Bottlehead Forum
Bottlehead Kits => S.E.X. Kit => Topic started by: mpent on April 25, 2013, 02:16:18 AM
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Hi,
Finished assembly of sex kit last night. After hooking up to speakers I am getting no sound from right channel and the output from left channel is scratchy. Starting with right channel, can you please advise me what to focus on to rectify the issue? I can post resistance and/or voltage measurements later today but assuming it's a soldering issue, wondering if someone can tell me what terminals to focus on. This is my first kit and hoping that the issue is poor soldering. Thanks!!
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Hey Michael - you have the right idea - check each solder joint - with the kit off, touch each joint. Especially the potentiometer, double check you wired it right. That can get tricky. If you are lucky it will jump out at you what needs to be done. - cheers - Eric
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Were the voltages and resistances spot on?
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No, not spot on. I will go back through the checks later and resolder those out of range and repost.
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A voltage or resistance that is out of range may be something other than a bad solder joint, feel free to post what you've got and we can point you in the right direction.
-PB
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Will do. Thanks. Any thoughts on why no sound from right channel?
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Will do. Thanks. Any thoughts on why no sound from right channel?
If the circuit is working correctly, then it's somewhere in the input or output wiring.
If teh circuit is not working correctly, then that might be the problem.
That's the reason for asking about the voltages and resistances.
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Ok. Thanks for breaking that down for me. I will post the numbers later. Thanks again!!
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Ok, here are the numbers:
Resistance:
Center pins 104.6, 100.
2 .2
3 .2.
7,17 .4, .4
8,18 0
9,19 1.203, 1.201
12,22 .5, .4
13,23 .3, .4
15, 25 .903, .902
A1,B1 1.421, 1.430
A3,B3 .692, .691
A6, B6 236.1, 218.2
voltage:
1. 205.2
2. -0.1
3. 0
4. 410
5. 205.2
6,16. 391, 391
7, 17. .2, .2
8, 18. 0,0
9,19. .1, .3
10,20. 412, 412
11,21. 373, 374
12,22. 0,0
13,23. 0,0
14,24. 0,0
15,25. 18.3, 17.35
A1,b1. .3, .5
A2,b2. 366.7, 368.7
A3,b3. 18.32, 17.25
A4,b4. 0
A5,b5. -97.7, -346
A6,b6. .506, .473
A7,b7. 3.44, 3.43
A8,b8. 2.8, 2.79
C1. 3.46
C2. 2.704
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Re: "Thanks for breaking that down for me." - I hear you; I also hate to do things when I don't know why!
The numbers at B4-5-6 and A6 look off kilter, especially B5. I suspect at least some solder joint problems. Also, check the 1270 ohm resistor at tube pins 6 and the 150K at pins 5 - are they the right value? (measure with the ohmeter across the two leads). If that doesn't turn up anything, swap the tubes and see if the voltage discrepancy follows the tube.
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Thanks, Paul. I will heed your suggestions tomorow morning when I'm able to get back in there and follow up here. On the resistor check, am I performing this with power supplied or unplugged?
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Measure resistances with NO POWER!! And wait for the caps to discharge. Read the warnings in the manual, between the resistance and voltage checks.
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Hahahahhahahahha....ok!!!! Resistor...resistance. Folks, I am not only learning but surviving. Really, thank you.
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235.5 for resistor at pin 6 and 148.7 at pin 5
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That's the 237 ohm resistor that should be in the C4S board; there should be a 1270 at pin 6. And watch the meter scale - if you actually have 150 ohms instead of 150K (=150,000) then it's a problem - this sometimes happens when parts get shipped to us.
If you're lucky, you may have only swapped the cathode resistor (pin 6) and the C4S R1 resistor. :^)
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Hmmmm...I did receive the C4S upgrade but did not open it. I guess I should open it up and see if the 1270 is in there. So overall, will resoldering the pins you mentioned and putting in the proper resistor at pin 6 rectify my issue?
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So the C4S parts pack does not have the 1.27k resistor in there and what was supposed to have been stocked in the sex kit were 2 237ohm resistors. I need to obtain these to swap them out. But Paul, the parts list for the C4s upgrade does not contain 237 ohm resistors just 499ohm and 150kohm resistors so I'm confused.
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Ok. I'm an idiot. I have the 1.27 resistors. I put them at the wrong terminal. Instead of the 249's I got 237's but Dan says that's fine. So I have to swap places with the 1.27 and 237.
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I misunderstood you on the phone. The 237 ohm resistors are very different than the 249K ohm resistors. We will send replacements for both.
