New Rocket blowing fuses

[redshark]

I had problems with my rocket build blowing fuses and after lots of posible things ruled out I replaced the fuse holder and that ended the problem.

[showsii]

First of all thanks so much for all the responses. I am starting to feel better about getting my issues resolved. I appreciate all the help and willingness to help here on TAG from all you guys.

ok here we go with the first round of respones

So here is the first common theme in my perception of yalls posts.

"(disconnecting the PT and making continuity checks) is the next logical step to figuring out what's wrong" Tilldog

"A good place to start troubleshooting would be to isolate your power supply from the rest of the circuit and verify that you do not have any unintentional shorts to ground."

"For starters, remove the heater lines from that terminal strip next to the output tubes and insulate those two wires with some shrink sleeving for the time being. Now verify that your heater lines to the chain of tubes sockets is not shorting to ground. If you do find a short, then locate the source of the short and correct it."

Badtweed



Ok so I unhooked the heater wires from the terminal and put some heat shrink on them. I also disconnected the secondary leads from the rec socket. (the yellow and green ones) (side note- I connected the cap to pin 2 on the rec socket intentionally. I am following Ron's rocket build and using his pictures as references and he has it put on pin 2)

So when I verify that I do not have any unintentional shorts to ground that is the same thing as doing continuity checks?

I set my multimeter to the continuity setting and started going through my heater connections. PLEASE FORGIVE MY IGNORANCE but when it starts to beep and display "short" this means there is continuity?

I am getting "short" displayed on ALL my heater connections across the board.

So????


PS: I promise the white cable was not a fashion statement or motivated to impress anyone. I honestly just had a ton of white wire and didn't want to purchase anymore. But, I hear you guys, duly noted for next time.

[M Fowler]

I should have saved the author of this good quote I saved in my files.

Using a GZ34/5AR4? Take the B+ from pin 8, not pin 2. Pin 8 is the cathode. Pin 2 is only the filament. You are loading up the filament supply with the whole circuit and it is dying under the load.

Mark

[showsii]

When you had the bulb limiter hooked up what wattage was the light bulb?

A 60w?

When you flipped the power switch on the amp, did the bulb light brightly for a second or two then go down to a low glow?

If the bulb stays bright, you have a short or other wiring fault that is drawing too much current.

Did you let any smoke out?

I am using a 40w bulb. I turned the mains on and it lit up bright. It never went to a low glow.

No smoke. Just a black fuse


Could my cap stack be faulty? potentially?



Ian

[badtweed]

Ok so I unhooked the heater wires from the terminal and put some heat shrink on them. I also disconnected the secondary leads from the rec socket. (the yellow and green ones) (side note- I connected the cap to pin 2 on the rec socket intentionally. I am following Ron's rocket build and using his pictures as references and he has it put on pin 2)

So when I verify that I do not have any unintentional shorts to ground that is the same thing as doing continuity checks?

I set my multimeter to the continuity setting and started going through my heater connections. PLEASE FORGIVE MY IGNORANCE but when it starts to beep and display "short" this means there is continuity?

I am getting "short" displayed on ALL my heater connections across the board.

So????

With no tubes installed you want to make sure that there is no path to your chassis from either of the two filament series wires that run between the tubes once you have the actual power tranny filament secondaries removed from them. Take your multimeter and set it to read resistance and take a reading between one of the filament wires (the series wires between the tube sockets not the power supply secondary taps) and your chassis. Take separate readings for each of the 2 wires and the chassis. You should get no resistance reading on your multimeter. If you read any resistance reading other than no resistance reading then you have a short to your chassis.
btw, a resistance reading of 0 is not the same as NO resistance.
A reading of 0 (zero) is a direct short and you do not want that condition.


Hope that helps clear it up a bit.

[martin manning]

I turned the mains on and it lit up bright. It never went to a low glow.

That says you have a short somewhere.

With no tubes installed you want to make sure that there is no path to your chassis from either of the two filament series wires that run between the tubes once you have the actual power tranny filament secondaries removed from them. Take your multimeter and set it to read resistance and take a reading between one of the filament wires (the series wires between the tube sockets not the power supply secondary taps) and your chassis. Take separate readings for each of the 2 wires and the chassis.

