Avalon VT 737 sp

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
There is probably a disconnect somewhere else. When youre ready to test, the first thing to do is test the signal path with all buttons turned off. If it doesn’t work, measure AC at each pin along the signal path until it disappears. The path with all buttons turned off is this:
View attachment 147889

Does the wire have insulation or is it bare copper wire with no colored jacket? I have never tried copper foil.
i dont have any relays left, so but i know i tested it before with every button disengaged, it never arrived at k9 pin 2 but instead pin 4

it stated on the productpages that it is for electronics https://www.amazon.de/dp/B09C1WPMZK?ref=ppx_yo2ov_dt_b_fed_asin_title

its conductive on the outer layer, but not on the glue side, but i guess thats fine?
 
i dont have any relays left, so but i know i tested it before with every button disengaged, it never arrived at k9 pin 2 but instead pin 4
On all relays, when the unit is turned off, pins 2 & 3 should be connected or else the relay is bad.

it stated on the productpages that it is for electronics https://www.amazon.de/dp/B09C1WPMZK?ref=ppx_yo2ov_dt_b_fed_asin_title

its conductive on the outer layer, but not on the glue side, but i guess thats fine?
Usually the glue is conductive too, which makes it conductive on both sides. I have used that tape on guitars for shielding, but not when trying to repair a PCB.
 
On all relays, when the unit is turned off, pins 2 & 3 should be connected or else the relay is bad.


Usually the glue is conductive too, which makes it conductive on both sides. I have used that tape on guitars for shielding, but not when trying to repair a PCB.
is there a way to test relays before soldering them?
in case i get a faulty again

yup just tested again pin 2&3 od k7 and k8 are on 0 resistance
 
Last edited:
is there a way to test relays before soldering them?
in case i get a faulty again
With any relay out of the PCB:
Resistance between pins 1 and 10 should be 800-1200 ohms (exact value not important)
Pins 2 & 3 should be shorted together (zero resistance)
Pins 3 & 4 should be disconnected from each other
Pins 8 & 9 should be shorted together
Pins 7 & 8 should be disconnected from each other
Pins 5 & 6 don't do anything so you can ignore them.

Edit: If it doesn't pass those tests, the relay is bad, so don't put it into the PCB. If it does pass, you still have to test the relay in the PCB to make sure the signal path works properly in combination with the other 3 relays. The 4 relays work together to make 8 different signal paths so you have to test to make sure each path works. I already posted paths #1 (blue) and #4 (green) but get #1 working before any of the others.
1. EQ>COMP off, EQ off, COMP off
2. EQ>COMP off, EQ on, COMP off
3. EQ>COMP off, EQ off, COMP on
4. EQ>COMP on, EQ off, COMP off
5. EQ>COMP on, EQ on, COMP off
6. EQ>COMP on, EQ off, COMP on
7. EQ>COMP off, EQ on, COMP on
8. EQ>COMP on, EQ on, COMP on

Another edit: Silly me, I left out 2 paths so I added them as 7 & 8.
 
Last edited:
With any relay out of the PCB:
Resistance between pins 1 and 10 should be 800-1200 ohms (exact value not important)
Pins 2 & 3 should be shorted together (zero resistance)
Pins 3 & 4 should be disconnected from each other
Pins 8 & 9 should be shorted together
Pins 7 & 8 should be disconnected from each other
Pins 5 & 6 don't do anything so you can ignore them.
Ok i got 2 relais next to the k12(k10,k11??) with 100kohms and 20kohmm betweens 3&4 and 7&8,
also k2 on the tube card has 0 instead infinite resistance between 3&4 and 7&8,
20k&15k on the first two relays at the input(xlr,line) section 3&4 and 7&8,
120k on k5 between 3&4 and 7&8,
53k on k4 between 3&4 and 7&8,
115k on k6 between 3&4 and 7&8,
k7,8 and 12 are fine
k9 isnt inside of the circuit

edit:

oh i just read thats the readings out of the pcb, still maybe they'll help

jsust checked the relays i swapped, they were apperantly, something else must have cause this
 
Last edited:
Ok i got 2 relais next to the k12(k10,k11??) with 100kohms and 20kohmm betweens 3&4 and 7&8,
also k2 on the tube card has 0 instead infinite resistance between 3&4 and 7&8,
20k&15k on the first two relays at the input(xlr,line) section 3&4 and 7&8,
120k on k5 between 3&4 and 7&8,
53k on k4 between 3&4 and 7&8,
115k on k6 between 3&4 and 7&8,
k7,8 and 12 are fine
k9 isnt inside of the circuit

edit:

oh i just read thats the readings out of the pcb, still maybe they'll help

jsust checked the relays i swapped, they were apperantly, something else must have cause this
The tests that I just listed in #264 were only for relays that are out of the PCB. When the relays are installed on the PCB, if you don't know how things are connected on the PCB, you could be measuring the resistance of other paths that connect the pins, not just the path through the inside of the relay.

For example, on K1 on the tube board, pins 3 & 4 are always shorted (on purpose) by a trace on the PCB. Edit: Sorry, I meant K1 (I fixed it.) On K2 on the tube board, I don't believe pins 3 & 4 are even used.
 
Last edited:
The tests that I just listed in #264 were only for relays that are out of the PCB. When the relays are installed on the PCB, if you don't know how things are connected on the PCB, you could be measuring the resistance of other paths that connect the pins, not just the path through the inside of the relay.

