DIY Factory

DIY - JLM99v project
A project brought to you by Joe Malone of JLM Audio
Updated 1 December 2004

JLM Audio can be found at : http://www.jlmaudio.com/

... and you should check Joe's specific web page as any amendments are likely to be posted here first.
the main 99v : http://www.jlmaudio.com/JLM99v.htm
power supply: http://www.jlmaudio.com/JLM%20Power%20Supply.htm

Kev's construction of a JLM99v
Below you can see a pile of components and as far as I know this the same pile you will get if you order 2 basic pre-amps and one power supply. Not that hard to see the three groups and I suggest you kep it that way as it may make identifying components easier if you are a newbie to all this.

I don't normally start with the power supply as I tend to use my battery box and other power supplys for testing purposes. As this has all been supplied and I am making this from a newbies stand point it might be appropriate to start here. This will reduce the number of total components and the complexity is low so it may give more confidence for the next stages. You will need the power supply to test the two modules if you aren't set up as I am.

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A large pile of components and on the right just the power supply

A PCB and a bunch of capacitors is all it looks liketo begin with and that is typical of any power supply. There are also diodes to make the bridge rectifier and voltage doubler and three regulators but from a distance all you really see is caps.

Starting with the smallest components we have resistors and diodes. The diodes are all IN4004 but for one Zener Diode ZD36. The 4004 are easy to identify. Look for 4004 on the component and PCB and also look for the ring around one end of the diode. This should be aligned with the similar marker on the PCB. Take your time things will be obvious if you don't rush. Keep you eyes open for the Zener Diode and is mostl likely the axial compont left over after you have identified all the other axial components. I use pointy nose pliers to bend over the legs at right angles. Mount them close to the board or a little up for air flow around the diode. It's up to you and probably doesn't matter on this units as the current should be high to stress the diode. A narrow bit of PCB can help keep these things at the same hight and neat. I tend to mount directly on the PCB unless I expect the component to run hot in normal use.

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There are six resistors in three values. The resistor colour code can identify them for you BUT it is always good to check with a multi meter as the clolour can easily be mistaken due to size and background colour of the resistors. You are going to need a multimeter for more DIY in the future anyway.

For those that don't have a meter and get theor resistors supplied from JLM yet this may help

10 R- brown / black / black / gold / brown
120 R- brown / red / black / black / brown
22 K - red / red / black / red / brown

A meter is much easier.

As I said this will leave one axial componet left. The 36 volt zener diode. My zener diode did actually have 36 on it so i have confidence it is the right oine but often zeners and other diodes are hard to identify. Components in general may be supplied packaged so keep them all in their packages until you fit them.

Note that all the diodes are orientated the same way. Oh so neat to look at and bring a smile to your face. A very clever Joe.

The small capacitors are next and being ecelctrolytics they are polarised. The PCB is marked with a + and the caps are marked with a - so beware. The caps also have one leg longer than the other and this is the + leg. Which ever methoid you chose to use is fine as long as you stop and have a think. Saves time in the long run. Fit just the small caps to start with and then move to the trim pots. Only one value of trim pot so this is easy. Do check the PCB and you will see an orientation. What could it matter. Well it may not but stick with Joe here as it may make sense when you come to trim and up is up and down is down.

Add the screw terminals and the non-polarised 0.1 cap , all too easy.

picture

this leaves just the larger electrolytic capacitors and regulators. The larger cap fitted as above and the regulators may need a little thought as the shassis could have bearing on how long the need the legs for heatsinking issues. This is more mechanical than electrical. One regulator is different so look and the PCB and the component for the right unit in the right place. Take your time and it is all pretty clear.

picture

All the large electros are orientated the same way as is much of the rest of the PCB. All very neat. A small compact power supply with lots of capacitance if the 1000uF 50V units are used. Joe is indeed quite a clever fellow. This PCB whould be a little hard to etch at home as it is quite tight and the pads are small. There is also the issue of top to bottom connections (called - vias) that are done with plate-through holes. JLM has these boards for sale and they will suite many DIY Mic-pre's requiring a balanced supply and 48 volts. If you want to etch your own some of the other single sided designs, of which there are a few, may better suite.

I made the above board in around an hour and that included taking the picture and writing this far into the web page. Below you will see the tools I used and the it was all done on my kitchen table and the picture were taken on a piece of MDF on the kitchen sink under the window for a little outside light.

Time to move to the main boards

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More to come

10k reverse log pot ..................... JLM output transformer ..........

JLM Audio have a couple of new products for 2005. A dual ganged version of the 10k reverse log pot pictured above and a new gapped output transformer that will impress. The one pictured is a prototype and the production model will have a mounting plate very similar to the Neve and the wire will go in favour of solder tabs. This will allow it to snuggly fit into a 1RU box.......

The JLM universal front panel

Parts List

PDF Files

Some thoughts

text to come

More suggested parts and future enhancements

this page is still under development
more will be added

brought to you by Joe
www.jlmaudio.com

and Kev from the DIY Team at :
www.diyfactory.com