Cutting circuit boards then reconnecting?

boriscrispin · Mar 28, 2024

Hello - this is potentially a dumb question but thats never stopped me before.....

There is a now faulty but salvagbly decent old mixer (an Allen Heath MOD 3 type, Discrete, transformer mic, 24v etc) I am looking at having worked up into a semi custom desk. For the main part the circuits are good as is, (I am not a tech myself, but I know first hand the difference between having some bones to work with and starting from scratch!)......but the strips are incredibly long and unwieldy and vomit coloured, and ironically faders are the short-throw type which I am not a huge fan of.

As I had already planned to reface the panels and use the old usefully angled as a sub-panel, reformatting the strips into an attractive multi-angle chassis would be excellent, but in order to do that one would have to split the long circuits and reconnect.

Is that in any way entirely possible? I can't help but wonder if this kind of practice already happens when people rack up channel strips or convert things for use into 500 series for example.
Is it as 'simple' as reconnecting by whatever means the paths might have been terminated by cutting, and reconnecting with wire or even proper ribbon connectors etc?

Though I have made the assumption that the most 'sensible' alternative to 'frankensteining' would be to re-layout and print new separated PCBs, I am fully aware, that in itself would take a decent amount of time/effort and cost than a brutal but efficient slicing (it really doesn't have to be pretty underneath).

I have attached a pic imagining where it might be good to separate into two (sorry based on whatever I can find online, I don't have the mixer yet) - interested to know if anyone has done this kind of thing.

Whoops · Apr 3, 2024

boriscrispin said:
Is that in any way entirely possible?

Yes and it's done all the time by people that rack console channel strips professionally.

boriscrispin said:
I can't help but wonder if this kind of practice already happens when people rack up channel strips or convert things for use into 500 series for example.
Is it as 'simple' as reconnecting by whatever means the paths might have been terminated by cutting, and reconnecting with wire or even proper ribbon connectors etc?

Yes, it is.

boriscrispin · Apr 3, 2024

Whoops said:
Yes and it's done all the time by people that rack console channel strips professionally.

Yes, it is.

Thank you

hghadia · Sep 10, 2024

Yes, it is possible to split and reconfigure the circuit boards to fit into a new, more ergonomic chassis, but it does come with its challenges and technical nuances.

1. Splitting Circuit Boards

If the PCB design is as linear and compact as many old analog mixers, splitting long circuits to make them more compact is feasible, but it requires precision. In essence, you would be "cutting" the board and re-connecting the circuit paths, either with wires, ribbon connectors, or other jumpers to preserve the electrical continuity. This is somewhat akin to what people do when converting rackmount channel strips or fitting components into 500-series racks.

How it's done:
- Identify critical paths: You’ll need to carefully trace each signal path before splitting, ensuring that you don’t interrupt important parts of the circuit.
- Use ribbon cables: Ribbon connectors or multi-wire looms are often used to keep the wiring organized and minimize signal interference.
- Soldering: If you’re manually cutting the board, each cut track would have to be reconnected via solder points, which can be tedious but effective if done right.
- Testing: After splitting the board, each section would need to be tested to ensure that the electrical integrity remains intact, as even minor changes in resistance or capacitance due to extended wiring can affect the audio quality.

2. Faders Replacement

If you're also thinking of upgrading to long-throw faders, this can usually be done as long as you match the impedance and taper (linear vs logarithmic). The main consideration here is ensuring that the faders fit physically into your new layout and electrically into the circuit.

Custom faceplates: Since you're refacing the mixer, you can create custom slots for longer faders. You would need to check if there are any pinout differences with the original short-throw faders and adjust accordingly.

3. Re-laying out PCBs

You’re correct that printing new separated PCBs would take more effort, time, and cost. A full re-layout of PCBs would allow you to fully customize the form factor without any need to Frankenstein the original boards. The advantage is cleaner work and possibly better performance since shorter signal paths reduce noise, but it's a much bigger project.

4. Things to Consider

Noise and interference: Extending signal paths with cables can sometimes introduce noise, particularly in an analog audio circuit. Shielding and grounding will be important considerations when reconnecting these circuits.
Heat dissipation: Ensure that any reconfiguration doesn't compromise the heat management of the system.
Maintenance: A "brutal but efficient" slicing approach may work, but consider how easy (or difficult) future repairs or adjustments might become.

5. Potential Consulting

Since you're not a tech yourself, consulting with a technician who specializes in vintage or custom audio gear is highly recommended. They can help you execute the split correctly and offer advice on whether your ideas for reconfiguration are feasible in the context of that specific mixer model.

In short, yes, it is entirely possible to split, reformat, and reconnect the circuit boards, but attention to detail and technical know-how are critical. The approach you choose (slicing versus new PCBs) depends on your balance between budget, time, and aesthetic/functionality priorities.

abbey road d enfer · Sep 10, 2024

boriscrispin said:
I have attached a pic imagining where it might be good to separate into two (sorry based on whatever I can find online, I don't have the mixer yet) - interested to know if anyone has done this kind of thing.

Considering there's almost nothing on the bottom part of the PCB, you may just ditch it and hard wire the rest.