Good catch on the Lorlin switch metal insert! I was working with 10 positions there for a minute. Fixed that.
Here's an interesting development: I plugged the unit back into the system and tried playing a record. Cycled through all positions of the Lorlin. Still no luck, on either hearing relays click or music play... but then I unplugged the RCA cables to try a different input and I heard some faint music coming through the speakers. Seems if I hold the male end of the RCA cable to to outer metal ring of the female insert, very low volume music plays. In fact, turning the volume pots has no impact on the sound level. When I plug the RCA cable back into the jack, no more sound. Then I tried my DAC with different RCA cables, and couldn't recreate the low volume sound... Not sure any of this is relevant, but figured I'd post just in case!
Here's an interesting development: I plugged the unit back into the system and tried playing a record. Cycled through all positions of the Lorlin. Still no luck, on either hearing relays click or music play... but then I unplugged the RCA cables to try a different input and I heard some faint music coming through the speakers. Seems if I hold the male end of the RCA cable to to outer metal ring of the female insert, very low volume music plays. In fact, turning the volume pots has no impact on the sound level. When I plug the RCA cable back into the jack, no more sound. Then I tried my DAC with different RCA cables, and couldn't recreate the low volume sound... Not sure any of this is relevant, but figured I'd post just in case!
^ I "think" you have two related, but separate issues to solve 'no sound / faint sound'. Not to jinx us, but they should be relatively simple to diagnose.
Here's how I work through it...
Goal 1 - make sure input signal gets to circuit
Goal 2 - If meeting goal one doesn't result in the happy dance, check output and audio circuit.
We're working on goal 1 part 1 for the moment.
One thing that's nice is that (I think) you said both boards are behaving the same.
Let's solve your relay issue.
Insert the cable into the box header on the board(s) - NOTE CAREFULLY the female ends that respond to + - and 1 2 3 4 5.
Repeat the exercise from before by shorting between + and the 1-5 on the opposite end of the cable. If no relays click... then it's the cable / bad connection / interface.
If the relays click, then it's the twister board / switch.
In the event that we also have an issue with the wiring / pot, can you take a series of photos and label the wires in the photos (so I / we don't have to visually trace them) of one input to the boards; and the pot wiring. Sketch it on a piece of paper too, please.
Getting close.
Here's how I work through it...
Goal 1 - make sure input signal gets to circuit
Part 1 - Won't get there unless relays work properly
Part 2 - Won't get there unless inputs (RCAs) and pot are wired properly.
Goal 2 - If meeting goal one doesn't result in the happy dance, check output and audio circuit.
We're working on goal 1 part 1 for the moment.
One thing that's nice is that (I think) you said both boards are behaving the same.
Let's solve your relay issue.
Insert the cable into the box header on the board(s) - NOTE CAREFULLY the female ends that respond to + - and 1 2 3 4 5.
Repeat the exercise from before by shorting between + and the 1-5 on the opposite end of the cable. If no relays click... then it's the cable / bad connection / interface.
If the relays click, then it's the twister board / switch.
In the event that we also have an issue with the wiring / pot, can you take a series of photos and label the wires in the photos (so I / we don't have to visually trace them) of one input to the boards; and the pot wiring. Sketch it on a piece of paper too, please.
Getting close.
it's easy as this:
remove notch washer from switch, rotate shaft to most left position, place notch in hole marked 6, tighten the screw
check do you have 6 positions from most left to most right (CCW to CW)
put switch in position 2 (second from CCW, counting that 1 is "mute")
put DVM set to Vdc across diode in parallel to relay 1 (input 1) and if thee is juice, DVM should measure something as 24Vdc (nominal voltage, exact is not important, depends of exact zener voltage and Ugs of series mosfet)
if there is no voltage, try next switch positions, measuring at corresponding relays/diodes
there could be no sound without input relay energized; one can check signal chain itself without flat cable and twister, simply shorting desired input pins at IDC header itself - put short between "+" and "1" pins, and you should have relay 1 energized, thus input "1" operative
now, for clarity sake, post just 2 pictures here :
first - showing wires to pot, clear enough that we can see colors
second - showing wires to pot pads at main pcb, clear enough that we can see colors
anyhow, if you rotate pots at- say - 2 O'Clock, you'll have enough resistance from wiper (mid pin) to each end, so you can check with DMM buzzer (buzzing when R<30R) pot pins to main pcb pot pins
wiper pin on pot must buzz to "wip" pad on main pcb
CCW pin on pot (that's bloody GND) must buzz to "CCW" pad on main pcb and - practically any GND point on main pcb
CW pin on pot must buzz to "CW" pad on main pcb
if that is not the case or you have some different buzzing, remove wires and do it again, properly
now, hair spppppplittttttttttting - using screw terminals for pot wiring connections is same wise as using nylon screws on your car wheels
convenient if/while doing some prototype work, but no go for good
remove notch washer from switch, rotate shaft to most left position, place notch in hole marked 6, tighten the screw
check do you have 6 positions from most left to most right (CCW to CW)
put switch in position 2 (second from CCW, counting that 1 is "mute")
put DVM set to Vdc across diode in parallel to relay 1 (input 1) and if thee is juice, DVM should measure something as 24Vdc (nominal voltage, exact is not important, depends of exact zener voltage and Ugs of series mosfet)
if there is no voltage, try next switch positions, measuring at corresponding relays/diodes
there could be no sound without input relay energized; one can check signal chain itself without flat cable and twister, simply shorting desired input pins at IDC header itself - put short between "+" and "1" pins, and you should have relay 1 energized, thus input "1" operative
now, for clarity sake, post just 2 pictures here :
first - showing wires to pot, clear enough that we can see colors
second - showing wires to pot pads at main pcb, clear enough that we can see colors
anyhow, if you rotate pots at- say - 2 O'Clock, you'll have enough resistance from wiper (mid pin) to each end, so you can check with DMM buzzer (buzzing when R<30R) pot pins to main pcb pot pins
wiper pin on pot must buzz to "wip" pad on main pcb
CCW pin on pot (that's bloody GND) must buzz to "CCW" pad on main pcb and - practically any GND point on main pcb
CW pin on pot must buzz to "CW" pad on main pcb
if that is not the case or you have some different buzzing, remove wires and do it again, properly
now, hair spppppplittttttttttting - using screw terminals for pot wiring connections is same wise as using nylon screws on your car wheels
convenient if/while doing some prototype work, but no go for good
Okay, stealing a bit of testing time on my lunch break here 
1. I tested the cables. When I short the female + to Pins 1-5 on both cables, the relays click. So cables appear to be good.
2. I tried testing the Vdc across the diodes according to ZM's instructions, using the selector switch. Attaching a pic here just to make sure I'm testing correctly. Assuming I have the multimeter hooked up properly on the diodes, I'm not getting anywhere near 24Vdc. A handful of mV at best. Would that point to the selector switch/twister board being at least one culprit?
3. And here are pics and a drawing of how I have the volume pot wired. I had a sneaking feeling when I installed the terminal blocks that I was cutting a corner. I agree that they don't inspire confident, even if they do seem to be making good contact. I will properly solder the wires once I get the issue figured out.
Thanks so much for all the help figuring this out!
Scott
1. I tested the cables. When I short the female + to Pins 1-5 on both cables, the relays click. So cables appear to be good.
2. I tried testing the Vdc across the diodes according to ZM's instructions, using the selector switch. Attaching a pic here just to make sure I'm testing correctly. Assuming I have the multimeter hooked up properly on the diodes, I'm not getting anywhere near 24Vdc. A handful of mV at best. Would that point to the selector switch/twister board being at least one culprit?
3. And here are pics and a drawing of how I have the volume pot wired. I had a sneaking feeling when I installed the terminal blocks that I was cutting a corner. I agree that they don't inspire confident, even if they do seem to be making good contact. I will properly solder the wires once I get the issue figured out.
Thanks so much for all the help figuring this out!
