Avalon VT 737 sp

[punkt]

Ok so K8 and K9 are receiving the correct control signal. That’s good. K7 is fine; it won’t have 12 volts DC across pins 1 & 10 unless the “COMP” button is on.

Try turning EQ and COMP off, but turn EQ>COMP on. Send the sine wave into line in. Set the meter dial to 200V AC. Hold the black probe on any convenient grounded place, such as solder point 12, 15, or T7. Then with the red probe measure the AC at these points:

Solder point T12
K8 pin 2
K8 pin 3
K8 pin 4
K8 pin 7
K8 pin 8
K8 pin 9
All the same pins on K9
Solder point 64

Edit: measure on K8 & K9, not K7

Solder point T12 4,6
K8/9 pin 2 4,5/0
K8/9 pin 3 0/4,6
K8/9 pin 4 0/4,6
K8/9 pin 7 0/4,6
K8/9 pin 8 0/4,6
K8/9 pin 9 0/0

Solder point 64 0

 

[TheseGoToEleven]

Solder point T12 4,6
K8 pin 2 4,5 k9 0
K8 pin 3 0 k9 4,6
K8 pin 4 k9 4,6
K8 pin 7 0/4,6
K8 pin 8 0/4,6
K8 pin 9 0,0

Solder point 64 0

What did you measure at K8 pin 4? I don’t see it there. On the PCB it connects directly to K9 pin 7, so they should be measuring the same.

 

[punkt]

What did you measure at K8 pin 4? I don’t see it there. On the PCB it connects directly to K9 pin 7, so they should be measuring the same.

if i remember correctly it was 0, but i willremeassure, give ma sec!

yea its 0

which pcb do u mean, the i/o board perhaps?, because at the beginning of the repair i got a lil piece of wood get stuck in one pin of the i/o board, i thought i managed to get it out

 

[TheseGoToEleven]

which pcb do u mean, the i/o board perhaps?, because at the beginning of the repair i got a lil piece of wood get stuck in one pin of the i/o board, i thought i managed to get it out

No I mean that on the motherboard there is a trace that connects pin 7 of K9 to pin 4 of K8. (You might need to shine a flashlight through the board to see it.) So if you are saying that pin 7 of K9 measured 4.6VAC but pin 4 of K8 measures zero volts… then they are somehow disconnected. Try reflowing the solder on those two pins and then see if the signal can reach K8 pin 4.

With EQ>COMP turned on, and EQ off, and COMP off, the audio signal should follow the green line.

 

[punkt]

No I mean that on the motherboard there is a trace that connects pin 7 of K9 to pin 4 of K8. (You might need to shine a flashlight through the board to see it.) So if you are saying that pin 7 of K9 measured 4.6VAC but pin 4 of K8 measures zero volts… then they are somehow disconnected. Try reflowing the solder on those two pins and then see if the signal can reach K8 pin 4.

With EQ>COMP turned on, and EQ off, and COMP off, the audio signal should follow the green line.

View attachment 147763

attached a video of the measurment, just resolderd no changes, but i just saw that some relais dont sit tight on the pcb, will completly resolder them now, also gonna replace k8 just incase

 

[punkt]

replaced k8 now, no changes

 

[TheseGoToEleven]

replaced k8 now, no changes

Ok so if you go back and measure the AC at all the places along the green line in the diagram, you should be able to find where it goes to zero.

 

[punkt]

Ok so if you go back and measure the AC at all the places along the green line in the diagram, you should be able to find where it goes to zero.

mate, ive done it, back to 70k ohm between 64 and t12, no soundoutput on anything, i just swapped k8 and resoldered k9.

damn i fed up with his unit

 

[TheseGoToEleven]

mate, ive done it, back to 70k ohm between 64 and t12, no soundoutput on anything, i just swapped k8 and resoldered k9.

damn i fed up with his unit

I’m sure you are!

You’ll have to measure the AC along the green line, starting with T12, and find where the signal disappears. Before you swapped K8, the signal was going all the way through K9 and K12 perfectly but not making it to K8.

 

[punkt]

I’m sure you are!

