Low heater voltage?

[daveyajd]

Hello,
I am wiring up my power section and everything seems to check out except my heaters are running at about 5.3v. With a tube in there is a slight glow. Seems less than normal. The transformer is new but it has been sitting on my workbench for a little while. Should I be concerned? What would I do to fix it if it is a problem?


Aaron

[AmberB]

Do you have the wrong heater hooked up to the tubes?  That 5.3 volt heater sounds like the heater for a 5 volt rectifier tube...
Are your heater wires from the transformer yellow or green?

[Bieworm]

5.3 seems kinda low. On my 18 watt amps I can't seem to get voltages higher than 5.7 to 5.8V , but everything works just fine.

[Latole]

5.3 seems kinda low. On my 18 watt amps I can't seem to get voltages higher than 5.7 to 5.8V , but everything works just fine.

If all on your circuit are ok, like bias to name just one :
You use a too low power Power Transformer, not enough milli amp.
Yes amp will work, you may loose some power and punch.

Same answer for daveyad

[Bieworm]

5.3 seems kinda low. On my 18 watt amps I can't seem to get voltages higher than 5.7 to 5.8V , but everything works just fine.

If all on your circuit are ok, like bias to name just one :
You use a too low power Power Transformer, not enough milli amp.
Yes amp will work, you may loose some power and punch.

Same answer for daveyad

18 watts are cathode biased amps. My amps are biased to 18 watt nominal output power, so that's ok.
The 3.2A heater current from the PTX is plenty for 2 EL84 and 3 12AX7 valves... so that's not the problem. And believe me, power is the least they lack. I have 2 18 watts, and they both do deliver bigtime.

[sluckey]

I am wiring up my power section and everything seems to check out except my heaters are running at about 5.3v. With a tube in there is a slight glow. Seems less than normal. The transformer is new but it has been sitting on my workbench for a little while. Should I be concerned? What would I do to fix it if it is a problem?

Yes, you should be concerned. It is a problem. You have either wired the PT wrong or it is defective. Post a datasheet for the PT.

[daveyajd]

I don’t have a data sheet as this was made to my specs from MPS. 345-0-345, 5v 2A, 6.3V 4A (no center tap) because I screwed up.😀 but I have an artificial created.


Aaron

[sluckey]

If your 6.3v winding is only measuring 5.3v then either the transformer is faulty or your meter is lying.

[Latole]

18 watts are cathode biased amps. My amps are biased to 18 watt nominal output power, so that's ok.
The 3.2A heater current from the PTX is plenty for 2 EL84 and 3 12AX7 valves... so that's not the problem. And believe me, power is the least they lack. I have 2 18 watts, and they both do deliver bigtime.

That is the amp we talking about ? I see nothing from daveyajad. It is from another post ?

With 6.3 v at 4.3 amp Power transformer look faulty or heater wiring are faulty.

[Bieworm]

18 watts are cathode biased amps. My amps are biased to 18 watt nominal output power, so that's ok.
The 3.2A heater current from the PTX is plenty for 2 EL84 and 3 12AX7 valves... so that's not the problem. And believe me, power is the least they lack. I have 2 18 watts, and they both do deliver bigtime.

That is the amp we talking about ? I see nothing from daveyajad. It is from another post ?

With 6.3 v at 4.3 amp Power transformer look faulty or heater wiring are faulty.

Correct... but you replied to my post , and I referred tom low heater voltage on my 18 watts

[daveyajd]

No this is not an 18 watt. I think that was referenced because lower heater voltage seemed to be fine in that case. This is a Friedman DS style build so it has 5881s.


Aaron

[DummyLoad]

Hello,
I am wiring up my power section and everything seems to check out except my heaters are running at about 5.3v. With a tube in there is a slight glow. Seems less than normal. The transformer is new but it has been sitting on my workbench for a little while. Should I be concerned? What would I do to fix it if it is a problem?


Aaron

the answer is obvious: if there's no wiring fault(s), you need the correct part.

respectfully,


--pete

[Latole]

No this is not an 18 watt. I think that was referenced because lower heater voltage seemed to be fine in that case. This is a Friedman DS style build so it has 5881s.


Aaron

No schematic ?

