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5e3 Build not working HELP!!

notune

Member
Messages
143
This is my first build, the filaments for the tubes are light up but the pilot light is not on and i have no sound. Where do I start ? I have a DMV but I don't know about this kind of troubleshooting.
 

xtian

Gold Supporting Member
Messages
2,322
Make sure a speaker is attached properly! Any hiss or hum at all?

For the pilot light, measure for AC across its terminals. Should be 6.3vAC. (Maybe the bulb is burned out.)

Next, check all your voltages. B+ should be around 400vDC. Make a chart of tube positions (V1a, V1b, etc.) and record DC voltages for each anode and cathode.

If all the voltages check out, then it's time to check the signal path.

I'm going fast. Let me know if you need more detailed instructions!
 

notune

Member
Messages
143
Make sure a speaker is attached properly! Any hiss or hum at all?

For the pilot light, measure for AC across its terminals. Should be 6.3vAC. (Maybe the bulb is burned out.)

Next, check all your voltages. B+ should be around 400vDC. Make a chart of tube positions (V1a, V1b, etc.) and record DC voltages for each anode and cathode.

If all the voltages check out, then it's time to check the signal path.

I'm going fast. Let me know if you need more detailed instructions![/QUOTE
How do I check my B+ with a meter?
 

joelster

Silver Supporting Member
Messages
3,133
Check you work. Match every wire and connection against the schematic, one by one. As you do, take a pencil and make a checkmark on the schematic at each confirmed connection and component. There are just too many possibilities to give an answer from your post but if you take your time you'll find it.
 
Last edited:

StanG

Member
Messages
4,660
Check you work. Match every wire and connection against the schematic, open by one. As you do, take a pencil and make a checkmark on the schematic at each confirmed connection and component. There are just too many possibilities to give an answer from you post but if you take your time you'll find it.

Because you probably didn't wire something correctly. Don't worry, most of us have been there.
 

UsableThought

Member
Messages
1,650
How do I check my B+ with a meter?
Very carefully.

There are a few different voltages you might typically check in an amp - one is the voltage drop across a component, another might be the voltage across transformer secondaries, and still another, the one being referred to here, is the voltage from a node in a circuit (e.g. B+ at the positive terminal of the reservoir cap) as measured to 0V ground.

When you're checking something like B+ voltage, which is DC, you put your meter on its highest DC voltage range, use an alligator clip attachment or jumper to clip the black probe to a secure ground point, e.g. on the chassis assuming it's properly grounded; and very carefully, not touching anything you shouldn't, place the point of the red probe on whatever node it is you're checking.

I assume you've gotten the obligatory lectures on safety? If you've never checked live high voltage points before, some things to think about: only use one hand & keep the other hand "in your pocket" (famous rule); make sure the meter is where you can see it easily & the probe leads are long enough so they won't pull it over; if the black lead's alligator clip to ground is not absolutely secure, tape it down so it doesn't slip - you don't want to short anything out accidentally; don't have a cat or dog or child in the room to disturb you; remember to unplug the amp & drain the filter caps afterward; etc.

It's good to think about how you are going to handle this before you actually do it for the first time. For a full list of suggested safety precautions, p. 189 of this PDF book on solid state amplifiers has an excellent summary.
 
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notune

Member
Messages
143
Very carefully.

There are a few different voltages you might typically check in an amp - one is the voltage drop across a component, another might be the voltage across transformer secondaries, and still another, the one being referred to here, is the voltage from a node in a circuit (e.g. B+ at the positive terminal of the reservoir cap) as measured to 0V ground.

When you're checking something like B+ voltage, which is DC, you put your meter on its highest DC voltage range, use an alligator clip attachment or jumper to clip the black probe to a secure ground point, e.g. on the chassis assuming it's properly grounded; and very carefully, not touching anything you shouldn't, place the point of the red probe on whatever node it is you're checking.

I assume you've gotten the obligatory lectures on safety? If you've never checked live high voltage points before, some things to think about: only use one hand & keep the other hand "in your pocket" (famous rule); make sure the meter is where you can see it easily & the probe leads are long enough so they won't pull it over; if the black lead's alligator clip to ground is not absolutely secure, tape it down so it doesn't slip - you don't want to short anything out accidentally; don't have a cat or dog or child in the room to disturb you; remember to unplug the amp & drain the filter caps afterward; etc.

It just makes me nervous when someone says "how do I check my B+ with a meter." It's good to think about how you are going to handle this before you actually do it for the first time. For a full list of suggested safety precautions, p. 189 of this PDF book on solid state amplifiers has an excellent summary.
Thanks for help so far. Good news I think I just have a bad bulb because I have 6.3v but my b+ is at 483 volts I am using 5a4c that still seems high can anyone confirm
 

ked

Member
Messages
911
That amp should be using a 5Y3 rectifier to keep the voltages lower. 6v6 power tubes are not going to live with 483 volts on the plates.
 

notune

Member
Messages
143
That amp should be using a 5Y3 rectifier to keep the voltages lower. 6v6 power tubes are not going to live with 483 volts on the plates.
I
I know what rectifier comes in a stock 5e3. I'm useing classic tone 20 watt trannys that are specd for different rectifiers
 

zenas

Member
Messages
8,262
Actually trannys aren't speced for specific rectifiers. Other than the filiment current if it's 2 amps you don't want to use a 5u4 but most aftermarket PTs have 3 amp rectifier filiment windings.

Also keep in mind not all rectifiers put out the same voltage even though they're the same type. For instance I had a JJ 5y3 that put out way more voltage than whatever old USA 5y3 I tried that day.
 

Jeff Gehring

Gold Supporting Member
Messages
5,805
Is that B+ of 483V measured with the tubes installed? It's neither here nor there about the transformers being rated for a GZ34, the 6V6's will not like that 483V at all. Right around 350V is a good spot to be...
 

notune

Member
Messages
143
Actually trannys aren't speced for specific rectifiers. Other than the filiment current if it's 2 amps you don't want to use a 5u4 but most aftermarket PTs have 3 amp rectifier filiment windings.

Also keep in mind not all rectifiers put out the same voltage even though they're the same type. For instance I had a JJ 5y3 that put out way more voltage than whatever old USA 5y3 I tried that day.
This is from the triode website.The 40-18016(120V) & 40-18017(120/240V) have a lower HV winding at 660V CT, increased current capability on all windings, which allows you to use different rectifier tube types, add additional tube stages, or upgrade your amplifier to use 6L6's! I would say that is a specifiicastion
 

cap47

Member
Messages
2,270
Use a 5y3 rectifier for proper voltage. Anything under 400VDC will work for 6v6 tubes. Mine is around 375V. I have 270 ohm 10W bias resistor in mine.
 

TweeDLX

Member
Messages
3,756
If you're using a 5AR4c rectifier and getting 483VDC with tubes installed, what are your filter caps rated for? You can have a nice little fireworks show if you exceed the voltage rating on those E-caps. Stop defending your choice of rectifier tube, and take the advice of these people who are trying to help you. I'm not trying to be a dickhead, but you really need to use a 5Y3 to knock that B+ down. As stated earlier, good high quality photos will go a long way in helping find your other problems.
 




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