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BTW, components that are shown “greyed out” on the schematics usually are not on the actual board but... you may find these parts on some versions of the board. Sometimes these parts are optional and installed on final test. “Not stuffed” just means that the part is not installed on the board. It may have been an afterthought which was removed later. All of these are nothing to be concerned about.
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Oh, and if you’re concerned about C2, remove it and test it. It shouldn’t be 0.3 ohms!Comment
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Hi gaztech and thanks for answering my questions! I posted a couple of shots of the circuit board in “Albums” under my profile. Is that something you can access? If not I can see about posting some pictures of the board. I don’t totally trust the readings I am getting, as I sometimes have to move the probes slightly before I get any reading. That as well as not knowing a lot of times which probe should be where. Could be a lot of user error going on on my part. Thanks for continuing to help me out with this!Comment
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Blimey! I blew out L2 on the circuit board checking some voltages. I’ve tried with Digikey parts supplier, but according to the info on the parts list, the only thing they can find for a “TL431” is a 3 pin through the hole inductor. The schematic shows L2 being a coil and underneath says “600R@100M”. The parts list for L1-4 says:
”IC REG ADJ PREC SHUNT <36V
TO-226AA(LP) TH TL431”
I gave all this info to digikey but they say if it’s adjustable, it would have to have 3 pins. Any idea what this might be? L2 is the first thing the AC coming from the AC adaptor sees when the 9VAC comes into the unit. Thanks!Comment
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I’m thinking L2 is a ferrite bead rated at 600 ohms?Comment
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In series with the supply, 600ohms seems a lot.Originally posted by Enzo
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Pg.25 of svce.man. refers to ferrite bead 600R@100MHz, 300mA.Originally posted by Enzo
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Thanks g1! I wonder which ferrite bead they are talking about, as there is no reference to a part on the circuit board?Originally posted by g1 View PostComment
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Not sure, but the 600R@100M is a match. It states that there are a total of 8 in the quantity column. Do you see more of them?Originally posted by Enzo
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Here's a ferrite bead with an impedance of 600 ohms at 100MHz
https://www.mouser.com/ProductDetail...aMkRkFsQ%3D%3DComment
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Thanks again g1 for the reply! Please excuse me for my "noobesence" as this is all pretty new to me. I'm thinking in the service manual the footswitch unit I'm working on shows 4 inductors on the circuit board (L1-L4). I can also see page 1 has L2-L7 in the lower right half of the schematic. On page 5 Guitar Output shows 15 (L1-A-D through L3-A-D). Page 6 RJ-45 Build lists L5-L12. I could be totally off base, but I'm thinking from about the middle of page 13 to about the upper 3rd of page 18 is listing all the parts for the footswitch, while lower 2/3 of page 18 - page 26 are showing the parts that go into the guitar. Does that seem to be the case? If so, I'm thinking the info I want is on pg 17, third item down. I now realize I thought the "Ref: L1-4" applied to the 4th item on pg 17 ("IC REG ADJ PREC SHUMT <36V"). DOH!!!!Originally posted by g1 View Post
One question I do have is on the same page (17) the sixth item down which says "IC REG -5V 79L05 100mA TH" does not have a "Ref:" I know the part is U5 on the circuit board. Did they leave this out for a reason, or is this a mistake? Thanks again for your time!
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Hi Bill,
We're way off base with this.. You keep referring to a TL431 - this isn't an inductor.
The TL431 provides the 2.495 reference voltage - which is component U8 - not L2.
If you really did blow out L2 (which sits right at the supply input) then you shorted something directly to ground. This could be really bad news.
For the moment, you can replace the inductor with an 1/8W 10 Ohm resistor. You will have to replace the inductor at some point but this component will make it work at least for testing. If anything else nasty happens it will blow out the resistor.
I'd be concerned now about Diode D10 - you might have taken that out as well. You really MUST be careful when taking measurements. These small components are very unforgiving. If you make a mistake then you can kill stuff very easily. When stuff blows out, it can "knock on" to other components that were previously ok. God only knows what has blown out now.
You still need to have the +7V working AND the -5V and the +5V. Without these, nothing will work at all. You will now need to go back to the beginning and start again.
Do you know how to test a diode? Do you have a diode test on your meter. If you do, you will need to make sure this done is ok before turning the unit back on. You "can" make a rudimentary test with a resistance mesurement but it's best to remove the component. If you remove it, Note the direction it was installed. There will be a stripe on one end. Note this. It's important. When out, test the diode. On a resistance only test yuo should see it conduct one way but not the other. If you have a proper diode test on your meter then it will not conduct one way and show about .6V the other way. (I'm trying hard to keep this as simple as I can but it's not easy...).
If it checks out ok, put it back into circuit.
Take out Q9. Take out U1, U2, U3. They could all now be damaged. Once you have removed all these components, plug it back in (not the guitar! - but with a jack in the input.)
Ok, now being VERY careful with your probes....
Check voltage across C9 - should be about +9V.
Now check voltage across C12 (negative probe to + on the cap). You should have -5V
Check voltage across C11 (negative probe on to - of cap). You should have +5V.
You should also have around 2.5V on two of the pins of the TL431 (U8) - I think... You might not. If you don't don't worry about this for the moment.
If any of these voltages are missing, do not try putting any components back. You need these voltages right first. Take these measurements and let me know what you find.Comment
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Thanks gaztech for the reply as well as your patience! My bad on looking up L2 on the parts list. I now realize the “Ref:L1-4” was talking about the information above it, not below it. Yes, I have a diode tester on my meter and have used it before, so I will take out D10 and give it a test. I’ll also take out Q9, U1,U2 and U3 and check the capacitors you’ve mentioned for voltages. Thanks for the reminder about where to put the negative probe for each capacitor. I’m thinking with any luck there is a good chance we’ll get this unit back up and running by the time they have approved a vaccine for the Corona virus. 🙂🎸Originally posted by gaztech View PostComment
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Hi Bill,
I took a look at your pictures. Yes... the board you have is a bit different! This won't help the process at all.
I'm going to appeal to Line 6 today to see if they will release a Version 2 drawing to me. Note that if I do get it I might not be able to share it. I'm very rigid on this. If a manufacturer tells me specifically NOT to share it, I won't. It's important to respect their wishes in this regard. If you don't they totally clam up which doesn't help anyone.
I'm expecting them to say no and refuse to give it to me but we'll wait and see. We might get lucky.Comment
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