July 14, 2019 at 10:31 am #6361
I am planning a Blues Buster and trying to figure out a few things, can you help?
- A/B mods – how do I NOT use the A/B mod ?
- How DO i use the A/B mod? The build sheet says this: “in the photo below (LEDs on one
side) and (3 silicon diodes with one LED) in tandem on the other side” – erm what does that mean?
Looking at the photo on the A section, there appears to be an extra solder point in between the two D3 points and the A point. Yet the D3 diode seems to have the cathode from A connected to the anode of D3. Whats the extra solder point for?
On the B side there is also an extra solder point, no diodes (unless they’re vertical), but an led. I imagine the cathode is in B and anode in D2? but it’s hard to tell from the photo.I’m having trouble squaring the circle between the photo and the description (I quoted above).
Help! In the end, I’d rather not drill any holes if they are needed and skip the A/B mod all together but I really can’t tell how to do either. Thanking you in advance.
philJuly 14, 2019 at 3:03 pm #6364wilkie1Moderator
1. To NOT use the A/B mod, simply install your D1-D4 diodes directly on the board.
2. To use the A/B mod, you need to add an external DPDT switch. This switch is best used with one of Barry’s DPDT wiring boards (temporarily out of stock). The switch is wired to the A and B pads and different diode pairs are wired on either side of the DPDT switch. A useful photo will be available when these switch boards are back in stock. When using this mod, you do not install any diodes on the main board in positions D1-D4.
The extra solder points that you mention are there to facilitate installing either a LED or a axial diode depending on the component’s lead spacing. You would only use 2 of the three in each position.July 14, 2019 at 3:11 pm #6365wilkie1Moderator
One other point to mention. On the Blues Buster board, there is a provision for another DPDT switch labeled SW1a and SW1b. This switch is used to select either diode pairs installed at A and B or the one installed at D5 and D6. This is NOT the same as the A/B mod discussed above.July 14, 2019 at 3:13 pm #6366
To learn more about diodes used as clipping options check out our supplemental guides on the Guides Page particularly Page 13 & 14 of the Beginners Guide to components.
The Guides Page can be found by using the large red button either on the Home Page or the Forum Home Page. The main build docs assume the basics and some understanding of schematics. Our supplemental guides are available for anything you wish to learn more about.July 14, 2019 at 3:48 pm #6367
OK, I think I understand, let me try again.
For normal usage, install D1-D4. There will be NO SW1 …
pgJuly 14, 2019 at 3:50 pm #6368
Great document btw, thanks Keymaster.July 14, 2019 at 3:54 pm #6369
(bad form to confuse anode and cathode!)July 14, 2019 at 4:32 pm #6370
Q: For normal usage, install D1-D4. There will be NO SW1 …
SW1 allows you to switch between the clipping options that are On-board. Only when using A/B pads for off-board modding you do you not need SW1 since you are already going to be switching using a switch which is Off-board.
Even if you do not have any experience reading a schematic you should always practice looking at them since in this case you will see D1 through D4 and you will see the switch symbol showing how it switches. It can become quite intuitive very quickly. In the image below it shows you that there are two sides to the switch SW1a & SW1b (see components guide) so the schematic shows you are switching between D1 through D4 on SW1a and D5 & D6 and SW1b for your two different on-board clipping options.
I hope that helps.July 14, 2019 at 4:49 pm #6371
Yeah I was doing exactly that and getting ready to correct myself. It’s been 25 years since I had a circuits class and the last time I really studied a schematic. I think I understand now. Back to the drawing board, well – back to reading schematics at least.
Thanks very much for helping!
pgJuly 18, 2019 at 9:01 pm #6389
Well I got the BB wired and working. Sounded pretty darn good, no buzzing humming or anything like that either.
But, I had the pots wired backwards. Ok, solder remover thingee, re-wired it and nothing. Upon close examination with a jewelers loop I had burned the pcb pretty bad, at #3 of the drive solder point. Tried to jump r6 to it with a resistor lead, but it was gorked. Oh yeah so were the other two pot solder points. dang…
But it worked! So I’m really glad about that, not so glad about the burned out pcb. I will order another one and also the Ancestral Apparition – I’ve got the bug!July 19, 2019 at 1:20 pm #6395July 19, 2019 at 10:11 pm #6405
Good stuff, I appreciate the guides, the last one you suggested helped a lot. I’ll keep reading.
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