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Bottlehead Kits => Crack-a-two-a => Topic started by: Love Rhino on February 12, 2021, 05:19:27 PM

Title: High voltage on IA and one LED not lit
Post by: Love Rhino on February 12, 2021, 05:19:27 PM
Hi helpful forum folks!

I have completed my build and passed resistance checks.  The only thing that might concern me on the resistance checks is 6 and 16 measuring 35k instead of the "might measure 25k" that the manual states.

When measuring voltage, I am getting a very high reading of 350 from IA.  I stopped measuring at this point to make sure I don't damage the amp.

The LED attached to A8 is not lit.  All other leds, including the other led on the A socket and both boards are lit.  The tubs all glow.  There have been no explosions as of yet, and I have not travelled back in time.  These are wins.

I have rechecked my wiring and visually inspected joints.  Any idea on an area of focus?  Thank you in advance!!!
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 13, 2021, 07:07:31 AM
What's your AC line voltage?  Can you post some photos of your build?

350V at IA would either mean your in a 220V-240V mains country and you wired the amp for 120V (unlikely), or you have a loose connection in your amp causing weird voltage issues (nearly certain).
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 13, 2021, 12:47:10 PM
Line voltage was 119, and the initial voltage tests were in range, at 3.0, 3.0, 6.1, and 166.

In the pictures I do not have the low current board screwed in, to be better able to see the sockets.  I'm not surprised
 the A8 led isnt lighting, I really struggled with that little bugger; it was probably that hardest thing to solder in the build for me.

Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 13, 2021, 12:49:34 PM
I can't see much in your photos because they are tiny.

I would reflow every solder joint in the amp other than the power switch and the center post of the 9 pin socket.  This is what I do on pretty much any repair that I get and that resolves most issues.

What is the DC voltage at terminal 24?  How about 25?
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 13, 2021, 01:18:31 PM
Paul,  thank you for your quick reply on a Saturday - you're the best.

DC voltage at 200 setting were 191 at terminal 24, and 0 at terminal 25.

I've adjusted the size of the photos, perhaps these will work better:

Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 13, 2021, 02:24:04 PM
DC voltages at 30 and 31?
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 13, 2021, 02:25:40 PM
When you connect something to a terminal, you need to bend the lead up (for the lower terminals) or up and around for an upper terminal.  Just letting a component lead poke through the terminal and soldering isn't adequate and will lead to an amp that doesn't work.   This is in red text on page 20 in the manual.
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 13, 2021, 02:26:46 PM
The resistor going to pin 7 on the 9 pin socket is untrimmed.
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 13, 2021, 05:05:26 PM
DC voltages at 30 and 31?

192 for 30 and 0 for 31.

Getting to work on cleaning it up now :).
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 13, 2021, 05:12:47 PM
The resistor going to pin 7 on the 9 pin socket is untrimmed.

This fixed the led lighting.  Voltage on IA dropped to 259, so something is still off but it’s getting better.
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 13, 2021, 07:34:29 PM
It would help if you listed the voltages for IA, OA, and OB on the large C4S boards.  It would help to have IA, IB, KregA, KregB, OA, and OB on the small board.

The IA voltage on any of the C4S boards will not be more than the voltage at 30 or 24.

What is your voltage at 32?
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 13, 2021, 08:04:57 PM
Here is the full voltage check:

Low current c4s
IA 281
OA 264
KregA 0
BRegA 261
IB 327
OB 165
KregB 12
BRegB 327

High current c4s
IA 422
OA 249
bA 0
IB 0
OB 233
bB 248

Tip and ring are 0

Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 13, 2021, 08:07:10 PM
Voltage at 32 is 465
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 13, 2021, 08:12:53 PM
The voltage for the board closest to the power switch measured slightly different.

IA 420 (about the same)
OA 325 (vs 249 on the board closest to the rca input)
BA and IB 0
OB 208 (vs 233)
bB 328 vs (248)
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 14, 2021, 05:17:08 AM
Yeah, you definitely have a loose ground wire in your amplifier.  Don't worry about actually having 465V at terminal 32, that voltage is only an indicator that things aren't well connected.

Reflow all of the solder joints, and whatever you do don't try to listen to it!
Title: Re: High voltage on IA and one LED not lit
Post by: Deke609 on February 14, 2021, 07:52:22 AM
Yeah, you definitely have a loose ground wire in your amplifier. 

My additional two pennies: (1) you've gone fairly light with the solder; and (2) none of your connections look crimped. That combo is a recipe for sketchy connections. If the leads are not crimped around the solder lug, there's a good chance there's no mechanical/physical connection and you must rely entirely on solder to make the connection.

I'd suggest crimping wherever remaining lead length permits, and adding some solder everywhere.

cheers, Derek
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 15, 2021, 02:09:00 PM
Well oooof.  I've spent the weekend trying to clean up connections, crimp, and add extra solder for connections that seem light.  I also went through the measurements again, starting with the original voltage check.

Unfortunately, pretty much no change.  I had some things lowered when I put in different tubes (I know, its not the tubes). 

