Simple SE - Right side with low volume and crackly sound - diyAudio
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Old 9th May 2010, 12:29 PM   #1
Salsero is offline Salsero  United States
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Default Simple SE - Right side with low volume and crackly sound

I assembled my simple SE and must say, the left side rocks. The right side, well it does not sound nearly, nearly as loud as the left side and it is crackly. I have tried re-melting the solder to the tubes sockets and caps, resoldered some odd looking resistor joints, checked the input and output connections, switched transformers, etc..... and nothing. I will report the separate voltages at different points later today.
In the meanwhile, I did notice that there are two open connections around C22 that I have nothing connected to. However, the picture in the website shows solder in those two holes (one of the holes sits on the outer diameter of C22). Am I missing a component in these holes? They are not marked as anything........
Secondly, I soldered a three way connector to the input of the right channel and later notices that it uses only a two wire connector. Is this a big issue?
Thanks for your input
Salsero
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Old 9th May 2010, 03:48 PM   #2
Salsero is offline Salsero  United States
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Default Left vs Right side measurements

OK, here are some measurements,

Primary transformer - 427V, both sides
Primary transformer to the UL connection = 4V, both sides
Voltage drop across the transformer primary - 10V both sides
C21 and 22 = 228V, 222V respectively
R17 and 27 = 36V drop across resistor
C10, 20 = 1.88V
R14, 24 = 83V drop across resistor
R13, 23 = 2.8V
R13 and 23 to ground = 230C and 224V respectively
R19 and 29 to ground = 231 and 225V, respectively

Is this 6V difference between left and right a concern?

I noticed that when I switch transformers, my problem tracks with the transformer since the good sounding side switches. This indicates that the circuitry most likely is OK.

If I switch speakers, my problem also switches indicating that the speakers are OK.

So I assume I have a transformer problem. How can I fix or verify this prior to sending these GSX Edcors back?

Thanks
Salsero
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Old 10th May 2010, 01:21 PM   #3
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Quote:
So I assume I have a transformer problem. How can I fix or verify this prior to sending these GSX Edcors back?
There have been two or three SSE's that had a bad channel upon initial power up. Most have been traced to a problem with the speaker jacks. The simplest way to test for this is to disconnect the output wires on the OPT from the rest of the amp and connect them directly to the speaker using clip leads. If this results in sound then there is a problem with the speaker jacks or the wiring.

The voltage readings that you posted look OK.
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Old 10th May 2010, 02:25 PM   #4
w5jag is offline w5jag  United States
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A bad cathode bypass capacitor will reduce the gain of the affected channel about 6-8 dB, but probably would not sound crackly.

Crackly is probably mechanical in nature.

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Old 12th May 2010, 12:21 AM   #5
Salsero is offline Salsero  United States
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Question Right side clear, but still low volume

OK, thanks for the ideas. I cleaned up the crackly sound by working on the speaker connection. However, the right side is still lower than the left and the bass is not as full.

Note - I am running ultralinear without Cathode Feedback.

Can the six volt difference between left and right be indicative of a problem with the ultralinear connection/circuit - I am tempted to resolder all UL connections.

Could the CFB feedback capacitor be the problem although I am not running CFB mode?

Thanks
Salsero
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Old 12th May 2010, 12:45 AM   #6
rknize is offline rknize  United States
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The slight difference in plate voltage is normal behavior from the CCS forcing the plate current for each tube to be the same. Also, you have to take into account the 5% tolerance of R14/24. Measuring across R13/23 instead of relative to ground would be more telling and I suspect you will find they are within 1%.

Check you solder work around C12/22. Also try disabling CFB for both sides and see what happens.
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Old 12th May 2010, 12:46 AM   #7
Salsero is offline Salsero  United States
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Question Some more measurements

OK, more measurements follow -
Voltage drop across R18 and R28 = 0.52V
Voltage drop across C12 and C22 = 35V each

Thanks in advance for any suggestions
Salsero
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Old 12th May 2010, 12:48 AM   #8
Salsero is offline Salsero  United States
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Default .........and we keep going here

Russ,
I am not running the CFB connections, they are shorted to each other as in the wiring schematics. What do you mean by "try disabling the cathode feedback"?

Thanks, gracias, merci
Salsero
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Old 12th May 2010, 12:59 AM   #9
rknize is offline rknize  United States
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From your previous post, I thought you were using CFB. By "shorted to each other" I assume you mean the CFB connection is shorted to their respective grounds? In other words T2-SEC and T3-SEC should each have a jumper between the two terminals.
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Old 12th May 2010, 01:14 AM   #10
Salsero is offline Salsero  United States
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Question and it keeps going........

Russ,
The T2SEC terminal 1 is connected to T2SEC terminal 2.
The T3SEC terminal 1 is connected to T3SEC terminal 2.

Does this disable CFB? or should I disconnect terminal 1 and terminal 2 for T2SEC and T3SEC?

Thanks for your time. I feel I am close but still not there yet.

Salsero
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