Finished build. Resistance issues. Need help troubleshooting.

vaplen · 2096

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Offline vaplen

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Reply #30 on: December 26, 2020, 07:54:21 AM
That's the part I don't understand.

How do I ground the left grounding tab?  My right one seems wired exactly the same and it is grounded.

Could it just need to be resoldered? Actually that would not make sense because the tab itself should be grounded
« Last Edit: December 26, 2020, 08:00:05 AM by vaplen »



Offline Paul Birkeland

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Reply #31 on: December 26, 2020, 08:02:48 AM
Please read the last two sentences in post 25.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline vaplen

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Reply #32 on: December 26, 2020, 08:42:29 AM
You're Awesome Paul.  Didn't think I skipped any steps but I guess I made a mistake at 3AM...

Here are my new resistance readings.  Much better but still something is off.

Terminal

1=0
2=OL
3=218.2
4=OL
5=0
6=OL
7=OL
8=0
9=0
10=OL
11=9.1
12=0
13=OL
14=0
15=0
16=OL
17=OL
18=OL
19=0
20=OL
21=OL
22=0
23=0
24=OL
25=OL
26=0
27=OL

30=108
31=108
32=108
33=OL
34=OL
35=OL
36=0

H1=0
H2=108
H3=OL
H4=108
H5=OL
H6=OL
H7=108
H8=0

RCA Jacks
L center pin = OL   Ground tab = 0
R center pin = OL Ground tab =  0



Offline Paul Birkeland

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Reply #33 on: December 26, 2020, 08:59:23 AM
We'll start with terminal 3 reading as 220 ohms.  I mentioned another issue in post #25 that would likely clear this up.  It might also help to know if that resistance changes depending on whether or not you have tubes in the sockets.

Terminal 3 is shorting to some other terminal with a 220 ohm carbon film resistor attached to it.  I pointed out my concerns about this in post 25, and you need to go in there and push anything apart that's a bare lead that's touching anything it's not soldered to.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline vaplen

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Reply #34 on: December 26, 2020, 10:04:29 AM
So I partially removed the 220 ohm resistors and the 1.5uF 630v metalized polypropylene capacitor.  The terminal is still reading 220 ohms.  Anywhere else I should check?

I also resoldered terminal 5 and moved the drain wire/foil away.



Offline Paul Birkeland

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Reply #35 on: December 26, 2020, 10:35:21 AM
So the shielded twisted pair of wires that goes between A1/A12 and B1/B12 really needs to be run the way we specify in the manual.  You have it rubbing up against a lug on the 12 pin socket that sits at about 350V, and if the socket pin contacts the shield on the STP, serious destruction will occur.

Terminal 3 goes to ground through the primary of the output transformer, then the 680 ohm cathode bias resistor.  The bias resistor goes from 5 (where you have a good 0) to 11, where you have a reading that's not correct.

Is is possible that you're seeing 220K on terminal 3 rather than 220 ohms?  220K wouldn't necessarily be a problem. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline vaplen

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Reply #36 on: December 26, 2020, 11:27:32 AM
I really wish it was 200k.

I just emailed [email protected] to see if I could send my unit in to diagnose.  I was hoping this would go smoother as I spent a lot of time on it.  I'm taking a break with my unit now.  Hopefully she gets back to me otherwise I will spend some free time trying to fix things.

I've built a couple pairs of speakers, this is definitely next level

Thanks again for your help.  Depending on her answer I might be asking more questions  :)



Offline Paul Birkeland

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Reply #37 on: December 26, 2020, 11:50:34 AM
I am the contact for the repair service, and Eileen will be out of the office till the 4th.  We are doing a revamp to the repair service to straighten out some kinks we are experiencing, so I would recommend taking a short break, then getting back to it.

It may help to go through the manual in its entirety and carefully read each step, then check your work.  Some wires and connections are going to need to be moved to the proper spots for ultimate reliability, and you may discover some other issues that aren't so visible in the photos you posted.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Natural Sound

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Reply #38 on: December 26, 2020, 03:25:21 PM
vaplen, if you let us know where you are located maybe a local bottlehead can help you sort it out.



Offline vaplen

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Reply #39 on: December 29, 2020, 03:38:25 AM
Hey Paul,

Eileen actually got back to me and sent me the invoice for repair, which I have paid.  I am just waiting on the box to be shipped (I have no update yet). Just wanted to let you know.