Bee Pre - Low Voltage values

Horatio · 1547

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Offline Horatio

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on: October 19, 2014, 02:25:42 AM
Hi, just been through the resistance and voltage checks on my Bee Pre build... Unfortunately the figures don't look quite right:

Resistance check appears close with:
 
A4 and B1 looking low
A1 and B4 looking high
10 and 15 falling rather than rising
27, 32, 39 looking high at 0.9v but that may be within the margin of error as most my 0's for resistance were actually showing 0.4

Voltage check appears further out with:

T6, T11, C / D 3, C / D 7, C / D 9 all appearing on the low side

It feels like I may have made the same mistake on both sides...

When I did run some audio through it to a solid state amp it sounded muffled with a lot of the high end missing...

Anyway, any advice at this point would be much appreciated... I will likely be reworking all the solder points on the circuit boards later today...

Line Voltage: 248.5

Tubes: EH 300b

All tubes light up...

My kit was short the R3 143K 0.5 W metal film resistors for the regulator boards and I have substituted a pair of 100K 0.6W and 43K 0.6W (soldered in series) in place of each as an interim measure until I get a local replacement.

Resistance:

Terminal   Manual   BeePre
      
1   High dropping to 4   4.4
2   Greater than 100K (OL)   288k
3   0   0.4
4   5-6 with 300b in socket, *   5.6
5   0   0.4
6   more than 30k   49.9
7   470k   473
8   0   0.4
9   0   0.4
10   starts low, rises to 20K+   *** starts high and falls to 20k+ ***
      
11   more than 30K   50.4
12   470K   473
13   0   0.4
14   0   0.4
15   starts low, rises to 20K+   *** starts high and falls to 20k+ ***
16   starts high, drops to 4   4.6
17   greater than 100K (OL)   282k
18   0   0.4
19   5-6 with a 300b in socket, *   5.6
      
20   0   0.5
21   0   0.5
22   greater than 100K (OL)   282k
23   0   0.4
24   0   0.4
25   greater than 100K (OL)   100k+
26   0   0.4
27   0   0.9
28   0   0.5
29   *   *

Terminal   Manual   BeePre
      
30   *   *
31   *   *
32   0   0.9
33   0   0.5
34   *   *
35   *   *
36   *   *
37   0   0.5
38   0   0.5
39   0   0.9
      
40   greater than 100K (OL)   100k+
41   0   0.5
42   0   0.5
43   greater than 100K (OL)   100k+
44   0   0.4
45   0   0.5
46   greater than 100K (OL)   100k+
47   N/A   N/A
48   stablise to 603   603
49   0   0.4
50   N/A   N/A
51   stabilise to 603   604
      
A1   starts high, drops to 4   5.5
A2   greater than 100k (OL)   282
A3   varies with volume / balance 0 to 50   16.6k
A4   5-6 with 300b in socket   4.3
      
B1   5-6 with 300b in socket   4.4
B2   greater than 100k (OL)   280
B3   varies with volume / balance 0 to 50   16.3k
B4   starts high, drops to 4   5.5

Terminal   Manual   BeePre
      
C1   N/A   N/A
C2   215   213
C3   OL   545
C4   greater than 100   greater
C5   greater than 100   greater
C6   N/A   N/A
C7   more than 30k   49.3
C8   N/A   N/A
C9   more than 30k   49.6
      
D1   N/A   N/A
D2   215   215
D3   OL   545
D4   greater than 100   greater
D5   greater than 100   greater
D6   N/A   N/A
D7   more than 30k   50k
D8   N/A   N/A
D9   more than 30k   50k



Voltage:

Terminal   Manual   BeePre
      
1   5v   4.95v
2   90-110v   102
3   0v   0
4   9.85v   9.73
5   0v   0
6   146v   103v
7   0v   0
8   0v   0
9   0v   0
10   186v   189.8
      
11   146v   93.7
12   0v   0
13   0v   0
14   0v   0
15   186v   189.1
16   5v   4.95v
17   90-110v   91.5
18   0v   0
19   9.85v   9.75
      
20   0v   0
21   0v   0
22   213v   216
23   0v   0
24   0v   0
25   213v   216
26   0v   0
27   0v   0
28   0v   0
29   6.8v   6.8

Terminal   Manual   BeePre

30   6.8v   6.8
31   13.6v   13.6
32   0v   0
33   0v   0
34   13.6v   13.6
35   6.8v   6.8
36   6.8v   6.8
37   0v   0
38   0v   0
39   0v   0
      
40   213v   216
41   0v   0
42   0v   0
43   213v   215
44   0v   0
45   0v   0
46   213v   215
47   N/A   0
48   0v   0
49   0v   0
50   N/A   0
51   0v   0

Terminal   Manual   BeePre
      
A1   Risky   Not Measured
A2   90-110v   98
A3   0v   0
A4   Risky   Not Measured
      
B1   Risky   Not Measured
B2   90-110v   91
B3   0v   0
B4   Risky   Not Measured

Terminal   Manual   BeePre

C1   N/A   
C2   0   
C3   3.5-4.5v   0.75 measured on 20v setting
C4   N/A   
C5   N/A   
C6   N/A   
C7   147v   101.1v
C8   N/A   
C9   147v   100.4v
      
D1   N/A   
D2   0   0
D3   3.5-4.5v   0.75 measured on 20v setting
D4   N/A   
D5   N/A   
D6   N/A   
D7   147v   93.3v
D8   N/A   
D9   147v   92.6v

Ignore the additional selector switch you see in the photos - that is not currently connected to anything and is a placeholder for a future upgrade to switch outputs...

Thanks,

Bill



Online Paul Birkeland

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Reply #1 on: October 19, 2014, 11:12:25 AM
Are you sure you have a TL431 in the 431 socket on the filament regulator boards?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Horatio

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Reply #2 on: October 19, 2014, 11:24:09 AM
PB, don't be ridiculous, the 431 socket is where I like to keep my PN2907 - there wouldn't be room for both!!!

Soldering iron once again heating up!!!

Thanks mate!

Bill



Offline Horatio

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Reply #3 on: October 19, 2014, 12:53:02 PM
What do you know, it turns out the PN2907 likes its own socket much better and the 431 has settled right in now the squatter has been removed. All voltages bang on perfect and I now have a fully operational Bee Pre sitting warming in the corner of the room.

PB - I can't thank you enough for all your help today you have been an absolute star at diagnosing both my stupidity and the effect it has had on my kit!

Thanks again!!!

Bill



Online Paul Birkeland

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Reply #4 on: October 19, 2014, 12:55:16 PM
Eh, PJ deserves the credit for the BeePre, but I'm glad you're up and running!

-PB
« Last Edit: October 19, 2014, 01:07:18 PM by Caucasian Blackplate »

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Horatio

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Reply #5 on: October 19, 2014, 01:04:55 PM
Whoops... PJ - thanks for your help - very much appreciated!!!

Bill



Offline Paul Joppa

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Reply #6 on: October 19, 2014, 03:25:49 PM
Hey, we're a team! I'll take credit for the circuit, but the layout (and the diagnostics in this thread) are PB's, and it would never have happened if Doc B hadn't kept pushing us all to try the 300B. He gets a long lease on the corner office for that!

Paul Joppa