"Superfly" - submini tube version of Doug H's Firefly

[duck_arse]

Second - what sort of power jack are you using ?

Is it a plastic center negative standard power jack like this ? :



I'm using this one: https://www.taydaelectronics.com/dc-power-jack-2-1mm-x-5-5-mm-round-type-panel-mount-dc-099.html

interested parties that noticed that comment and link would find this at the other end ....



which, as we all know, is a metal DC jack. metal DC jacks short to the case, which will usually short your power supply, if fitted to a metal box. is your jack fitted to a metal box, along with the in/out jacks? if so, you need to isolate the body of the DC jack from the metalwork, or get a plastic jack.

[rankot]

Is it possible to use some kind of PT for output? For example, 220V / 6V ct? Or it needs CT on primary side of PT?

[jma38]

Second - what sort of power jack are you using ?

Is it a plastic center negative standard power jack like this ? :



I'm using this one: https://www.taydaelectronics.com/dc-power-jack-2-1mm-x-5-5-mm-round-type-panel-mount-dc-099.html

interested parties that noticed that comment and link would find this at the other end ....



which, as we all know, is a metal DC jack. metal DC jacks short to the case, which will usually short your power supply, if fitted to a metal box. is your jack fitted to a metal box, along with the in/out jacks? if so, you need to isolate the body of the DC jack from the metalwork, or get a plastic jack.

Can I ask where you got the plastic jacks in those pictures on your last post?

[jma38]

^^   Yep, that diagram nailed it - it's the PS, not a protection diode.    Also, that diode NEEDS to be a UF4004 or similar 'fast' diode in order to work.   Sorry if you have already covered this ground...I don't believe a typical Si rectifier diode will do the job.    It's easiest to make this kind of circuit by building the power supply and testing it, then assembling the valve stuff, just my opinion.   

Be aware that is the high voltage switch supply, which can put out 'potentially lethal voltage' within the circuit and at its output...    No fingers in there, buddy.

I can confirm the diode is a UF4004. and thanks for the warning, I definitely don't want to be shocked by something that high voltage.

[GibsonGM]

The schematic is on page one of this thread, the layout is on page 2. Here's the layout:

Ok, so...the diode seems ok.   Where you want to use your meter to look for DC volts is at the bottom of C3..and pin 4 of the 555 timer chip (IC1).  Let's determine if you have power there.    That blue line at the bottom is  your 'power rail' for 12V, and ground is the next rail above it. 

[jma38]

The schematic is on page one of this thread, the layout is on page 2. Here's the layout:

Ok, so...the diode seems ok.   Where you want to use your meter to look for DC volts is at the bottom of C3..and pin 4 of the 555 timer chip (IC1).  Let's determine if you have power there.    That blue line at the bottom is  your 'power rail' for 12V, and ground is the next rail above it.

Just tested, at first I get 0v but then I get an intermittent reading of 0.1v, like every few seconds that's the reading I get.

[thomasha]

Have you tried checking if there is a short between 12V and ground, without the supply?

And check if you have continuity between jack and board. Just to check that the wires are correctly soldered. Happens with everybody.

If that does not work, it is time to check the circuit by areas. You can unsolder the trace that goes to the 555, to cut the 12V connection and check the if you have 12V at the tubes. For this test, you can even measure it with the tubes disconnected. We just want to know if there is a problem with the tubes or with the 555. If the first section of the tubes is OK, you can add the tubes and see if they light up. If it still works, the problem is with the SMPS. If not, you have bad tubes.

To check the tubes, measure the resistance of the heaters. It should be very low, but higher than 1 to 4R. If you have a low resistance at the filaments, the tube is shorted and you will have to fin another one. Normally they do not fail that way, but who knows.

Which kind of supply are you using? Does it have any kind of protection? I had some good supplies which would shut off when shorted. In some cases the heaters of the tubes look like a short. In your case, I think it will be OK because they are in series.

