Testing a Battery Snap

[vigilante397]

The last Crybaby I had that passed clean signal but didn't wah had a bad transistor. Could you give us the voltages on all three pins of each of the transistors? We can tell A LOT of what's going on with voltages.

[MustangMartigan]

Which ones are the transistors from thee picture I posted? And is it possible to reach the pins without removing,the circuit board?

[thermionix]

The transistors are the 3 black things with 3 legs each, bent over.  I've seen those legs break because there is some tension from the bend-over, so that's a good suggestion for a place to start looking.

You don't need a socket wrench to get the board out, you can remove the jack nuts with a common adjustable wrench or even needlenose pliers.

[stallik]

To me, that tension clutch in the oroginal picture just looks like it's got white grease on it which is embedded with hairs,mdust & the like. Nothing to worry about.
Humour me. Instead of turning the wah on using your foot, get your finger under the treadle and activate the switch manually. It's possible that the treadle is not going down far enough to fully activate the switch.

[MustangMartigan]

To me, that tension clutch in the oroginal picture just looks like it's got white grease on it which is embedded with hairs,mdust & the like. Nothing to worry about.
Humour me. Instead of turning the wah on using your foot, get your finger under the treadle and activate the switch manually. It's possible that the treadle is not going down far enough to fully activate the switch.

Haha. I wish I was dumb enough for that to be the solution. Tho you are kinda right.. A while back I had to wedge a folded piece of paper in there so it would click with my foot. I've had to eventually do this with every wah I've owned tho. What causes this to,happen over time?

[stallik]

Switches can and do fail. In the case of a wah, there is often a piece of felt or similar, attached to under side of the treadle. This compresses over time so the stroke on the switch is reduced. Usually, the switch can be raised in the housing but eventually, you run out of thread on the switch.

You've eliminated the battery snap and the next easiest option to test is the switch especially as you've previously had to use the paper trick

[patrick398]

Which ones are the transistors from thee picture I posted? And is it possible to reach the pins without removing,the circuit board?

Looks like you'd be able to probe the transistors without removing the board. Put the black probe on the negative pin on one of the jacks, i think it's the one furthest from the enclosure walls (not sure as i never use these type of jacks) then probe each pin of the transistor and note the voltages (if any)...then someone clever will tell you what's going on and i'll come back and say 'yeah that's what i thought too' 

[MustangMartigan]

Looks like you'd be able to probe the transistors without removing the board. Put the black probe on the negative pin on one of the jacks, i think it's the one furthest from the enclosure walls (not sure as i never use these type of jacks) then probe each pin of the transistor and note the voltages (if any)...then someone clever will tell you what's going on and i'll come back and say 'yeah that's what i thought too' 

Do I need the battery plugged in and a cable in the instrument jack to run this test? Does it matter if the switch is engaged? Also, does it matter which jack I use for the test.. input or output?

I googled testing transistor voltage and think I figured out how to set the multimeter.. Rotory dial to highest ohm rating, which is 2000k on mine. Black probe in COM. Red probe in V(omega)mA. Is this correct?

[patrick398]

Yep battery plugged in since you want to see if that juice is getting to where it needs to be on the board. Assuming the input jack is wired so that the battery is disconnected when nothing is plugged in you will need to have a cable connected to the input yes.

It doesn't matter whether the switch is engaged since the voltage exists on the board regardless or whether the effect is bypassed or not.

You don't want the ohm section of your multimeter, that'll measure resistance. You want the Vdc section. Usually ranges from about 600 down to a few millivolts depending on your meter. I can't see yours particularly clearly from the picture but it looks like you've got a 20v setting. Select that, black probe on inside lug of a jack (doesn't matter which since all ground points are connected to each other) and then each pin of the transistor with the red probe. Write down all voltage readings for each and double check them. If you don't know which pins are the collector, base, and emitter don't worry too much, somebody should be able to work out which is which based on the voltage readings at each pin (assuming they're all firing correctly)

[MustangMartigan]

Yep battery plugged in since you want to see if that juice is getting to where it needs to be on the board. Assuming the input jack is wired so that the battery is disconnected when nothing is plugged in you will need to have a cable connected to the input yes.

It doesn't matter whether the switch is engaged since the voltage exists on the board regardless or whether the effect is bypassed or not.

You don't want the ohm section of your multimeter, that'll measure resistance. You want the Vdc section. Usually ranges from about 600 down to a few millivolts depending on your meter. I can't see yours particularly clearly from the picture but it looks like you've got a 20v setting. Select that, black probe on inside lug of a jack (doesn't matter which since all ground points are connected to each other) and then each pin of the transistor with the red probe. Write down all voltage readings for each and double check them. If you don't know which pins are the collector, base, and emitter don't worry too much, somebody should be able to work out which is which based on the voltage readings at each pin (assuming they're all firing correctly)

Rad! Gonna try this out when I get home in an hr. Is there also a test I can do to determine if it's a bad switch? One that doesn't involve dismantling the circuit board. Also, is there opening to the switch that I'm not seeing (similar to the one that pots have) where you can spray some F5 inside? Or do you have to take the entire thing apart to clean it?

Thanks.

[patrick398]

Set your meter to continuity test and check for continuity between the lugs. I might be wired something like this but i'm not too familiar with non true bypass wiring. When the effect is bypassed you should have continuity between the 'input' and 'output' lugs and when engaged between 'effect output' and 'output'...somebody please correct me if i'm wrong...there's a good chance i'm wrong 





*This reminds me of that bit in The Simpsons where Marge decides to give piano lessons by just staying one lesson ahead...

[stallik]

Different kind of switch in this wah - it's a 3 pole jobbie. I think green is input and it switches between purple (bypass) and blue(wah)
IF that is correct, you won't be able to just short the switch as the signal will go to bypass as it's the path of least resistance. Use your Meter - set to Ohms and check green/purple and green/blue in both switch positions

Anyone know for sure how these 3 poles are wired?

[patrick398]

Different kind of switch in this wah

Dang, assumed they just used dpdt because they weren't true bypass

[MustangMartigan]

Yep battery plugged in since you want to see if that juice is getting to where it needs to be on the board. Assuming the input jack is wired so that the battery is disconnected when nothing is plugged in you will need to have a cable connected to the input yes.

It doesn't matter whether the switch is engaged since the voltage exists on the board regardless or whether the effect is bypassed or not.

You don't want the ohm section of your multimeter, that'll measure resistance. You want the Vdc section. Usually ranges from about 600 down to a few millivolts depending on your meter. I can't see yours particularly clearly from the picture but it looks like you've got a 20v setting. Select that, black probe on inside lug of a jack (doesn't matter which since all ground points are connected to each other) and then each pin of the transistor with the red probe. Write down all voltage readings for each and double check them. If you don't know which pins are the collector, base, and emitter don't worry too much, somebody should be able to work out which is which based on the voltage readings at each pin (assuming they're all firing correctly)

Alrighty. Here are the results. I was touching the 3rd and final lug (furthest from enclosure) on the output jack. I tested the transistors from right to left (when looking at the picture I uploaded). I also tested the three transistor pins from right to left, so the three readings will be right, center, left. Again, all these left and rights are taken from my picture in one of the above posts.

Tranny 1:
R: 0.08
C: starts at .42 and goes up to .54
L: 0.58

Tranny 2:
R: 0.56
C: 0.08
L: 0.0

Tranny 3:
R: 0.59
C: 0.18
L: 0.0

So there they are. Hopefully they point to the problem. Thanks.

[Elektrojänis]

One thing to check that I don't see mentioned is the power supply jack. They are usually wired in series with the battery in a way that the battery will be disconnected when a power supply is connected. The part that switches the battery out migh be corroded.

I'm not quite sure if those voltages on the transistors would be that far from zero if that was the case, but I quess it would be possible that the corroded contacts could pass just a tiny bit current to make the voltages like that. You could try cleaning the contacts on the power supply jack. There should be two contacts that are in contact with eachother but would be pulled apart when a power suply plug is inserted. That's the contact you should try cleaning.

Anyway... Those voltages are too low for the transistors to operate properly, so whatever the problem is, it is in the powering. Something is not letting the current from the battery get through.

[duck_arse]

I was touching the 3rd and final lug (furthest from enclosure) on the output jack.

the connection farthest from the enclosure, that is, the inner most, will be the tip. you want the sleeve, the ground connection, the one closest to the metalwork of the enclosure.

[MustangMartigan]

Different kind of switch in this wah - it's a 3 pole jobbie. I think green is input and it switches between purple (bypass) and blue(wah)
IF that is correct, you won't be able to just short the switch as the signal will go to bypass as it's the path of least resistance. Use your Meter - set to Ohms and check green/purple and green/blue in both switch positions

Anyone know for sure how these 3 poles are wired?

Does it matter what probe touches what? How high of an ohm limit do I set? And the battery and cable should in, yes?

[MustangMartigan]

I was touching the 3rd and final lug (furthest from enclosure) on the output jack.

the connection farthest from the enclosure, that is, the inner most, will be the tip. you want the sleeve, the ground connection, the one closest to the metalwork of the enclosure.

Ok, ill run the test again. And this is with the dial set to DCV, right?

[thermionix]

yes

[MustangMartigan]

I was touching the 3rd and final lug (furthest from enclosure) on the output jack.

the connection farthest from the enclosure, that is, the inner most, will be the tip. you want the sleeve, the ground connection, the one closest to the metalwork of the enclosure.

Ok then, here are the results of tranny test deuce. Had the battery attached to snap and an instrument cable plugged into the input. Again, I tested the trannies from right to left, according to the picture in the post.

RESULTS:

Tranny 1:
R- .07
C- starts at .40 and creeps up to mid .50s
L- .58

Tranny 2:
R- .58
C- .09
L- .00

Tranny 3:
R- .48
C- .14
L- .00

Since these results seem quite similar to the ones from the first test, I took a couple quick pictures to make sure I'm not doing something wrong. Here's the Multimeter with the rotary dial and probes still in their same spots:



And here's the Crybaby innards.. yellow circle is the lug I have the black probe on. The three red/orange circles indicate the trannies I've been testing.