problem with Audio Art 200.2

Nico156 · Post by **Nico156** » Fri Jul 02, 2010 4:41 am

Hi!
I bought a 200.2 this month but when I install it in my car to hear how it sounds it doesn't work!

Led turned on but no sound. So I turned the gain up and a little of sound came out the speakers. At 9/10 of gain this amp sound like it has 5 watt output!

I have another 200.2 in mint condition and I know how it should work

Any idea?

I bought it from dbincognito and I think he sold me a good one but maybe the amp got damaged in the shipping?

please help me

oldskoolmseriesfan · Post by **oldskoolmseriesfan** » Fri Jul 02, 2010 8:22 am

I have and numerous others have bought from Randy, hes a great guy, give him a pm and he should be able to work through it with you

pnyryd · Post by **pnyryd** » Fri Jul 02, 2010 11:32 am

oldskoolmseriesfan wrote:I have and numerous others have bought from Randy, hes a great guy, give him a pm and he should be able to work through it with you

I agree 100%

Nico156 · Post by **Nico156** » Sat Jul 03, 2010 9:22 am

thank you

I've already talk with randy but he didn't know what to do. So I decided to ask everybody.
If anyone know how to test the amp (mosfet for example) please let me know.

dBincognito · Post by **dBincognito** » Sat Jul 03, 2010 10:08 am

EricD would be the person to talk to, I have no problem helping out where I need to.

Nico156 · Post by **Nico156** » Sat Jul 03, 2010 10:50 am

perfect!

I really apprecciate this.

I'm asking already in my forum in Italy and they suggest me to test transistor.

Here something that help:

I have another 200.2 in mint condition so I can test and look difference between the amps;

pcb has not burns or broken welding;

rca seems ok (there's continuity with potentiometers)

the two horizontal cap have voltage ( 32,3-32,4 V )
resistances near transistors have voltage ( -5,28 V )

edit: I correct the voltages found with amp linked to 12,08 V

Nico156 · Post by **Nico156** » Sat Jul 03, 2010 11:54 am

I've noticed these strange weldings.. are they ok?

dBincognito · Post by **dBincognito** » Sat Jul 03, 2010 5:50 pm

Q215, Q214, Q213 all look to be missing solder in one hole.

Nico156 · Post by **Nico156** » Sun Jul 04, 2010 1:46 am

Yes I was thinking the same

I try gently with a clamp but it doesn't move. anyway today I reinforce those welding and cross my fingers

probably they launch it down from the airplane

Nico156 · Post by **Nico156** » Sun Jul 04, 2010 3:27 am

I've re-done the welding oh those point. I install the amp. But nothing change

Nico156 · Post by **Nico156** » Sun Jul 04, 2010 10:29 am

op near rca input, Nec C4072C, has 28,2 V ( pin 4 and pin 8 ) ( other 200.2 has 27,9 V )

op near toroid, TexasIst TL494CN, has - 2,48 V ( pin 7 and pin 12 )

rest current is 0,55 A ( other 200.2 has 0,41 A )

I have tested quite half of resistances and they are quite all equal from the two 200.2

Nico156 · Post by **Nico156** » Mon Jul 05, 2010 7:51 am

look these caps. they are different on the top. can be this the problem?

Post by **ttocs** » Mon Jul 05, 2010 8:00 am

the one that is popped out looks like it has seen better days. Take some paper and see if they are wet on the bottom....

Thunderdome · Post by **Thunderdome** » Mon Jul 05, 2010 8:33 am

Nico156 wrote:look these caps. they are different on the top. can be this the problem?

probrably not the cause of your problem this time, but if left unchanged will likely become one later and while the board is out it is just to convenient to change them

dBincognito · Post by **dBincognito** » Mon Jul 05, 2010 10:39 am

Have you tried measuring for DC offset ?

Here is how to do that

http://phoenixphorum.com/amplifier-dist ... t3428.html

Cecil Says :

As a semi-poll, I'd like to see those on this board whip out their multimeters and take a look at the DC that is being presented to the speakers. This means..

1. Speakers disconnected (or connect the meter to the 'B' speakers and set the front panel speaker control accordingly)
2. Input set to an unusued position (not Phono)
3. Volume control at minimum.
4. Balance in center
5. Tone controls either defeated or set to mid position
6. Set your meter to read DC, and set to a low scale (300mV scale is common) Connect directly to the Pos and Neg of the speaker terminals
7. Give the amp 10 minutes to settle. Report back...I'd like to see how healthy all these old amps are.

If you read:

0 - 15mV: Damn good!! If you read '0V', you may have a capacitor output, or your meter is set wrong

16mV - 50mV: An acceptable value, especially at the lower end of this range. 2nd harmonic distortion is probably twice to four times what manufacturer's spec calls for at higher frequencies. Probably not audible, as the distortion is mostly in the upper octaves. At the upper end of this range I begin to raise an eyebrow.

50 - 85mV: Something is certainly amiss, and while this is not enough to put your speakers or equipment in jeopardy, the amp is running nowhere near where it should. I'd venture to guess that most of the DC-coupled amps that are in use by forum members here fall into this range.

100mV to ?: A high enough voltage will cause the DC protection to kick in. This happens at a level determined by the designer, but is usually equivalent to about a diode drop (600mV)or so. Needless to say, if you are listening to an amp with 100mV or more of DC offset, you have no idea what the amp really is supposed to sound like. Indeed, some amps without a differential input are actually designed to have a bit of DC at the outputs, but this is triple-rare, and I don't think anyone here owns one. (in my book it's piss-poor design, but if you can sell it WTH..)

Soooooo...go grab a meter and tell me what you find...

