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April 02, 2023, 09:01:03 AM

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Recent posts

#1
Tubes and Hybrids / Re: AC30/6 ticking/motor boati...
Last post by phatt - Today at 08:02:48 AM
Does the trem speed knob change the speed of the tick?
On most trem circuits the LFO still runs even if it is switched off.
Maybe check you have the right valve in the tremolo socket as that can cause issues.
Poke around the trem circuit with a wood chop stick and see if you can hear any change.
Phil.

#2
The Newcomer's Forum / Re: are rows of knobs (pots, p...
Last post by phatt - April 01, 2023, 10:21:59 PM
Well you have no +9 volt rail.
Now go check you have +9Volts at the output of Q8 the 7808 reg chip.
The output leg is on the left (looking at the layout) it goes to C58.
If no +9V then likely the chip is fried.
Phil.
Speaker is not needed for this test.
#3
The Newcomer's Forum / Re: are rows of knobs (pots, p...
Last post by saturated - April 01, 2023, 09:07:28 PM
sorry forgot to add...the speakers were disconnected during the testing...dunno if that matters
#4
The Newcomer's Forum / Re: are rows of knobs (pots, p...
Last post by saturated - April 01, 2023, 08:49:47 PM
well I googled 4558 pin out, removed the chassis and turned it on and measured the pins 4 and 8

I need to find my mini grabbers because I was slip slidin away like Paul Simon worried I was going to short something out.

anyhow
pin 4 to ground -9.36v

pin 8 to ground -0.64v

pin 4 to pin 8  -8.73v

all measurements rechecked a few times

btw my chip or whatever had these markings

731 A B
RC 4558P

with a Texas Instruments? logo
and thank God for that circle mark I guess that helped me know which way was up...TM Richard Pryor

 :)
#5
The Newcomer's Forum / Re: are rows of knobs (pots, p...
Last post by saturated - April 01, 2023, 08:20:51 PM
also I noticed a nice wooden adjustable chassis holder in a D-Lab video I thought he had bought it but a vendor sent it to him.
I want to put something like that together sure would be nice
#6
The Newcomer's Forum / Re: are rows of knobs (pots, p...
Last post by saturated - April 01, 2023, 08:12:07 PM
thanks for the homework assignment I was going to check in and say I bid on a scope earlier today but didnt win. 

well....Im off to find pin 4 and pin 8  :)
#7
Tubes and Hybrids / AC30/6 ticking/motor boating n...
Last post by Psabin8951 - March 31, 2023, 10:20:41 AM
Having resolved rectifier issue on this amp and having replaced all tubes the amp now works BUT when I plug a guitar lead in, what is a barely audible tick becomes loud and clear. Turning the cut control down makes it worse. It is there where tremelo circuit is on or off.
The tick pattern is constant changing to a harder tick every few seconds.
Can anyone assist? Is it a filtering cap gone awol?
#8
Schematics and Layouts / Re: Sunn Beta PCB
Last post by Tassieviking - March 28, 2023, 03:52:39 PM
Unfortunately I haven't completed this one yet, my dad got really sick early last year so I flew up to where he lived and stayed with him for quiet some time.
And then it was the funeral, cleaning up his house and sorting out what I wanted to keep etc.
It kept me occupied for 6-7 months and then I didn't get back to the Sunn Beta project.
I did finish one of the Marshall 12 watt amps I made a PCB for though.

I remember I was tweaking the resistor values in the channel switching circuit so it would work better and only use 1/4 watt resistors, I don't think I had a lot left to do before the PCB was finished for the BASS version I was building.

I can not see any reason why it will not work, I left the Gerber files I sent to JLCPCB to get the PCB's made in the first post

Thanks for reminding me, I will drag it out and get into it again very soon.
Are you interested in the Lead version or the Bass version ?

#9
Amplifier Discussion / Re: op amp voltage and tone
Last post by Zozobra - March 27, 2023, 05:43:58 PM
Ok, I'll stick to ±15V rails then  :)
#10
Schematics and Layouts / Re: Sunn Beta PCB
Last post by Jimladladlooklike - March 27, 2023, 09:56:38 AM
Hey Tassieviking. Awesome work on this, I'm jealous of your PCB design skills!

I was just wondering if you'd made any progress with the building process as I'd be really interested to have a go at this project myself. I've built two tube amps (currently on my third!) but I'm a big fan of SS stuff and would like to branch out.

Cheers.