Colorsound - Power Boost 18V  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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bettsaj
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Post by bettsaj »

I think I need to trace the layout in eagle... and then place the components in it to see where they go...
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Post by bettsaj »

Tropical fish caps on order :-)
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Post by bettsaj »

Just a quick question....... Any idea how big the PCB is?.... Like the actual size of the board?
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Post by Electric Warrior »

No idea. I could measure mine, but you might as well straighten a photo out in Photoshop and use caps and pots as a size reference.

This may come in handy:

Image

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Post by bettsaj »

These little beauties arrived yesterday :-)
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Post by bettsaj »

Oh, and the board looks like it's around the 3.25 x 3.9 inch in size..... at least that's what I'm going with. I'll lay the PCB traces out on that.

I'm in the process of laying it out in eagle at the moment so I can have a decent board layout for etching. I want to etch the board as close to the original layout as possible..... Including the board soldered pots.
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Post by bettsaj »

Has anybody got copies of these tracing files.... I've asked Sinner but he no longer has them

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Post by bettsaj »

Straight forward question.

I know there's a lot our there regarding carbon resistors and metal film... But what in your experience would be better for the power boost?

Looking at the photos they look like they're carbon film resistors... So I'm a little confused as to what's best to use. I've been led to believe you shouldn't use carbon on high gain circuits... The Power boost I suppose could be looked at as a high gain circuit..... All the resistors I have around me at the moment are carbon, so should I just build it... test it and if it's noisy start swapping out resistors for metal film... if should I just say to hell with the expense and get metal film now before I start soldering?

Any advice would be greatly appreciated.... Resistors are a bit of a grey area for me at the moment, with a lot of conflicting information.

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Andy
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Post by ilcaccillo »

bettsaj wrote:Straight forward question.

I know there's a lot our there regarding carbon resistors and metal film... But what in your experience would be better for the power boost?

Looking at the photos they look like they're carbon film resistors... So I'm a little confused as to what's best to use. I've been led to believe you shouldn't use carbon on high gain circuits... The Power boost I suppose could be looked at as a high gain circuit..... All the resistors I have around me at the moment are carbon, so should I just build it... test it and if it's noisy start swapping out resistors for metal film... if should I just say to hell with the expense and get metal film now before I start soldering?

Any advice would be greatly appreciated.... Resistors are a bit of a grey area for me at the moment, with a lot of conflicting information.

Regards,

Andy
I personally always use Metal Film resistors, and I'm sure if those were around in the 60s and 70s manufacturers would have used those ones also.

Carbon film are totally fine

Carbon composition are said to be more noisy and possibly more prone to problems with moisture. Being inherently more noisy in operation than carbon film or metal film doesn't mean that you will hear any noise created by carbon compositions.


Simple answer,
you will be fine with either of them.
The reissue looks great and seems to use Carbon Film, so they felt those were fine.

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Post by ilcaccillo »

Electric Warrior wrote:I guess you'll have to draw the circuit board yourself. Photos of the trace side are around..
Building it just like that may be harder than you might think as you probably can't get the right pots. Colorsound has to custom order them.

Where you should buy the blue Vishays depends a lot on where you are located...
Electric Warrior wrote:They may have to get the other pots directly from Omeg as well. I don't think I've seen this particular style for sale anywhere.
I'm sorry if I'm missing something but I dont really see any problem with the Pots, you can get all the pots easily from Alpha and other brands, worst thing that could happen is that you had to mount the pcb in a different way (not supported by the Pots thread) and run wires from the Pots lugs to the pcb correspondent holes.

