[baronbeehive]

I heard putting your amp in a bathtub filled with water and turning it on helps.

 
 

 
Do you have to be in the bath at the same time ? 

 
After you!

 

[baronbeehive]

I noticed it looked like a lot of heatshrink had melted into one of the wire ends on the switch mod, but on closer look it is OK.
 
However .......... I think I've found the problem which probably arose with the rearrangement of the parts inside before putting the bottom back on, it was a bit of a tight squeeze! One of the WCF leads in circuit 2 was loose and came out of the hole along with the pad so I'm looking into how to fix it. Either push the wire right back into the hole and hope there is enough solder on both sides to hold it, or glue the pad back, or get the board out again to solder it properly on the other side and possibly fix wire across the hole as well.
 
Edit:
I've decided on what to do. I'm not going to glue it because I don't know what that will do to the board conductivity, I've going to try to solder it from the component side and hope enough solder runs through to the other side to hold it firm. I know from past experience that plenty of solder usually does go through the hole, so that might do it. If not I will have to get the board out again and run some wire past the hole, or get the engineer out to do a proper repair to the pad.

 

[baronbeehive]

Oh well, I've done that and the joint seems solid ..... but the 2 meters are still reading the same. Could it be the lack of a pad on the component side is still affecting it, or is it something else, I don't know. Maybe something on the reverse of the board?

 

[SonicTrance]

Which pad is loose? Where does the trace go? Check for continuity from the cap lead to where it's suppose to connect.

 

[baronbeehive]

Which pad is loose? Where does the trace go? Check for continuity from the cap lead to where it's suppose to connect.

 
Thanks Sonic! I've checked the trace and it is continuous with tube pin 2 which is where the trace goes so it seems to be alright.
 
I've turned my attention to the switch and here's a pic just to make sure it's OK, I'm sure it is but I may be missing something.
 

 
It would probably have been quicker to take a photo of the board!

 

[baronbeehive]

Oooops, I tested the amp after checking everything was in place as usual, but forgot I had been testing the switch and it was on the 421A setting so I quickly switched off and no harm done I think. I will check the resistors when it's cooled down but this is so easy to do - that's about the only time I left the switch in the 421A setting.
 
I did notice something interesting though, the right hand meter always reads half of the left hand meter reading, this time the right hand meter reads around 55mA and the left hand meter was off the scale at 100+mA. When the switch was in the 6AS7G setting the right hand meter reads 38mA and the left hand meter reads 70mA.
 
Is there any significance in this and is there any fault that you know of that would explain this?
 
I've thoroughly checked that circuit again and resoldered the cap connection which appeared faulty but the problem remains and I don't know what to do now other than take the back off again. I'm thinking of desoldering the switch but I don't see how it can possibly be wrong.

 

[SonicTrance]

  Oooops, I tested the amp after checking everything was in place as usual, but forgot I had been testing the switch and it was on the 421A setting so I quickly switched off and no harm done I think. I will check the resistors when it's cooled down but this is so easy to do - that's about the only time I left the switch in the 421A setting.
 
I did notice something interesting though, the right hand meter always reads half of the left hand meter reading, this time the right hand meter reads around 55mA and the left hand meter was off the scale at 100+mA. When the switch was in the 6AS7G setting the right hand meter reads 38mA and the left hand meter reads 70mA.
 
Is there any significance in this and is there any fault that you know of that would explain this?
 
I've thoroughly checked that circuit again and resoldered the cap connection which appeared faulty but the problem remains and I don't know what to do now other than take the back off again. I'm thinking of desoldering the switch but I don't see how it can possibly be wrong.

It just means the switch is working as it should. Lower cathode resistance suppose to give an increase in Ia, which is clearly did.
 
It's hard to give advice on this now other than to check every connection in the faulty channel and compare to the working channel.

 

[baronbeehive]

  It just means the switch is working as it should. Lower cathode resistance suppose to give an increase in Ia, which is clearly did.
 