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Oh, ok. Thank you much!
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Apologies for my confusion - too many kits and versions, so I mis-remember the values.
There is a 220 ohm grid stopper at pin 4 on the circuit, which has (I think) been replaced with the 237 since we have a large number of them on hand for many kits.
There is a 150K 2-watt resistor on pin 5; it's larger than the others.
There is a 1270 on pin 6.
The C4S kit has 499 ohm resistors and 150K 2-watt resistors - yes, a second set of the latter - it's easier than trying to re-use the old ones!
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Ok, so I got replacement resistors coming in the mail. That being said, is it possible that once the out of spec voltages are corrected that my issue of no second channel and scratchy left channel will be resolved?
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So far we have addressed one channel's driver, pins B4-5-6. There are probably similar problems with A4-5-6 - at least the wrong 1270 ohm resistor. I can't figure out why the plate voltage A6 is correct but the cathode A5 is not, so check and fix all those resistors and we'll see what problems remain.
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Ok, sounds good. Thanks again!
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Ok. Corrected placement of 1.27 resistors and installed 249ohm resistors. Went back through resistances and voltages out of spec and everything now within range. Left channel seems to be working properly. Output is clear and strong.
However, still no sound from right channel. Checked wiring at output transformers. Resoldered some connections at transformers and headphone jack but still nothing. Removed left channel from operation and turned volume all the way up and right channel has very dim, scratchy sound. Any guidance would be greatly appreciated.
Michael
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If the voltages on the tube pins are within the normal range, then the tubes are working correctly and the problem is at either the input or the output.
With gain all the way down, listen very closely (headphones are easier to hear with if you have some; otherwise put your ear right at the speaker, in a quiet room if necessary). If both channels produce the same tiny level of hiss and hum, then the problem is probably at the input or gain control. If you can hear some left channel but the right is completely silent, then it is at the output or the output transformers.
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Ok....slight hiss (wow this amp is quiet) in both speakers.
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Check your input jacks for a solder bridge from the center post to the outer shell.
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Yahooooooooooooo!!!!!! That did the trick!!!!!! I sured up the jacks with additional solder. Thank you so much for all your assistance and patience!!!
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Excellent! Enjoy!
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Ok, so after installing the C4S upgrade I have noticed that I am having the same problem again with the right channel...the sound output issue. Since I thought I rectified it last, I have not messed with the RCA connections but in completing the upgrade I disconnected the RCA cables and obviously reinstalled thereafter. I do get sound, but if I touch the cord connected to the jack, sound will drop and I have to manipulate the cord inserted into the right channel to obtain sound again. My wife's response to this is the obvious....leave it alone and stop messing with it. I had thought I rectified the issue by touching up the solder joint but apparently that did not completely cure the problem. Should I be troubleshooting elsewhere?
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Should I be troubleshooting elsewhere?
Nope, just confirm that the cable isn't the issue (switch channels at the SEX amp), then perhaps consider replacing the jack or checking for metal burrs that are making your short.
-PB
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Argh! It appears that I have a faulty jack. After resoldering the connection 2x and rewiring the jack after that didn't work, I inspected the jack comparing it to the other and I'm guessing that it is defective in that the base of the jack where the center pin protrudes...there is no seal around the pin. The working jack has a small white ring which what I think to be the defective jack is missing. Also, peering inside the connection port to where the RCA cable connects, doesn't look the same...looks perhaps corroded if that's possible. It also grabs the cable pretty tight whereas the working jack has a smooth insertion and release.
Michael
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So I got the replacement RCA jack today. Was sure this would be the fix but unfortunately it was not. Replaced jack and still no sound from right channel. I then replaced the whole wiring scheme from right input jack to volume pot and still...nothing.
Went through voltages and some values have changed. Those that are off are:
B1- 135.5
A5- upper terminal reads 2.117 while lower terminal reads 77.1
I am at a loss at this point. Having the same overall issue as before. Right channel, with volume all the way up, sound output is barely existent and scratchy. Can anyone help?
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If B1 is 135.5, then 19 should also be 135.5.
If 19 is not 135.5, but 0 instead, pull the 220 Ohm carbon comp from 19 to B1 and replace it with a piece of wire.
-PB
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There is only one B5 terminal. I guess you mean the upper and lower holes in the terminal? If they read different voltages, then something is not connected - i.e. not soldered well. Since the plate load resistor is soldered first, it's probably in the lower hole, and it reads 77 volts, within spec - it's probably OK. However, the coupling cap between stages (0.1uF) apparently reads near zero, indicating that it is not soldered well to the terminal. That would mean that it cannot carry signal to the second, power stage - hence low volume, no bass, and likely an intermittent (scratchy) contact.
If the terminal seems to have too much solder on it, remove the solder (either the wire braid stuff or a solder-sucker) and start over with clean parts. But if it looks short on solder, you can just make sure the wire AND the terminal are both hot enough to melt solder before removing the iron, by touching the solder to the terminal and again to the wire, melting a bit each time. The solder bits should then flow together and you'll have a nice joint.
Of course I may have mis-interpreted the post - words are a poor substitute for actually seeing the thing!
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Ok, I just switched unit back on to double check voltage. B1 was 135 and 19 was 150, then the 220ohm carbon comp connecting the terminals sizzled and fell apart.
Paul, I was referring to terminal A5 with the reading 2.117. B5 reading was 64.
As such, I am assuming I need to replace the 220ohm resistor and troubleshoot terminal A5 as per Paul's instructions.
Can anyone speculate how/why this is happening? I know this is a long thread but I am not understanding how I went from all voltages within spec with a proper functioning unit to this? The lingering issue has been the sound output from right channel so I guess the unit has not really been properly functioning per say. Paul, PB...can you please read through this thread and perhaps clue me in????
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The 220 Ohm carbon composition resistors are a little delicate. Replace the sizzled one with a piece of wire and let us know if that solves your problems.
-PB
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I replaced the 220 ohm resistor throughout. At B1 and 19 I got readings in the 60s before it blew again. Replaced with piece of wire and getting about the same readings.
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The LED at position D2 on the B side of the board went out too.
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Woah, pull the C4S boards and put the plate load resistors in. It's really important to have a working kit before installing the upgrade.
When you say "it blew", what blew? How did it blow?
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The 220 ohm resistor at B1 and 19. When I went to measure the voltage at b1 as soon as I touched te terminal with the red probe the terminal popped with electricity and the resistor blew.
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I'm kind of discouraged and really confused. The unit was working before i installed the upgrade and after. Voltages were withing range overall including those for the upgrade but clearly that right hannel issue remained an eventually got worse. But i have no clue why it now seems to be falling apart. I will pull the C4s board and replace the resistors that were removed to install the upgrade then repost.
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It sounds to me like a good evening to take off from working on the amp. Coming at it fresh will often give you a new perspective.
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Put a piece of wire in place of that 220 Ohm carbon composition resistor, then let us know about your voltages.
If the amp was working pre-C4S, then go ahead and leave that in.
-PB
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The wire is already in there as you previously suggested. Just to be clear I soldered in a piece of black hook up wire from B1 to 19 in place of the 220 resistor. The voltages I got in both terminals fluctuated in the 60s.
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Just for the sake of curiosity, remove the 0.1uf cap on that channel, then recheck the voltage at 19.
-PB
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After removing the .1uf cap from the circuit I checked the voltage at 19 and it rose steadily, slowing down a but at 200 but continued to rise until 251 at which time I pulled the lead of the meter off the terminal. Presumably it would have continued to rise.
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There are really two options here:
1. The 249K resistor is not connected or not working - measure it and really be sure it is properly soldered in place.
2. You have a badly defective tube and this problem will move to the other channel if you swap the tubes.
I'm pretty sure you've tried both of these, but I would triple check this. There should just be the wire leaving 19 and going to your tube socket, and the 249K resistor going to ground on that T-strip.
-PB
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Checked the resistance on the 249k and it reads well. Switched the placement of tubes and the issue went to the left channel. Voltage on pin 9 was steadily rising into the 300s. Voltage on pin 19 was fluctuating in the 26 range. So what next???
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Based on Paul's last post, it sounds like you've got a bad tube. Get a new one and you could be all set.
Best,
Adam
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You can contact Eileen to request a replacement.
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So when you swap tubes, you still get DC voltage at 19? Do you also get DC voltage at the same position on the other side of the amp?
-PB
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Yes. The voltage reading at 19 was fluctuating in the 26 range. With the red lead clipped onto terminal 19 it was reading 26 with the fluctuations in the tenth of a point...26.3, 26.8, 26.5 etc. Terminal 9 was giving me a steadily rising reading into the 300s.
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So, PB, what do you think?
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Set the tube that you believe to be the culprit to the side, try listening to each channel, shutting the amp off and moving the good tube between channels just to be sure this is the issue.
