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PostPosted: Thu Dec 24, 2020 1:46 pm 
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Joined: Thu Nov 19, 2020 11:55 pm
Posts: 6
Location: McKinney, Texas
Just finished building my 5E3 kit. It was loads of fun.

I ran through the voltage checks this morning. There were some readings that were off by more than what seemed reasonable so I wanted to confirm. While touching the tube terminals for the voltage chart I would hear a click (sometimes a bit loud) when I first touched the tube terminal. When I plugged in a patch cable to the input jacks and touched the tip I am getting squeeling on all but one of the inputs.

Voltage Chart (expected values in parenthesis, JJ 5Y3):

Code:
Pin # ->   1              3               4               6                 7                8

V1      120(120)      1.88(1.8)                         116.8(120)                        1.8(1.3)

V2      156(148)      1.26(1.3)                         241(191)        19.5(17)           57(45)

V3                    370(356)         331(326)                                            20.6(20)

V4                    371(356)         331(326)                                            20.6(20)


I'm concerned about:

V2,pin6 241(191) ; V2,pin8 57(45) ; V3&V4,pin3 370(356)


Eyelet Board Test Points (left to right, expected values in parenthesis):

20.6(22), 376.4(360), 330(348), 240(255), 57.3(50), 19.6(18), 240.4(204), 155.5(158), 1.26(1.4), 120.6(130), 117.8(130), 1.85(2.0)

I'm concerned about numbers 3, 4, 7.

I ran the volume-to-V2 shielded cable under the eyelet board.

Any concerns about the voltage readings? Also any advice for the squeeling?

Thanks


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PostPosted: Fri Dec 25, 2020 11:08 am 
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Joined: Thu Nov 19, 2020 11:55 pm
Posts: 6
Location: McKinney, Texas
After digging into this a bit more I see that V2,pin6 is connected to the 7th eyelet board test point. At least that's one problem and not two.

The other voltage concern is the two test points immediately after the B+1. From what I'm reading, these are step down voltages on the 2nd and 3rd filter caps. Given they are both below the expected values while most of my readings were somewhat above the expected values, I'm suspecting the step down resistors. I was having some trouble with a cheap pencil tip on my soldering iron during those joints (up to 30 seconds to flow) and I'm wondering if it fried those resistors.

This is my first build and I don't really have any intuition for what is or is not a problem with the voltages. Any insight would be greatly appreciated.

I have some things to look at concerning the squeeling when touching the tip of the patch cable.

Thanks again and Merry Christmas!


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PostPosted: Sun Dec 27, 2020 6:04 pm 
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Joined: Thu Nov 19, 2020 11:55 pm
Posts: 6
Location: McKinney, Texas
Got it all sorted out. :happydance:

It is surprisingly loud without much distortion... I wonder why that may be.


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