PCB with turret?

[BOWMUSIC]

This a prototype board for my new amp build BOW Morse 6V6(3 12ax7, 1 6v6gt, 5W) with solid relays. It's a mess I know, so I'm thinking to design a PCB board, but the PCB boards are not friendly for repairing and modifying, What about a hybrid approch? PCB with turret ? PCB for control components only? What do you think? Dose anyone have a better idea?

[loudthud]

Using a PCB for front panel controls has it's problems. If you use PCB mount pots and jacks, any twist or bump to the chassis is apt to fracture connections and finding PCB mount pots is always a pain after a couple of years. If you use little jumper wires to connect to the pots and jacks, that's ok but hardly worth the effort.

Using turrets or eyelets on a PCB is possible, you just need to create the footprint to get needed clearance and the correct hole size. It's best to use a turret or eyelet for any wire that connects to the board, practically bullet proof. No lifted pads no matter how many times you have to pull the board.

If using a PCB for the main board, you really won't save much time or labor. Just use one of those phenolic boards with an array of holes. If you search you can find one with 0.062 inch holes and Hoffman has turrets that will fit those holes. You may have to improvise something to install turrets in a board that is already populated with components.

[BOWMUSIC]

Using a PCB for front panel controls has it's problems. If you use PCB mount pots and jacks, any twist or bump to the chassis is apt to fracture connections and finding PCB mount pots is always a pain after a couple of years. If you use little jumper wires to connect to the pots and jacks, that's ok but hardly worth the effort.

Using turrets or eyelets on a PCB is possible, you just need to create the footprint to get needed clearance and the correct hole size. It's best to use a turret or eyelet for any wire that connects to the board, practically bullet proof. No lifted pads no matter how many times you have to pull the board.

If using a PCB for the main board, you really won't save much time or labor. Just use one of those phenolic boards with an array of holes. If you search you can find one with 0.062 inch holes and Hoffman has turrets that will fit those holes. You may have to improvise something to install turrets in a board that is already populated with components.

thank you , I have two options now , First, PCB with turrets on one side and SMD components for relays on the other side. Second, full PCB approach , but with a service window for easy accessing the back of the PCB board.

[Mick Bailey]

I quite like the hybrid approach of having turrets (or eyelets) for the main amp circuit and separating out the signal switching etc onto its own dedicated PCB. With amp builds I do a drawing of the layout before building and rationalize the design as far as possible to minimize wiring. The idea of a service window to get to the underside of the circuit is really useful. Quite a few PCB hi-fi amps have a removable panel which means that nearly all testing and component replacements can be done without removing the board.

Ray Wilson (Music from Outer Space) used to include what he called a "kludge area" on some of his PCB artwork and I've since incorporated this idea myself when building circuits that I may want to add to or change in the future. Just a matrix of spare pads in a corner or where there's room on the board.

[J M Fahey]

This a prototype board for my new amp build BOW Morse 6V6(3 12ax7, 1 6v6gt, 5W) with solid relays. It's a mess I know, so I'm thinking to design a PCB board, but the PCB boards are not friendly for repairing and modifying, What about a hybrid approch? PCB with turret ? PCB for control components only? What do you think? Dose anyone have a better idea?

Of course you can.

IF you build a very simple amp, say a Tweed or Blackface or equivalent, keep turrets or eyelets, personally I prefer the latter because turret work includes twisting part legs around them before soldering and worse: untwisting while drenched in solder to remove them, a PITA, while with eyelets you justb insertb legs in, or melt solder and pull leg with long nose pliers, MUCH easier and faster.

I HATE turrets and think a great part of their "attraction" is MOJO or association with Military wiring .... 1943 military that is.

Leo never used them and Jim quickly transitioned to PCBs, go figure.
Ampeg too.

How deep will you modify?

Change some components to get different tone or gain? No big deal.

Draw a regular PCB BUT add a few turrets or eyelets at critical points: cathodes, plate resistors, plant "a forest" of them at the Tone Control area, to build any conceivable variation shown in TSC, replacing all components at will to fine tune.

That would give you an about 80:20 mix: 80% pads and tracks, 20% eyelets/turrets or so.

You will NOT fully turn your build from a Tweed to Blackface to Marshall to Ampeg to VOX to Silvertone to Gibson .... I hope.

Using a PCB for front panel controls has it's problems.

OP didn´t mention or ask for that.

If you use PCB mount pots and jacks, any twist or bump to the chassis is apt to fracture connections

But *everybody* is doing that, I mean major companies.
Only Boutique and Boutique wannabes (Mesa cough cough) have time for that.
Not a deal breaker by any means but in any case OP didn´t mention that.