Scott
step 1.
considering that volpot is wired properly (judging by pics) .....
disconnect flat cable from pcb, arm input 1 shorting pins numbered "1" to "+" pins with wire bridge
confirm that you have 24Vdc across relay 1 dode
connect some musak, source to preampp and preamp to amp and speaks and try to listen
while you're listening, post pics of twister and flat cable, so we can see is there anything wrong
take care that we can see twister pcb from both sides
did you arrange notch washer as I described?
considering that volpot is wired properly (judging by pics) .....
disconnect flat cable from pcb, arm input 1 shorting pins numbered "1" to "+" pins with wire bridge
confirm that you have 24Vdc across relay 1 dode
connect some musak, source to preampp and preamp to amp and speaks and try to listen
while you're listening, post pics of twister and flat cable, so we can see is there anything wrong
take care that we can see twister pcb from both sides
did you arrange notch washer as I described?
ZM's advice is always best, and he and I are following same path to diagnose it would seem. Follow ZM current instructions. You got the real man on the case.
However... if you'll indulge me... if you do not get music.
You're confirming to make sure proper relay actuates to pass input signal, which we need to confirm.
Pot is wired fine (best we can tell).
Can you please take a few secs to: set the pot to roughly mid point and do a quick resistance check between ...
However... if you'll indulge me... if you do not get music.
You're confirming to make sure proper relay actuates to pass input signal, which we need to confirm.
Pot is wired fine (best we can tell).
Can you please take a few secs to: set the pot to roughly mid point and do a quick resistance check between ...
Out+ and JP+ Pin 2 inside/middle pin. Put jumper cap back on firmly and check to wiper of P3 (middle pin on back of board if you can get to it)
Out - and JP- Pin 2 inside/middle pin Put jumper cap back on firmly and check to wiper of P4 (middle pin on back of board if you can get to it)
On your pot boards... to the main boards
CW+ / AIN and R28
CW- / BIN and R29
+WIP / AOUT and R28
- WIP / BOUT and R29
+ CCW / ACOM to GND
- CCW / BCOM to GND
Reasoning... just takes a small effort to make sure signal from input has a chance to get where it needs to go if the relay works... You likely won't find anything off, but it just takes a minute.
Following Mighty ZM's advice (I have the IDCs shorted between + and pin 4) ... and I have sweet sweet music playing!!!!!
I need to get back to work but below are pics of the twister board.
Patrick: I'll do the resistance check that you describe this evening.
Thanks everyone! This is a thrilling development to hear music through the speakers. Heck, who needs a selector switch, anyway?!
I need to get back to work but below are pics of the twister board.
Patrick: I'll do the resistance check that you describe this evening.
Thanks everyone! This is a thrilling development to hear music through the speakers. Heck, who needs a selector switch, anyway?!
^ From pics no, but there are wonky type cables on the market. I thought even with those though that red stripe to red stripe was proper.
Anyway... would it be good to have them short from the female end of cable first as suggested previously to see if it follows board position? Seems you and I leaning same way.
Is it cable... is it Header... is it switch.
Anyway... would it be good to have them short from the female end of cable first as suggested previously to see if it follows board position? Seems you and I leaning same way.
Is it cable... is it Header... is it switch.
checking switch itself is easy; remove flat cable from twister and attack it with buzz test:
in position all CCW (mute) , no buzz between "+" and any of pins
in position "1", buzz in-between "+" and "1" pins
in position "2", buzz in-between "+" and "2" pins
etc.
if that is pass, follow Patrick's - leave flat cable connected to main pcb and try measuring on free end of cable, following same logic as measuring IDC on pcb itself
or just fiddle shorting ''+" hole with appropriate holes 1, 2, 3, 4 ,5
in position all CCW (mute) , no buzz between "+" and any of pins
in position "1", buzz in-between "+" and "1" pins
in position "2", buzz in-between "+" and "2" pins
etc.
if that is pass, follow Patrick's - leave flat cable connected to main pcb and try measuring on free end of cable, following same logic as measuring IDC on pcb itself
or just fiddle shorting ''+" hole with appropriate holes 1, 2, 3, 4 ,5
AND NOT "-"
Beating that poor horse until it's tender enough to serve.
I got in a hurry doing the same thing... and I was VERY sad about my ookup.