Testing points

[johnheath]

Hi all...

I am looking for something that could be described as a testing point.

What I would like i some sort om contact that is isolated from the chassi... a point where I can measure low voltages for bias adjustment without having to open up a heavy tube amp.

Have not seen one so any information about it is better than nothing. I am thinking about using a RCA-connector.


Best regards

/John

 

[JohnRoberts]

You need to be careful about bringing possibly dangerous high voltages outside the chassis.

You have to be doubly careful about putting said voltages in a common audio connector, because somebody will surely try to plug something audio into it... 

JR

 

[Rochey]

could you use a right angle IDC connector?
Something similar to:

Put it on the edge of your PCB. You could then get a ribbon cable and bring it to a PCB outside your device under test for measurements.

 

[johnheath]

@ John Roberts - Yes, I am aware of that... in this very specific case it is about being able to measure the cathode voltage of a pair of EL34's. Their cathodes are grounded via a 15R6 resistor and the voltage should be 1,56V when they are drawing 50mA each... so being able to measure 1,56V without having to turn the amp upside down and unscrew the bottom plate.

Preferably I would like to have something with some form of protective cap... or whatever.

I could install a small voltage meter but that is a lot of money compared to a simple connector

Best regards

/John

 

[johnheath]

could you use a right angle IDC connector?
Something similar to:

Put it on the edge of your PCB. You could then get a ribbon cable and bring it to a PCB outside your device under test for measurements.

Thank you sir

The idea is very close but in my case it is enough with a single test point... what you suggest might be a bit too many?

Best regards

/John

 

[zamproject]

Hello

An isolated banana socket...

https://fr.rs-online.com/web/p/fiches-et-prises-de-test-4-mm/2306287/

Best
Zam

 

[Bo Deadly]

A female banana socket is the usual solution for checking a bias voltage externally. There are ones that do not have any metal close to the outer edge.

 

[johnheath]

Hello

An isolated banana socket...

https://fr.rs-online.com/web/p/fiches-et-prises-de-test-4-mm/2306287/

Best
Zam

Thank you sir... it looks just like something I could use. Need to find one in Europe to minimize the cost though

Best regards

/John

 

[johnheath]

A female banana socket is the usual solution for checking a bias voltage externally. There are ones that do not have any metal close to the outer edge.

Thank you sir

Good advice... I will have a look at it

Best regards

/John

 

[Rob Flinn]

I have ueed isolated banana sockets before

http://cpc.farnell.com/mc-multi-contact/9131100/4mm-banana-socket-black/dp/CN00258?st=banana%20socket

 

[desun]

https://www.digikey.com/products/en/connectors-interconnects/banana-and-tip-connectors-jacks-plugs/302

These will give a bit higher density-- for tube amps 'bias test point jack' is what people are often using in the guitar amp world.

 

[rackmonkey]

I usually use these. For PCBs, but just drill a properly sized hole in the enclosure and solder them in.



https://www.mouser.com/ProductDetail/Keystone-Electronics/5006?qs=sGAEpiMZZMtzcnMBgC2bs9AdrKY7Wm7fVsEDaVUu%2fNU%3d

 

[johnheath]

@desun and Rob Flinn: Thank you guys... I think that I have decided to go for something like a single pole banana connector... seems just fine

Best regards

/John

 

[johnheath]

I usually use these. For PCBs, but just drill a properly sized hole in the enclosure and solder them in.



https://www.mouser.com/ProductDetail/Keystone-Electronics/5006?qs=sGAEpiMZZMtzcnMBgC2bs9AdrKY7Wm7fVsEDaVUu%2fNU%3d

Thank you sir

I have found those but I don't think they are all that useful for outside chassi mounting... probably very useful inside an amp though.

Best regards

/John