Besides, modding is fine, it´s a DIYer amp, but worrying too much about repairs in a new amp built with modern components is not very realistic.
IF, and that´s a big IF, something fails in 2-5-10 years, then it will be dealt with.

And nightmare stories mostly come from early PCB amps, which used weak phenolic paper pcbs, easy to tear out, or modern ones which use computer board standsrd tiny pads and hair thin tracks ... and most stories are told by noobs or wannabe Techs.
Exprienced ones just roll up their sleeves and do the job.

The MAIN consideration with PCBs is NOT to wiggle part legs while trying topull them out, specially with either overheated sputtering solder or pasty too cold one, at solder temperatures base adhesive (Phenolic or even Epoxy) holding copper to base is semi-molten and easy to tear out.
BUT if you first clean solder out competently: proper iron temperature, good solder sucker, solder absorbing braid/wick if necessary, then you can cleanly pul leg or pin out.
In some cases and in multi pin components it´s advisable to plain cut leg off and pull it individually.

finding PCB mount pots is always a pain after a couple of years

I find it quite the opposite: most abbundant generic pots BY FAR are with PCB pins, some sellers look me sideways when I ask for "wire terminals".

Of course, those who want future availability must stick to most popular and generic versions: 16mm or 25mm single 3 leg pots, with generic necks and shafts.

Dedicated/unique pots, say stereo 6 pin in a single line, 9-12mm case, built in push pull switches to save space, etc. are justified only in pedals,procesors, keybords, etc. , not the case here.

Same with custom PCB holding "wings" such as Peavey or Fender, or the infamous Peavey "Spider" pots, but again not the case here.

PCB with turrets on one side and SMD components for relays on the other side

^^^^^ THAT ....or else, SMD is PCB or else.
Since you will use that basically for switching, I would put them on the back side and NOT route relay contacts to needed points on the board (which can vary according to your experiments) but to stand alone turrets or simply solderable pins going through PCB, so you wire them with flying wires wherever needed and easily mod that at will.

with a service window for easy accessing the back of the PCB board

Brings memories but have not seen that since 60´s Ampeg, go figure.
And cutting such large holes in a chassis is almost impossible for home builders.

Your best bet is to try to put all wiring reaching through *one* side of the board, or at least mount all front pots and jacks on a long narrow board, so pulling knobs and nuts leaves it free to pull out, so you can lift main PCB by 90 degrees, perpendicular to chassis, to have access to both sides for easy Servicing/mods without massive desoldering.

[Helmholtz]

Jim Marshall used slotted turrets in the JTMs (at least until 1966) that don't require wrapping wires around.
They are a joy to work with and I much prefer them to the cheaper eyelets in Fenders.
Even with non-slotted turrets a simple wire hook is sufficient. Just hook the wires into the hollow turret.

A PCB makes sense with a proven, final design.
It can save space and cost - especially with large volumes, where it allows for automatic component insertion and wave soldering.

I share loudthud's aversion against print-mounted pots.
Even less I like print-mounted tube sockets.

[xtian]

A well designed PCB with extra large solder pads and with components loaded from the top makes it easy to swap components later. Example: https://luigiretro.com/HRD2ODS_retrofit_pcb

[BOWMUSIC]

Thanks for all your advices, I now decide to go with full PCB approach . I will post the final result here .

[tschrama]

Could you share what relays you are using. They look nice and tiny

[BOWMUSIC]

Could you share what relays you are using. They look nice and tiny

Hi Etschrama,

For low voltage and signal chain I use TLP176AM from Toshiba, It runs on short on Mouser, but you can use any relays which fulfill your technical specifications.
For high voltage B+ I use VOR1142B6T from Vishay.

And don't forget to put a resistor in front of the Led input of the relays.

[tschrama]

For low voltage and signal chain I use TLP176AM from Toshiba, It runs on short on Mouser, but you can use any relays which fulfill your technical specifications.
For high voltage B+ I use VOR1142B6T from Vishay.

Thanks!

[Leo_Gnardo]

I share loudthud's aversion against print-mounted pots.
Even less I like print-mounted tube sockets.

I second... now third, that emotion.

[J M Fahey]

Thanks for all your advices, I now decide to go with full PCB approach . I will post the final result here .

You can still go mixed technology: use PCB for most components (and of course all SMT stuff) and some turrets/small eyelets/pins for parts which will much tweaked.

Typical eyelet size is 1/8" or 3.2-3.5 mm but sometimes I add small 2mm or 2.5mm ones where needed at otherwise "normal" PCBs.
I always keep a 100-200 bag around, as well as the proper die set for my trusty eyelet machine, bought in 1970 or so.

Instead of turrets I use this kind of pins, which pressure fit a PCB hole and then are soldered on the bottom side: