Newbie BootHill 5E3 build

[King Fan]

Test at the top of the 56k tail, may look more reasonable

Are you doing this? More generally, with that exception, are you using these voltages? Weber layout, but voltages by our own @Telenut62. I put 'em here for everyone's reference.

Output jacks can be a problem for sure. Also did you do the D'tar test on your input jacks?

 

[Supertzar]

The 1M grid leak will mess with most meters...
Test at the top of the 56k tail, may look more reasonable

Testing V2 P7 to chassis is 18.9 vDC at the 56k tail I see 17.8 vDC.

 

[andrewRneumann]

Here’s where I am at with my understanding.

With no AC signal applied on this circuit, there should be pure DC voltage on the grid and cathode of V2B. The cathode (P8) should be around 45Vdc and the grid (P7) should be around 43.5Vdc.

If the cathode is at 45Vdc and the grid is at 18Vdc then Vgk is -27Vdc and the tube is biased in cutoff. The 17V depicted on that diagram is most likely the AC voltage appearing there when 100mVac is applied at the input jack. This might be a crazy coincidence that the DC voltage happened to be near that target AC value.

I would be checking the cathode bias and tail resistors on V2B for correct resistance and solid connection.

 

[Supertzar]

Are you doing this? More generally, with that exception, are you using these voltages? Weber layout, but voltages by our own @Telenut62. I put 'em here for everyone's reference.

View attachment 913052

Output jacks can be a problem for sure. Also did you do the D'tar test on your input jacks?

View attachment 913064

Are you doing this? More generally, with that exception, are you using these voltages? Weber layout, but voltages by our own @Telenut62. I put 'em here for everyone's reference.

View attachment 913052

Output jacks can be a problem for sure. Also did you do the D'tar test on your input jacks?

View attachment 913064

I used the Boothill layout with the elevated CT that I found in another post this drawing from @Lowerleftcoast . I have been referencing those voltages against my mine.
I have done the D'tar test on my input jacks and they all checked out fine, so I thought but I didn't have that bottom section. I seem to have a problem with the Bright Low side tip to sleeve as I am only getting 68K not the 136K.

 

[Supertzar]

Here’s where I am at with my understanding.

With no AC signal applied on this circuit, there should be pure DC voltage on the grid and cathode of V2B. The cathode (P8) should be around 45Vdc and the grid (P7) should be around 43.5Vdc.

If the cathode is at 45Vdc and the grid is at 18Vdc then Vgk is -27Vdc and the tube is biased in cutoff. The 17V depicted on that diagram is most likely the AC voltage appearing there when 100mVac is applied at the input jack. This might be a crazy coincidence that the DC voltage happened to be near that target AC value.

I would be checking the cathode bias and tail resistors on V2B for correct resistance and solid connection.

I get 1.5K and 58K, nothing changes while chop-sticking around these.

 

[Supertzar]

I used the Boothill layout with the elevated CT that I found in another post this drawing from @Lowerleftcoast . I have been referencing those voltages against my mine.
I have done the D'tar test on my input jacks and they all checked out fine, so I thought but I didn't have that bottom section. I seem to have a problem with the Bright Low side tip to sleeve as I am only getting 68K not the 136K.

View attachment 913086

Actually both Low side Tip to Sleeve resistance are not correct. Bright Low is 68K and Normal Low is 1M.

 

[Lowerleftcoast]

Actually both Low side Tip to Sleeve resistance are not correct. Bright Low is 68K and Normal Low is 1M.

Are you plugging a cord in and measuring these values from tip to sleeve on the open end of the cord?

 

[Supertzar]

Yes I am. I got to poking around the jacks and got right readings so I need to look closer won't be tonight though.

 

[Telenut62]

Check your output jacks wiring.

 

[Supertzar]

Check your output jacks wiring.

View media item 47711
Looks right to me.

 

[King Fan]

On Monday I was trying to understand what you found on the 'D'tar test.’

I have done the D'tar test on my input jacks and they all checked out fine, so I thought but I didn't have that bottom section. I seem to have a problem with the Bright Low side tip to sleeve as I am only getting 68K not the 136K.

Actually both Low side Tip to Sleeve resistance are not correct. Bright Low is 68K and Normal Low is 1M.

Today, Friday, I’m still not sure. Can you clarify?

BTW, note the bottom table in my post doesn’t change anything in the top table; it just tries to spell out the details on a 4-hole amp like the 5e3. Both tables are saying the same thing.

 

[Supertzar]

On Monday I was trying to understand what you found on the 'D'tar test.’




Today, Friday, I’m still not sure. Can you clarify?

BTW, note the bottom table in my post doesn’t change anything in the top table; it just tries to spell out the details on a 4-hole amp like the 5e3. Both tables are saying the same thing.

Sorry been a rough week.
On the Bright side #2 low input my tip to sleeve was 68k instead of 136k. I did some poking around my wiring and got a good 136k reading. They all look good today.