You’ll have to measure the AC along the green line, starting with T12, and find where the signal disappears. Before you swapped K8, the signal was going all the way through K9 and K12 perfectly but not making it to K8.

if iam correct it now goes to k8, but k12 and k9 are now giving troubles, i attached the video

need to smoke a toke, will be back in bout 15-20 minutes

i will replace k9 as the next step

again thank you so much for guiding me thorugh this

 

[punkt]

replaced k9, no changes, no sound at all, even with eq>comp off...

k12 and k9 are fine, k8 still makes trouble

and the 70k resistance is back

wished i didnt opend it up again.

again a video of the measurments

 

[TheseGoToEleven]

if iam correct it now goes to k8, but k12 and k9 are now giving troubles, i attached the video

need to smoke a toke, will be back in bout 15-20 minutes

i will replace k9 as the next step

again thank you so much for guiding me thorugh this

In the video, it was hard to see but I think it showed signal reaching K8 pin 8. That means signal was going through all 4 relays and went almost to 64.

Maybe in some places you're trying to measure too quickly and showing zero when there is actually signal there? But also, if the soldering isn't good, then pushing on a pin with the probe could connect/disconnect it from a trace. A bunch of these traces appear to be somewhere inside the PCB. Not on top or bottom, but inside. So when you solder the pins, make sure that at least a little of the solder sinks into the hole. Otherwise the pin might be connected on the surface but not connected inside the board.

 

[punkt]

In the video, it was hard to see but I think it showed signal reaching K8 pin 8. That means signal was going through all 4 relays and went almost to 64.

Maybe in some places you're trying to measure too quickly and showing zero when there is actually signal there? But also, if the soldering isn't good, then pushing on a pin with the probe could connect/disconnect it from a trace. A bunch of these traces appear to be somewhere inside the PCB. Not on top or bottom, but inside. So when you solder the pins, make sure that at least a little of the solder sinks into the hole. Otherwise the pin might be connected on the surface but not connected inside the board.

read my next post too, maybe it will help, i will reflow everything now

 

[punkt]

In the video, it was hard to see but I think it showed signal reaching K8 pin 8. That means signal was going through all 4 relays and went almost to 64.

Maybe in some places you're trying to measure too quickly and showing zero when there is actually signal there? But also, if the soldering isn't good, then pushing on a pin with the probe could connect/disconnect it from a trace. A bunch of these traces appear to be somewhere inside the PCB. Not on top or bottom, but inside. So when you solder the pins, make sure that at least a little of the solder sinks into the hole. Otherwise the pin might be connected on the surface but not connected inside the board.

just discovered a pcb burn
i think i ****** up earlier, before asking how to measure dc, i think i shorted pin 1 and 10 on 12, it was for barley a second, but yea, i think i fried it maybe?

 

[TheseGoToEleven]

just discovered a pcb burn
i think i ****** up earlier, before asking how to measure dc, i think i shorted pin 1 and 10 on 12, it was for barley a second, but yea, i think i fried it maybe?

Make sure that the power supply is still supplying +12 volts DC. You can measure that at solder point 20.

Then measure DC voltage across pins 1 & 10 of K12. It should be zero when the EQ button is off, and 12 volts when the EQ button is on. If that's ok, then go back to measuring AC along the green line in the diagram and find out where the signal disappears.

Edit: The picture is blurry but that looks like something that would have been done while soldering. Pin 10 looks kind of spherical to me. They should all look the same, like the 2 columns of 10 pins to the right of it.

 

[punkt]

Make sure that the power supply is still supplying +12 volts DC. You can measure that at solder point 20.

Then measure DC voltage across pins 1 & 10 of K12. It should be zero when the EQ button is off, and 12 volts when the EQ button is on. If that's ok, then go back to measuring AC along the green line in the diagram and find out where the signal disappears.

replaced k12 already, dc is ok, but the way bigger problem for me now is the 70k ohms again, i get no output whatsoever

 

[TheseGoToEleven]

replaced k12 already, dc is ok, but the way bigger problem for me now is the 70k ohms again, i get no output whatsoever

That's almost certainly a solder thing with one of the relays. Measure AC along the green line on the diagram or else measure AC on all the pins of K8 and K9. Then reply with what you find.

 

[punkt]

That's almost certainly a solder thing with one of the relays. Measure AC along the green line on the diagram or else measure AC on all the pins of K8 and K9. Then reply with what you find.

yea just figured it out while measuring, resolderd works again, will go back to tracing

 

[punkt]

That's almost certainly a solder thing with one of the relays. Measure AC along the green line on the diagram or else measure AC on all the pins of K8 and K9. Then reply with what you find.

signal lost is between k12 and k9
its leaving k12 but never arrives at k9

k9 is soldered properly now, just in case i extra put care into the pin going fromk12 into k9, nothing

 

[TheseGoToEleven]

signal lost is between k12 and k9
its leaving k12 but never arrives at k9

So you get signal at K12 pin 8? But no signal at K9 pin 8? If so, reflow those two pins and maybe add a little more solder.