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PostPosted: Fri Jun 19, 2020 11:24 pm 
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I am hoping that someone can point me in the right direction as to what the check before completely racking my brain and poking and prodding unnecessarily...

I finished the build and checked all connections. (I was pretty diligent in tracing connections with a separate print out as I went through the build.) The amp works and nothing is overheating, etc. but generally, I have a weak signal with hum.

My B+ measured 434, and was showing on all of the plates before I installed the tubes.

Once I installed the tubes and fired it up, the voltages on V1-V4 and V7 were all a little high, but relatively so (if that makes sense). For example, Pin 1 of V1 was 103 instead of 85. The weak signal makes sense as there is an issue with the voltages of V5 and V6. Pins 3 are showing as .5DC and pins 9 as -.5VDC rather than the expected 8.3 / 242.

Here is a list of my voltages measured matching the table in the builder's guide:
V1 103 2 154 2
V2 178 1.58 178.5 1.58
V3 178 1.46 312 178
V4 298 53 77 290 51.4 77
V5 .5 419 -.5
V6 .5 419 -.5
V7 419

Any help is much appreciated.


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PostPosted: Sat Jun 20, 2020 12:37 am 
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Joined: Sun May 17, 2020 5:14 pm
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Update:
First, I noticed that the supplied power cable does not seat properly in the IEC socket, so I swapped it out to another which makes a good connection. I also swapped to two EL84 tubes and and was able to get a louder signal (also with near-appropriate voltages) at Pins 7 of V5-6. However, now there is still only .5 showing on pin 3 of the two tubes. I will try reversing them again tomorrow to see if this is consistent-- if so, would this be an indication of a bad tube?


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PostPosted: Sat Jun 20, 2020 12:33 pm 
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Joined: Sat Dec 04, 2010 3:42 pm
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Location: Qualicum Beach, BC
Hi, welcome to the forum.

Sounds like you have most of the amp working.

Check the wiring to the screen grids (pin 9) on V5 and V6, all the way back through the 100R resistors, the terminal strip, and the 22K resistor until it gets to B+ on the board. Look for bad solder connections and missing wires. Check the 22uF capacitor as well.

Also check wiring to the cathodes (pin 3) back through the 150R resistor until it gets to ground on the board. Check the 220uF capacitor as well.

It helps if you post a picture or two of this area.


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PostPosted: Sat Jun 20, 2020 5:10 pm 
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Ch. 1 had signal but no clean tone. With the volume slightly on it was distorted and with it ¾ of the way to full volume, it was very muddy. Ch. 2 has a very low audible but clean signal in the HI input and barely audible clean signal when plugged into the LO input.

I checked all the connections leading back to the board as you suggested (using the schematic and layout and found that I had missed the wire connecting the board to the terminal strip between V5 and V6. :roll:

A new issue arose when I was checking everything where I also wasn't getting the correct voltage on V3 after the 100k resistor at pins 1 and 7 so I swapped it out with another I had on hand. That took care of it, so I'll follow up on that later to see if the tube is bad or was just not sitting properly at the time.

Anyhow, the amp is up and running now, so its time to play around with all the bells and whistles and get to know how it works. :happydance:

I was testing it with a low-end jenson speaker, so I'm looking forward to plugging it in to the 2x12 cab I built with WGS speakers and playing around a bit before installing the fx loop. I'll post some pictures as well, since I found another thread or two with gut shots helpful to double-check some things as I went along.


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PostPosted: Mon Jun 22, 2020 6:36 pm 
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Location: Central California
What WGS speakers are in your 2x12? Just curious... I'm a huge ET65 fan, but I actually am not ashamed to say I like my TC15 better with a Veteran than the ET65.


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PostPosted: Mon Jun 22, 2020 8:52 pm 
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Funny you should mention those two WGS speakers-- the 2x12 I built a while back to accompany my silver jube clone has both a Veteran 30 and ET65 loaded in it... I played around a bit with each separately and thought the ET65 sounded better, but will give the Veteran a second chance.

Image

Image


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PostPosted: Mon Jun 22, 2020 9:23 pm 
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That pairing should sound great with the amp.


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