Ok, here’s a example for you right from the 1968 Fender Bassman I am working on right now in fact with it right in front of me.
This amp uses SS diodes so it’s just like your amp, but for a bit less ac voltage out of the secondary.
My ac input voltage across the red wires with the standby switch open ( and my standby switch is wired In such that it acts like having your .500. Fuse out or in ) is 664, the DC output which would be like your pin 8 is 358 volts.
With my standby switch closed and the amp now operational, I now have 654 VAC across the red wires, and 431 VDC feeding the amp.
I do not know how you are reading over 700 volts dc where you are on that socket on pin 8!
I don’t know how that copper cap works , but if with your standby switch closed you are indeed getting 433 vdc on on both outputs pin 3, and at least -52 , if not -55 as the schematic calls for on pins 5 then the amps output stage should be working as intended!
6H100 Build Issues
Moderators: pompeiisneaks, Colossal
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Stevem
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Re: 6H100 Build Issues
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
From the Weber website: WS1 8-pin Copper Cap. Diodes and Limiter only, No Sag. Vdrop: 1V max @ Imax: 1000ma
I also can't imagine how you can see 700v at pin 8. There should only be rectified DC voltage at pin 8. If input is 340-340, the maximum output would be (sqrt(2)*340)-1 = 480VDC. Maybe something is wrong with the copper cap?
I also can't imagine how you can see 700v at pin 8. There should only be rectified DC voltage at pin 8. If input is 340-340, the maximum output would be (sqrt(2)*340)-1 = 480VDC. Maybe something is wrong with the copper cap?
Re: 6H100 Build Issues
Is there an independent test i can do on the cap that would tell me if it is bad?Phil_S wrote: ↑Wed Mar 03, 2021 2:02 pm From the Weber website: WS1 8-pin Copper Cap. Diodes and Limiter only, No Sag. Vdrop: 1V max @ Imax: 1000ma
I also can't imagine how you can see 700v at pin 8. There should only be rectified DC voltage at pin 8. If input is 340-340, the maximum output would be (sqrt(2)*340)-1 = 480VDC. Maybe something is wrong with the copper cap?
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Stevem
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- Location: 1/3rd the way out one of the arms of the Milkyway.
1 others liked this
Re: 6H100 Build Issues
Ditch that darn thing already and wire in 6 1n1007 diodes like it was a simple Fender Bassman, bandmaster, twin reverb or duel showman power supply!
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
Have you checked the HT fuse isn’t blown?
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him!
Re: 6H100 Build Issues
Dude, I was wondering if I could. That's what all our previous builds were. The cap seemed new and exciting. Also, Can we just get a rectifier tube?
Re: 6H100 Build Issues
I set the bias to -55v and put the power tubes in and got readings. This is with the cap in, power tubes in, no preamp tubes, both power and standby on, and amp warmed up. The heaters are all still good.
Cap
4 - 381v (AC)
6 - 340v (AC)
8 - 336v (DC for the rest)
Both power tubes were the same
3 - 355v
4 - 336v
5 - -55v
B+
A - 335v
B - 336v
C - 335v
D - 332v
E - 330v
I also measured the voltage going into the preamp tubes. They are numbered from right to left (starting with the input tube)
Valve 1
1 - 326v
6 - 326v
Valve 2
1 - 329v
6 - 329v
Valve 3
1 - 326v
6 - 329v
Valve 4
1 - 332
6 - 332
What now?
Cap
4 - 381v (AC)
6 - 340v (AC)
8 - 336v (DC for the rest)
Both power tubes were the same
3 - 355v
4 - 336v
5 - -55v
B+
A - 335v
B - 336v
C - 335v
D - 332v
E - 330v
I also measured the voltage going into the preamp tubes. They are numbered from right to left (starting with the input tube)
Valve 1
1 - 326v
6 - 326v
Valve 2
1 - 329v
6 - 329v
Valve 3
1 - 326v
6 - 329v
Valve 4
1 - 332
6 - 332
What now?
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Stevem
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- Joined: Fri Jan 24, 2014 3:01 pm
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Re: 6H100 Build Issues
The problem may be that the copper cap is rated for 1000 ma which is 1 amp.
Your preamp tube voltages are meaningless without those tubes in there sockets!
Please at this point either normal diodes and see if the dc voltage on pins 4 and 6 get much more balanced out,
Please also do us and yourself a favor, untape those 2 red and white wires a check to see what those 2 read ac wise between each and ground.
Do those 2 wires read much closer to being balanced then the 2 red wires, or are they off by more then 5 volts also?
Your preamp tube voltages are meaningless without those tubes in there sockets!
Please at this point either normal diodes and see if the dc voltage on pins 4 and 6 get much more balanced out,
Please also do us and yourself a favor, untape those 2 red and white wires a check to see what those 2 read ac wise between each and ground.
Do those 2 wires read much closer to being balanced then the 2 red wires, or are they off by more then 5 volts also?
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
The two red wires were the same reading when I measured each to the red/yellow wire like instructed. They are only off when the rest of the components are connected. Someone posted that the red/yellow being grounded could through off the number. What will reading the red/white wires do? Also, am I ready to put preamp tubes in or is something else wrong?Stevem wrote: ↑Thu Mar 04, 2021 1:53 am The problem may be that the copper cap is rated for 1000 ma which is 1 amp.
Your preamp tube voltages are meaningless without those tubes in there sockets!
Please at this point either normal diodes and see if the dc voltage on pins 4 and 6 get much more balanced out,
Please also do us and yourself a favor, untape those 2 red and white wires a check to see what those 2 read ac wise between each and ground.
