5E3 Clone (HUM)Help

[Dmac252]

Does pulling out the preamp tube stop the hum

I will check this in the morning when I get back to the shop

Thanks

pulling V1 has no appreciable affect. Pulling V2 silience

[Phil_S]

While not 100% certain, if pulling V1 does nothing and pulling V2 kills the problem, you can look for the problem between V1 and V2.

All the ground connections between V1 and V2:
-Tone and Volume pots
-V2 cathodes
should be tied together at the same ground point.
I am thinking this is not the problem and wouldn't fiddle with this just yet. This sort of ground problem causes 120Hz hum.

You describe 60 Hz hum. I think you should have a close look at rewiring the heater connections at V2. Look: http://i35.tinypic.com/1675kkg.jpg

[Dmac252]

While not 100% certain, if pulling V1 does nothing and pulling V2 kills the problem, you can look for the problem between V1 and V2.

All the ground connections between V1 and V2:
-Tone and Volume pots
-V2 cathodes
should be tied together at the same ground point.
I am thinking this is not the problem and wouldn't fiddle with this just yet. This sort of ground problem causes 120Hz hum.

You describe 60 Hz hum. I think you should have a close look at rewiring the heater connections at V2. Look: http://i35.tinypic.com/1675kkg.jpg

Heating the iron now, Yea it should look like that can't cheat

Is 22awg good for heater power leads

[ToneMerc]

Is 22awg good for heater power leads

22 AWG is fine

TM

[Dmac252]

LATEST UPDATE

As you can see from the new photo I have rewired the heater power leads. and have tried to dress the turret leads to come straight down over the tube socket.

Hum remains:

I did find an open in the jumper on V! pin3 to pin 8. fixed that

now if I remove the 12AY7 in V1 the hum is almost, i say almost bearable. I have reflowed all the ground connections just for good measure.

[IMG:768:1024]http://i838.photobucket.com/albums/zz308/dmac252/Mobile%20Uploads/2014-09/0391CF1C-E94F-486D-8E9F-02E7F9603F87_zpsbh1fje4r.jpg[/img]

[cbass]

You have swapped tubes right ? Post your voltages on the tube pins

[Dmac252]

You have swapped tubes right ? Post your voltages on the tube pins

Tubes swapped

Voltages

V1

Pin 1- 107.4 vdc
Pin 3 - 1.84 vdc
Pin 4/5 - 3.19 vac
Pin 6 - 118.6 vdc
Pin 8 - 1.82 vdc
Pin 9 - 3.15 vac

V2
Pin 1- 148..4 vdc
Pin 3 - 1.16 vdc
Pin 4/5 - 3.18 vac
Pin 6 - 185.3 vdc
Pin 7 - 16.4 vdc
Pin 8 - 48.5 vdc
Pin 9 - 3.17 vac

V3
Pin 1-
Pin 2 - 3.18 vac
Pin 3 - 346 vdc
Pin 4- 316 vdc
Pin 5- .040 vac/ or .016 vdc don't know what it is supposed to be AC/DC
Pin 6 - SAME AS PIN 5
Pin 7 - 3.16 vac
Pin 8- 19.9 vdc

V4
Pin 1-
Pin 2 - 3.16 vac
Pin 3 - 339 vdc
Pin 4- 313.2 vdc
Pin 5- .075vac/ or .027vdc don't know what it is supposed to be AC/DC
Pin 6 - SAME AS PIN 5
Pin 7 - 3.12 vac
Pin 8- 19.81 vdc

V5
Pin 1-
Pin 2 - 354 vdc
Pin 3 -
Pin 4- 354 vac
Pin 5-
Pin 6 - 355 vac
Pin 7 -
Pin 8- 352 vdc

[cbass]

Are you getting any scratchiness on the volume tone controls or on the guitar volume?

[Dmac252]

Are you getting any scratchiness on the volume tone controls or on the guitar volume?

No scratchiness on the pots the hum increases and decreases smoothly. No issues with the guitar controls. There is no increase or decrease ln the hum just by inserting the guitar.

[Phil_S]

For starters, I think you have a bad rectifier. A 5Y3 should produce 1/2 VAC * 1.1 = VDC. In your case, 355VAC * 1.1 = 390VDC. You are reporting 352VDC at pin 8. I wonder if you've got more than one problem contributing.

Try swapping the rectifier. BTW, a Sovtek 5Y3 isn't really a 5Y3 and will output more DC voltage.

You say pulling V1 improves things. Does the hum go away completely if you pull both V1 and V2?

Your plate voltages are low all around by about 50+ volts. You should see around 185-200V on the first three triode sections, and about 230-245 on the phase inverter (2nd half of V2.)

Have you double checked the resistor values in the power supply? These should be 5K and 22K. Maybe someone made a mistake and is using 50K or 220K. Actually, I'd check all the resistors.

Nice looking job on the heater wiring!

[Dmac252]

For starters, I think you have a bad rectifier. A 5Y3 should produce 1/2 VAC * 1.1 = VDC. In your case, 355VAC * 1.1 = 390VDC. You are reporting 352VDC at pin 8. I wonder if you've got more than one problem contributing.

Try swapping the rectifier. BTW, a Sovtek 5Y3 isn't really a 5Y3 and will output more DC voltage.