A better way to test for a short to ground is to disconnect only the center tap ground for the filament circuit, then check the resistance to ground from any point on the filament string. With the CT disconnected (tubes in or out) you should read infinite resistance. I'd leave the tubes in so you can insure that there isn't a heater-cathode short in one of the tubes. Then with tubes out you can disconnect one of the filament leads from the transformer and measure across two filament lugs on any socket. You should see an open circuit there too.

[Randy Magee]

I don't know what power transformer you used, but usually the 5V filament wire to the tube rectifier are yellow wires and I see that those wires are shrink wrapped... what transformer did you use?

Disregard... I see that the Heyboer has gray 5V filaments...

[badtweed]

I'd leave the tubes in so you can insure that there isn't a heater-cathode short in one of the tubes.

I recall he performed his power up attempt sans tubes.

It is a good idea to remove the power tranny heaters from the circuit as I recommended since there is a chance the transformer itself might have an internal short.

[showsii]

Ok so I unhooked the heater wires from the terminal and put some heat shrink on them. I also disconnected the secondary leads from the rec socket. (the yellow and green ones) (side note- I connected the cap to pin 2 on the rec socket intentionally. I am following Ron's rocket build and using his pictures as references and he has it put on pin 2)

So when I verify that I do not have any unintentional shorts to ground that is the same thing as doing continuity checks?

I set my multimeter to the continuity setting and started going through my heater connections. PLEASE FORGIVE MY IGNORANCE but when it starts to beep and display "short" this means there is continuity?

I am getting "short" displayed on ALL my heater connections across the board.

So????

With no tubes installed you want to make sure that there is no path to your chassis from either of the two filament series wires that run between the tubes once you have the actual power tranny filament secondaries removed from them. Take your multimeter and set it to read resistance and take a reading between one of the filament wires (the series wires between the tube sockets not the power supply secondary taps) and your chassis. Take separate readings for each of the 2 wires and the chassis. You should get no resistance reading on your multimeter. If you read any resistance reading other than no resistance reading then you have a short to your chassis.
btw, a resistance reading of 0 is not the same as NO resistance.
A reading of 0 (zero) is a direct short and you do not want that condition.


Hope that helps clear it up a bit.

So everyone can agree that there is a short some where. I think that is for sure.

Badtweed,

set it to read resistance is just the regular Ohm setting on the multimeter correct? not the continuity setting right?

So basically, I will set the multimeter to read resistance and put one test lead on say pin 5 of V2 and the other lead to ground on the chassis. Then I would repeat for pin 9 of V2 to check the other string of heater wire. I should get NO resistance. If there is resistance I have a short in my heater wiring correct?

I will do this tonight and report back on my findings!

Thanks so much!

Ian

[showsii]

I should have saved the author of this good quote I saved in my files.

Using a GZ34/5AR4? Take the B+ from pin 8, not pin 2. Pin 8 is the cathode. Pin 2 is only the filament. You are loading up the filament supply with the whole circuit and it is dying under the load.

Mark

Mark,

I will attach it to pin 8 upon rewiring once we find this short. Thanks for the help!

Ian

[badtweed]

Ok so I unhooked the heater wires from the terminal and put some heat shrink on them. I also disconnected the secondary leads from the rec socket. (the yellow and green ones) (side note- I connected the cap to pin 2 on the rec socket intentionally. I am following Ron's rocket build and using his pictures as references and he has it put on pin 2)

So when I verify that I do not have any unintentional shorts to ground that is the same thing as doing continuity checks?

I set my multimeter to the continuity setting and started going through my heater connections. PLEASE FORGIVE MY IGNORANCE but when it starts to beep and display "short" this means there is continuity?

I am getting "short" displayed on ALL my heater connections across the board.

So????

