TSE Bias Trimmers and Check Points

[jeffx]

First, I want to thank everyone for helping me get my TSE up and running. It sounds good!

Now that I have it built, I would like to make some changes so that I can check and adjust the bias from the top. I have used 1/4" phono jacks and plugs on another amp for the test points, but I would like to use something that I can just stick the DVM probes in. It seems that I have seen red and black sockets somewhere for this but I can't remember where. Any thoughts, ideas or suggestions?

Also, does anyone have a DigiKey/Mouser part number for a multi-turn trimmer pot to replace the single-turn stock ones that are used for bias adjustment?

 

[Tubelab_com]

What you are looking for are called tip jacks, or probe tip jacks. They are like a bananna jack with a small hole and sold at Digikey and Newark. I know that I have posted part numbers on this forum maybe a year ago but I can't find the post now.

 

[pso]

Test points.
Mouser.
530-108-0902-1
530-108-0903-1

 

[pso]

Probe tip jacks.
Mouser.
565-6263-2
565-6263-0

 

[boywonder]

If your test points are across R18 and R29 (the 10 ohm measuring R's) they are at high voltage, are you sure that you want them exposed on the top deck?

IIRC, Rknize found a somewhat upgraded/more robust trimmer pot that fits the board, but it was still single turn........

 

[jeffx]

Thanks for the help and suggestions. I am leaning towards Digi-Key pn 501-1346-ND. Thanks for the concern Boywonder, but I have no little prying hands around the house. Also, the ones I am looking at are insulated on top with the holes only big enough(2 mm) to get the probes in.

I wish I had these installed for I now have distortion in the left channel. I have changed everything - cables, preamp, speakers and input tubes - and the problem remains. However, I have not switched the 300Bs around to see if the left one is causing the distortion. Is it ok to switch and run them for a short period without checking/verifying that the bias is good?