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December 05, 2019, 04:51:57 AM

Author Topic: A little help please [resolved]  (Read 2898 times)

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Offline Karl5150

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A little help please [resolved]
« on: June 27, 2015, 09:39:09 AM »
I thought I'd start a new topic to attract attention. I finished the build and ran the resistance checks and all was well until #45.
It should be 0 Ohms, but it reads like the other side, varying readings up into the mega ohms.
I re-flowed both 45L and 45U
Bad cap?
Thanks for any help on this.
« Last Edit: June 29, 2015, 02:42:39 PM by Caucasian Blackplate »
Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Offline howardnair

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Re: A little help please
« Reply #1 on: June 27, 2015, 12:00:22 PM »
Karl. I have the first version but if that is a resistor across the electrolytic it looks broken

Offline Karl5150

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Re: A little help please
« Reply #2 on: June 27, 2015, 12:51:20 PM »
Thanks for looking, it is a bad phone picture, just to show proper location and orientation. 45U is on the right end of the strip, striped side of the electrolytic, nothing else attaches to 45U. All the other electrolytic caps read 0 in the striped side.
Still puzzled
Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Online Paul Joppa

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Re: A little help please
« Reply #3 on: June 27, 2015, 08:31:34 PM »
It appears to me that T45 and T42 might read high or low depending on which meter terminal is grounded.
Paul Joppa

Offline Karl5150

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Re: A little help please
« Reply #4 on: June 28, 2015, 06:42:46 AM »
Paul, thanks for the reply. I tried 2 meters, both terminal alignments but 45U always acts like the unstriped side of any of the electrolytic caps. Still stumped.
Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Online Paul Birkeland

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Re: A little help please
« Reply #5 on: June 28, 2015, 08:58:07 AM »
45 and 42 are connected, and will not measure 0 Ohms.  This is an error in the manual.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Karl5150

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Re: A little help please
« Reply #6 on: June 28, 2015, 10:47:45 AM »
Thanks Paul. I will proceed with the V checks.
Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Offline Karl5150

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Re: A little help please
« Reply #7 on: June 28, 2015, 01:51:58 PM »
I went ahead with the power-up and voltage checks. All tubes and LEDs glow, no sparks, no smoke & no odd smells (from the amp anyway)
Three voltages came up way off:

#4-   Manual: 0V                Actual: up and down, max observed 58V
#7-   Manual: 170-230V      Actual: up and down, max observed 290V
#17- Manual: 0V                Actual: up and down, max observed 48V



Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Online Paul Joppa

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Re: A little help please
« Reply #8 on: June 28, 2015, 02:52:35 PM »
If you observed this by conecting the meter, then turning on the amp, then turning it off to change the meter connection, and repeating this sequence, these are reasonable numbers - but what the manual reflects is the steady state voltage after the turn-on transient, which you have not provided.

If on the other hand you left the amp on for all the voltage checks, and the steady-state includes fluctuation of these maximum magnitudes without ever settling on a steady value, then there are some severe problems.

Please let us know how you made these measurements.
Paul Joppa

Offline Karl5150

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Re: A little help please
« Reply #9 on: June 28, 2015, 03:23:00 PM »
Paul,
The voltage checks were all made with the same auto range meter (Klein MM200) with the common clipped to the safety ground tab. The numbers reported were recorded after running through all the voltage checks and determining they were the only anomalies, the amp being powered on for several minutes.
I went through the resistance checks again and all AOK (the issue with #45 being solved earlier) I will do another step by step visual check with manual to see if I missed something the first couple times through.
Again, thanks for the quick feedback.
Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Online Paul Birkeland

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Re: A little help please
« Reply #10 on: June 28, 2015, 05:16:40 PM »
#4-   Manual: 0V                Actual: up and down, max observed 58V
#17- Manual: 0V                Actual: up and down, max observed 48V
Are you 100% sure about this?  There's a 249K resistor between 4 and 5. 4 is grounded, and the 249K resistor is supposed to hold 4 to ground.  Are you seeing some mild fluctuations that might be 58mV? (or 48mV?)
#7-   Manual: 170-230V      Actual: up and down, max observed 290V
That may settle after the amp has been run for a while.  If you want to check, swap the 12AT7's and that voltage should move over to T14.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Karl5150

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Re: A little help please
« Reply #11 on: June 29, 2015, 01:07:34 AM »
I went through the manual again, step by step visually confirming all locations/connections. I even ran the transformer output checks again: As with the resistance checks, all good.
After work I will check Vs on #s 4 & 17 to make sure I didn't misread the meter.
As for #7, I must be, in some small way, catching on a bit because my plan was, as you suggest, to swap tubes, since #14 reads a steady 191V.
Again, thank you guys for the support.
Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Offline octavian

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Re: A little help please
« Reply #12 on: June 29, 2015, 04:58:50 AM »
Hi Karl,

I just finished mine last night and all of the voltages checked out, so I suspect it's not an error in the manual, if that helps!

Offline Karl5150

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Re: A little help please
« Reply #13 on: June 29, 2015, 06:30:52 AM »
Octavian, you got 0 Ohms on #45?
Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Offline Karl5150

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Re: A little help please
« Reply #14 on: June 29, 2015, 06:34:51 AM »
My bad. I see you said voltages. Thanks
Karl
Downstairs: Planar3>Eros / X-12>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Upstairs: DIY RP1>Reduction / CD5004>SEX 3.1.1>FH3/DT770 pro
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK