MTM Magnetophon

[boombipbass]

I just soldered together a Megnetophon, so far Ive succeeded the Mikrophonie and the Music thing, I am sure I've checked the making the module manual quite close but it doesn't generate any sound from my tape loops I've stuck on a piece of wood with the 2nd head, also the 1st head is not responding nor do I get a feedback hum from other modules form the output.

How could I check with a multimeter if the module is getting power in the circuitry?

Best bbb

[boombipbass]

Ok well Ive just learned that you should atleast never put a just soldered module in your Eurorack..

Oups haha. Well atleast Ive learned something on my own, but now to think, I do have a multimeter or are there better solutions?

Best bbb

[TomWhitwell]

If the module is completely dead, check the op amp chip is getting power - look at the data sheet (google TL072) and see which pins need +v and -v. Put the black probe on -v and the red probe on +v and you should see around 23-24volts. Check the chip is correctly oriented.

[boombipbass]

Is this the data sheet? https://github.com/TomWhitwell/Magnetophon/blob/master/Magnetophon_Schematic.pdf

How do I know which is 5+ and -6 of the 8 pins? Its faceing the right way aswell as the OpAmp Holder.

Also how can I check if the TapeHead/minijack male is working with my Multimeter?

Thanks for helping me ^-^

Love your stuff!

[TomWhitwell]

It’a on page 5 here : http://www.ti.com/lit/ds/symlink/tl072.pdf

(NOT page 4, that’s the tl071)

[boombipbass]

Ah yes by following the copper route on the backside I already found out that R17 connected with 7 and thus which 5 must be since that one connected to the OpAmp nr. 1 in the schematics, wow learning new things here 🗡

[boombipbass]

Strange that a black probe must be on the - and a red on the + since the ribbon is otherwise in color :)

[boombipbass]

is it AC of DC?

[boombipbass]

Nope not with AC nor with DC its getting 23/24 volts. On my multimeter set to 20 V. I've checked with the OpAmp holder aswell as with the OpAmp itself :- (

[TomWhitwell]

OK, that’s something to hunt for - a missing connection somewhere - you can upload pictures of the boards here but I’m about to go away for two weeks.

On 30 Jul 2018, at 10:09 am, boombipbass notifications@github.com wrote:

Nope not with AC nor with DC its getting 23/24 volts. On my multimeter set to 20 V. I've checked with the OpAmp holder aswell as with the OpAmp itself :- (

— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[TomWhitwell]

Power is DC

[boombipbass]

I do have to say I havent put it in my modular system, because I read thats stupid and I should actuaklly use a Bench power supply or some sort?

[boombipbass]

I am (almost) sure all connections are soldered good though

[boombipbass]

[boombipbass]

Also on modulargrid it says this about the magnetophon which i dont udnerstand?

[TomWhitwell]

That just means nobody has put the power specs into modular grid - it draws around 25mA or less on each rail

[boombipbass]

Ok thats good to know, then the only thing I am wondering, do I need a Bench power supply to test DIY kits or not?

And should I recheck the module in the case with the IC to see if it gets 24 volts, it has been in the case and no smoke or explosions so thats a good thing :)

[boombipbass]

Ok well checked it with Power on and still no Votlage, any solution? :)

[realitycontrol]

If you're measuring between the +V and -V pin on the OpAmp using the 20V DC setting on your multimeter (as stated above); you will not get a reading.

You want to be using the 200V setting when you are expecting anything over 20V. If using the 20V setting you could separately measure the + and - pins to ground.

[zerojardins]

As I can see on the pictures of your board, you misplaced both fuses with the two 100n capacitors (C4 & C5)

hope that helps