Anyway, if the Volume pot is 10K Rev Log,
you can get this Omeg from Audiomaintenance, they have it in stock:

http://www.audiomaintenance.com/acatalo ... _gang.html

Other options,
You can also make this ones work even for supporting the pcb, probably just have to spread a litle bit the Pot pins to solder them on the pcb holes, easy enough:

https://www.banzaimusic.com/Alpha-16-PC ... V-log.html

https://www.banzaimusic.com/Peavey-16-S ... V-log.html

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Post by ilcaccillo »

bettsaj wrote:As an aside... n the macaris picture the Blue cylindrical 22uf caps.. Where would I get those from? The brand looks like Vishay.... Just curious where I could source those from.
you can order them from Banzai:

https://www.banzaimusic.com/Vishay-BC-Components/

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Post by bettsaj »

Hi guys,

It's been a while, and I've been busy but I'm now at a stage after much fiddling and re-arranging and tweaking that I have an almost finished reproduction of the Colorsound Power Boost PCB layout in Eagle.... However I've hit upon a problem that maybe some of you can help with. I just can't get my head around it. For starters, after looking at the gut shots of the PB, I decided to make the earlier design with the extra 10k resistor and the 4.7uf caps. I've managed to source all the necessary caps etc, and I'm almost in a position to etch the board. Now to my problem.

below is the schematic that I'm working from......
Image

I've copied this faithfully into eagle, here is the Eagle reproduction

Image

And here is the board layout in Eagle from that schematic

Image

next we have a mirrored image of the actual PB PCB layout. I've scribbled onto it the location and value of the various components..... This was my aid when laying out the PCB in Eagle.

Image

I'm looking at the 2 4k7 resistors R8 & R9 on the Eagle schematic, on the board photo I've highlighted a track in yellow, on the schematic it would appear this is not correct. On the schematic it shows that track going to U$6 however on the actual board photo it's going to U$7.
Also on the photo layout the track from the 22uf cap U$13, is going to resistor R8 and NOT R9 as it shows on the schematic.

The photo is correct...... The schematic shows some issues but I can't get my head around what changes are required on the schematic to correct these issues.

Any ideas??
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Post by Electric Warrior »

I don't see the problem in my schematic. That trace you highlighted connects the 4.7µF coming from Q2C with the 4k7 (R8) going to the bass pot/0.1µF (U$8) and the 0.01µF (U$6) going to the treble pot.

The problem with your board layout is that the numbers you assigned to the connectors of the bass pot do not match the ones in your schematic. R8 and R9 are mislabled. So are U$6 and U$7. Swap them around.

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Post by bettsaj »

Hi Electric Warrior, many thanks for getting back to me...

As I've been looking at this and reviewing what you've said... Looking at the photo I believe that the 4.7µF coming from Q2C then passes to the 0.01uf U$7 then to the 4k7 (R9) which then passes to the 0.1uf U$8 then to pin 3 of the bass pot. R9 passes to U$8 and pin 3 of the bass pot as it should...... I'm confused. Like I said, newbie alert LOL.... HELP!
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Post by bettsaj »

Also if I swap around the two resistors R8 & R9 that will make the trace for pin 3 of the bass pot incorrect. At the moment the trace for pin 3 of the bass pot goes UNDER R8 to connect the top of R9... If I swap the resistors around that connection won't be correct. See the updated image below with the added trace for pin 3 on the bass, going to the top of the R9 resistor.... This is correct, however the other end of the R9 resistor should be going to U$7 according to the board but the schematic is saying it must connect to U$6 which isn't correct to the original board layout.

Also the negative end of U$13 according to board layout should connect to R8.... But the schematic is saying it's got to connect to R9.

The resistors are in the correct place when you look at the other connections and where they're going........ Something is not correct according to the original board layout.....

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Post by bettsaj »

Right.... All sorted, and the schematic is correct although the orientation of the bass pot was wrong on my copy of the schematic which buggered up everything else.

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Post by bettsaj »

Hi guys,

It's taken a while as I had some issues with the schematic... blah blah blah. I won't go into that here, suffice to say you can read all about it ion another thread.

Here is the completed Colorsound Power boost 18v version, for those of us that maybe want to lay the board out as per the original with board mounted pots. I've added it as a PDF and it should print out to actual size.

This is not a reversed layout, so if you intend to iron the layout onto a board it will need to flipped.

If anyone wants to know part number of caps, etc I'll work on a list and post it together with where to source them. This is basically a like for like board....... The traces are pretty much exactly the same.
Attachments
powerboost.pdf
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Post by bettsaj »

Hi guys,

It's been a while but I thought I'd give you an update on my Power boost quest.

I've made two pedals, and both have been sold :D Both worked like a dream. There was only one difference between the two.... One was made with my revision 1 board as attached in an above post. this board was totally designed and printed from Eagle. it worked ok, but I wanted to get closer to the original layout, so I hand drew the PCB from a PDF of the eagle layout and have ended up with something that is identical to the original.

The attached PDF should be printed out at 100% size, it is already mirrored to enable you to heat transfer it onto a board. I've also included a Bill of Materials so you know what to buy for the build. this includes board mounted pots.... Word of warning.... I have tried but can't get pots that will fit. You need 16mm 100k linear pots for the bass and treble, and a 10k rev log for the volume. The problem is that you need to get pots with at least 10mm long threads so you can mount them to the board, and then pass the threaded shaft through the enclosure with enough thread protruding to enable you to engage the nut. unfortunately off the shelf pots don't have a long enough thread so both pedals had to be wired in the normal way.

If anyone knows of a supplier who sells these pots please let me know.

Word of warning... This pedal has no master volume, so consequently is really loud. it breaks up at about 75% on the volume (this should really be labelled gain and not volume) into a nice overdrive.

Any questions, please don't hesitate to ask....
Attachments
BOM.xls
Bill of Materials
(32.5 KiB) Downloaded 150 times
powerboost_rev2_mirror.pdf
Power Boost Board trace
(86.55 KiB) Downloaded 227 times
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Post by bettsaj »

UPDATE: The pedal is finished, and sounds aw some..... Here are the first tentative pictures of the board and the enclosure. Please bear in mind that this enclosure is NOT being sold on and is for my use only... So I plagiarized the logo etc for my build. If however somebody wanted me to make a power boost for them I would most certainly change the name and not use the Colorsound name. Anyhoo... Here are the first set of pics:

Enclosure, done with water slide decal...

Image


Here is the component side of the board...

Image

Image

And the solder side...

Image


I had one issue, that was that the pots couldn't be mounted "through" the board as the original as the thread on the pots isn't long enough to engage the board and the thickness of the enclosure, so I simply mounted them the other side.

Secondly, I have one slight noise issue, which i suspect might just be my set up... When the volume is on max I here a slight ticking noise... it's not there when it's turned down only when the volume is over around 75%. Apart from that the pedal is brilliant, made with all vintage correct NOS parts (apart from 2 resistors which I couldn't track down) As an aside, I may install a master volume knob on the side.... It's really loud as it is, even when the volume is min setting it boosts the output by around 20db.
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Post by Electric Warrior »

bettsaj wrote: I had one issue, that was that the pots couldn't be mounted "through" the board as the original as the thread on the pots isn't long enough to engage the board and the thickness of the enclosure, so I simply mounted them the other side.

Secondly, I have one slight noise issue, which i suspect might just be my set up... When the volume is on max I here a slight ticking noise... it's not there when it's turned down only when the volume is over around 75%. Apart from that the pedal is brilliant, made with all vintage correct NOS parts (apart from 2 resistors which I couldn't track down) As an aside, I may install a master volume knob on the side.... It's really loud as it is, even when the volume is min setting it boosts the output by around 20db.
Yeah, this kind of layout sure is optimized for a particular type of Radiohm pots or their clones.

Have you tried putting the circuit into the enclosure yet? Maybe it just needs a little shielding. I don't have any ticking problems with my vintage unit.

It sure is loud as f***, but that's the whole point of the pedal, isn't it? :mrgreen:
I built a volume pedal to put after the boost, but I never use it. The distortion this circuit can produce sounds better to me when the amp is being hit hard.

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