Forgot to mention - on the photo you posted on the 13th showing the pc board, I see Red wires being used to the ground connections and Green for the +24v. That's the opposite of what most people would assume if hooking this up.
Didn't think of the color combo when wiring it up, but verified that green is +24, blue is -24, and red common. Along with so much other stuff, color coding is something I have yet to learn.
That makes me feel better about the power supply and com+signal ground should be ok.
If you fired it up without having the -INP tied to ground, that may have caused something to go South. Could have been oscillating causing high current draw without that feedback loop.
At first, I wasn't sure which point was -inp as 3 connection points are very close to the -inp marking, as in any of them could be -inp. If I understand it correctly, -inp leads directly to R9. In the 2nd jpg, what should be -inp is circled as 'to ground'. Is this correct? It is connected to chassis ground.
Don't see anything visibly toasty. Haven't figured out the mistake yet.
Stupid question, but does it need a tube installed before powering it up?
Correct on the -INP leading to R9, then to pin 8 of the tube. I'm guessing Q1 and Q2 were not happy without the tube, since they both tie to plate of the first section. I don't really know much about these newfangled transistor devices, but I do wonder how much voltage &/or current might have been flowing through the gate of Q2 without the tube in place?
C3, 220uf power supply cap, got hot enough to unsolder itself from the board. Around certain solder points the shininess of the board has changed which tells me those points were also hot (dead short). Double checking components and they all look correct. All markings on ebay parts look correct.
Had the mm connected to the audio outputs, dc2.7v. I need to figure out if powering up the board w/out a tube caused all the trouble or it was a wrong connection. I 'think' they are enough spare parts to rebuild both boards but must find my mistake before running out of parts. On one of the threads I was reading, they mentioned to turn down the 100Ωdc bias pot before powering it up, but does mean 12 turns out (center) or 25 turns clockwise (full in).
Have to find some anal ease for the tube sockets, super difficult to seat.
Well that sucks! You might want to invest $20 on one of those little Chinese component testers just to see if all of your semiconductors are still functional. I'm guessing one of them is now shorted.
Be careful with electrolytic capacitors, they can literally explode if you over voltage or reverse their polarity. When I was in school, we purposely blew them up inside a cardboard box, and the shrapnel from the can was capable of almost making it through the cardboard.
@ugly_woofer said:
Be careful with electrolytic capacitors, they can literally explode if you over voltage or reverse their polarity. When I was in school, we purposely blew them up inside a cardboard box, and the shrapnel from the can was capable of almost making it through the cardboard.
We used to wait for some poor guy to leave the room, power his project down, and reverse one of the caps. Always fun.
My HS instructor never blew up any caps, but he seemed almost giddy while burning up resistors to teach us about why there are wattage ratings. Very nice guy & a bit of a square...his words, not mine.
When I saw the cap lead smoking the thought of an explosion did cross my mind as there could be 48v. on those and they are rated for 50v.
I'll have to do some digging on this Chinese tester thingy.
I'd like more headroom than that but I 'think' they are only supposed to see 24v as one is positioned in each 24v leg, but if I did something wrong, and apparently I did, I wonder if they are seeing the full swing of +/-24 which would be 48v. Really don't want to order more parts but if so, higher voltage caps will be on the list.
Couldn't see where the smoke was coming from at first and swapped the safety glasses for the wife's reading glasses. Bad things can happen when glasses are used for safety glasses.
While my frames are no longer the safety-type as it's not required of me, nor the side-shields, I still require myself get polycarbonate lenses as a must. They're more durable, and have saved my eyes on more than one occasion.
When I got clocked with a baseball and broke my nose back in 2003, the safety-frames broke, but the lenses survived and protected my eyes under the impact.
Yes on the component tester. They are all over Amazon too. In fact I just ordered one - all of $19! They might not be absolutely accurate, but it should tell you if something is no longer functioning - like a transistor that it thinks is a diode or a resistor.
Tester thingy on the way.
W/1k+ thread views, I'd guess most of you guys have been peaking in on this misadventure and getting a good laugh ... maybe shaking your head in dismay as if watching Elmer Fudd host a talk show, or a slow-mo train wreck.
While I do at times get frustrated, and things cost more than they should because of my ineptness, I kind of enjoy the journey as much, or more than the destination. Bonus points for learning something along the way.
Comments
Forgot to mention - on the photo you posted on the 13th showing the pc board, I see Red wires being used to the ground connections and Green for the +24v. That's the opposite of what most people would assume if hooking this up.
Didn't think of the color combo when wiring it up, but verified that green is +24, blue is -24, and red common. Along with so much other stuff, color coding is something I have yet to learn.
That makes me feel better about the power supply and com+signal ground should be ok.
Time to do more digging.
If you fired it up without having the -INP tied to ground, that may have caused something to go South. Could have been oscillating causing high current draw without that feedback loop.
At first, I wasn't sure which point was -inp as 3 connection points are very close to the -inp marking, as in any of them could be -inp. If I understand it correctly, -inp leads directly to R9. In the 2nd jpg, what should be -inp is circled as 'to ground'. Is this correct? It is connected to chassis ground.
Don't see anything visibly toasty. Haven't figured out the mistake yet.
Stupid question, but does it need a tube installed before powering it up?
Correct on the -INP leading to R9, then to pin 8 of the tube. I'm guessing Q1 and Q2 were not happy without the tube, since they both tie to plate of the first section. I don't really know much about these newfangled transistor devices, but I do wonder how much voltage &/or current might have been flowing through the gate of Q2 without the tube in place?
What we need here is a bonafide EE to chime in.
Luckily, I ordered one extra pair of most everything. No more toasting!
Was not wanting to risk a tube but it looks like there is no alternative.
Odd, arrived from The Tube Store, in Canada, in less time than orders from TubeDepot, in Memphis TN. We're ~3hr. North of Memphis.
Oh those crazy Canadians
And more tooby goodness. Thanks Tom.
Two of the best (per my value / sound anyway)
Yeah ... I made more smoke.
Oh no....what happened?
C3, 220uf power supply cap, got hot enough to unsolder itself from the board. Around certain solder points the shininess of the board has changed which tells me those points were also hot (dead short). Double checking components and they all look correct. All markings on ebay parts look correct.
Had the mm connected to the audio outputs, dc2.7v. I need to figure out if powering up the board w/out a tube caused all the trouble or it was a wrong connection. I 'think' they are enough spare parts to rebuild both boards but must find my mistake before running out of parts. On one of the threads I was reading, they mentioned to turn down the 100Ωdc bias pot before powering it up, but does mean 12 turns out (center) or 25 turns clockwise (full in).
Have to find some anal ease for the tube sockets, super difficult to seat.
Well that sucks! You might want to invest $20 on one of those little Chinese component testers just to see if all of your semiconductors are still functional. I'm guessing one of them is now shorted.
Be careful with electrolytic capacitors, they can literally explode if you over voltage or reverse their polarity. When I was in school, we purposely blew them up inside a cardboard box, and the shrapnel from the can was capable of almost making it through the cardboard.
We used to wait for some poor guy to leave the room, power his project down, and reverse one of the caps. Always fun.
.....ahhh, electronic school...😁
My HS instructor never blew up any caps, but he seemed almost giddy while burning up resistors to teach us about why there are wattage ratings. Very nice guy & a bit of a square...his words, not mine.
When I saw the cap lead smoking the thought of an explosion did cross my mind as there could be 48v. on those and they are rated for 50v.
I'll have to do some digging on this Chinese tester thingy.
ROT is to have 1.5 to 2x the voltage rating on the caps vs the voltage running through them- or at least that is what I was told.
InDIYana Event Website
I'd like more headroom than that but I 'think' they are only supposed to see 24v as one is positioned in each 24v leg, but if I did something wrong, and apparently I did, I wonder if they are seeing the full swing of +/-24 which would be 48v. Really don't want to order more parts but if so, higher voltage caps will be on the list.
Couldn't see where the smoke was coming from at first and swapped the safety glasses for the wife's reading glasses. Bad things can happen when glasses are used for safety glasses.
Is this the tester thingy? https://ebay.com/itm/New-Multifunction-Transistor-LCR-TC1-Tester-Diodes-Full-Color-Graphics-Display/184449768033?hash=item2af2101a61:g:EwEAAOSwdVBfYYhZ
...unless your glasses are your safety glasses.
While my frames are no longer the safety-type as it's not required of me, nor the side-shields, I still require myself get polycarbonate lenses as a must. They're more durable, and have saved my eyes on more than one occasion.
When I got clocked with a baseball and broke my nose back in 2003, the safety-frames broke, but the lenses survived and protected my eyes under the impact.
InDIYana Event Website
Yes, that is a good ROT for us DIY guys.
Edit/correction: "Voltage across them". Voltage doesn't run through anything, current does.
Point taken, poorly worded on my part.
InDIYana Event Website
Not trying to nit pick you Ben.
I know, but you are correct.
InDIYana Event Website
I got an 'agreed' out of a trained person in the electrical arts, from me who is not. I'm good.
InDIYana Event Website
Yes on the component tester. They are all over Amazon too. In fact I just ordered one - all of $19! They might not be absolutely accurate, but it should tell you if something is no longer functioning - like a transistor that it thinks is a diode or a resistor.
Tester thingy on the way.
W/1k+ thread views, I'd guess most of you guys have been peaking in on this misadventure and getting a good laugh ... maybe shaking your head in dismay as if watching Elmer Fudd host a talk show, or a slow-mo train wreck.
While I do at times get frustrated, and things cost more than they should because of my ineptness, I kind of enjoy the journey as much, or more than the destination. Bonus points for learning something along the way.
Enjoy.
I actually admire your tenacity. They say you learn just as much, if not more from your mistakes!