Show posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Show posts Menu

Messages - Tassieviking

It sounds like the OP made his PCB's by using a printout of the original layout drawing and transferring the tracks to a PCB that he then etched himself.
If that is the case then he would end up with a fairly close copy of the original amp dimensions.
The original amp was 26 inches wide so the original PCB must have been over 24 inches wide (610mm), no wonder he made the PCB in 3 sections.

AIONFX has kits and bare PCB's to make a full L5 pedal minus the reverb, they also have kits for just the clean channel and just the drive channel.
If you don't want a pedal then it would be best to make a new PCB that incorporates the mod that AION made to change from the CA3080 and CA3094 IC's to a single LM13700 IC

I resized the original PCB's drawings to 150DPI approximately and ended up with this:
I have been given some cheaper practice amps and beginner amps that needed some small repairs over the years, usually just a good clean of the pots and jacks got them working.
I ordered new pots and new jacks for these to make them reliable.

I think most local schools would love them for the young kids in the music department.
In Australia there would be 2 x SPDT switches and the last switch is a special 4 terminal switch called an intermediate switch made for this purpose.

If you are using normal toggle switches then you would need 2 x SPDT and 1 x DPDT switches for the 3 switches and one light.

Just imagine a really long hallway with a door in the middle and doors at each end of the hallway.
You would want to be able to turn the light on/off whichever door you go through.

I have to agree with Phil, too much theory can get in the way if you don't do a lot of practice with real circuits.

I think what would be good for you is to get a breadboard and start building small circuits like stomp-boxes and even small SS amps, and then you can modify them to see what happens in real life with the signal.

You would not need to spend a fortune on parts because you will be able to re-use all the components, just build up a common variety of parts and off you go.

A bread board needs to be a good size to start with, I would buy one with at least 800 points on it.
You can always get another one and use several breadboards for a single build if the circuit is big.
Here is a link to a well priced one:

I get most of my components from Tayda, if I order resistors I get 50 at a go and then slowly order more values as I need them.
any components that are regularly used I order multiples of them, and if there are better ones for the same price I get the better ones.
One part comes to mind, 1N4001, 1N4004 diodes are used a lot, I get the 1N4007 instead as they have a higher voltage rating but are the same size and price.

All I have is the power amp schematic, I have never seen the pre-amp schematic.
It shows there is a send and return jack so that might be good news.

If the noise disappears when you plug a patch cable from the line out to the line in jacks as Loudthud suggested it means the line in jack is dirty.

The line in jack has a switch in it that disconnects it from the line out jack when a plug is inserted into it, no plug and it is connected to the line in jack.

A quick spray with Deoxit and then insert a plug several times might dislodge the dirt and restore the amp to normal.

You cannot view this attachment.
It looks like the Blue and Yellow wires are reversed, as long as the wires are connected correct on the PCB.

Check the colour of the 2 wires that are closest to the headphone jack, directly behind the jack on the PCB.
They should be the positive wires, the 2 wires closer to the back of the amp are the negative wires.
I have come across many instances where thermal grease has dried up and is no longer performing well, most of these instances were DC drives for very large motors.(200kw+)
I used to remove all components on the heat-sink and clean the old thermal paste away and apply a very thin coat of new paste before re-assembling the units.
I have also seen this in many computers on the CPU, clean and reassemble.

Unless there was a fault I would not replace any components, just fresh thermal paste applied very thin and fully covering the transistor and heatsink.

Make sure you use good quality insulating thermal paste, there are thermal paste that conducts electricity, they should not be used in amplifiers.
Schematics and Layouts / Re: Sunn Beta PCB
April 26, 2023, 12:23:09 PM
I think I was going to put it in a 2U rack case originally, but I think it would be better in something like a Hammond 1441-33 case (17x4x10).

You also have to consider what Power amplifier you are going to use with the pre-amp, that will determine the transformer you need.

If you are looking for the font for the writing on the front panel (c-mos) I think the font "FontsFree-Net-bitwise.ttf" comes close.

here are some pics of a front panel PCB I was working on, I sometimes use a PCB as a fascia on my home jobs.
I have made the front for Lead and the back for Bass, on the Bass I labeled the reverb pot as comp as I was going to add a 1 knob compressor to it separately and place a pot in the reverb position.
Schematics and Layouts / Re: Sunn Beta PCB
April 25, 2023, 09:59:42 AM
If you have problems finding the B1M dual gang pots you can get them from Tayda, that's where I get most of my parts from

I have read that changing the level and master pots to A100k instead of B100k makes it easier to control the volume, also one of the tone pots can be improved by going to C100k, but I can't remember which one right now.(Treble ?)
I also changed the values of the resistors in the foot pedal circuit to higher values and 1/4 watt but I haven't proven that yet except on a breadboard.

The Sunn Beta has a strange plug for the foot pedal, I was going to use a 4 pin GX12 or GX16, but any 4 pin plug will do.
Silicon Chip magazine tested several cheap modules and felt that the two they picked would actually pass Australian safety standards, and the components ratings were up for the job.
They did recommend that the speakers should be 4ohm or above which de-rates the setup to approximately 500 watts @ 4ohms and not the advertised 1000 watts @ 2 ohms.

Here are the links to the amp and power supply provided by the magazine:

They stuck them in a metal case 304mm wide (12") x 279mm deep (11") and 88mm high (3.5") along with an 80mm quiet fan.

I thought it would make for a nice Bass amp for home, I would just make a pre-amp PCB that sits against the front panel, pots mounted on the PCB.

Maybe a Lab Series L4 or a Sunn Beta Bass, there are lots of bass amps that are solid state.

I think it would fit nicely in a Hammond 1444-12103 aluminium case (12x10x3)
or a Hammond 1444-12123 case (12x12x3)

I don't need it but it would be fun making it anyway, my daughter could use a louder Bass amp for home.

G'day all.
I am thinking of trying out  some of the high power "D" amp modules that are everywhere.
Silicon Chip magazine had a story on some modules they tried out, a 1000 watt amp and 1000 watt power supply that they called a 500 watt amp put together.
I might try this out with a Bass preamp I am making.

The problem is that the power supply has only got +- 70v rails, and a single +15v output also.
I guess the easy option would be to convert the +15v to -15v with a LT1054 or similar but it would be a bit less then -15v at the output.

Since I would be dropping from 70 volts to 15 volts at an unknown current I don't really want to use a dropping resistor, not even going into a 7815 regulator.

The 7815 and 7915 can go up to 35 volts max so they are out.

This would be a common problem with any design requiring more then +-35 volts going to the power amplifier PCB, most pre-amps will want a nice +-15 volt supply.

Does anyone have a good solution ?
Maybe a Zener diode with a low loss mosfet or transistor to do the dropping ?
I would love to hear what methods others have used in the past.

The Newcomer's Forum / Re: hey guys Saturated here
April 21, 2023, 12:21:13 AM
Welcome Saturated, yeah I know , a bit late but I am always a bit slow.

If you are new to soldering then the best thing you can do is get a soldering iron with a temperature control and some small tips.
I use a 50 watt iron with a digital temperature display, 50 watt lets it keep the heat better then a smaller iron.

Never buy solder cheap online, you will just produce *s!!t* solder joints that might not make a connection.

I use a 1mm solder tip and good solder that is 0.5mm thick, 0.8mm is ok as well.

I use a magnifying loupe  10x or 20x to check all my solder joints, its amazing how much you will miss if you don't check them properly.

I have been building stuff since I was a young smart-arse way back, my first serious project was a 16 channel mixer desk (ETI I think) around the mid 70's, along with 2 x 100 watt amplifiers that a friend used as a mobile disco.

Once you start building your own stuff you never stop, and why would you when you can make your own amps and pedals cheaper then what you can buy them for.

Shop around for parts as you can get some stuff a lot cheaper if you do, I buy a lot of stuff from Tayda because the price is good.

Sounds good, I would love to see some pictures of it.
It sounds like you made yours the same size as the original.
Did you make a copy of the power amp as well, or just the pre amp
I have no idea where I got the idea that one of the pots was a G50k taper but that's what I thought it was, most likely confusing this with a post on another forum.
A25k pots with a push pull switch should not be hard to source, the pots on the pictures reminds me of an old type of Noble pots from the 80's.
The Noble pots were a bit "chunky" around the shaft base where the thread starts.

I don't know where "gastric" lives but if in the states then these guys have a switched pot that could be made to fit :

You would have to solder some stiff wire on the pot lugs to poke through the PCB,just some leads cut of some 1N4004 diodes would be good enough.
Standard A25k pots are easy to source, I get mine from Tayda mainly and I find them good.
Check Ebay for "A25k push pull"

I would be 99% sure that the pots are standard 16mm with 5mm leg spacing, but they might 5.08mm as well.

I personally would remove the PCB and then mount it from the outside of the case by tightening all the pot nuts before soldering the new pots in, that way the pots are aligned before the solder locks them in position. You really want the pots tight against the panel before soldering, if you solder them first and then tighten up the pots you could put strain on the pots and solder joints.