The Joyner boys are back with another build. This time it is the Weber 6H100 (Hiwatt clone). It is built and not working. The Sound out of it is not right. It is very quiet and thin and nastily distorted. The first thing I am looking into is the power. This build uses the Weber copper cap for the rectifier. The voltage at pin 4 it 391 and pin 6 is 339 (across the 2 is 681). The volts at pin 8 is is 94. That seems low to me based on other builds. Also, the volts at pin 3 on both KT88s are about 14 volts which I know is wrong. The bias voltage shows 0 on the meter. If I turn them all the way down I get a negative number. Below are the layout and schematic link and photos. Also, the schematic shows the 2 pin and the 8 pin on the copper cap jumpered but the layout does not. I cannot find any info on that thing. Thanks.
https://tedweber.com/media/kits/6h100_layout.jpg
https://tedweber.com/media/kits/6h100_schem.jpg
6H100 Build Issues
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6H100 Build Issues
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thetragichero
- Posts: 478
- Joined: Tue Sep 10, 2019 7:46 pm
Re: 6H100 Build Issues
until you're reading proper bias voltage on the grids i wouldn't put tubes in it
PRR wrote: Plotting loadlines is only for the truly desperate, or terminally bored.
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Stevem
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Re: 6H100 Build Issues
Is your 1/2 amp fuse good at the end of the PTs red and yellow wire?
And yes, don’t install any of the output tubes until you have at least a - 52 volts on pin 5 of each of the output tubes!
Those are expensive tubes to burn up, and in fact until you get things up and running and so you do you don’t burn up the OT or the KT88s I would change that .500 amp fuse to a .250 amp fuse!
The amp fitted with a .250 amp HT fuse should still be able to make 20 watts of output before going open on you.
I would disconnect the pin 8 wire from that recto and the recheck the ac voltage readings to ground from pins 4 and 6 again, they should be the same 390 vac.
If not then your power transformer has a issue, or one end of that secondary winding was made with a wrong color code , or somethings up with that copper cap.
Once you get the V+ voltage in the ball park and before you stuff the output tubes back in be sure to set the bias voltage on each pin 5 to the highest negative voltage available from the bias pots.
At a minimum since this is looking like a 100 watt amp I would like to see no less then a - 34 volts of bias on each pin 5!
I also think that with this kit you have a build a little above your skill level as in your photos I see your using electrical tape instead of shrink tubing to insulate off unused wires.
This not the way to build even a 5 watt amp, no less a 100 watt amp with expensive transformers and output tubes!
And yes, don’t install any of the output tubes until you have at least a - 52 volts on pin 5 of each of the output tubes!
Those are expensive tubes to burn up, and in fact until you get things up and running and so you do you don’t burn up the OT or the KT88s I would change that .500 amp fuse to a .250 amp fuse!
The amp fitted with a .250 amp HT fuse should still be able to make 20 watts of output before going open on you.
I would disconnect the pin 8 wire from that recto and the recheck the ac voltage readings to ground from pins 4 and 6 again, they should be the same 390 vac.
If not then your power transformer has a issue, or one end of that secondary winding was made with a wrong color code , or somethings up with that copper cap.
Once you get the V+ voltage in the ball park and before you stuff the output tubes back in be sure to set the bias voltage on each pin 5 to the highest negative voltage available from the bias pots.
At a minimum since this is looking like a 100 watt amp I would like to see no less then a - 34 volts of bias on each pin 5!
I also think that with this kit you have a build a little above your skill level as in your photos I see your using electrical tape instead of shrink tubing to insulate off unused wires.
This not the way to build even a 5 watt amp, no less a 100 watt amp with expensive transformers and output tubes!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 6H100 Build Issues
Sort out power supply issues before you attempt to sort out the problems with the circuit. As suggested, start by pulling all the tubes and the copper cap.
You should have the same voltage at pins 4 and 6 without the copper cap or a tube rectifier. If that checks out, plug in the copper cap and check voltage again. If you still see the unbalanced voltage there might be a few different things causing the problem. Let's hold that for a little while.
Start by seeing the unloaded, no copper cap voltage at pins 4 and 6. Then plug in the copper cap and post voltages for takeoff points A-E.
