Bottlehead Crack

[Applemacman]

Hi all, I noticed that after switching on the bottlehead crack, Im having a louud buzzin/humming noise from the transformer. i didnt get to check voltages because I thought it wise to switch it directly off first and seek some advice.

 

[Jameson]

Has it passed its resistance checks? Can you post some photos?

 

[Applemacman]

This issue is I hv the speed ball, and was working fine untill I tranferred it to a new chassis. Ive taken some pics and heres the resistances with the speedball connected.

1.551 ohms
2. OL
3. OL
4. Fluctuates between 2.8 ohms and 3.3 ohms
5. OL
6. 1.2 ohms
7. 6.3 M
8. 0.9 ohms
9. 32 M
10. 15.5 ohms
12. 1.3 ohms
13. 0.92 ohms
14. 2.1 ohms
B3. 6.2 m
B6. 30M
Rca center 86K
Ground 0.7 ohms

 

[2wo]

That looks to be a well coated chassis, I would double check that what needs a good chassis ground has one.

Also getting ahead here; if things check out electrically, maybe mounting the transformer to such a large plate has set up a mechanical resonance.

 

[Applemacman]

Ive tested the grounds using continuity on my fluke multimeter. They seem ok beeping when tested.

 

[Applemacman]

Ive tested the grounds using continuity on my fluke multimeter. They seem ok beeping when tested.

 

[Applemacman]

Ive fixed the humming issues, i had an incorrectly orienrared diode now the hums gone. However im getting no sound through the headphones

 

[Paul Birkeland]

What are the DC voltages?

 

[Applemacman]

What are the DC voltages?

I will get back on this as im away at the moment

 

[Applemacman]

I must hv something wrong. Taking the measurement with the speedboatd installed i get. OA-0123 OB 0V G 0V B+ 1.2V something is wrong?

 

[Paul Birkeland]

Yes, OA can't really be less than B+. This can appear to be the case from missing/loose ground wires.

 

[Applemacman]

Ok got somewhere, today I have sound out of both channels, but the right side is lower than the left and has a slight hum. I also noticed some of the leds are not lighting. Took a puc

 

[Applemacman]

I found the issue I missed two wires going to the speedball off. With it attached to my ear834p clone sounds lovely. All valve front end. Just one question is it normal to hv hum at high levels. At mid level you dont hear it

 

[Paul Birkeland]

At high levels, yes, you are amplifying whatever can make it into the amp with so much gain that you will be able to hear it, but this isn't applicable since listening at such high levels would damage your headphones and your hearing.

 

[Applemacman]

Ok then as this is normal no more help needed. Other than to say thanks to all for your advice and support.