I've cracked

[sdf8]

I started building my Crack and things were looking pretty good, until they weren't.  Things got bad.  Then they got worse...

I probably won't need to state this, but I'm pretty much a novice at all this.  I assembled the case and the snap on/screw on components and then soldered the power switch.  I'm pretty sure that went fine, but my first warning sign came up and indicated I really don't know what the heck I'm doing with a multimeter.  Many of the readings are clear enough, but some just flummox me (it is an fairly ancient analog meter).   In particular, low and high readings for resistance aren't super clear.  But, the tests on the switch were showing up on opposite ends of the scale when toggling on/off, so I figured I was good and forged ahead. 

I measured my voltage at 127V and proceeded with attaching/soldering the wires following the 115V to 130V section.  Testing seemed to confirm all was good.

However, when I moved to the green wiring, things went down hill in a hurry. 

First, I couldn't find a green wire.  After searching a little harder on the distant edges of my work area, I realized I had a green wire...and it was sitting with some red, white and black wires.  Not ones I had used, mind you.  After attaching the tiny buss wire, it didn't bother me in the slightest to continue on with the same gauge black and red wires I had carefully laid out next to the buss wire.  At least not at the time. 

So, I set about unsoldering all the little wires and replacing them with the right wires.  As I proceeded, I was getting some strange readings from my multimeter.  I decided it needed new batteries.  I replaced them and things were still kind of inconsistent and I decided it was probably not calibrated properly and I really didn't feel comfortable that I wasn't just screwing it up more.  When I was trying to zero it out, the needle wouldn't get close to 0. So, I decided I'd get a digital multimeter and get rid of some of the guesswork. 

While not top of the line, it is an autoranging meter (Klein MM400) which seemed easier to deal with and plenty good for my purposes.  But, I still can't tell how the heck to determine high and low values for resistance.  The instructions are kind of vague.   0L seemed like it ought to be low but I couldn't figure out if I was hitting overlimit(or I wasn't).  And, if I recall it kind of seemed backwards from what it should be.  But, I forged ahead hoping once I got everything back together, if I was getting decent readings in the testing, things were probably fine. 

So, I finished up the initial soldering of the red/black wires and did the testing.  Sadly, nothing was working.  I was getting 0 or close to 0 volts on both tests.  I assume I burned up the switch after soldering and unsoldering a few times.  But, I don't really know how to verify it, short of tearing everything back apart and trying to burn up more components in the process.   And, I still can't read the darn meter, so it is unclear I'll be able to prove anything. 

I'm thinking it will just be easier to order a new switch and see what happens.   But, are there other things I should be doing?  And, is there any way to forge ahead while I wait for the switch?  I assume since the switch has some resistance, I can't just wrap the wires attached to the switch together and treat it as "on", for the time being.  Of course, I don't want to proceed without passing the tests, I'm just looking for a way to do the tests without the switch.

Any thoughts or suggestions?

thanks,
sf

[Tom-s]

First. Go to youtube. Watch video's on how to work with a multimeter. Especially resistances, for now. If needed, ask help from a friend.

Second. Never power up a Bottlehead amp that hasn't passed resistance tests. Stick to the manual.

[bernieclub]

The kit is full of resistors of various values.   Practice measuring them individually until you're confident using your meter.

[adydula]

I would try to find someone near you that understands electriity and electronics to help you out....Unless your sure of your work and talents, working with high voltages and tubes can be very harmful if your not careful.....

Get some help!!

Alex

[Deke609]

I assume I burned up the switch after soldering and unsoldering a few times.  But, I don't really know how to verify it ...

(1) UNPLUG THE POWER CORD FROM BOTH THE AMP AND THE WALL, AND LEAVE IT UNPLUGGED FOR ALL STEPS BELOW

(2) Check continuity of the switch: set your meter to continuity (see your manual); connect one of your meter's leads to one bottom solder lug of the switch, and connect the other lead to the other lug of the switch; set the switch to the "on" position -- on my meter, continuity (a closed circuit, which is what you want when the switch is on) is indicated with a constant sound.  Your meter may be different, so check the manual for how continuity is indicated (e.g., possibly with text or a symbol on its screen if it's digital).

If there is no continuity, the switch is fried and needs to be replaced. If there is continuity, the switch is likely still good.

(3) If the switch is good, but you got 0V when doing voltage tests, check that fuse is inserted in the IEC slot; if it is, check that the fuse is not blown.

(4) Post detailed pics of your build. PB of Bottlehead has a eagle eye for spotting wiring and soldering errors.

[sdf8]

Thanks for your replies.  Perhaps I've overdramatized my incompetence.  It is not as if I can't read anything on the multimeter.  When a 270 ohm resistor reads somewhere in the vicinity of 270, I can figure that out on both the analog and especially the digital.  It is just that certain readings are not as clear.  OL seems like low limit, but I'm not sure what I should be seeing for a high limit, for instance. 

I have perused several youtube videos.  Usually they tell me what I already know and are often specific to a given meter.  The general stuff that applies to all meters is generally the stuff I have figured out already.  I'll be researching that some more and chasing down more info in the manual, but I get that understanding the meter is important.  You guys are just one more avenue to try to figure that stuff out.

I *think* I'm being safe with my practices.  While it was suggested not to power up without testing, of course, you have to power up *to* test.  The only place I have deviated from the instructions was getting a clear reading on the switch (on the second pass).  My assumption is that if the switch is burned up, no electricity is flowing through the circuit.  If I'm wrong about that, please correct me.  Mind you, I'm not sticking my hands in there, just saying I felt safe to plug it in for testing.

thanks,.
sf

[Deke609]

While it was suggested not to power up without testing, of course, you have to power up *to* test. 

Your meter has a battery that will generate a small current for checking continuity (just as it does for checking resistances).  IOW, it provides sufficient power to check continuity.  DO NOT test contnuity with the amp plugged in - even if you are not harmed, it could potentially fry your meter.

[kgoss]

" OL seems like low limit, but I'm not sure what I should be seeing for a high limit, for instance."

"0L" is over limit on your meter,  You need to switch to a scale one larger than the value you are measuring.

Please slow down, read and follow each step in the manual exactly, and make sure your work (wires, solder joints, etc,) looks exactly like the pictures.

Bottlehead has wonderful manuals for all of their kits.  But people get in trouble skimming instead of carefully reading.  I know you are excited and want to listen to your new amp as quickly as possible but I also bet you dont want to spend weeks chasing down problems after completing it.

[fullheadofnothing]

"OL" means over limit. It means that  the resistance is so high that the meter cannot measure it. It's what you should see with the leads on the switch lugs when the switch is off.

A low resistance will read as [close to] zero ohms. That is what you should see when the switch is in the on position.

You can absolutely shock yourself on a device with the power switch turned off. If you are not measuring a voltage, your power cable should ALWAYS be unplugged for safety.

[Doc B.]

https://bottlehead.com/smf/index.php?topic=8458.0

https://bottlehead.com/smf/index.php?topic=8457.0

[sdf8]

Sorry, I'm not being as precise as I could be.   I am going slow and following directions. And, I already watched both the referenced videos. 

It was mentioned not to be plugged in when checking continuity.  I'm not.  When I said you needed to be plugged in to check things, I was referring to the voltage checks in the next section.  I wasn't thinking about the previous check. However, I'll concede that I was much more cautious moving forward, but when I had problems and had to backtrack, I haven't been as careful.  So, point taken.

I have an autoranging meter, so I shouldn't need to change the scale. 

0L being overlimit is huge.  Thanks.  I went back and checked again and I was still getting 0L when off.  With my misunderstanding, that felt like it was backwards, but it sounds like it is exactly what is supposed to be happening.  And, I'm getting a very low value when switched on, which also seems to be correct. Originally, I was assuming high limit was off the charts and low resistance meant 0.  Since I was slightly above 0, (and had the limits switched in my head) it all seemed out of whack. 

But, based on all that, it seems like my switch is fine.  So, I'll review my wiring again and see if I see any obvious problems (obvious to me, anyway).  If I can't find anything I'll post pictures to see if anyone else might be able to help.

thanks much,
sf

[sdf8]

Okay, I think I'm ready to go braid green wire....wearing a dunce cap.

After confirming the switch was working, I still wasn't getting a voltage reading.  So, I started ripping out all the red/black wire to get back to a point where I could check the initial voltage reading to confirm I was still getting 120V right after the continuity check on the switch.  As I removed the last wire...the cord fell out from underneath.  Now, I can't say for sure I didn't have a problem with my wiring, but I have a pretty good hunch the issue was just that the cord didn't get fully seated after the continuity check.  It was dangling from the connection (hidden underneath the chassis)  so I had no reason to think it wasn't plugged in properly.  Sigh.  We're off to a promising start...

But, on the bright side, the initial testing was all spot on, so flailing aside, I can move forward and don't have to buy any new parts.

Thanks for all the help,
sf

[Paul Joppa]

Just a short note to remind you and everyone that another word for "flailing" is 'learning" ... :^)

[Deluk]

Flailing is something you might be doing if you come into contact with high voltage, but yes you do learn by your failures. Usually mentioned is that you do not apply any voltage to the circuit until you are satisfied that the resistance checks are correct or are within acceptable limits. The manual gives advice about this but if you get readings outside of those limits, post for advice.