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**52 Bill** · 03-24-2015, 05:08 AM

Originally posted by trem View Post

But... both of the solder pads of R52 still read as a short to ground.

And does changing the setting of the volume pot change the reading at the junction of R9 and R52?

**Enzo** · 03-24-2015, 06:14 AM

That^^^^

A relay is just a switch. The contacts of K1a are either open or closed. When they are open, that opens the circuit through pot R6. When they close, that completes the circuit, putting R6 in parallel with R52. And under that condition as 52Bill suggests, if the volume control R6 is all the way down, you get zero ohms.

Less likely but possible, R6 is defective and internally shorted to its cover or frame. You could simply remove R6 and see if the short across R52 disappears. K1a completes the circuit through R6, but cannot make it shorted to ground at both ends unless the control is zeroed.

K1b is a different story, sorta. When it is closed, it bypasses cap C53 connecting R52 to the coax going into R85 and V1b. If that coax is shorted shield to conductor, you would have a grounded R52.

**trem** · 03-25-2015, 12:32 AM

Yeah...Sorry, I'm an idiot....was misreading (completely opposite) the way that Relay works. During the relay NC the circuit works just as the two of you describe.

My problem (or rather the amps problem) lies elsewhere.
Sorry About That.
Will be back when I find the real issue.
Thank You

**Enzo** · 03-25-2015, 01:35 AM

Not an idiot, now you know how that part works.

**Jazz P Bass** · 03-25-2015, 02:53 AM

Check the footswitch 'mute' circuit.

If that jfet failed, well.....

The gate should be seeing -16Vdc.

blues_deluxe-deville Mute circuit.pdf

**trem** · 03-25-2015, 02:58 AM

OK...so I followed my signal across C53 and R55.
It shows on the gird of V1-b, but not on the plate of V1-b.
I thought maybe the ribbon cable was broken, so I probed right on Pin #6 of V1-b and there is nothing.
I took a look at the parts for the tone stack...nothing "looks bad".....nothing seems to be shorted to ground.

I yanked the signal...so there is nothing going to the input jacks.
All the knobs are turned to Zero.

Pardon my ineptitude.....would seem I was not as thorough as I thought.
V1-a plate 245 VDC
V1-b plate 375 VDC

1-a Cat 2.0 VDC
1-b Cat 0.0 VDC

I tried a new tube and all stays the same.

The ribbon cable.
PW 1B and PW 1A have continuity, and then the Cat Resistor has continuity with the ribbon cable.
The cat resistor reads good. The cat resistor and by-pass cap are both hitting ground on one end.

R44 (510k) reads a short.

What have I got going on here.?
Thank You

**trem** · 03-25-2015, 02:59 AM

Originally posted by Jazz P Bass View Post

Check the footswitch 'mute' circuit.

If that jfet failed, well.....

The gate should be seeing -16Vdc.

[ATTACH]33342[/ATTACH]

OK.....will check that ASAP.
Thank You

**52 Bill** · 03-25-2015, 03:16 AM

Originally posted by trem View Post

R44 (510k) reads a short.

Not to sound like a broken record, but what happens when you turn up the volume control?

The obvious problem here is indicated by the plate and cathode readings for V1b, it is not conducting. If you have tried a different tube and have checked the ribbon cable and the cathode resistor is okay, then check the tube socket.

**trem** · 03-25-2015, 04:57 AM

Originally posted by 52 Bill View Post

Not to sound like a broken record, but what happens when you turn up the volume control?

The obvious problem here is indicated by the plate and cathode readings for V1b, it is not conducting. If you have tried a different tube and have checked the ribbon cable and the cathode resistor is okay, then check the tube socket.

Sorry...did not do that to you on purpose...just meant that it is a short with knobs at Zero.

It plays with the volume pot, just like the previous circuit.

Trying to get a meter and/or solder iron onto the socket board...see if there might be a bad/cold joint.....check continuity, etc.
Thanks

**Enzo** · 03-25-2015, 06:23 AM

Bill steered you right, if the plate voltage is real high and the cathode voltage is zero, then that side of the tube is not conducting. Also if the signal is on the grid and not on the plate, that also says the tube is not conducting. The grid and plate connectins through a ribbon are OK because the voltages are reaching the tube. Ii am unclear on your readings of the cathode. It isn't enough to measure the resistor and see that it is grounded and also checking the ribbon. The only test that matters is whether you measure 1.5k to ground from pin 8 of the socket. That tests the resistor and all the connections.

My guess? One side of the tube has a cold heater. You swapped tubes already, so I suspect the socket, as Bill suggested. On that tube, heater current feeds to pin 9 and pins 4 and 5. If the solder to pin 4 or 5 has failed or if the socket has a loose pin on 4 or 5, then that half of the tube won't light. With the amp running, look into the top of that tube. DO you see TWO little glowing heaters or just one?

**trem** · 03-25-2015, 06:11 PM

Yeah...weird.
Trying to be objective, because I KNOW there is an issue with V1, but.......it lit both Cats, but they are Not as bright as the other (same) JJ tubes.
I wiggled the tube (it is pretty loose in there) and the V1-b Cat went dark. Wiggled more, but I could not get the Cat to light again. V1-a stayed lit the whole time.
Turned amp off for a few seconds, and then back on...both Cats lit again.
1. I will try to re-tension the socket.
2. I have heard several times that JJ can have small diameter pins.?
Maybe try a New Sensor brand.
3. I think I will de-solder the heater pins, and re-solder with "normal" lead solder. Kester 60/40.....63/37...or something like that.
4. Report back to you guys.
Thank You

**trem** · 03-25-2015, 06:47 PM

Yeah...OK.....tube socket.
I re-tensioned it, and installed a Tung-Sol. It kind of sputtered...I wiggled the tube, and it came to life.
I never, really, liked the whole re-tension thing. I'm sure you guys have done it way than I have, but I always feel if the retainers are loose enough to cause problems, bending them back is a stop gap, temporary fix at best.
Seems like the better solution is to install a new socket.?
And yeah.....the pins on these JJ do not fit as tight as the New Sensor does.

On a side note.....sometimes I go a few months without having my hands in an amp. I really start to loose some of my Experience/Common Sense/Intuitive Judgement...etc etc.
So, I really appreciate your patience with what really was a "simple" problem.
Probably gets frustrating for you guys sometimes, when a guy can't step from A to B to C to D, without a lot of hand holding.
Again.....I Do Not take your time or help for granted.
Thank You

**Leo_Gnardo** · 03-25-2015, 07:10 PM

Originally posted by trem View Post

Seems like the better solution is to install a new socket.?
And yeah.....the pins on these JJ do not fit as tight as the New Sensor does.

On a side note.....sometimes I go a few months without having my hands in an amp. I really start to loose some of my Experience/Common Sense/Intuitive Judgement...etc etc.
So, I really appreciate your patience with what really was a "simple" problem.
Probably gets frustrating for you guys sometimes, when a guy can't step from A to B to C to D, without a lot of hand holding.
Again.....I Do Not take your time or help for granted.
Thank You

Yes a new tube socket would be a hit. When replacing the ones in modern Fenders I choose ceramic sockets. Not a fan of the Beltons that are now found everywhere.

Skinny pins on JJ OCTAL tubes was a problem 10-15 years ago. They fell right out of their sockets

but that's long since been solved. In 9-pin tubes I note some small differences in pin diameter, but never anything that's a deal breaker. (Would you can your Telefunkens because the pins are a little on the skinny side? I didn't think so.) JJ has their own set of QC problems, some tubes good, others not so much. Same can be said for China and Russia manufacturers. In fact I've recently noticed some Shuguang 6L6 and EL34 where the pins are too fat! Usually due to solder beads at the ends of the pins. Pain in the butt to have to file down pins to fit sockets. What happens when some non-tech person buys 'em? Do they hammer them in?

I see a lot of dogged-out preamp sockets lately because of the new hobby of tube-rolling. When the socket's beyond re-tensioning gotta replace it. Those who recommend tube-rolling always neglect to mention the down side.

+1 on losing touch when not working constantly on gear. Not just a tech thing. A former employer used to jam with Steve Morse who said "If I skip 2 days of practice, it's like starting all over again." Even the best have to keep their chops up.

**52 Bill** · 03-25-2015, 07:12 PM

Originally posted by trem View Post

Yeah...OK.....tube socket.
I re-tensioned it, and installed a Tung-Sol. It kind of sputtered...I wiggled the tube, and it came to life.
I never, really, liked the whole re-tension thing. I'm sure you guys have done it way than I have, but I always feel if the retainers are loose enough to cause problems, bending them back is a stop gap, temporary fix at best.
Seems like the better solution is to install a new socket.?
And yeah.....the pins on these JJ do not fit as tight as the New Sensor does.

What color are the sockets black or beige?

Did you check to see if the solder joints were okay on the pc board?

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