 

[Supertzar]

Guys my build is really quiet in the hum department, actually sound s pretty good to this newbie, just isn't very loud. Volume goes up with the pots and tone is affected as I read it should. I can sit right in front of it and crank it and it doesn't bother me.

My input jacks test good consistently, continuity checks all check good, resistor values all good, voltages seem good.
One thing that I don't understand is when I check the output jacks is there is continuity to chassis from tip and sleeve even with speaker plugged in. Is this due to the OT circuit?

I appreciate all of your help so far.

 

[Lowerleftcoast]

One thing that I don't understand is when I check the output jacks is there is continuity to chassis from tip and sleeve even with speaker plugged in. Is this due to the OT circuit?

The secondary in the OT is just a coil of wire so there is very little resistance there. There is also the 8 Ohm speaker in parallel so even the small resistance of the OT secondary has a low ohmage coil in parallel.
And... when there is no speaker plugged in the jack switch makes a short to ground.

 

[Supertzar]

I was thinking that was the case. Still learning here. Just want to figure out the lack of volume. I've got an old Squier cheapie in the closet we bought for my daughter 10 years ago that's got more volume than this.

 

[King Fan]

So input and output jacks test right, voltages are (all??) fine, and the amp is still way too quiet? Things that helped me in a similar situation:

1. Do Doug Hoffman's hi-liter layout verification. Details here.
2. Do the hi-liter thing but with the schematic instead of the layout.

With both tests, the key thing is to see the build with fresh eyes. When these steps didn't work for me, it was because I was already seeing the wiring as right, even when it was wrong.​

3. While you have the schematic, do this simple, powerful (amp off) Steve Luckey test: "Use the schematic and an ohmmeter to verify that grid and cathode resistances measure expected values to ground and that plates are correctly connected to the proper B+ nodes.”

If no problems found, you might move on to active circuit tracing. Simplest (did you do this already) is the 'pop' test. Probing the grids of each tube from V1 on up should get louder and louder as you go.

To go one (much) better, an audio trace is pretty easy, as described by our super-smart friend @FenderLover : "...do you have another amplifier (you must)? Use it as a signal tracer and you can follow the signal through the schematic. Remove one plug from a guitar cable and solder a 0.1uF cap on the center lead. The other cap lead becomes your probe. Connect the cable shield to the PR chassis with an alligator clip. Plug the other end of the cable into your back-up amp with the volume as high as necessary and start to follow the input signal on your PR from stage to stage. Since you have sound, you will listen for when things start going south. With respectable volume settings on the PR, it should be clear as a bell as you follow it through."

Note: You can just probe the grids on each tube, ie, pins 2 and 7 in the preamp, pin 5 on the output tubes. Obviously the signal should get louder as you go toward the output. If it's nice and loud on the output tube grids, probe the tip lug on the speaker jack, which should also be loud.

You could also do a voltage trace, as described by our super-smart friend @elpico : "...using a steady AC test signal you can trace through things with the meter. You don't need anything fancy, the line out of a keyboard or computer you already own will be fine to generate a 1V signal. You can set the keyboard to make a sine wave then tape a key down, and on the computer you can download an mp3 of a test tone, or an app that generates tones for free. I just cut the cord off some broken headphones and put some flea clips on the ends."

Note: A way to expand this TP thing is to look at the *relative* voltages on the VAC test points (TPs) on a modern '57 Deluxe Schematic, available here. For instance, if you inject 100mVAC at a 'hi' input jack (TP12) you should get roughly 3.8VAC at TP13 and roughly 300mVAC at TP14. But see the details in their **note 6** on the schematic about voltages, esp. that these are done with all panel controls at 50% rotation.

But remember, as pointed out by elpico, these voltages are approximate, depending on your tubes and how close to 50% you can get your pots. Also, you don't have to inject exactly 100mVAC. For example, TP14 doesn't have to be 300mVAC, but it should be *roughly* 3X as big as TP12.

One more thing, especially if it turns out your trouble seems to lie between the output tubes and the speaker jack. He notes you can test the OT in reverse: "For example if you clip your test signal across the secondary of the output transformer you can verify that it sucessfully transforms that signal to the expected voltage on the primary (transformers aren't directional; they work just as well backwards as forwards)."

***But*** note his important warning doing this OT test: "Amp off, speaker disconnected." BTW, you'll see from the schematic that 1VAC clipped across the secondary should produce roughly 19VAC on the primary.

 

[SacDAve]

^ what King Fan. Myself not being the technical guy. I think something simple is going on maybe a missed ground or bad connection. The other thing I would on the jacks with nothing plugged in make sure the contacts are closed see if you can slide a piece paper between them then plug the cord in make sure they open. On one of my amps when I tightened the jack holding the solder lugs I messed up the contacts witch caused no sound anyway simple to physically check contacts worth trying.

 

[D'tar]

So input and output jacks test right, voltages are (all??) fine, and the amp is still way too quiet? Things that helped me in a similar situation:

1. Do Doug Hoffman's hi-liter layout verification. Details here.
2. Do the hi-liter thing but with the schematic instead of the layout.

