Weird Heater Supply Problem - And other solutions!
Moderator: VelvetGeorge
-
- Senior Member
- Posts: 200
- Joined: Fri Dec 06, 2013 9:27 am
- Just the numbers in order: 13492
- Location: United Kingdom
Re: Weird Heater Supply Problem - And other solutions!
I don't think swapping the primaries would have hurt. In fact it shouldn't have made any difference.
Have the heater secondaries got a centre tap? Or are you using resistors to create ground reference?
Have the heater secondaries got a centre tap? Or are you using resistors to create ground reference?
-
- Senior Member
- Posts: 169
- Joined: Wed Jun 10, 2015 1:58 pm
- Just the numbers in order: 13492
- Location: Oceanslime, CA
Re: Weird Heater Supply Problem - And other solutions!
Yeah, I would think it wouldn't damage the PT but, I figured I would mention it.
The heaters do not have a center tap. So I had to create one with 100 ohm jobbers to ground. I will recheck all of my wiring and pull it off the tube sockets and test for the correct voltage.
The heaters do not have a center tap. So I had to create one with 100 ohm jobbers to ground. I will recheck all of my wiring and pull it off the tube sockets and test for the correct voltage.
-
- Senior Member
- Posts: 200
- Joined: Fri Dec 06, 2013 9:27 am
- Just the numbers in order: 13492
- Location: United Kingdom
Re: Weird Heater Supply Problem - And other solutions!
Yeah double check the 100ohm resistors. Do you read 6.3V if you put your meter leads across the secondaries rather than from one side to ground?
Do they read the same without valves?
Do they read the same without valves?
-
- Senior Member
- Posts: 169
- Joined: Wed Jun 10, 2015 1:58 pm
- Just the numbers in order: 13492
- Location: Oceanslime, CA
Re: Weird Heater Supply Problem - And other solutions!
The resistors are good. I just double checked and I get 6.5 vac across the secondaries. Then I test from one side to ground and I get 2.7 vac and 3.8 vac on the other.Littlewyan wrote: ↑Wed Oct 18, 2017 6:51 pmYeah double check the 100ohm resistors. Do you read 6.3V if you put your meter leads across the secondaries rather than from one side to ground?
Do they read the same without valves?
This is with the secondary artificially center tapped but not wired to the sockets.
Strange!
- neikeel
- Senior Member
- Posts: 7231
- Joined: Tue Dec 06, 2005 8:31 am
- Location: Suffolk, England
-
- Senior Member
- Posts: 200
- Joined: Fri Dec 06, 2013 9:27 am
- Just the numbers in order: 13492
- Location: United Kingdom
Re: Weird Heater Supply Problem - And other solutions!
It is weird but personally I wouldn't be overly concerned about it. As long as it doesn't go higher than 6.5VAC. Have you tried different meter settings? Like voltage limits just in case it's reading a bit funny?
And yeah what neikeel asked.
I'm actually in the process of tweaking my Marshall Master Volume 20W amp at the moment so will be interesting to see what you do with your amp
And yeah what neikeel asked.
I'm actually in the process of tweaking my Marshall Master Volume 20W amp at the moment so will be interesting to see what you do with your amp
-
- Senior Member
- Posts: 169
- Joined: Wed Jun 10, 2015 1:58 pm
- Just the numbers in order: 13492
- Location: Oceanslime, CA
Re: Weird Heater Supply Problem - And other solutions!
The HT is fine. What I don't understand is why the imbalance exists now when it didn't before I fired up the amp.
- neikeel
- Senior Member
- Posts: 7231
- Joined: Tue Dec 06, 2005 8:31 am
- Location: Suffolk, England
Re: Weird Heater Supply Problem - And other solutions!
As long as your heaters are 6.3vac +/-10% you will be fine with your virtual centre tap.
Are you getting around 490v dc after the rectifier now?
Are you getting around 490v dc after the rectifier now?
Neil
-
- Senior Member
- Posts: 169
- Joined: Wed Jun 10, 2015 1:58 pm
- Just the numbers in order: 13492
- Location: Oceanslime, CA
Re: Weird Heater Supply Problem - And other solutions!
I guess I figure it would be bad to have one side of the tube's heaters getting 2.7vac and the other 3.8vac. I am getting 535vdc after rectification.
-
- Senior Member
- Posts: 200
- Joined: Fri Dec 06, 2013 9:27 am
- Just the numbers in order: 13492
- Location: United Kingdom
Re: Weird Heater Supply Problem - And other solutions!
Yeah I see what you're saying about the heater voltage. Isn't the heater circuit often out of balance anyway? When people install those humdinger pots to get rid of hum, aren't they adjusting the balance of the heater voltage?
- neikeel
- Senior Member
- Posts: 7231
- Joined: Tue Dec 06, 2005 8:31 am
- Location: Suffolk, England
Re: Weird Heater Supply Problem - And other solutions!
The heaters will get the 6.3vac between the pins as long as you have the centre tap arrangement you describe, the imbalance has effectively been taken out by joining them with the 100Rs so you can forget that.
535 is a bit high for EL34s but most will cope, make sure you have at least 1k on the screens of each socket. It may drop lower when the tubes are in, drawing juice and biased up properly.
535 is a bit high for EL34s but most will cope, make sure you have at least 1k on the screens of each socket. It may drop lower when the tubes are in, drawing juice and biased up properly.
Neil
-
- Senior Member
- Posts: 169
- Joined: Wed Jun 10, 2015 1:58 pm
- Just the numbers in order: 13492
- Location: Oceanslime, CA
Re: Weird Heater Supply Problem - And other solutions!
Alright! The amp is up and running. I am surprised how dark the amp is and it has tons of low end. I am running 6L6s so I think that's a lot of it.
I tried installing the bright cap but it didn't make a lick of difference.
I tried installing the bright cap but it didn't make a lick of difference.
-
- Senior Member
- Posts: 200
- Joined: Fri Dec 06, 2013 9:27 am
- Just the numbers in order: 13492
- Location: United Kingdom
Re: Weird Heater Supply Problem - And other solutions!
Great! You sure it's dark? Mine takes my head off!!! Completely stock 2203 preamp?
-
- Senior Member
- Posts: 169
- Joined: Wed Jun 10, 2015 1:58 pm
- Just the numbers in order: 13492
- Location: Oceanslime, CA
Re: Weird Heater Supply Problem - And other solutions!
Yeah it was completely stock. I have done some tinkering already. I need to recheck my values I guess. I used the Cerra Tone 2014 guide as my template. It has the bright cap removed on their layout.
-
- Senior Member
- Posts: 200
- Joined: Fri Dec 06, 2013 9:27 am
- Just the numbers in order: 13492
- Location: United Kingdom
Re: Weird Heater Supply Problem - And other solutions!
Ah that'll be it. Try the bright cap, see what you think