Check first the supply voltage. If you have only 2 separate AC sources you must connect the other channel in parallel.
12 VAC is a bit little so check the raw voltage. It must be 20 volts at least if you want 15 volts out. If the voltage is under that you can change the regulators down to 12 volts. 33 k in parallel over the 3k3 (or 3k0) at the regulators.
AC source 1 connect it to X1, pin 1 and 2
AC source 2 connect it to X1, pin 3 and 4
Mount B1 and B2
Check then that you'll have 15 volts and -15 volts in the both channels.
I'm not sure how your adapter looks like. Have you 3 or 4 wires?
The possibly fried opamp might be alive, not risky to mount it correctly and test.
ok
i dind't try anything yet, dind't have time
( putting time on the working and amazain 07 )
The ac adapter ( transformer ) as 3 wires out!
2 wires give +12ac
and 1 wire is ground i guess
cna this work ? or i have to connect it in paralell and bridge the B1-B2?
Please instruct me on where exactly to take measurements!
i do not quite understand what to look for
i soldered the chip back on the correct side,
let's hope that i dind't fry the 40$ OPA chip under it :p
let me know what to test exaclty with # and pins :)
If you AC adapter has a centertap, connect this to ground, pin 2 or 3. The other wires to 1 and 4.
Notice though that 12 VAC is good for 12 VDC stabilized.
is that enough to make the amplifier run normally ?
this is only a temporary transformer
i'll get audio toroidal tranfos once everything is setup !
what do you think ?
the connection seems ok from what you say
what to check then ?
not all the leds are lit! :(
is there a place where i can check for correct voltage ?
Study the schematics carefully. You have a net called 15V_L and -15V_L (left channel). Those points can be reached in many places but pin 4 and 7 of the opamp may be the easiest to reach.
I'll it's possible to have a bit low voltage but be aware of some hum due to partly stabilized voltage.
About the LED's: (have you read this?)
QuoteIf you don't want to trim the idle current you can omit P1, R15, R16 and T4. The LED's creates sufficient idle current of T5 and T6. If you want more current in an easy way, change colour of the LED's! If you have T4 mounted you can either have or loose the LED's. If you do have the LED's you will get a limitation of max bias current
ok i'll have a look at the schematics later on at home
but i don't quite understand the "LED" thing and the trimmers?
i never read that passage you quoted...where is it from ?
i know that i installed 2 trim pots
but i'll check tonight wich one
i didn't adjust it at all though
The text is from the building description. I'll recommend that you read the text I have written.
ahah
well i had read it a few times, while assembling the unit
but as i told you previously in emails,
i am a total NOOB
so i can't just look at schematics and see what does what and where it goes to
i have a basic idea of how electronic works, and i can isolate different parts of a schematic ( PS, output stage, input stage ) and that's about it!
let me know if you can be of more help regarding the power supply
i need to take measurements to see if i have a problem somewhere
( i think )
meanwhile i'll reread the building description a few times :)
PerAnders i need help!
i tried to check out voltages, i don't even know where to start!
Please i need guidance to complete this amplifier!
ok i checked for power supply voltage
i got +13.82V on both side measuring at C30/G30 postisive side
what can i verify next??
i also checked voltage between R17 and R18
not too sure if i took the measurement the correct way
but i get 0.12v on each side
with my + and - from the voltmeter on R17 and R18
what do you think ?
First of all you must check your supply voltage. 13.7 V is probably OK (a bit low according calculations), how about the negative? How much voltage do you have in, the voltage before the regulators?
0.12 volts across R17 means 5.5 mA which is a bit low. Should be more than 20 mA. Do you use only LED's or do you have P1, R15, R16 and T4 mounted? You should not have both LED's and the transistor.
I know you say you can't read the schematic but try to indentify for example R1 and then check where it is on the pcb. Each part in the schematic corresponds to a real part on the pcb. If you are going to troubleshoot you must be able to read the schematic.
Sorry for my late response. The email notification did not work of some reason. It usually does.
hi PER :)
well i have them ALL mounted :p
that could be the problem ?
i have installed all the LEDS
then P1, R15 R16 and T4
what do i need to remove ?
let me know :)
It's no harm to have them all mounted but this wasn't the idea. The drawback you'll get (not sure it is for you) is that the max idle current is determined by the LED's.
The LED's serves as a fixed voltage source of 1.5-1.6 volts each. The other circuitry is a variable voltage which also senses the temperature.
If you have the LED's, they should also be lit.
Please do read the text I have written. :idea:
ok per,
i have read, reread, and rere re read it all over again
building, description, schematics ...
i can't find where to start at!!!
What to do next ?
please let me know in clear steps ,
i seriously don't know what to do!
i want this amp to work!
would it be a good idea for me to post a photo of the board?
A photo would help. You could also measure voltages. Print the schematics and write down on the paper and send a scanned copy to me (or by regulator mail).
When you do troubleshooting you must start in one end and the most suitable is checking the supply voltage, then checking all currents and voltages and the apply a signal at the input.
here is a picture of the board
(http://www.orijinmotorsports.com/special/DSC01879.JPG)
note that the following resistors are soldered under the board
cause i either dind't have enough space or had to change them of place
and it was easier to work from underneath ...
E9-R9
R6 and E3
Ther are 2 leds on the up side of the board that doesn't lit at all
and 1 that lights only half way trhough
Should i remove the P1 pot for now ?
i have used OPA amp ..
I beg once again to get the schematic in front of you, read the explanations I have written, read the whole circuit description also and the building instrunstruction, even though it's a bit too late now. I see that you have mounted too much stuff and clearly not tested each part.
From the picture I can see if the feedback is correctly done. R5, do you have a wire there?
C6, C7 are not necessary but do no harm either.
If you short R16 both H1 and H2 should be lit.
First you must check so you'll have +- 12 V at least at all points where I have 15_L, -15_L, 15V_R and -15V_R
Check also that you have the right transistor type PNP, NPN.
Check all LED's. You can check this with diode test with your DVM and the supply voltage cut off. The instrument delivers 1 mA or so and the LED shines very weak.
The AC connection looks weird. You must have 4 wires to each connector. You must have two AC sources.
Winding 1 should go to 1-2 X3, and winding 2 to 3-4 X3.
When you do this troubleshooting, test only one channel at the time. Wait with mounting B1 and B2 until everything is OK. If you have two transformers you should not mount B1 and B2.
hi again :)
OK i did some tests ...
First i measured the voltage against both voltage rails
( R10 -R22 )
i got 12V ( 11.58V )
equally on both sides
Then i removed and shorted R16
the LEDS don't come On more ..only 1 on each side is lighted when no input/headphones plugged
H3
Then i put in input and output(headphones )
to check out
well now H3 is dim but on a bit
and H2 is light
but H1 is still off
When i put power ON, i hear the music for like 1 second
then everything goes BUZZZZZZZZZZ
not too loud noise, stable noise ..something like 100-120hz tone sound
I also removed P1
I checked the transistors type, seems to be ok on both sides
Then do i need to check the 12V on all points ?
where do i find all the points? looking at schematics?
let me know :)
At least this time i HEARD something out of it :p
( wich is a good sign right ? :p )
Quote from: JinMTVTThen do i need to check the 12V on all points ?
where do i find all the points? looking at schematics?
You'll have to look atthe schematics and identfiy all parts that re involved. The same parts can easily been identified on pcb.
Have you checked the LED's with a DVM as I suggested? The dark one my be lit.
Check all transistors, 0.6-0.65 V between base and emitter, otherwise something is wrong.
When you do all these measurements you do that with no input signal.
AC wiring was wrong, have you fixed that?
ok ok
i still haven't fixed anything at all !!!
Please help me out PER
i don't wanna have lost all that time on this amp for notting :p
Tell me how to connect this amplifier.
What i have is a wall type transformer that takes 120 AC
and gives roughly 12V AC
the output has only 3 wires though
2 seems to be the 2 +
and 1 would be the - ?
it is said to be a dual power supply with a ratio of 1:10
Then once this is connected
how do i start checking everything
and where to start from.
I have checked and rechecked all the schematics
and i think that i don't quite understand what is going on.
What do i need to start with ?
please be explicit, as i am a total noob into all that stuff :p
ahhaah
I think that you mentionned checking all the 12V points?
where do i know how to check all those?
let me know
thanks
The transformer, is it AC coming out of the wires? Do you get approx. 24 VAC between the "+" and 12 VAC between either "+" and the "-"?
If yes, have you connected only _one_ channel and omitted B1 and B2?
If yes, how much DC voltage do you have between the groundplane and before the regulators? 15-17 VDC? How much after the regulators?