Bigbottle Phonostage Builders thread.

[patrickblue]

Ok, I'm back in business. My relays are flipped. I have been measuring against the HT ground so I am hoping nothing is damaged. I checked the heater pin's you mentioned patrickblue and I am getting 5 volts across all of them. Is this something to do with the Zenner?

Just looking at your photos again, R2P and R3P look as if they need more solder on one side.

 

[StevenCrook]

Looking at the valve side of the board, is that a solder bridge between pins on Q1R/HS1R?

 

[sasha70]

Good evening all.
Thank you Vivant, I have replaced ZD2P 12v zener and voltage measurement:
C4P - 255.7v
C5P - 253.3v
C7P - 251.3v
C8P - 250.6v
Voltage reading at Pin 1 and Pin 6:
V1 - 144.4v
V2 - 160.4v
V3 - 250.9v

Best regards.
Sasha.

 

[Vivant]

The capacitor voltage readings are without the valves fitted I presume.

The voltages are essentially correct, however they are all on the high side. It is best with 235 to 240 on C4.
What is your high voltage AC reading from the transformer?

 

[sasha70]

Hi Vivan, thank you for your reply.
Yes, voltage measurements without tube installed.
Transformer is special order according specification (165v 2x9,5v), but actual voltages: 185v, 2x10,9v without tubes installed.
Tomorrow will install tubes and measure again.
Best regards.
Sasha.

 

[sasha70]

Good afternoon Vivant,
I have installed tubes and measured voltage:
AC voltage - 182v,
V1 pin1 - 90v,
V2 pin2 - 130v,
V3 pin1 - 232v
Its working, will give a listen tomorrow.
Could you please confirm switch position?
LED is on when preamp in MC?
Thank you.
Best regards.

 

[jamie123]

hi,the led's are only on when in moving magnet

 

[Vivant]

Jamie is correct, Led's on in MM mode.
Voltages are perfect.

 

[sasha70]

Thank you, will give it listen tonight.
Best regards.
Sasha.

 

[sasha70]

Good afternoon all.
I have a few questions about loading resistor.
My understanding in case of MM cart I can add loading capacitor?
In case of MC cart I can add loading resistor?
Could you please share your findings about best values?
Best regards.
Sasha.

 

[Vivant]

Adding capacitance for MM is very dependent on the cart used, also depends on how much capacitance is in your tonearm wiring and connecting phono leads.
The board has 100pF fitted as standard.

Generally 100 ohms is a good all round load for a lot of MC carts.

 

[sasha70]

Thank you Vivant,
I have made loading resistor for MC cart.
Sweet, wonderful sound from Denon DL-55 cart.
A bit of noise, need to install board in enclosure.
What will be your recommendation for loading for MM cart?
Best regards.
Sasha.

 

[BassyCakes]

Just looking at your photos again, R2P and R3P look as if they need more solder on one side.

The other side was fine but added some more for good measure. I switched out the zener now i am getting 7 volts at my heaters. I then plugged in the HT and got the following readings on my caps:

C4P - 243v
C5P - 134v
C7P - 133.7v
C8P - 133v

I was not getting any voltage between pins 1 and 6.

 

[sasha70]

Hi BassyCakes,
I have experience same situation and explain it in post 1018,
Then I got reply from Vivant at post 1020.
Replacing faulty 12v zenner diode sort the issue.
Hope this will help.
Best regards.
Sasha.

 

[Flikoman]

For the multifet boards ... what is the recommended BF862 Idss range and source resistor?

Thanks

 

[TomBrian]

Ah, yes. Thank you.

It looks very nice. Was it easy to apply?

Hey,
I tried to contact them via Email and sadly I did not get a reply... But I found these guys that make custom various signs too. They replied fast and sent me my sign in a week. I think you may find a better one online, but this one was really fine. Check them out: https://www.marktek.co.uk/

 

[pelayostyle]

Does anyone have a copy of the updated BOM? The google drive links aren't working. Thanks.

 

[patrickblue]

Updated BOM.
Ignore the highlighting, that's just me ticking off items.

 

[pelayostyle]

Thanks @patrickblue
The BOM is missing values for R7L, R7R. Is that still supposed to be 47R per the original BOM?

Also, is the LED color is supposed to be Yellow? I remember reading something about that and how the forward voltage is important.

 

[patrickblue]

it's a long time since i built it, and am in the process of moving house, so as luck would have it the phonostage is 150 miles away, otherwise I could check R7L&R. From what I remember they are as per original BOM.

As for the LEDs, yellow seems to be what you should use according to post 863 in this thread, although when I built mine the BOM at the time said red or yellow, and I used red with no apparent issues.

Edit:
Just remembered I used multifet PCBs on my build, and R7L&R were replaced by wire links