[daveyajd]

No I’m sorry I don’t have a schematic. This is my attempt at reverse engineering a Dirty Shirley from pictures and the knowledge that it is a JTM variant. 🤞


Aaron

[sluckey]

Don't need no schematic to analyze low filament voltage.

[daveyajd]

True fact! Thanks everyone. I’m going to get a fresh set of voltages tonight with new eyes and see what I can figure out.


Aaron

[tubeswell]

Maybe the error is the PT winder’s. Someone in the factory might have scribbled ‘6.3‘ and another guy looking at the handwriting thought it was ‘5.3’.  ?

[Latole]

Don't need no schematic to analyze low filament voltage.

No ? Wich tubes, how many....?
I'd like to know what we are talking about.

[shooter]

their talking about 6.3 volts that is 5.3 volts
a schematic isn't needed to figure out "why"
pull all tubes, fixed?
no, measure no tubes, good?
no, look into what tubeswell postulated
so far no schematic needed 

[AmberB]

I still gotta wonder if the 5 volt heater and the 6.3 volt heater were mixed up...
5.3 volts with no load would not be too weird for a 5 volt heater...

[daveyajd]

Ok, well after some more measurements the award goes to......AmberB! It appears that the 6.3v and 5v are labeled wrong! And I had everything dressed so nicely! 


Aaron

[bmccowan]

Time to start prepping that chicken dinner.

[AmberB]

Ok, well after some more measurements the award goes to......AmberB! It appears that the 6.3v and 5v are labeled wrong! And I had everything dressed so nicely! 


Aaron

That's the worst part, having to pull the wires and re-route them...

[Bieworm]

Amp humor?

[Latole]

Ok, well after some more measurements the award goes to......AmberB! It appears that the 6.3v and 5v are labeled wrong! And I had everything dressed so nicely! 


Aaron

That's the worst part, having to pull the wires and re-route them...

Just few inches from P.T

[Latole]

Ok, well after some more measurements the award goes to......AmberB! It appears that the 6.3v and 5v are labeled wrong! And I had everything dressed so nicely! 


Aaron

Tubes heater wires code ; green
Rectifier heater code : yellow

You mean color are reverse ?

[daveyajd]

Well the labeling for this PT said yellow-6.3v, green-5v but yes they were reversed.


Aaron

[Latole]

Well the labeling for this PT said yellow-6.3v, green-5v but yes they were reversed.


Aaron

Green are always 6.3V
The guy who put label made a mistake. Transformer manufacturer is right

[daveyajd]

Well that may be the traditional color code but it’s not the case here. This guy is the manufacturer and the labeler! I have used trans from them before and yellow was 6.3v.


Aaron

[sluckey]

Well that may be the traditional color code but it’s not the case here. This guy is the manufacturer and the labeler! I have used trans from them before and yellow was 6.3v.

You need to tell "the guy" to get with the program. That could have been a costly mistake.

[dude]

Wow, never heard this one before. I have never seen a 6.3 filament wire that wasn't green in a less than 20 year old PT. I've seen crazy colors on old PT wires from the 60's and maybe 70's and down. Seems the guy needs to be more careful but all you had to do from the beginning was to measure "both filament wires voltage" when you first got the low reading, that would have been my next step.   

[Latole]

It is a beginner mistake....... and from a transformer builder !!!

[daveyajd]

100% correct in all statements. I’m so glad it turned out to be as easy to remedy as it did! Thank you. Now my power section is complete and functional so I can move onto the real fun!


Aaron

[sluckey]

Great! What are you building?

[shooter]

has to be something by Gibson, none of the other Amp makers consistently have mis-labeled stuff   

[Latole]

Great! What are you building?

Reply no 13 ;

....that it is a JTM variant. 🤞

[daveyajd]

As I said above it is my attempt at a Friedman Dirty Shirley which is a certain version of JTM 45. With a name that nods to the times I am happy with how it looks so far!


Aaron

[Latole]

Nice wiring, you start building

Why some Marr ?

[Latole]

Wow, never heard this one before. I have never seen a 6.3 filament wire that wasn't green in a less than 20 year old PT. I've seen crazy colors on old PT wires from the 60's and maybe 70's and down. Seems the guy needs to be more careful but all you had to do from the beginning was to measure "both filament wires voltage" when you first got the low reading, that would have been my next step.

Transformer builder is color blind