If it works with the tubes, but not with the SMPS, try disconnecting stuff from the 555, if it's possible. Ideally you would test if the 555 is working, without the mosfet and diode. Just to see if there is something wrong with this part of the circuit. If the 555 is socketed, you can remove it and measure if you get 12V without it (bad 555) or if it is still at 0V.
You can check if the Mosfet (IRF740) is good by measuring the resistance between pins. It should be around 740R, if I am not mistaken. A shorted mosfet is the most common problem with the SMPS I build, you just need to short the HV line and gnd and it kills the mosfet and the 555.

Good luck! This is a really nice amplifier.
 
PS.: I checked your board, and there are some suspicious points...the schematic was mirrored to be easier to compare. Check at the points with red circles, if there is a short between traces.
I would suggest that you use less solder, or if you can, remove some of it. The large blobs do not help, most of the time, when it looks like a nice sphere, you have actually a bad joint.

[bluebunny]

Just tested, at first I get 0v but then I get an intermittent reading of 0.1v, like every few seconds that's the reading I get.

That periodic reading sounds like a power supply trying to protect itself (for example, against a short), and repeatedly checking if the fault has gone away.

[jma38]

No continuity between jack and connection to the board. I'll be touching up the connection with solder after I'm done work. It might not be the only problem with my build but this seems to be the main problem. Thanks for the suggestions, I'll be doing the other tests after work.

[jma38]

Have you tried checking if there is a short between 12V and ground, without the supply?

And check if you have continuity between jack and board. Just to check that the wires are correctly soldered. Happens with everybody.

If that does not work, it is time to check the circuit by areas. You can unsolder the trace that goes to the 555, to cut the 12V connection and check the if you have 12V at the tubes. For this test, you can even measure it with the tubes disconnected. We just want to know if there is a problem with the tubes or with the 555. If the first section of the tubes is OK, you can add the tubes and see if they light up. If it still works, the problem is with the SMPS. If not, you have bad tubes.

To check the tubes, measure the resistance of the heaters. It should be very low, but higher than 1 to 4R. If you have a low resistance at the filaments, the tube is shorted and you will have to fin another one. Normally they do not fail that way, but who knows.

Which kind of supply are you using? Does it have any kind of protection? I had some good supplies which would shut off when shorted. In some cases the heaters of the tubes look like a short. In your case, I think it will be OK because they are in series.

If it works with the tubes, but not with the SMPS, try disconnecting stuff from the 555, if it's possible. Ideally you would test if the 555 is working, without the mosfet and diode. Just to see if there is something wrong with this part of the circuit. If the 555 is socketed, you can remove it and measure if you get 12V without it (bad 555) or if it is still at 0V.
You can check if the Mosfet (IRF740) is good by measuring the resistance between pins. It should be around 740R, if I am not mistaken. A shorted mosfet is the most common problem with the SMPS I build, you just need to short the HV line and gnd and it kills the mosfet and the 555.

Good luck! This is a really nice amplifier.
 
PS.: I checked your board, and there are some suspicious points...the schematic was mirrored to be easier to compare. Check at the points with red circles, if there is a short between traces.
I would suggest that you use less solder, or if you can, remove some of it. The large blobs do not help, most of the time, when it looks like a nice sphere, you have actually a bad joint.

Thanks a lot for taking the time to mark those soldering points. I'll fix those soon.

[jma38]

Have you tried checking if there is a short between 12V and ground, without the supply?

And check if you have continuity between jack and board. Just to check that the wires are correctly soldered. Happens with everybody.

If that does not work, it is time to check the circuit by areas. You can unsolder the trace that goes to the 555, to cut the 12V connection and check the if you have 12V at the tubes. For this test, you can even measure it with the tubes disconnected. We just want to know if there is a problem with the tubes or with the 555. If the first section of the tubes is OK, you can add the tubes and see if they light up. If it still works, the problem is with the SMPS. If not, you have bad tubes.

To check the tubes, measure the resistance of the heaters. It should be very low, but higher than 1 to 4R. If you have a low resistance at the filaments, the tube is shorted and you will have to fin another one. Normally they do not fail that way, but who knows.