Nico156 · Post by **Nico156** » Mon Jul 05, 2010 1:08 pm

thank you guys!

the caps doesn't look to leave oil but I have not tried with paper. I'll do it soon.

ok I will that speakers test! ...if I can understand all..

Nico156 · Post by **Nico156** » Mon Jul 05, 2010 2:09 pm

ok
with rca not connected (as I understand)

it does 5 mV.

when I turn off it goes up to 700 mV and then go down to 0 gently.

paper is dry.

Nico156 · Post by **Nico156** » Tue Aug 03, 2010 4:18 am

The amp is given to a technician who is trying to repair it.
He said that internally the amp is ok but he can't understand why the signal doesn't ''turn'', so he need the scheme..
these days I shipped the technician another 200.2 so he can compare the two ones..

Nico156 · Post by **Nico156** » Thu Aug 19, 2010 10:37 am

Problem found!!
Technician compare the two amps and find that the bad one has not equivalent transistor mounted

so he change them with some equivalent ones and everything run ok!
He also changes two caps on the supply line because they were leaking and eating the board.
During the research time he changed the caps on the signal tryng to find problem but he did not ask money for these (cause they were not the problem).
I pay 70 euros for repair.

dBincognito · Post by **dBincognito** » Thu Aug 19, 2010 10:41 am

Nico156 wrote:Problem found!!
Technician compare the two amps and find that the bad one has not equivalent transistor mounted so he change them with some equivalent ones and everything run ok!
He also changes two caps on the supply line because they were leaking and eating the board.
During the research time he changed the caps on the signal tryng to find problem but he did not ask money for these (cause they were not the problem).
I pay 70 euros for repair.

Ya, I'm gonna need to see some high res pics and some paperwork to go with that. No need for the rolling eyes considering the amp had never been worked on...let alone a transistor swapped.

Nico156 · Post by **Nico156** » Thu Aug 19, 2010 10:56 am

This is why you didn't answer my pm?
Mm.. you think I spent all this time and money for what? Not my style don't worry

I think it's right what you ask. Monday I will receive the two amps and so I'll get paperwork and I could post pics.

Nico156 · Post by **Nico156** » Thu Aug 19, 2010 11:02 am

''No need for the rolling eyes considering the amp had never been worked on...''

sorry I didn't think rolling eyes could offend you..
rolling eyes for me was for (mean): ''damn all this time researching and finding not elettronic damages and then the problem was that transistor were not right?''

''let alone a transistor swapped'' what do you mean?

dBincognito · Post by **dBincognito** » Thu Aug 19, 2010 11:17 am

''No need for the rolling eyes considering the amp had never been worked on...''

sorry I didn't think rolling eyes could offend you..
rolling eyes for me was for (mean): ''damn all this time researching and finding not elettronic damages and then the problem was that transistor were not right?''

''let alone a transistor swapped'' what do you mean?

I am not sure how I was supposed to take rolling eyes at me.

ok
with rca not connected (as I understand)

it does 5 mV.

when I turn off it goes up to 700 mV and then go down to 0 gently.

paper is dry.

As I understood, you got 5mv when you tested for dc offset. This would tell me that there was no wrong with the amplifier.

Then in another forum

http://forum.audiocarstereo.it/showthread.php?t=21779

you did all kinds of stuff to the amp, literally trying to find something wrond with it.

''let alone a transistor swapped'' what do you mean?

I have many pics showing that the transistor's were never worked on, still in the buy/sell thread, and here on my computer.

I'm asking for some kind of proof showing that there was ever a problem with the amp.

dBincognito · Post by **dBincognito** » Thu Aug 19, 2010 11:21 am

Nico156 wrote:This is why you didn't answer my pm?
Mm.. you think I spent all this time and money for what? Not my style don't worry

I think it's right what you ask. Monday I will receive the two amps and so I'll get paperwork and I could post pics.

Yes, when I send a working amplifier to a new member and then they have " problems " with it almost a month after purchasing it, and then attempt to work on it themselves rather than sending it back or taking it to a professional. I need to see something, especially when you're talking about swapped transistors and leaking capacitors. Not to mention it's almost as much as I sold it for.

Nico156 · Post by **Nico156** » Thu Aug 19, 2010 12:46 pm

quote: ''I am not sure how I was supposed to take rolling eyes at me''

ok sorry.. probably I don't know the meaning of ''rolling eyes'' so consider like I never write that..

quote: ''As I understood, you got 5mv when you tested for dc offset. This would tell me that there was no wrong with the amplifier''

it didn't work, I heard it with my ears. As I say the amp was not burnt or anything else elettronically.. we can see the pics I sent to eric.. but it had wrong transistor on it.

quote:''you did all kinds of stuff to the amp, literally trying to find something wrond with it''

and you must be thankful to me because I tried finding help anywhere (http://www.diymobileaudio.com/forum/diy ... ost1087410) to solve the problem at home without spending money. I also contact Eric and do what he suggest me.

quote:''Yes, when I send a working amplifier to a new member and then they have " problems " with it almost a month after purchasing it, and then attempt to work on it themselves rather than sending it back or taking it to a professional. I need to see something, especially when you're talking about swapped transistors and leaking capacitors. Not to mention it's almost as much as I sold it for''

Sorry but professional told me that so I think the amp was not broken by shipment.
I didn't have problem almost a month after purchasing it but since the first time I check it on my car just few days after he arrived me.
I explain you why I try to fix by myself with forum help. (and I couldn't give you back it with 70 usd of shipment)
You will see paperwork on monday or tuesday.
It's a good price. Consider at least 15 euro/hour of work and 20 euros of caps and transistors. How much would cost a repair in USA?