It's hard to give advice on this now other than to check every connection in the faulty channel and compare to the working channel.

 
Yes, that's what I thought, at least my mistake showed the switch was working correctly! I've checked the resistors and no harm done.
 
This is baffling when all I've done since it was last working flawlessly is to solder the switch, apart from other minor things.

 

[SonicTrance]

Here're the schems drawn by MrCurwen. Some values, like anode, cathode resistors and coupling caps are not correct. But you'll get the idea. Study these easy to read schems and then check each and every corresponding connection in your amp. Might seem like a big job but you'll have a much greater understanding on how the amp works.


 

 

[Maxx134]

 
It just means the switch is working as it should. Lower cathode resistance suppose to give an increase in Ia, which is clearly did.

It's hard to give advice on this now other than to check every connection in the faulty channel and compare to the working channel.

Yes, that's what I thought, at least my mistake showed the switch was working correctly! I've checked the resistors and no harm done.

This is baffling when all I've done since it was last working flawlessly is to solder the switch, apart from other minor things.

The Meters correspond to the bias level which is what those voltage measurements that you measured .

Somehow your one tube not have correct voltages.

also,
just because the switch is functional doesn't mean it's wired it totally correctly ...

there's a lot of wires there,
And I thought you disconnected the switch....

you supposed to disconnect the switch ...

To remove any doubt from that area ,
You need to remove and then put the back if it's no difference ...

you're beating around the bush by not ruling the switch wiring out...

Think of one tube having both triode in series which is what a WCF circuit has...

You already narrowed it down to the tube and the triode section of the tube, by comparison to other tube voltages. .

 

[Maxx134]

Actually wire disconnection of just the tube in question should be all that necessary to find out (if wiring is culprit).

 

[baronbeehive]

The Meters correspond to the bias level which is what those voltage measurements that you measured .

Somehow your one tube not have correct voltages.

also,
just because the switch is functional doesn't mean it's wired it totally correctly ...

there's a lot of wires there,
And I thought you disconnected the switch....

you supposed to disconnect the switch ...

To remove any doubt from that area ,
You need to remove and then put the back if it's no difference ...

you're beating around the bush by not ruling the switch wiring out...

Think of one tube having both triode in series which is what a WCF circuit has...

You already narrowed it down to the tube and the triode section of the tube, by comparison to other tube voltages. .

 
OK. I've disconnected the switch, and we can rule out that as the problem because the 2 meters are still reading as they were.
 
I'm convinced that there isn't a problem with the circuit, the joints and wires are all good although I haven't thoroughly tested the whole circuit yet, so if it isn't that could it be something loose on the back of the board?
 
Edit: I've checked most of the resistors on that circuit and they seem to be good, ie they read what they say. I also tried taking resistance measurements at various points round the circuit but rapidly lost patience due to having to wait for the values to stabilize.

 

[coinmaster]

Bro just move to Connecticut in the USA and I got u covered. EZ fix.

 

[coinmaster]

I'm currently thru-hiking the AT so I haven't had time to read your problems but I'm chillin out today so I will offer some help.
From your previous post stating voltages, circuit 2 does not appear to be drawing much or any current.
Pin 1 should be showing around -20v. However it seems to be nearly at what the cathode voltage should be, assuming it is actually a negative and not a positive like you posted, but if it was a positive we would be seeing excess current rather than no current.
-65v on grid 1 would certainly cause the issue.

In either case the opamp is not capable of supplying 65v so check your grid connection for shorts.

 

[coinmaster]

I should probably have worded that better. Dont check the grid connection for shorts per se, check anything connected to pin 1 and see if you can find the source of the -65v. Also make sure that the opamp is functioning properly, test pin 6 on the opamp, find the little dot next to one of the pins on the opamp, that would be pin 1. Count the pins counter clockwise from there until you reach 6. Let me know the voltage.