While you are at it, check the bias voltages. The bias voltage is derived from pin 6 of the rectifier. I am suspecting the rectifier circuit is causing the problem at pin 6. What is the AC voltage at D1 without the copper cap and with the copper cap plugged in? Without the copper cap plugged in what is the maximum negative DC voltage you can generate at takeoff points F and G? Then, with the copper cap plugged in, what is the maximum negative DC voltage at points F and G?
Remember, no tubes plugged into the amp for any of this. Stop here. Post results. Let's see if there is any useful info.
You should have the same voltage at pins 4 and 6 without the copper cap or a tube rectifier. If that checks out, plug in the copper cap and check voltage again. If you still see the unbalanced voltage there might be a few different things causing the problem. Let's hold that for a little while.
Start by seeing the unloaded, no copper cap voltage at pins 4 and 6. Then plug in the copper cap and post voltages for takeoff points A-E.
While you are at it, check the bias voltages. The bias voltage is derived from pin 6 of the rectifier. I am suspecting the rectifier circuit is causing the problem at pin 6. What is the AC voltage at D1 without the copper cap and with the copper cap plugged in? Without the copper cap plugged in what is the maximum negative DC voltage you can generate at takeoff points F and G? Then, with the copper cap plugged in, what is the maximum negative DC voltage at points F and G?
Remember, no tubes plugged into the amp for any of this. Stop here. Post results. Let's see if there is any useful info.
Re: 6H100 Build Issues
Man, great stuff. We will get on that this weekend. It is not our first build but we are definitely still learning. Thanks.
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Stevem
- Posts: 5144
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- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: 6H100 Build Issues
I know that it’s temping to use tape in tight spots instead of shrink tubing, but I just touch the shank of the soldering iron on the tubing to heat and shrink it.
I like to fold the end of a cut wire over by a bit more then 1/4” then apply the tubing and shrink it? In use this way it will not slip off all on its own!
I like to fold the end of a cut wire over by a bit more then 1/4” then apply the tubing and shrink it? In use this way it will not slip off all on its own!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 6H100 Build Issues
All right, this is what we did/got.
We removed all tube so everything past this point will sans tubes. We measured the volts on both red wires from the PT not connected to anything. They were not the same. 452v and 79v. However, the volts between the 2 wires was 686v which the diagram of the PT that we got says 700v so that seems right. We then hooked the red wires back up and measured the volts without the copper cap (CC) installed. Post 4 was 248v and post 6 was 422v. We then installed the CC and got 248v on 4 and 419v on 6. We got 700v on post 8.
We then measured the power tube sockets (sans tubes). They were both the same. Post 3 was 433 and post 4 was 433. Post 5 ranged from -0 to -59 depending on the bias adjustment. These numbers seem right as well but the only difference was the lack of tubes.
The heaters were 3.38v to ground and 6.77v across each other on all tubes.
Where do I go from here? Why am I getting different readings on each red wire but they are correct across the 2. If post 4 and 6 on the CC are different then which do I connect the bias power to?
We removed all tube so everything past this point will sans tubes. We measured the volts on both red wires from the PT not connected to anything. They were not the same. 452v and 79v. However, the volts between the 2 wires was 686v which the diagram of the PT that we got says 700v so that seems right. We then hooked the red wires back up and measured the volts without the copper cap (CC) installed. Post 4 was 248v and post 6 was 422v. We then installed the CC and got 248v on 4 and 419v on 6. We got 700v on post 8.
We then measured the power tube sockets (sans tubes). They were both the same. Post 3 was 433 and post 4 was 433. Post 5 ranged from -0 to -59 depending on the bias adjustment. These numbers seem right as well but the only difference was the lack of tubes.
The heaters were 3.38v to ground and 6.77v across each other on all tubes.
Where do I go from here? Why am I getting different readings on each red wire but they are correct across the 2. If post 4 and 6 on the CC are different then which do I connect the bias power to?
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: 6H100 Build Issues
The voltage between either red wires and the red yellow wire when unloaded should be within 5 volts of each other, if not then the power trans is bad or its color coded secondary leads where install wrong when the thing was made.
While your working on it if you want a very long lived standby switch that does not produce pops when you use it then rewire it into that red and yellow wire and just run th V+ voltage right straight thru to the first power supply node.
