No sound after upgrade install [solved]
- Thread starter mcwhart
- Start date
Alright,
What you want to do is download or obtain a 60Hz test tone. This will let us play AC through your amp and you can use your meter to measure it as it passes through each stage.
The first step is to play the tone into your SEX amp, then measure the AC voltage between ground and each lug on the volume control (turn it all the way up).
After getting these numbers, we can move on with testing other points in the circuit. To perform the measurements on the pot, the amp can be off, but for the other points we may look at, it will need to be on.
-PB
What you want to do is download or obtain a 60Hz test tone. This will let us play AC through your amp and you can use your meter to measure it as it passes through each stage.
The first step is to play the tone into your SEX amp, then measure the AC voltage between ground and each lug on the volume control (turn it all the way up).
After getting these numbers, we can move on with testing other points in the circuit. To perform the measurements on the pot, the amp can be off, but for the other points we may look at, it will need to be on.
-PB
Alright, this means that you have sound passing through your RCA jacks and out your level control, so we can rule those out.
The next spot to measure this AC voltage will be A1/B1.
-PB
The next spot to measure this AC voltage will be A1/B1.
-PB
fullheadofnothing
Moderator
You need the power on and the 60Hz signal. PB is having you trace the signal through the circuit step by step to find out where it is dropping off.
Alright, well, the signal is dead there...
What do you get at 19 and 9?
What do you get at 19 and 9?
Grainger49
New member
If you get a negative voltage you are measuring DC. The signal is AC.
Check the setting on your meter and make all the measurements again.
Check the setting on your meter and make all the measurements again.
Very sorry about that. Meter was on auto setting.
Here we go again:
Volume Pot all the way up with power off and 60 Hz tone:
top lugs, from A side to B side: .5 mV, 1.377 V, 1.377 V
bottom lugs, A side to B side: .5 mV, 1.039 V, 1.039 V
Volume pot all the way up, Power on, 60Hz tone:
A1: 17.36 V B1: 23.1 V
9: 17.38 V 19: 23.1 V
Thanks for your help and patience
Here we go again:
Volume Pot all the way up with power off and 60 Hz tone:
top lugs, from A side to B side: .5 mV, 1.377 V, 1.377 V
bottom lugs, A side to B side: .5 mV, 1.039 V, 1.039 V
Volume pot all the way up, Power on, 60Hz tone:
A1: 17.36 V B1: 23.1 V
9: 17.38 V 19: 23.1 V
Thanks for your help and patience
Grainger49
New member
Ok, the signal is getting through to these points. A lot of signal!
Grainger49
New member
Let me make sure I am following you. The first measurements should be from the three lugs on each side of the pot to ground or the chassis. The second measurements are to pins 1 of each tube (grid of the second stage).
If you are measuring this, you are getting amplification from the volume pot (about 1V) to the grid of the second stage of the tube (17V AC/23V AC). That is what is supposed to happen.
You should also get more AC voltage on pin 2 of each tube.
If you are measuring this, you are getting amplification from the volume pot (about 1V) to the grid of the second stage of the tube (17V AC/23V AC). That is what is supposed to happen.
You should also get more AC voltage on pin 2 of each tube.
Grainger49
New member
Yes, we are moving in the right direction. I'm guessing it will be something silly like I did 2 weeks ago. So far you are doing all right.
Grainger49
New member
The output section of the tube is pin 2. You should have DC and AC amplified voltage there. You should be able to turn it on, re-verify the AC voltage on tube pin 1 then you should read more on pin 2 of each channel.
If the DC there messes with the reading measure instead to terminals 20 and 40. That is after the Parafeed cap and the input to the output transformers. There should be a transformer wire on terminals 20 and 40 as well as the Parafeed cap.
If you get amplified voltage on these terminals the signal is dead somewhere in the transformer wiring to the speaker outputs.
Or, maybe, the headphone jack has failed and permanently opened the circuit to the speaker outputs.
If the DC there messes with the reading measure instead to terminals 20 and 40. That is after the Parafeed cap and the input to the output transformers. There should be a transformer wire on terminals 20 and 40 as well as the Parafeed cap.
If you get amplified voltage on these terminals the signal is dead somewhere in the transformer wiring to the speaker outputs.
Or, maybe, the headphone jack has failed and permanently opened the circuit to the speaker outputs.
Your C4S upgrade is working perfectly, we can now move completely away from that as a source of not having sound.
Grainger is correct, pin 2 on each tube socket is the next place to measure voltage.
Then terminals 15 and 25.
Then where each red wire connects on the binding posts.
Grainger is correct, pin 2 on each tube socket is the next place to measure voltage.
Then terminals 15 and 25.
Then where each red wire connects on the binding posts.