With both tests, the key thing is to see the build with fresh eyes. When these steps didn't work for me, it was because I was already seeing the wiring as right, even when it was wrong.​

3. While you have the schematic, do this simple, powerful (amp off) Steve Luckey test: "Use the schematic and an ohmmeter to verify that grid and cathode resistances measure expected values to ground and that plates are correctly connected to the proper B+ nodes.”

If no problems found, you might move on to active circuit tracing. Simplest (did you do this already) is the 'pop' test. Probing the grids of each tube from V1 on up should get louder and louder as you go.

To go one (much) better, an audio trace is pretty easy, as described by our super-smart friend @FenderLover : "...do you have another amplifier (you must)? Use it as a signal tracer and you can follow the signal through the schematic. Remove one plug from a guitar cable and solder a 0.1uF cap on the center lead. The other cap lead becomes your probe. Connect the cable shield to the PR chassis with an alligator clip. Plug the other end of the cable into your back-up amp with the volume as high as necessary and start to follow the input signal on your PR from stage to stage. Since you have sound, you will listen for when things start going south. With respectable volume settings on the PR, it should be clear as a bell as you follow it through."

Note: You can just probe the grids on each tube, ie, pins 2 and 7 in the preamp, pin 5 on the output tubes. Obviously the signal should get louder as you go toward the output. If it's nice and loud on the output tube grids, probe the tip lug on the speaker jack, which should also be loud.

You could also do a voltage trace, as described by our super-smart friend @elpico : "...using a steady AC test signal you can trace through things with the meter. You don't need anything fancy, the line out of a keyboard or computer you already own will be fine to generate a 1V signal. You can set the keyboard to make a sine wave then tape a key down, and on the computer you can download an mp3 of a test tone, or an app that generates tones for free. I just cut the cord off some broken headphones and put some flea clips on the ends."

Note: A way to expand this TP thing is to look at the *relative* voltages on the VAC test points (TPs) on a modern '57 Deluxe Schematic, available here. For instance, if you inject 100mVAC at a 'hi' input jack (TP12) you should get roughly 3.8VAC at TP13 and roughly 300mVAC at TP14. But see the details in their **note 6** on the schematic about voltages, esp. that these are done with all panel controls at 50% rotation.

But remember, as pointed out by elpico, these voltages are approximate, depending on your tubes and how close to 50% you can get your pots. Also, you don't have to inject exactly 100mVAC. For example, TP14 doesn't have to be 300mVAC, but it should be *roughly* 3X as big as TP12.

One more thing, especially if it turns out your trouble seems to lie between the output tubes and the speaker jack. He notes you can test the OT in reverse: "For example if you clip your test signal across the secondary of the output transformer you can verify that it sucessfully transforms that signal to the expected voltage on the primary (transformers aren't directional; they work just as well backwards as forwards)."

***But*** note his important warning doing this OT test: "Amp off, speaker disconnected." BTW, you'll see from the schematic that 1VAC clipped across the secondary should produce roughly 19VAC on the primary.

HELLA POST @King Fan

That VAC tracing is excellent way to see the signal gain and isolate problem areas!
I would appreciate a higer res photo so we can see color bands. Maybe just my eyes but I can not see the 6v6 grid leak bands for example. measuring would verify their value ans as always dont be fooled by an order of magnatude. 25k vs 250k etc.

I had a simmilar issue on my build where I thought the output was pretty weak and wondered why everyone loved the 5e3 as there could be no way I made a mistake in the building process!LOL

If one were to mistakingly swap the tone cap and the bright cap you would end up with a neutered prize bull! Those ceramic disc are hard to pinpoint value without seeing the codes on them!

Here someone who shall remain nameless had made this error!

 

[King Fan]

Heh, @D'tar , my 'very quiet' amp had a *much* dumber mistake than that.

EDIT: BTW, supertzar, do the checks suggested by @SacDAve and @D'tar before you do mine. And then do my steps 1, 2, 3 before the active trace tests. Quoting Vince Lombardi: Staying sane isn’t everything, it's the only thing.

 

[SacDAve]

HELLA POST @King Fan

That VAC tracing is excellent way to see the signal gain and isolate problem areas!
I would appreciate a higer res photo so we can see color bands. Maybe just my eyes but I can not see the 6v6 grid leak bands for example. measuring would verify their value ans as always dont be fooled by an order of magnatude. 25k vs 250k etc.

I had a simmilar issue on my build where I thought the output was pretty weak and wondered why everyone loved the 5e3 as there could be no way I made a mistake in the building process!LOL

If one were to mistakingly swap the tone cap and the bright cap you would end up with a neutered prize bull! Those ceramic disc are hard to pinpoint value without seeing the codes on them!

View attachment 915348

Here someone who shall remain nameless had made this error!

View attachment 915350

I can't see the color bands either, better pics would help.