With no tubes installed you want to make sure that there is no path to your chassis from either of the two filament series wires that run between the tubes once you have the actual power tranny filament secondaries removed from them. Take your multimeter and set it to read resistance and take a reading between one of the filament wires (the series wires between the tube sockets not the power supply secondary taps) and your chassis. Take separate readings for each of the 2 wires and the chassis. You should get no resistance reading on your multimeter. If you read any resistance reading other than no resistance reading then you have a short to your chassis.
btw, a resistance reading of 0 is not the same as NO resistance.
A reading of 0 (zero) is a direct short and you do not want that condition.


Hope that helps clear it up a bit.

So everyone can agree that there is a short some where. I think that is for sure.

Badtweed,

set it to read resistance is just the regular Ohm setting on the multimeter correct? not the continuity setting right?

So basically, I will set the multimeter to read resistance and put one test lead on say pin 5 of V2 and the other lead to ground on the chassis. Then I would repeat for pin 9 of V2 to check the other string of heater wire. I should get NO resistance. If there is resistance I have a short in my heater wiring correct?

I will do this tonight and report back on my findings!

Thanks so much!

Ian

yes and yes to your 2 questions.

You want to verify that you haven't created a short to the chassis along your heater wiring due to solder blobs touching the chassis etc. If you leave the transformer heater secondaries hooked up to your series wiring with their CT lifted from ground, you might get a reading indicating a short but that reading could be due to an internal short in your transformer or due to a short from your wiring to the chassis. Best to use a straightforward approach to first verify the integrity of your series heater hookup to the sockets by getting the transformer heater secondaries out of your initial checking equation.

[martin manning]

I'd leave the tubes in so you can insure that there isn't a heater-cathode short in one of the tubes.

I recall he performed his power up attempt sans tubes.

It is a good idea to remove the power tranny heaters from the circuit as I recommended since there is a chance the transformer itself might have an internal short.

Re leaving the tubes in, I was writing for the general case there. You will detect an internal short to ground in the PT doing the testing as I described because the entire filament circuit should be isolated from ground once the CT is lifted. You can rule out a shorted tube, a shorted (to ground) transformer winding, and either side of the filament wiring being shorted to ground by lifting one wire and making one measurement. Detecting shorted turns would require an altogether different test.

[showsii]

Ok here is an update.


I went through all my heater wires and checked for resistance to ground. Everything looked ok. There was NO resistance to ground found anywhere throughout the whole series of heater wires. (This was done tubes out by the way.) It seems that my string of heater wires contains no short.



However, I took off the shrink wrap from the heater wires coming of the PT (brown wires) and performed the same test. When I did this off each of the leads there was resistance to ground. The CT was connected as well. This is normal because I had the CT connected to ground, right? or not?

What is next now?

Should I try this approach to see if there is a short internally?

"A better way to test for a short to ground is to disconnect only the center tap ground for the filament circuit, then check the resistance to ground from any point on the filament string. With the CT disconnected (tubes in or out) you should read infinite resistance. I'd leave the tubes in so you can insure that there isn't a heater-cathode short in one of the tubes. Then with tubes out you can disconnect one of the filament leads from the transformer and measure across two filament lugs on any socket. You should see an open circuit there too."- martin manning


Thanks everyone!

Ian

[martin manning]

Testing for an internal short to ground will require disconnecting the CT from ground. Then measure from the CT or either of the other two leads to ground. You want to see an "open circuit" or "infinite resistance" to ground. On Fluke meters this is displayed as "OL" (overload). To me "no resistance" is the same as zero ohms or a short circuit.

If the short to ground test is good you can put the filament circuit back together and look elsewhere.

[showsii]

Testing for an internal short to ground will require disconnecting the CT from ground. Then measure from the CT or either of the other two leads to ground. You want to see an "open circuit" or "infinite resistance" to ground. On Fluke meters this is displayed as "OL" (overload). To me "no resistance" is the same as zero ohms or a short circuit.

If the short to ground test is good you can put the filament circuit back together and look elsewhere.

Ok Just did this. I disconnected the CT of the heaters. I put my multimeter on the continuity setting and i got an OPEN circuit. This means I do not have an internal short correct?


So as of now we have ruled out

1) string of heaters- no short
2) internal PT short based on heater CT- no short


Should I put things back together and look somewhere else? Where would be the next place to look?


Ian