While your working on it if you want a very long lived standby switch that does not produce pops when you use it then rewire it into that red and yellow wire and just run th V+ voltage right straight thru to the first power supply node.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 6H100 Build Issues
I suggest we concentrate on the power transformer high voltage secondary, which is giving the appearance of a problem. I am not convinced it is bad just yet, though I agree (FWIW) with Stevem's general assessment.
You state that you "measured the volts on both red wires from the PT not connected to anything." (I don't believe you measured correctly.) You report 452VAC and 79VAC. That sort of unbalanced reading can only be right if the PT is bad and I don't believe it is. The total is 531VAC and that seems about right. If the red/yellow center tap wire is still grounded to the chassis, your measurement might be affected by that. There is no need to desolder the red wires from pins 4 and 6 of the copper cap socket. When you remove the copper cap, those connections are isolated. Remove the red/yellow center tap from the chassis ground and insulate it. (Tape is OK for temporary insulation, but not for anything permanent.) Remove the copper cap. Clip your meter leads (set for AC voltage) to pins 4 and 6 of the copper cap socket. Turn the power on. Record the reading and tell us what it was. Power off.
Then, very carefully, remove the tape from the red/yellow center tap. The CT will be floating in the air, so make sure it doesn't contact anything. Clip one meter lead to the CT and the other to pin 4 of the copper cap socket. Power on and record and report the AC voltage. Power off.
Move the meter lead from pin 4 to pin 6 on the copper cap socket. Leave the other meter lead on the floating red/yellow CT wire. Power on and record and report the AC voltage. Power off.
Both red wire readings should be about the same. If 531VAC was an accurate reading, then we are looking for about 265VAC on each half. If you don't get this, I'm inclined to suspect same as Stevem, either the color coded wire leads are not attached correctly or the PT is bad. If you didn't get approximately equal readings, stop here and post what you found. If readings are about 265VAC on both red wires, continue below.
Ground the red/yellow CT on the chassis. (I am guessing you are using a ring lug that goes over a bolt, as it takes a lot of heat to solder a wire directly to a chassis. Also, if the chassis is aluminum, you would not be soldering directly to the chassis.) Insert the copper cap. Make sure all tubes are removed. Clip your meter leads to pins 4 and 6 of the copper cap socket. Confirm you still see about 531VAC across these two pins. Power off. If not close to this, stop here and report what your reading. If about 531VAC continue.
Set the meter for DCV. Clip the red lead to pin 8 of the copper cap socket and the black lead to chassis ground. Power on and record your DCV reading. Report here. That is all. Stop and allow us to assess what you report.
If you think you've already done all of this, please humor me and do it again. I have some suspicions about the problem. I'd like to be proven wrong.
You state that you "measured the volts on both red wires from the PT not connected to anything." (I don't believe you measured correctly.) You report 452VAC and 79VAC. That sort of unbalanced reading can only be right if the PT is bad and I don't believe it is. The total is 531VAC and that seems about right. If the red/yellow center tap wire is still grounded to the chassis, your measurement might be affected by that. There is no need to desolder the red wires from pins 4 and 6 of the copper cap socket. When you remove the copper cap, those connections are isolated. Remove the red/yellow center tap from the chassis ground and insulate it. (Tape is OK for temporary insulation, but not for anything permanent.) Remove the copper cap. Clip your meter leads (set for AC voltage) to pins 4 and 6 of the copper cap socket. Turn the power on. Record the reading and tell us what it was. Power off.
Then, very carefully, remove the tape from the red/yellow center tap. The CT will be floating in the air, so make sure it doesn't contact anything. Clip one meter lead to the CT and the other to pin 4 of the copper cap socket. Power on and record and report the AC voltage. Power off.
Move the meter lead from pin 4 to pin 6 on the copper cap socket. Leave the other meter lead on the floating red/yellow CT wire. Power on and record and report the AC voltage. Power off.
Both red wire readings should be about the same. If 531VAC was an accurate reading, then we are looking for about 265VAC on each half. If you don't get this, I'm inclined to suspect same as Stevem, either the color coded wire leads are not attached correctly or the PT is bad. If you didn't get approximately equal readings, stop here and post what you found. If readings are about 265VAC on both red wires, continue below.
Ground the red/yellow CT on the chassis. (I am guessing you are using a ring lug that goes over a bolt, as it takes a lot of heat to solder a wire directly to a chassis. Also, if the chassis is aluminum, you would not be soldering directly to the chassis.) Insert the copper cap. Make sure all tubes are removed. Clip your meter leads to pins 4 and 6 of the copper cap socket. Confirm you still see about 531VAC across these two pins. Power off. If not close to this, stop here and report what your reading. If about 531VAC continue.
Set the meter for DCV. Clip the red lead to pin 8 of the copper cap socket and the black lead to chassis ground. Power on and record your DCV reading. Report here. That is all. Stop and allow us to assess what you report.
If you think you've already done all of this, please humor me and do it again. I have some suspicions about the problem. I'd like to be proven wrong.
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: 6H100 Build Issues
There is no need to unsolder or unhook that red/ yellow wire to do these requested test, just pull the .500 amp fuse out, then if you do the test and the voltage readings change from what you last posted (assuming they where done right) that then confirms a bad PT!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 6H100 Build Issues
This is what I did. I removed the B+ fuse as to disconnect the red/yellow wire from ground. I removed the copper cap. I clipped a lead to the red/yellow wire and checked the reading on post 4 and 6. Both were 340v. Then I measured the volts between 4 and 6 and got 680v. I replaced the fuse and inserted the copper cap. I rechecked between 4 and 6 and got 685v. I switched to DC then checked post 8 and got 706v.
What is next?
What is next?
Re: 6H100 Build Issues
I would check that again. The theoretical maximum DC you can get from that 340-0-340 PT is 480Vdc. What meter are you using?I switched to DC then checked post 8 and got 706v.
Re: 6H100 Build Issues
Yep, that’s correct. I have 2 meters (Kaiweets TRMS 6000 and Innova 3320) and they both read the same. That is with the standby off. I turned it on and after a 10 minute warmup post 8 read 433v but was still very slowly climbing.
Re: 6H100 Build Issues
340VAC per side and 680VAC total suggests there is nothing wrong with the PT. If this was mine, I'd stop looking there.
I'm not familiar with the operation of the copper cap. It seems odd that it isn't putting out full B+ after 10 minutes with the standby open (off.) According to Weber's website, the WS1 is a solid state diode rectifier and isn't intended to emulate a rectifier tube. If that's the case, I'd guess output should be about 1.4x 340 or about 475VDC, so what you see is low. I wonder if there is something wrong with the copper cap. You won't get a "true" reading without putting in the tubes.
(I see in your original post, you say the schematic shows pins 2 and 8 of the copper cap are jumpered. That is not a correct reading of the schematic. The schematic shows the 2-8 internal configuration of a rectifier cathode. Follow the layout drawing for that.)
At this point, I think I'd be wanting to put the power tubes in their sockets and take voltage readings. I'm not sure what bias voltage should be for this amp. Go with Stevem's recommendation of -52V or colder (more negative.) Then, insert the power tubes. Turn on the power and close (on position) the standby switch. Record and report voltage readings on both tubes, all pins, but you can omit the heaters, pins 2 and 7. You've already posted that heater voltage looks OK. While the power is on, take voltage readings at points A to E and post those too.
I'm not familiar with the operation of the copper cap. It seems odd that it isn't putting out full B+ after 10 minutes with the standby open (off.) According to Weber's website, the WS1 is a solid state diode rectifier and isn't intended to emulate a rectifier tube. If that's the case, I'd guess output should be about 1.4x 340 or about 475VDC, so what you see is low. I wonder if there is something wrong with the copper cap. You won't get a "true" reading without putting in the tubes.
(I see in your original post, you say the schematic shows pins 2 and 8 of the copper cap are jumpered. That is not a correct reading of the schematic. The schematic shows the 2-8 internal configuration of a rectifier cathode. Follow the layout drawing for that.)
At this point, I think I'd be wanting to put the power tubes in their sockets and take voltage readings. I'm not sure what bias voltage should be for this amp. Go with Stevem's recommendation of -52V or colder (more negative.) Then, insert the power tubes. Turn on the power and close (on position) the standby switch. Record and report voltage readings on both tubes, all pins, but you can omit the heaters, pins 2 and 7. You've already posted that heater voltage looks OK. While the power is on, take voltage readings at points A to E and post those too.
Re: 6H100 Build Issues
To be clear, when the standby is off (as in the amp would not make a noise if it worked properly) post 8 was 706v. It wasn’t until I turned standby on (as in amp would make a sound) and let it warm up did it hit 433v.