beepre resistance check issues

[fritzthecat]

hi there

just got problems with the resistance checks (no tubes inserted)

1 4.2
2 10 M rising
3 0.1
4 unstable (no 300b inserted)
5 0.1
6 132.7 K
7 473.1 K
8 0.1
9 0.1
10 starts around 100 K rising to 430 K

11 138.4 K
12 472.5 K
13 0.1
14 0.1
15 450 K dropping
16 4.1
17 7 M rising
18 0.1
19 unstable (no 300b inserted)

20 0.1
21 260 K (strange to me?)

accidentially I measured PT7 A iron and got around 25 ohms while I get 600 K @ PT7 B iron - shouldn't that be the same value? Does it matter at all?

22 400 K dropping
23 0.1
24 0.1
25 213 K rising
26 0.1
27 0.1
28 0.0

using Fluke 175 with new batteries

29 unstable sometimes 150
30 climbing to 150
31 300 K
32 0.1
33 0.1
34 300 K
35 150
36 150
37 0.1
38 0.1

39 0.1
40 starting @ 700k stabilizing @ 265.7 K
41 0.1
42 0.1
43 1,5 M
44 0.2
45 0.2
46 1.5 M
47 -
48 604
49 0.2
50 -
51 606

Removed the drain wire from 21L - there are 260k ? but it actually ends unconnected???

Initial pt voltage checks went fine...

Didn't continue, as I thought the issue @ 21 and the differences betwenn Pt7 A and B should be resolved first. And where the 260k come from?

Any advice where to look at?

Looking forward to get any hint - and sorry - got no engoneering background.

Cheers,

Chris

[Chris65]

Would be helpful to the BH guys if you included more information:

Which resistance readings do not match those in the manual?
The PT-7 transformer has 6 terminals, which terminals did you measure?
Did you perform the power transformer test as per the manual? and the result?
Is this a stock build? (your previous questions note a desire to modify the unit)

[fritzthecat]

thank you Chris

Just modified my post and will include more info. Initial power check went fine by the way...

Yes, it's a stock build - I always first go for a stock version and update from there and once I know the kit better I may modify directly as I did with some Kaijus.

Actually I did not measure any PT terminal - should I?

Just accidentially touched one of the pt irons with my probe - got a value there - got curious and measured both - and got the different values I mentionned above, thought it should be the same on both??? But does that matter at all or is it saying that there might be a connection to internal winding somhow? But actually the voltage checks went spot on and I guess then it already was like that -  so maybe I see problems where I should not even worry...

I removed the drain wire from 21L measured and got 260K @ drainwire ending unconnected - somehow strange to me???

Will replace it and therefore removed the C4S boards.

I'll include where I got different measurents from what the manual says tonight.

Thank you for your input.

Chris

[Paul Birkeland]

Can you perform the checks with 300Bs installed and just note those terminals that aren't correct?

[fullheadofnothing]

The only thing in that whole list that seems incorrect is 21.

21 is supposed to be grounded via the body of the transformer. The shield wire is attached there because 21 should be a ground point. Yours isn't, which points to some kind of mounting error. I'd recommend tightening the screw as a first step. Did you paint the end bells, by chance?

The power transformer is not specified in the resistance readings, and seems to be attached here for coincidence's sake...? The most valid check you can do of a power transformer would be to check its voltages. Which you say you did, so there isn't a problem with your transformer.

[fritzthecat]

Hey Josh!

Thank you sooo much... you guys are amazing!

The Bells are not painted - the plan is to have them chromized. 

Regarding mounting errors: consulting the manual I carefully checked step by step for any mounting errors - nothing there... Hmmm... me being a perfectionist makes me check everthing at least three times before moving to the next construction step, so I guess I'm on the safe side here.

The power transformer voltage checks really went fine - no problem there - voltages spot on.

Measuring the ground point @ 21 after removing drain wire from 21 -  I get 0.1 Ohms there, so it looks like 21 is a ground point as supposed.

So the 260K resistance must come from that drain wire! Maybe I caused internal shorting by overheating while putting on shrink tubes???

Already removed the old cable - checked it for any signs of shortings between the wires - bended and stretched it whith probes attached - nothing...:-(

Will install the new one tonite hoping to get rid of that strange 260K thing...

Thank you Josh!

[fritzthecat]

Thank you Paul

Will replace the shielded cable connecting terminals 1 & 2 of both transformers today, remount C4S Boards and perform all resistance checks again - once without and once with tubes installed and will post the results (only including terminals that are not correct).

(?) Should I include all tubes or the 300B only?

Looking forward to get it solved

I really appreciate your support and all the tips / input from your side!

Thank you so much!

[Paul Birkeland]

I wouldn't replace any wiring, that doesn't make any sense.

I'd tighten up the power transformer screws and maybe post some photos of how they are mounted.

[fritzthecat]

Hi Paul


just for the sake of it I replaced that wire and now have 0.1 Ohms @ 21. I was 100% sure that I mounted the transformers properly as I normally check, recheck and recheck everything I put together - so the issue @ 21 is solved.


I did all the resistance checks again with all tubes installed and it looks like it's fine now - just some values I am not 100% sure about:


2) 2.4 M rising
4) 4.7 Ohms
6) 144.9 K
10) starts high and drops to 269.1 K (manual says it should start low)
15) starts high and drops to 268.6 K (manual says it should start low)
22) starting @ 450 K drops to 265 K
25) starting @ 140K rising to 217K
48) 605 Ohms
51) 606.3


A1/B1) 4.8 Ohms / 4.25 Ohms
A3 / B3) 1.8 Ohms - 53.13 K / 3.4 Ohms - 52.3 K
A4 / B4) 4.55 Ohms / 4.7 Ohms

C1/D1) 13.4 M / 0L (swaps with tubes)


May I continue with the voltage checks?


Thank you for your help...


Cheers,


Chris

[Paul Birkeland]

2) 2.4 M rising

The manual says more than 100,000.  You have 2,400,000

6) 144.9 K

The manual says more than 30K.

10) starts high and drops to 269.1 K (manual says it should start low)
15) starts high and drops to 268.6 K (manual says it should start low

Not a problem.

22) starting @ 450 K drops to 265 K
25) starting @ 140K rising to 217K

Manual says greater than 100K.

48) 605 Ohms
51) 606.3

Manual says 603 Ohms.  605 and 606 are well within 1% of the resistor value that's measured there, and this may be somewhat reflective of meter accuracy as well.

A1/B1) 4.8 Ohms / 4.25 Ohms

Same as above.

A3 / B3) 1.8 Ohms - 53.13 K / 3.4 Ohms - 52.3 K

Manual says that these could be 0 to 50K.  You're within that range (again, the 53.13K is close enough).  If you're worried about this one, turn the volume pot all the way down (not the balance pot) and you'll get about 0.

A4 / B4) 4.55 Ohms / 4.7 Ohms

Well within resistance/measuring tolerances.

C1/D1) 13.4 M / 0L (swaps with tubes)

There's an N/A in the manual here because you don't need to measure or report this socket pin.

I would proceed with voltage checks.

[fritzthecat]

Hi Paul


Thank you! Just wasn't sure - sorry for asking unnecessary questions.


In the end it seems the wire was causing the 260k @ 21. Guess I caused internal shorting by overheating when putting shrink tubes to the ends.


Have a great day,


Chris

[fritzthecat]

Thank you for helping...🤗


Voltage tests with different sets of tubes went fine - all values are within tolerances.


First listening test tonite...😊


Great experience again - thank you guys so much!


All the best wishes,


Chris