question on wiring blues jr tube board

[rsr]

I'm starting on replacing just the tube board (for now) in my blues jr, couple questions i want to verify...

1) the pictures showing the ribbon cable connections  http://el34world.com/Hoffman/images/Img_8722.jpg
don't appear to match the pin numbers shown in this image: http://el34world.com/Hoffman/images/Img_8860.jpg

The picture reads 678132, but appears in the picture to be connected to 123687, and also appears to be connected that way in the picture of the original PC board http://el34world.com/Hoffman/images/Img_8704.jpg.  I think the A/B sides are just swapped and maybe that's OK, so i could do it either way?  My inclination is to keep the ribbon cable connected to the same tube pins as the PC board, where there is a conflict.  Yes?

For v2, the picture looks like pins 1,2,3 are all jumpered together to the first ribbon cable strand. Right?

For v3, the image shows a jumper wire on the tube socket that goes from pins 3 to 8 (i think, hard to tell) and again it looks like the A and B sides are swapped or maybe just not right.  Looking at the both after picture and the original PC tube board, it looks like the ribbon cable should be connected like  x, 3-8, 2, 1, 7, 6
I don't see anything in the instructions about such a jumper. Am i missing something there?

Lastly, the wires that runs through pins 4, 5, and 9 and connects to the two lugs on power tube side of the board - these appear to connect to a couple of green wires coming off the PC board labeled WJ6 and WJ7.  Does it matter which of those goes to pins 4,5 and which to pins 9?   I can figure it out when i get the board out and can follow the traces better, but if it doesn't matter, then i won't have to bother.   

I may well do the full board replacement later, at which time i will have to add a couple resistors on the tube board as described.  Is that the only change on the tube board at that point, or do the tube socket connections need to change at that time?

Thanks for helping to clear this up for me.
roger

[rsr]

Well, i finished up the tube board replacement today. 

The only difficulty that i had, really, was as i described in the previous post - the ribbon cable / pin numbers noted don't seem to match up.  Could be that the pictures were for a newer or older blues jr than i have.  (mine is a cream board from early 2000s i think, which makes it a "blues jr 2", if they would have called it that then. The picture of the old PC tube board is identical to mine). 

It could be that the values in the instructions are equivalent and it would have been fine to use them, even though they don't match the original wiring, or what is shown in the pictures.  But i figured i couldn't go wrong by wiring it up exactly as it was before, regardless of what the instructions said, so that's what i did.  Which, for the record, that is like so:

v1:   1, 2, 3, 6, 8, 7
v2:   1-2-3, 8, 7, 6   
v3:   3-8, 3-8, 2, 1, 7, 6  (first two ribbons go to pin 3, which is jumper'd to pin 8)
v4:   3, 2, 9, 7
v5:   2, 9, 7, 3

I didn't do the bias pot change because i already have the billm bias pot installed. I also didn't replace the resistors on the main board as suggested, because i didn't end up taking the board out to work on it.

I'd still be curious to hear from anybody that can talk about the discrepancy, and comment on whether the instructions are correct, incorrect, or maybe represent some sort of improvement from the standard version, or whatever....

Finally, is this the right/best place to ask questions like this?  I got no responses to the initial question, so i went it alone (since i could follow the original connections)  But I'm pretty sure that when i get around to the main board replacement i'm going to have a couple questions.   I'm not real experienced with this sort of work and i'd be a lot more comfortable if i felt like there's help on the other end of the line when needed...

Thanks

roger

[sluckey]

the ribbon cable / pin numbers noted don't seem to match up.

The three 12Ax7s contain two identical triodes. Hoffman switched triodes. I don't know why but it makes no difference to the functionality of the circuit. Wiring the tube board as you did is correct and wiring it the way Hoffman did is also correct. I've attached a pic that shows your pin numbers in yellow and Hoffman's pin numbers in red.

and comment on whether the instructions

I clearly understood Hoffman's instructions, but then I've been doing this stuff for over 50 years. I can see where someone with little or no experience could get confused by the pin number changes, but still, if you just blindly follow the instructions I think you would end up with a working amp.

Finally, is this the right/best place to ask questions like this?

This is the right forum for this discussion. You're the first person I've seen that has only replaced the tube board. That's probably why you got no replies initially.

Something I've always done when removing many wires in an unfamiliar circuit... As soon as I unsolder a wire I put a temporary tape label on that wire. Makes reconnecting the wires a no brainer. I would have used labels for this project. Then you don't have to rely on someone else's instructions.

[rsr]

Thanks for the reply.

I figured it was probably equivalent, and yes, for a rookie like me it is difficult to know which differences are important and which aren't.

The reason i did just the tube board first was partly as a test, and on the off chance that it actually had resolved the problem with the amp, would not have affected the sound of it, which, as i said in another thread, is really really good, and so i'm not all that anxious to scrap it and start over.

But it didn't fix it and so i'll be doing the full replacement next. 

Thanks again,
roger

[sluckey]

I've seen several people do the Hoffman full conversion. When you start the project start a discussion. There will be lots of interest and people who have actually done the conversion will be able to answer questions if they pop up. And you will be able to totally get rid of those ribbon cables and use real wire. Do a forum search for BJ conversion and you will find several threads that may be of interest to you. Since you figured out the tube board wiring I bet you can do the complete conversion with little problems. Stay in touch... Steve