You say pulling V1 improves things. Does the hum go away completely if you pull both V1 and V2?

Your plate voltages are low all around by about 50+ volts. You should see around 185-200V on the first three triode sections, and about 230-245 on the phase inverter (2nd half of V2.)


Have you double checked the resistor values in the power supply? These should be 5K and 22K. Maybe someone made a mistake and is using 50K or 220K. Actually, I'd check all the resistors.

Nice looking job on the heater wiring!

Thanks (2nd go round)

When I pull V1 as stated the hum is cut considerably, pulling V2 i have to put my ear in front of the speaker to tell that is is on.

I was wondering when we would get to the components. I was hoping to salvage the spare parts from the original beast but it looks like I may have to do at least some resister replacements. a lot of the bands are smudged off when I did the rebuild I simply went component by component removing and cleaning termination posts and putting the resisters/caps back where they were so in many cases it will be hard to identify. I will try reading across the resisters tomorrow to see what I see. I will probably just replace the power supply resisters though.

The rectifier is a new JJ 5Y3 I do have an NOS sylvania I can use

[beasleybodyshop]

For starters, I think you have a bad rectifier. A 5Y3 should produce 1/2 VAC * 1.1 = VDC. In your case, 355VAC * 1.1 = 390VDC. You are reporting 352VDC at pin 8. I wonder if you've got more than one problem contributing.

Try swapping the rectifier. BTW, a Sovtek 5Y3 isn't really a 5Y3 and will output more DC voltage.

You say pulling V1 improves things. Does the hum go away completely if you pull both V1 and V2?

Your plate voltages are low all around by about 50+ volts. You should see around 185-200V on the first three triode sections, and about 230-245 on the phase inverter (2nd half of V2.)


Have you double checked the resistor values in the power supply? These should be 5K and 22K. Maybe someone made a mistake and is using 50K or 220K. Actually, I'd check all the resistors.

Nice looking job on the heater wiring!

Thanks (2nd go round)

When I pull V1 as stated the hum is cut considerably, pulling V2 i have to put my ear in front of the speaker to tell that is is on.

I was wondering when we would get to the components. I was hoping to salvage the spare parts from the original beast but it looks like I may have to do at least some resister replacements. a lot of the bands are smudged off when I did the rebuild I simply went component by component removing and cleaning termination posts and putting the resisters/caps back where they were so in many cases it will be hard to identify. I will try reading across the resisters tomorrow to see what I see. I will probably just replace the power supply resisters though.

The rectifier is a new JJ 5Y3 I do have an NOS sylvania I can use

do you have an oscilloscope? you could connect it to the speaker terminals and physically see if you have 60hz hum. youtube 60 hz test tone and play it next to the amp, see if it sounds the same.

[Dmac252]

For starters, I think you have a bad rectifier. A 5Y3 should produce 1/2 VAC * 1.1 = VDC. In your case, 355VAC * 1.1 = 390VDC. You are reporting 352VDC at pin 8. I wonder if you've got more than one problem contributing.

Try swapping the rectifier. BTW, a Sovtek 5Y3 isn't really a 5Y3 and will output more DC voltage.

You say pulling V1 improves things. Does the hum go away completely if you pull both V1 and V2?

Your plate voltages are low all around by about 50+ volts. You should see around 185-200V on the first three triode sections, and about 230-245 on the phase inverter (2nd half of V2.)


Have you double checked the resistor values in the power supply? These should be 5K and 22K. Maybe someone made a mistake and is using 50K or 220K. Actually, I'd check all the resistors.

Nice looking job on the heater wiring!

Thanks (2nd go round)

When I pull V1 as stated the hum is cut considerably, pulling V2 i have to put my ear in front of the speaker to tell that is is on.

I was wondering when we would get to the components. I was hoping to salvage the spare parts from the original beast but it looks like I may have to do at least some resister replacements. a lot of the bands are smudged off when I did the rebuild I simply went component by component removing and cleaning termination posts and putting the resisters/caps back where they were so in many cases it will be hard to identify. I will try reading across the resisters tomorrow to see what I see. I will probably just replace the power supply resisters though.

The rectifier is a new JJ 5Y3 I do have an NOS sylvania I can use

do you have an oscilloscope? you could connect it to the speaker terminals and physically see if you have 60hz hum. youtube 60 hz test tone and play it next to the amp, see if it sounds the same.

no Oscilloscope. I'm a just a custom guitar builder


I checked the resister values on the entire board with Ohm meter and they look to be spot on or close

I recall when I first got the amp the first filter cap ( 16uf 475V ) was in reversed I am sure it was powered up several times in that condition before i got it. Just thought I would through that in, in case it points some where

Just a side not to all that have chimed in here,
THANKS SO MUCH FOR ALL THE PATIENCE & HELP

[cbass]

You didnt reuse that cap did you? If it got fired up backwards its toast

[Dmac252]

You didnt reuse that cap did you? If it got fired up backwards its toast

Yes i did reuse the caps. New caps on the way.. Actually i ordered all new parts except jacks and pots new fiber board as well just in case to replace the old turret board. I have a dealer relationship with mojo so not to costly. It will be worth it i think.