Which kind of supply are you using? Does it have any kind of protection? I had some good supplies which would shut off when shorted. In some cases the heaters of the tubes look like a short. In your case, I think it will be OK because they are in series.

If it works with the tubes, but not with the SMPS, try disconnecting stuff from the 555, if it's possible. Ideally you would test if the 555 is working, without the mosfet and diode. Just to see if there is something wrong with this part of the circuit. If the 555 is socketed, you can remove it and measure if you get 12V without it (bad 555) or if it is still at 0V.
You can check if the Mosfet (IRF740) is good by measuring the resistance between pins. It should be around 740R, if I am not mistaken. A shorted mosfet is the most common problem with the SMPS I build, you just need to short the HV line and gnd and it kills the mosfet and the 555.

Good luck! This is a really nice amplifier.
 
PS.: I checked your board, and there are some suspicious points...the schematic was mirrored to be easier to compare. Check at the points with red circles, if there is a short between traces.
I would suggest that you use less solder, or if you can, remove some of it. The large blobs do not help, most of the time, when it looks like a nice sphere, you have actually a bad joint.

Looks like there's a short between 12v and ground, I'll be fixing that soldering and the soldering of the other problem spots you pointed out tomorrow morning. Looks like we're getting to the bottom of this thing.

[duck_arse]

here, see, many options for DC sockets, some metal [avoid those], some plastic body.

https://www.taydaelectronics.com/hardware/dc-power.html

please, please, PLEASE ..... take a photo/s of the thing you have built as you now have it, so that we can see the lay of the land, an overview. jacks, pots, wires, all that stuff. there is no point messing aboot w/ the high volts circuit if you are shorting your power supply at the first  .. erm .. hurdle.

[jma38]

here, see, many options for DC sockets, some metal [avoid those], some plastic body.

https://www.taydaelectronics.com/hardware/dc-power.html

please, please, PLEASE ..... take a photo/s of the thing you have built as you now have it, so that we can see the lay of the land, an overview. jacks, pots, wires, all that stuff. there is no point messing aboot w/ the high volts circuit if you are shorting your power supply at the first  .. erm .. hurdle.

Here are some pictures:

[jma38]

After doing some soldering to disconnect the short between 12v and ground my multimeter is still showing that the two are connected at that point. I've closely inspected the area where the rogue connection that I cleared was and it isn't connected there anymore.

[thomasha]

How much resistance is it reading?
Remember that tube filaments have very low resistance and would show as a short if measured. If you check the resistance in ohms it will be as low as 8 to 20 ohms.

Thanks for the new pictures.
Because of the shape of the solder it is hard to tell from the picture if they are indeed touching, but I would check every solder point where there is a solder ball. If you have an utility knife you can try passing it between the traces so that it scrapes off any small contact points. I do this sometimes too, when the traces are too close together. It also will show you where the solder is connected, since you will not be able to go forward.

[jma38]

How much resistance is it reading?
Remember that tube filaments have very low resistance and would show as a short if measured. If you check the resistance in ohms it will be as low as 8 to 20 ohms.

Thanks for the new pictures.
Because of the shape of the solder it is hard to tell from the picture if they are indeed touching, but I would check every solder point where there is a solder ball. If you have an utility knife you can try passing it between the traces so that it scrapes off any small contact points. I do this sometimes too, when the traces are too close together. It also will show you where the solder is connected, since you will not be able to go forward.

Resistance is reading 6.7 ohms. Thanks I'll do a bit of a scrape with my utility knife and see if that does anything.

[thomasha]

Yes, and test it without the tubes, just to be sure that you are not reading the tubes resistance

[jma38]

Yes, and test it without the tubes, just to be sure that you are not reading the tubes resistance

Tested without tubes. Reading between 6 and 8.2 ohms

[jma38]

The scraping is clearly doing something because when I test for continuity there's no beep for a couple of seconds and then eventually it's a constant tone on my multimeter. This might take a while.

[jma38]

This particular problem point has been scraped as you can see but the multimeter is still showing continuity. Could there be something I'm missing?