-PB
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So yes it was definitely a tube issue. I got a replacement tube, put it in and there was a firework show inside the replacement when I switched the amp on. My guess is that tube was bad as well. Luckily, I ordered a couple more replacements off eBay. I removed the C4S board and replaced the 150k resistors. Previously, one of the LEDs went out so I wanted to just kind of start fresh and deal with the C4S after I get the amp working properly. So now, 2 new tubes in there. Voltages have improved. Voltages that are off:
A1-36
9- rapidly fluctuates bet 45-52
B1-18
19-rapidly fluctuates bet 18-21
No sound from right channel. If I turn the gain all the way to the max, sound then kicks in at right channel
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Now is probably a very good time to post a photo of the socket wiring on the side having issues.
-Paul
(don't throw any new tubes in there until you post this photo, fireworks indicate a pretty serious problem)
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Both a and b sockets. Not sure if these pics will be good enough.
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It is very, very, very important that two bare leads which do not connect to the same terminal do not touch each other inside the amplifier.
In your first picture, I see several places where this is occurring.
I also see things like the STP going to tube socket pins 7/8 on the right side going up and over the 8.2K resistor. If that piece of STP pushes that resistor into the chassis plate, it will vaporize the resistor with a loud bang, and possibly damage the other components.
I would suggest going back to the manual and attempting to mimic what is shown in the manual as much as possible.
One short that I see in particular would cause fireworks inside the tube.
-PB
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Ok, understood. I am trying to tie this together in my head. So as of the last time I checked, I have voltages within range with the exception of A1, 9, B1 and 19 as indicated in my post on 6/19. Moreover, the issue of no sound in right channel unless I turn the gain to the max. Would this short you see be causing this?
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Well, I finally got it working!!! Voltages and resistances all check out. The right channel issue was apparently a short in the gain. I think the reason why I thought I previously fixed this issue earlier in the build was because I had the SEX acting as a power amp with the gain all the way up with a preamp connected. Since removing the preamp and notwithstanding the tube that went bad, the issue was there all along. I insured not components were touching and double checked the wiring...resoldered a few joint and still no sound from right channel unless gain was set to max. Playing with the gain, I pushed it past the max gently and this seems to have corrected the issue. Not sure how really but I am getting good sound across the continuum of the gain. I hope I am good to go now. PB, thanks so much for bearing with me and for all your advice.
Michael
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Hi all....so unfortunately I have to revive this thread. The sound from my right channel is dropping again. There seems to be a short somewhere and I am not certain how to address it. Again, the problem is rectified when I turn the gain all the way up to the max...sound form the effected channel re-appears and I can attentuate across the continuum yet after listening for extended periods, the sound will once again drop out after a period of time. Any advice? I am wondering if I could have a faulty volume pot? Is that possible?
Michael
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Try exercising the pot by rotating it through it's entire range 20 or 30 times and see if the problem goes away.
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Will do. Thanks.
Michael
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Try exercising the pot by rotating it through it's entire range 20 or 30 times and see if the problem goes away.
hummm....
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Try exercising the pot by rotating it through it's entire range 20 or 30 times and see if the problem goes away.
Ok, so I heeded this suggestion but it did not solve the issue. Again, when I turn the gain to max, sound will appear from right channel and will maintain across the continuum thereafter for an unspecified period of time. If I listen for several hours, at some point the sound drops again from right channel.
Moreover, after completing Reduction build and hooking that to SEX and turntable, no sound whatsoever from right channel. Even if I turn the gain to max on SEX, no sound appears. I hooked the Reduction up to another power amp in a separate system and it worked great so I think the problem persists with the SEX.
I am really at a loss. Paul mentioned earlier in the thread that if there is a tiny level of hiss/hum with the gain all the way down in both speakers that the problem should be at the input or gain control. I performed this test again and yes, with gain all the way down i do hear hiss in both channels...performed this with headphones as well to confirm. Any suggestions??
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Have you gone through and re-soldered every joint on the right side circuit? It kind of sounds like an intermittent connection that is happening when parts in the amp run for a while, warm up, expand and maybe a connection that looks good opens up.
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Yes, I did when I rewired the right circuit. I will go through it again though.....thanks.
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This sounds just like a bad solder joint. Do as Dan says and report back. You don't need to add a lot of solder, that just makes "solder blobs" which are bad joints. A tiny amount is fine.
Just heat each joint with the soldering iron on the tube pin or terminal and touching the component lead/wire. When it becomes liquid count to three and let it cool.
