You are here

Interesting PCB jack input help needed.

Customising, building or repairing your own gear? Need help with acoustic treatment or soundproofing? Ask away…

Moderator: Moderators

Re: Interesting PCB jack input help neede

Postby Animalbeats » Sun Jan 17, 2021 6:12 pm

Ok, my initial post was poor.

My level of electronics are basic, I’ve just been studying for a couple of months now and thanks Hugh for the input so-far.... for a start I wasn’t looking into the traces path and got stuck at the disconnect, I won’t be making that mistake in the future (look beyond, as the new mantra goes)

I’ll make sure my questions are suitably detailed in the future with a proper introduction.

It is a pcb mounted instrument input Jack.

Really I just wanted to know how the circuit drawn would connect to the electrolytic and WIMA, as I can’t see where the signal path goes, and there are no traces on the underside.

Small resistors are used for anti pop, and RF protection.

Input cap blocks DC and provides simple high pass filtering, as well as potentially affecting signal Impedance.... I thought

The resistors in series are yellow, violet, black, black.

The large dielectric and WIMA I’m really not sure on, there are no traces I can see on the top or bottom.

Everyones help is appreciated and excuse me for being an frustrating beginner. I will improve.
Animalbeats
Poster
Posts: 11
Joined: Mon Feb 05, 2018 7:57 pm

Re: Interesting PCB jack input help needed.

Postby zenguitar » Sun Jan 17, 2021 6:23 pm

What is the make and model of the equipment that you have.

That's all we need to begin to help you. But after several requests you still haven't given that simple detail.

Andy :beamup:
User avatar
zenguitar
Moderator
Posts: 11247
Joined: Thu Dec 05, 2002 1:00 am
Location: Devon
liberté, frivolité et vanité

Re: Interesting PCB jack input help needed.

Postby Animalbeats » Sun Jan 17, 2021 6:35 pm

I know, I’m being all cagey...

I’m gluing up my gunk gun as we speak.
Animalbeats
Poster
Posts: 11
Joined: Mon Feb 05, 2018 7:57 pm

Re: Interesting PCB jack input help needed.

Postby zenguitar » Sun Jan 17, 2021 6:42 pm

You're not being cagey. You come here asking for help, people are genuinely trying to help, but you continually refuse to offer the one useful piece of information they need.

That is a poor way to treat people who have no obligation to help but give up their time and effort.

Andy :beamup:
User avatar
zenguitar
Moderator
Posts: 11247
Joined: Thu Dec 05, 2002 1:00 am
Location: Devon
liberté, frivolité et vanité

Re: Interesting PCB jack input help neede

Postby Hugh Robjohns » Sun Jan 17, 2021 6:59 pm

Animalbeats wrote:It is a pcb mounted instrument input Jack.

Okay... So those transistors could well be FETs... It would be helpful if you can find some identification for them.

Really I just wanted to know how the circuit drawn would connect to the electrolytic and WIMA, as I can’t see where the signal path goes, and there are no traces on the underside.

A multimeter can be helpful in tracing out what is connected to what...

Small resistors are used for anti pop, and RF protection.

Resistors are used for all manner of different things. It's where they sit I the circuitry that determines their role...

Input cap blocks DC and provides simple high pass filtering, as well as potentially affecting signal Impedance.... I thought

They do... But only in concert with all the components around the input stage. That's why it's important to have the full schematic.

The resistors in series are yellow, violet, black, black.

So 4k7s?

Everyones help is appreciated and excuse me for being an frustrating beginner. I will improve.

Can I suggest reading Small Signal Audio Design by Douglas Self? I think you'd find it helpful in gaining a better understanding of the aspects that interest you!
User avatar
Hugh Robjohns
Moderator
Posts: 30099
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound
In my world, things get less strange when I read the manual... 

Re: Interesting PCB jack input help needed.

Postby Animalbeats » Sun Jan 17, 2021 7:47 pm

Sorry Zen, should have made it clear I was being cautious about what I was studying (most likely needlessly)

Hugh

Thanks for the book recommendation, I’ll give it a good read.

I’ll also follow your other tips.

The resistor code confused me as there’s no option for two blacks in a row....

Here’s one from the microscope!

Image
Animalbeats
Poster
Posts: 11
Joined: Mon Feb 05, 2018 7:57 pm

Re: Interesting PCB jack input help needed.

Postby Folderol » Sun Jan 17, 2021 8:30 pm

It's a 4 band resistor
Band 1 = 4
Band 2 = 7
Band 3 = 0
Multiplier band = 0 = no additional zeros :)
So it's 470 ohm


A three band one would be
Band 1 = 4
Band 2 = 7
Multiplier band = 0 = no additional zeros
So would be 47 ohm
User avatar
Folderol
Jedi Poster
Posts: 12376
Joined: Sat Nov 15, 2008 1:00 am
Location: The Mudway Towns, UK
Yes. I am that Linux nut.
Onwards and... err... sideways!

Re: Interesting PCB jack input help needed.

Postby Hugh Robjohns » Sun Jan 17, 2021 9:36 pm

:oops: Oops. silly me, yes of course, 470R Doh!
User avatar
Hugh Robjohns
Moderator
Posts: 30099
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound
In my world, things get less strange when I read the manual... 

Re: Interesting PCB jack input help neede

Postby N i g e l » Sun Jan 17, 2021 10:25 pm

Hugh Robjohns wrote:Can I suggest reading Small Signal Audio Design by Douglas Self? I think you'd find it helpful in gaining a better understanding of the aspects that interest you!

:thumbup:
a very good book.
Also study existing schematics to see how to exclude real world interference from mobile phones, stage lighting, etc from making it through your input stage.
N i g e l
Frequent Poster
Posts: 1377
Joined: Sun Aug 12, 2018 2:40 pm
Location: British Isles

Re: Interesting PCB jack input help needed.

Postby Animalbeats » Mon Jan 18, 2021 12:06 am

Thanks Folderall for your keen eye.

Hugh, I’m glad a man like you can make a mistake :headbang: (I’m sure you thought a faulty sighting ;) )
Animalbeats
Poster
Posts: 11
Joined: Mon Feb 05, 2018 7:57 pm

Previous