Input resistance measurements

[Mr.Death]

I've finished up mods to my Traynor Custom Special YBA3 and find the amp to be rather tame for the mods I have done so I started taking resistance measurements to see if everything is good starting at the front end. For the low input I get 138K which is good(so Ive read) but the Hi channel only reads 220k. Attached is a schematic. The front end is like a JCM800 with the 1 meg grid leak resistor and the 68K grid stoppers. Should my reading for the hi channel be 1Meg (ish)? Thanks and again sorry for my ignorance. Ive researched this all morning and have come up short so I thought I'd ask the pros. Thanks
Rick

[Mr.Death]

Just need to know what the high jack's resistance should be from tip to pin 7 of V1 as well as the lo inputs resistance. Thanks.

[pdf64]

Just need to know what the high jack's resistance should be from tip to pin 7 of V1 as well as the lo inputs resistance. Thanks.

68k
68k+68k//470k=59k4

the Hi channel only reads 220k

Expected value is 470k+68k=538k

[Mr.Death]

Where are you getting the 470K from? I used a 1 meg resistor
Thanks

[Mr.Death]

Should hi input resistance read 1meg plus 68k= 1.68meg?

Thanks.   

[sluckey]

Should hi input resistance read 1meg plus 68k= 1.68meg?

No. 1M + 68K is 1.068M. This is resistance between tip and ground.

Resistance between tip and pin 7 is 68K.

[Mr.Death]

Well then somethings wrong with my wiring as my results are different. My wiring...Also just a note.... I didnt touch the jack wiring, was like this when I got it. Looks like the jacks are touching in a spot.

[sluckey]

Should hi input resistance read 1meg plus 68k= 1.68meg?

No. 1M + 68K is 1.068M. This is resistance between tip and ground.

Resistance between tip and pin 7 is 68K.

I should clarify. The above numbers apply if you have a dummy plug inserted into the hi jack. With no plug inserted you should measure zero ohms between tip and ground and you should measure 68K between tip and pin 7.

[thetragichero]

sluckey has a pdf amp scrapbook on his site. i always copy the fender jack wiring from it, although i like to have the 68k grid stoppers soldered directly to the tube pin

[pdf64]

Where are you getting the 470K from? I used a 1 meg resistor
Thanks

You hadn’t noted any deviations from the schematic you included, which shows 470k, not 1M.

[Mr.Death]

Should hi input resistance read 1meg plus 68k= 1.68meg?

No. 1M + 68K is 1.068M. This is resistance between tip and ground.

Resistance between tip and pin 7 is 68K.

I should clarify. The above numbers apply if you have a dummy plug inserted into the hi jack. With no plug inserted you should measure zero ohms between tip and ground and you should measure 68K between tip and pin 7.

Great! THanks for the reply. I insrted a dummy plug and got the numbers I was looking for. Perfect!

[PRR]

You hadn’t noted any deviations from the schematic you included, which shows 470k, not 1M.

It is not clear who put that very pretty "M" on the drawing, but Death's text does reference "1 meg".

[pdf64]

You hadn’t noted any deviations from the schematic you included, which shows 470k, not 1M.

It is not clear who put that very pretty "M" on the drawing, but Death's text does reference "1 meg".

Oh yeah, the cursive italic script used didn’t register with me