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Unfortunately I need to resurrect this thread. So after last post I went through and re-soldered every terminal and pin. It seemed to have fixed the issue but only for a time. Yesterday, I turned the amp on and again, no sound from right channel. If I turn the volume all the way up to max then I will get a very weak output from the right channel. Went through visual inspection again...and resistance/voltage checks. All resistances check out ok. All voltages check out ok except:
Terminal 9, 19: Fluctuating reading 4-6mV; Fluctuating reading 7-17mV...the readings just fluctuate back and forth variably between these two numbers for each terminal respectively
Pin A1, B1: Same issue as above: 6-8mV and 10-12 mV respectively.
Any ideas?
Mike
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Hello Michael,
Can you try connecting the two middle lugs on the pot?
When you do this, do you get both channels, same as before, or other?
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Ok, excuse my ignorance. How do I go about connecting the middle lugs?
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Temporarily solder the same piece of wire to each of them. (Or use a clip lead)
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After soldering the wire in connecting the middle lugs of the pot, I get sound from both channels. So what does this mean? Should I leave the wire in there and consider the problem rectified?
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By shorting the two decks of the pot together, you have made your amp mono. Not the worst thing in the world, but you probably want it to be in stereo.
The purpose of this exercise was to determine where your problem is, and you have now proven that both channels of your amplifier work, but one channel is not getting signal. You have a bad solder joint or a short somewhere earlier in the signal path, either at the pot, or the RCA jack. Check your RCA jack closely to see if there is any solder bridging the pin to the barrel. It is also possible that the problem is in your source or the interconnect cables, but I assume you've already checked for that by swapping cables.
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Nope, you have mono Left channel now. Next you want to remove the wire/jumper.
But you have located the problem to before the volume control. This means the connection at the pot from the left channel and at the RCA jack. Touch up those two solder connections. Verify continuity with your meter set on ohms from the metal on the RCA jack to the metal on the right side of the pot where the red wire comes in.
Or your source is not feeding both channels. There are very few possibilities.
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You may have also fried the carbon comp grid stopper resistor or have a bad tube socket.
-- Jim
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As above shorting the connection eliminated all that, all that is left is 12" of cable and two RCA jacks.
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My guess is maybe it's the cable because earlier on I thought it may be the jacks and I inserted new jacks which clearly did not correct the problem. So am I looking at the signal wire running from the right rca jack to the volume pot?
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After soldering the wire in connecting the middle lugs of the pot, I get sound from both channels. So what does this mean? Should I leave the wire in there and consider the problem rectified?
If you like listening in mono, you could indeed leave that wire there.
This suggests that you either have a bad connection from the center lug of the right jack to the outer lug of the pot for the right channel, or (more likely) you have excess solder shorting out the jack, or perhaps some metal-to-metal contact on the jack itself that can be cleared out.
When you look at the bottom of the right input jack, you should see the center post, then a ring of open space between that and the outer shell of the jack. Can you see any metal bits in there shorting things together?
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There really isn't an open space per say. If im looking correctly, there is the center post sitting in the ring. Within the ring appears to be a white piece of perhaps plastic. That is the left jack. The right jack has what appears to be burnt flux in that area where the center post is seated. Aside from that, I touched up the lugs on the pot and the right rca jack and I am now getting sound from the right channel. Do you think that flux residue can be causing the problem??
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Yeah, some residue could be an issue. Rubbing alcohol and q-tips would be your friend here.
On the bright side, you have whittled the problem down to only two components (level control and RCA jack), so the rest of the amp can be ignored.
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Although this is another topic, I re-installed the C4S board again last night. One LED does not light. However my voltages are within range at pins 10 and 20. The OA side voltage is 54 and OB side is 76. OA side has the blown LED. I think I have a blown transistor which I have identified. Question is why do I get good voltages at the terminals and when I listen I hear no audible problems in sound?
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If you swap the inputs and outputs of the board, do the voltages change?
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Would I accomplish the swap by reversing the wiring at terminals 10/20? Attaching the leads fro. 10 to 20 and vice versa? If not, how?
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Would I accomplish the swap by reversing the wiring at terminals 10/20? Attaching the leads fro. 10 to 20 and vice versa? If not, how?
I can't see how that would apply to either the C4S issue or the right channel not working.
The inputs/outputs on the C4S boards is the red and white twisted pair of wires that comes from IA/OA and IB/OB.
Is the right channel issue resolved?
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The right channel issue is resolved. My other question had nothing to do with the right channel. Was asking why my C4S board "appears" to be working even though one LED is not lit. I am getting correct voltages at terminals 10/20. You asked whether the voltages change if I swap the inputs/outputs of the board. I am not certain how to perform that action.
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Desolder the red/white pair from the tube sockets/terminal strips, then swap them (Left to right).
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C4S problem solved. Swapped out transistor and blown LED. Thanks everyone!