfortunately isn't working anymore)
I know this discussion is a few years old, but if you could help me, I would really appreciate.

PJ

[Chuck H]

Hi enzo,

I'm looking for the main amp schematics PDF for the ashdown Mag 300 EVO 2 (the board says it is APC041 issue 4)
I can't find the right version anywhere, but I think you posted the right link above (which unfortunately isn't working anymore)
I know this discussion is a few years old, but if you could help me, I would really appreciate.

PJ

We have a forum specifically for schematic requests. This is the most effective way and place to request a schematic. It's called "schematic requests". You should post your schematic request there. In the schematic requests forum. This also avoids the cumbersome reanimation of old threads. I'm not going to move this post there myself because it seems that doing so can leave new members unaware and they lose track of their request. So please post your request in the correct forum and try to avoid reanimating old threads or continued posting on this one.