Current voltages:
IA 208
OA 169
KregA 0
bRegA 208
IB 327 (unchanged with different tube)
OB  161
KregB 10
bREgB 327

I'm sadly questioning my ability to complete this :(.
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 15, 2021, 04:01:34 PM

Current voltages:
IA 208
OA 169
KregA 0
bRegA 208
IB 327 (unchanged with different tube)
OB  161
KregB 10
bREgB 327
Are these all on the center C4S board?  A list of voltages would be:

High Current C4S B Side:
IA, OA, IB, OB
High Current C4S D Side:
IA, OA, IB, OB
Center C4S Board:
IA, OA, IB, OB, KregA, KregB

What DC voltage do you have at 32? 30? 24?

If you can put this information into a single, well organized post we can let you know what to look at next.

-PB
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 15, 2021, 05:56:53 PM
DC voltage 32: 211
30: 197
24:191

B board:
IA: 418
OA: 209
IB: 0
OB: 176

D Board:
IA: 414
OA: 328
IB: 0
OB: 211

Center board:
IA: 208
OA: 169
KregA: 0
bRegA: 208
IB: 327
OB: 161
KregB: 10
bRegB: 327

I really appreciate your help :)
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 16, 2021, 05:29:32 AM
DC voltage 32: 211
30: 197
24:191
B board:
IA: 418
24 and IA are wired together with a piece of wire.  You appear to have 200V across said piece of wire.  Perhaps it's broken or not well connected, or you have a loose ground.  This is the only issue to focus on right now, it needs to be resolved before moving on to anything else.
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 16, 2021, 05:17:25 PM
Paul, I reconnected 24 and IA of the B side board.  Will it be an issue to connect to 24U instead of 24L?  It was easier to ensure I have a good connection and solder point. 

There was no change with the voltages compared to the measurements yesterday.
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 17, 2021, 07:09:34 AM
Yes upper vs. lower isn't the end of the world. 

Again, 24 and IA connect with a piece of wire.  If they don't have the same voltage, they are not connected with a piece of wire. 
Title: Re: High voltage on IA and one LED not lit
Post by: Doc B. on February 17, 2021, 09:39:45 AM
If there is no change your wire is probably broken inside the insulation. Sometimes they get nicked by wire strippers and break there when getting installed.
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 17, 2021, 05:35:07 PM
I replaced the red wire from 24 to IA with some black wire (the only wire remaining with enough length) and now the voltages match at 191 each.  I've worked more on other wires and solder points, and low and behold some of the measurements are in the proper range.  Some have dropped low.

Center board:
IA 94
OA 78
KregA 0
bRegA 94
IB 68
OB 61.4
KregB 1.1
bRegB 70

B Board:
IA 194
OA 94.4
IB 0
OB 80

D Board:
IA 198
OA 70.5
IB 0
OB 61.8

32: 211
30: 197
24: 191
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 18, 2021, 06:17:10 AM
I would suggest taking all your boards off and reflowing all the solder on the boards and what's under them.

If you have one broken wire, you probably have more.  It's possible that you may be best off getting a fresh wire bag and a better set of wire strippers and replacing most of the wires in the kit. 
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 18, 2021, 08:59:58 AM
A quick side question: is it normal to have the led on the center board be much less bright than the other leds?  I want to check before I reflow on all the boards to see if this is an additional problem to correct.  They are all lit, but harder to see than the others based on their brightness.
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 18, 2021, 10:18:50 AM
The LEDs are not intended to be a diagnostic tool.  The brightness of the LEDs themselves depends on the current running through them and we run different amounts of current through the LEDs depending on what they are doing in the circuit. 

Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 19, 2021, 08:42:08 PM
So there is a led that is not lit on the D side board on D1 on the A side.  I changed out the wire on the board and reflowed/resolderd the entire board.  I wanted to start with this board because this is the only led not lit.

My next step is to resolder and rewire the other two boards.  Will this have any effect on the led on the D board, or do I need to look elsewhere?
Title: Re: High voltage on IA and one LED not lit
Post by: Paul Birkeland on February 20, 2021, 05:05:18 AM
So there is a led that is not lit on the D side board on D1 on the A side.
The LEDs are not intended to be a diagnostic tool. 

In order to determine whether your efforts have had any positive impact, you'd need to post that complete list of voltages again so we can look for changes.
Title: Re: High voltage on IA and one LED not lit
Post by: Love Rhino on February 20, 2021, 07:33:34 PM
Went through the other two boards today and rewired and reflowed solder.  Had a bit of a frustrating result as the voltages remained the same, and two additional led on the center board stopped working.  I went back to resistances to check those, here are the results:

1. o
2. *
3.0
4. 140
5. 2.14k
6. 58.8k
8. 0
10. *
11. 0
12. 160
13. 0
14. *
15. 2.14k
16. 49k
18. 0
20. *
21. 0
22. Over limit (highest setting)
23. Over limit (highest setting)
24. *
25. 0
26. *
27. *
28. 0
29. 0
30. *
31. 0
32. *
33. 0
34. 0