Do those 2 wires read much closer to being balanced then the 2 red wires, or are they off by more then 5 volts also?
Re: 6H100 Build Issues
These voltages are too low. Were you using a light bulb current limiter when you made these? If you do not have a light bulb current limiter, stop now and make one before going any further.
Note that the "ground" lugs on cap cans number one and number three are at high voltage (about 1/2 of B+). If any of these ground lugs touch the chassis, then "bad things" will happen. One of them might be voltages being too low. The other is you have 250 volts or so on your chassis. Check these two cap cans and make triple sure that the ground lugs (which again are at 1/2 the B+) are not touching the chassis.
I used a dremel rotaty tool on mine and enlarged the holes the cap cans were in and insulated these pins with shrink tubing. I suggest you also do something similar.
Don't use any tubes yet. You should have around 480V DC on the whole rail *without* any tubes. Since you do not, then I suspect there is a short to ground somewhere. Since your A and B nodes are too low, I think I'd look at those two cap cans very carefully.
And do not power it up without a limiter in place.
Mike
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Stevem
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- 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
Enough of this going in circles here gang!
If we go back to the 7th post at the start of this string about this amp, it' is posted that with all the HV secondary wires of the PT disconnected the readings are 457 vac from one red wire to ground and 79 vac from the other red wire to ground, ( and I would have to assume that the .500 amp fuse was good ) these voltages if still testing out the same means that the power transformer is at fault , period end of story!!!
Does anyone of greater knowledge here on this site disagree with my stated assessment above?
If we go back to the 7th post at the start of this string about this amp, it' is posted that with all the HV secondary wires of the PT disconnected the readings are 457 vac from one red wire to ground and 79 vac from the other red wire to ground, ( and I would have to assume that the .500 amp fuse was good ) these voltages if still testing out the same means that the power transformer is at fault , period end of story!!!
Does anyone of greater knowledge here on this site disagree with my stated assessment above?
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
Yes, there’s either a problem regarding the PT, the reservoir cap, or the return to 0V of the CT in the HT winding.
The imbalance and the test below indicates the latter to me.
The imbalance and the test below indicates the latter to me.
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him!
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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
I beg to different, because there's no way with every wire off of that recto socket that the first filter node will have any impact on anything going on here!
Just note that it takes a bare bones minimum of 480 VDC on the plates of those two output tubes at idle to make just 60 watts rms, no less 100 watts of clean power once you start to Crank the amp up!
The voltages that he reported back about previously with the output tubes in and just idling where starting to sag just under that amount current load, no less playing thru the amp!
In short, that copper cap needs to be tossed out and that PT needs to be sent back as its defective!
One sure fire unquestionable way to prove out if the PT is at fault or not and end all of this Head scratching and Beard pulling is to disconnecting every wire, both primary and secondary, then pump in 120 volts off the wall outlet in to one red wire and the red/ yellow wire and then read the vac you get out of the primary wires, it will be less then the 120 volts your pumping in.
Next do the same thing with the other red wire wire and I bet your two readings will be vastly different which will then prove out that the PT IS BAD!
From what I can figure out by my math is that if both sides of the secondary winding where indeed good you would be reading 26 VAC on those primary wires assuming that you where pumping in 120 VAC, it's about a 4.5 step down factor it would seem.
Just note that it takes a bare bones minimum of 480 VDC on the plates of those two output tubes at idle to make just 60 watts rms, no less 100 watts of clean power once you start to Crank the amp up!
The voltages that he reported back about previously with the output tubes in and just idling where starting to sag just under that amount current load, no less playing thru the amp!
In short, that copper cap needs to be tossed out and that PT needs to be sent back as its defective!
One sure fire unquestionable way to prove out if the PT is at fault or not and end all of this Head scratching and Beard pulling is to disconnecting every wire, both primary and secondary, then pump in 120 volts off the wall outlet in to one red wire and the red/ yellow wire and then read the vac you get out of the primary wires, it will be less then the 120 volts your pumping in.
Next do the same thing with the other red wire wire and I bet your two readings will be vastly different which will then prove out that the PT IS BAD!
From what I can figure out by my math is that if both sides of the secondary winding where indeed good you would be reading 26 VAC on those primary wires assuming that you where pumping in 120 VAC, it's about a 4.5 step down factor it would seem.
Last edited by Stevem on Thu Mar 04, 2021 1:19 pm, edited 2 times in total.
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
Consider that the reservoir cap is far more than just a ‘first filter’; rather it increases the VDC to the peak value of the rectified VAC.
Hence without an effective reservoir cap in circuit, the rectified VDC will be (a very ripply) 340V. Which is not far off what is being reported. With standby open, the reservoir cap is C4, 47nF.
When standby is closed, C18 and C19 should come into play, forming an effective reservoir cap of 110uF.
Note that the test result I quoted indicates that the HT winding is good, and so further testing of the PT, at this stage, seems pointless.
I suggest that the next steps should be the check the resistance between the chassis and the red/yellow CT wire from the PT. And to check that the reservoir caps C18 & 19 are good, and are properly connected.
Hence without an effective reservoir cap in circuit, the rectified VDC will be (a very ripply) 340V. Which is not far off what is being reported. With standby open, the reservoir cap is C4, 47nF.
When standby is closed, C18 and C19 should come into play, forming an effective reservoir cap of 110uF.
Note that the test result I quoted indicates that the HT winding is good, and so further testing of the PT, at this stage, seems pointless.
I suggest that the next steps should be the check the resistance between the chassis and the red/yellow CT wire from the PT. And to check that the reservoir caps C18 & 19 are good, and are properly connected.
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him!