Guide to fix up a Cmoy 2

[Kube 0]

Lol. I'm also apprehensive about the meet. Don't want to be the only young guy there, as it seems alot of members here are old and working...Thanks anyway.

 

Thanks jasonhanjk, hope to see you this sun. Btw, do you do drilling too? Don't have a drill at home, and I don't want to screw it up then go all the way down to eunos just to get another casing. Need to follow an experienced diyer.

[Kippei 0]

-.- how young can you be... I only 20...

[squalle 0]

You just have to take care not to drive too much current as it will distort like hell.

May I know the source of distortion?

 

the MAX4167 as far as I've read its data specs, it cant drive high voltage neither high current

then with no LM6171, wat's the direct impact? the virtual ground not as precise? am I correct? as there's a lack of buffer hence the v ground will be affected by load itself?

 

luckily, I have no high impedance cans

highest I have is 60 ohm only

[squalle 0]

Lol. I'm also apprehensive about the meet. Don't want to be the only young guy there, as it seems alot of members here are old and working...Thanks anyway.

 

Thanks jasonhanjk, hope to see you this sun. Btw, do you do drilling too? Don't have a drill at home, and I don't want to screw it up then go all the way down to eunos just to get another casing. Need to follow an experienced diyer.

find me

 

I can help u "provide" drilling tools

other machinery... err.. a bit complicated. but can be worked out with

 

btw, drilling is such simple job if you've got all the right tooling

 

[heady 0]

Btw, do you do drilling too? Don't have a drill at home, and I don't want to screw it up then go all the way down to eunos just to get another casing. Need to follow an experienced diyer.

Kube,

Where in Eunos did you get your casing? What kind of casing is it? Thanks.

[Kube 0]

Hammond from Farnell, which happens to be in Eunos? And I'm 17, which is pretty damn young considering

 

Well, it's not that I don't know how to drill or anything...I just need to see someone mark out drilling position, etc. Cause if I make a mistake, it's costly for me.

[kross 0]

You just have to take care not to drive too much current as it will distort like hell.

hmmm...i am using a battery holder pack with 8x 1.5V AA batteries inside to make up about 12V for my cmoy2. like this should be ok right? how to not drive too much current? if voltage is around 12V current should be ok for the amps to take it right?

[Kube 0]

I think that would depend on the caps and resistors your using.

[squalle 0]

sure can

 

AA can provide a lot more power than ur 9v

 

but it's going to be huge man

[kross 0]

caps have a tolerance of 16V while the resistors used are the default values, like 10K ohms. should be alright??

[kross 0]

sure can

 

AA can provide a lot more power than ur 9v

 

but it's going to be huge man

yup it is huge....but i using rechargeable batteries, more economical and because it is bulky i only use the battery pack at home. outside i'm using 9v.

 

thanks squalle.

[squalle 0]

I see

 

at home make your own power supply even more economical

I'll make one myself

maybe when I'm going to start I'll check with you again.

 

the resistor values.. hmm... I've got made some changes

the input line high pass filter, I've increased them to 100k each. make the attenuation freq 10 times lower. it means that more bass freq can pass thru instead of going off to drain hehe

[Kube 0]

Finally got my pot from Federal...but still crappy. I think I've narrowed down the problems.

1. I'm using wrong caps - 25v 470uF rubycons. (Doubt this is wrong, tropicalrips gave these to me), and am using 9V.

 

2. Some of my opamps are fried. All my ground opamps(lm6171 and lm6181) produce oscillations. And it gets pretty bad when using 2228's and 2227's.

 

3. The board is flux cleaned.

 

Strange thing is, just after soldering the pot in, I tested the sound and it was quite ok, even with 2227's. Now there's oscillations.

 

Any ideas?

[squalle 0]

hmm

 

after ur testing, what did u do?

wat op amp do u use? wat's ur gain setting?

the cap 470 uF shd be quite ok. that one just to provide clean supply into the circuit, but as u're using battery, well I dont see lower values of the caps will cause oscillations.

 

EDIT: also if possible take pics of ur PCB, both sides.

a clear and sharp ones will help us troubleshoot better, IMO

Edited October 27, 2005 by squalle

[Kube 0]

1. After testing, I jumped for joy Then I tried changing opamps.

 

Opamps I used : 2228AP, 2227AP, and 2132AP. Also, LM6171 and LM6181 for the ground opamp.

 

Gain setting is as first page, no change of resistor values.

 

Source: Zen Micro

 

Output: Generic earphones

 

Battery: 9v Sony dry.

 

Connecting wires: Multi-strand thin copper (the ones you can find on a normal stereo cable)

 

Solder: 60/40

 

Flux Cleaner: Electrolube's FLU

 

Soldering iron: Antex spade tip

 

Pot: Green Alps, as of first page

 

Will try to take, but I don't exactly have a digital camera on hand at home.