For example, on K2 on the tube board, pins 3 & 4 are always shorted (on purpose) by a trace on the PCB.
yea i've got that, added a edit where i stated that ive misreaden your post

yea did that, beginning from pin 4 of k9 i got 70k resistance to all the other pins k12 etc

so but if we suppose the relais of k9 were ok, whats then the isse, because no matter what the signal always arrives at pin 4 of k9 which means it gets misrouted

since the relay of k9 was ok while testing outsde of the circuit, i really dont know whats causing this



but i will try to fix the broken solder pads tommorow
 
so but if we suppose the relais of k9 were ok, whats then the isse, because no matter what the signal always arrives at pin 4 of k9 which means it gets misrouted
Signal should always arrive at K9 pin 4, because it is connected directly to T12. That doesn't mean that K9 pin 4 is always connected to K9 pin 3 inside the relay. K9 pin 3 should always have a signal, but when EQ>COMP is off, it must come from K9 pin 2, not from K9 pin 4.
 
Signal should always arrive at K9 pin 4, because it is connected directly to T12. That doesn't mean that K9 pin 4 is always connected to K9 pin 3 inside the relay. K9 pin 3 should always have a signal, but when EQ>COMP is off, it must come from K9 pin 2, not from K9 pin 4.
ehh one more question, in theory k9 only needs solid soilder connection on pin 1,4 and 8, or?
because as far as i understand all the other pins get connected inside of the relay?
so do i really have to care about the missing pad on pin 3 and 2?
 
ehh one more question, in theory k9 only needs solid soilder connection on pin 1,4 and 8, or?
because as far as i understand all the other pins get connected inside of the relay?
so do i really have to care about the missing pad on pin 3 and 2?
Each pin on the K9 relay is supposed to connect to its own PCB trace except for pins 5 & 6 which aren’t used at all by any of the relays. Otherwise how does the signal keep going on the path all the way to the Output knob?

(And if you can’t connect a pin to its PCB trace because of board damage, that's where you have to substitute something else like a wire.)
 
Last edited:
Each pin on the K9 relay is supposed to connect to its own PCB trace except for pins 5 & 6 which aren’t used at all by any of the relays. Otherwise how does the signal keep going on the path all the way to the Output knob?
oh, is it inside of the pcb or what? because i cant see any traces leaving the relay except 1.4.8
 

Attachments

  • WhatsApp Bild 2025-03-13 um 18.23.08_d6d481ce.jpg
    WhatsApp Bild 2025-03-13 um 18.23.08_d6d481ce.jpg
    432.4 KB
so if i see that right k9 pin 2 > k8 pin 9
k9 pin 6> k8 pin 4
k9 pin 9 > k9 pin 3?

these are the connections i have to make with a wire? right?
 
Last edited:
To see all the connections, you can look at the diagram with 4 relays that I posted.

so if i see that right k9 pin 2 > k8 pin 9
Yes

k9 pin 6> k8 pin 4
K9 pin 6 is not connected to anything. It only helps to physically secure the relay to the board. K9 pin 7 connects with K8 pin 4.

k9 pin 9 > k9 pin 3?
K9 pin 9 connects with K8 pin 7. And also with solder point 64 near the output knob. So if you need to solder a wire to K9 pin 9, the other end of the wire can be soldered to either place.
 
To see all the connections, you can look at the diagram with 4 relays that I posted.


Yes


K9 pin 6 is not connected to anything. It only helps to physically secure the relay to the board. K9 pin 7 connects with K8 pin 4.


K9 pin 9 connects with K8 pin 7. And also with solder point 64 near the output knob. So if you need to solder a wire to K9 pin 9, the other end of the wire can be soldered to either place.
Where does pin 3 then connect to? the image is pretty blury, but it was hard holding the avalon and taking a picture

but i think u can see what i mean
 

Attachments

  • WhatsApp Bild 2025-03-14 um 00.49.14_9c7d0ba4.jpg
    WhatsApp Bild 2025-03-14 um 00.49.14_9c7d0ba4.jpg
    468.3 KB
Do you mean pin 3 of K9? If so, then you can see in the diagram that it has to connect to pin 3 of K12.
Yea pin 3 k9, yea i saw that, but cant find any trace leading there
attached a picture in my previous post

but yea i will first try to fix it with the copper foil tommorow, if it doesnt work i will connect the pins with a wire, which i also ordered, only had cables which are fibery
 
Yeah you are right, I don’t see the trace either. But there is one in there somewhere. Maybe on the top side of the board and hidden by all the light green? Maybe pucho knows.
so i just checked the signal flow with the continuity setting the path from t12 to k8 pin 3 isok, but it doesnt travel to k7 pin 3

k9 pin 2 is connected to k7 p3 according to the multimeter, weird, according to your diagram there should be definitly be a connection between k7 p3 to k8 p3

i scraped away the burnt pcb and was able to trace all the broken pads, except for k8 p3>k7 p3

@pucho812 do you might have a clue here?
 
Last edited:
so i just checked the signal flow with the continuity setting the path from t12 to k8 pin 3 isok, but it doesnt travel to k7 pin 3
K8 pin 3 should connect to K7 pin 3. I can see the trace in the picture below. Make sure you are measuring the right pins because it is definitely confusing! But if they are really not connected, it would mean that one of those pins is not connecting to that trace. So you can try to reflow those 2 pins and see if that helps. Maybe add a little solder in case it didn’t flow deep enough into to the hole. If it still doesn’t connect, then you may have to wire them together.
IMG_3525.jpeg
 
Last edited:

Latest posts

Back
Top