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Per-Anders Sjöström

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QRV-02 support JIN

Started by peranders, January 19, 2006, 09:10:51 AM

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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.
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff


here is a picture of the board

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 ...

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.
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff


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


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?
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff


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

I think that you mentionned checking all the 12V points?
where do i know how to check all those?

let me know



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?
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff