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Messages - phatt

Hi wim, first up, Does the Amp work as per normal?
For that era the Foot switch is likely a latching type.
Use what you have or use an open plug and bridge the terminals you will soon work out if it's latching or not.
I have no idea about the flying resistor, hard to tell what it's connected to??
As for the Caps padding, Yes often done when they run out of parts.
As I've never seen these amps, looks like it's a budget brand so could be factory layout.
(I've seen worse from Early Roland amps)

Re Speaker issue,, why not use the original spades?

80Watts clean from 130 Watt rig is par for most gear,, Sand or Glass

Amplifier Discussion / Re: Reverb spring hitting
August 11, 2023, 08:27:16 AM
Welcome to the crazy forum, :) 
One of the springs may have broken off. You will need to open it up and have a look. Maybe post some pics of what you find inside the tank.
Before you assume the amp has a problem, Try another guitar and another guitar lead just to rule out the obvious stuff.
Most of the magic you hear is most likely created in the power stage ,,,so highly likely if you mess up that you will regret.

you have negative Feedback connecting the output back to those 2 transistors so there is a lot to consider before you mess with that section,,, as I said you need to fully understand before you mess it up. If you blow that OTx you will struggle to find a replacement Rendering it land fill.

I'd advise you to check out simple Non invasive options.
Google L pads, or add a fixed resistive divider at Spk output.
Or try to find a less efficient speaker.
No no no, :o
         Those 2 transistors are DC coupled they work as one, as the amp seems to be working after removing the mod then consider yourself very lucky. :-X

Research a small attentuator on the speaker output or throw a heavy blanket over the speaker but never interfere with the power section unless you know exactly what you are doing.
Yes RL is a resistor. RL is the left over from my simulation drawing. (It's R9 on the PCB)
I think it's mainly there as a discharge path, as long as it's high enough to not load down the signal then it's fine.
Hi Joe,
         Well after some digging into old CD's I did find this which may help you.
A screen shot of PCB layout for Version4, the one I made for my Pedal board.
If you want it to fit onto a standard pedal case then you will have rethink the layout as you can only fit 3 16mm pots side by side in a Boss size pedal case.

You can reduce the slope R1 for say 56k will give a little more bottom end but 68k seems to be about right to my ears.
As mine is on all the time I just used a simple flick switch instead of a stomp Switch. As there is enough info on the net for bypassing and battery setup I've left all that out of the Schematic.
 The Protection Diode (Orange) is in the wrong place on this layout, it should be in series before the resistor.
Also R000 is just a wire link.

I still have never been able to perfect KiCad it's a bit of a pain to work with but it was free and board size was not limited like Eagle so I persevered with Kicad.
Sadly now my Eyes are letting me down and I don't do much work on circuits but I still try to fix stuff for other muso's if it's not too fiddly.
Have fun with it. Cheers, Phil. 8)
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Hi Joe,
        Sadly no as that hard drive died and took with it a lot of stuff. I do have some pcb pictures on CD somewhere but they are the early versions which were hand drawn and the early circuits are different.
It's not a hard circuit to layout as there are not many parts and only one chip.
Someone on another forum posted a perfboard layout of it, just let me know if you go in that direction and I'll post it.
The Triumph Overdrive was impressive.
Smart move adding a decent tone control on a dirt pedal.
And designing one where the midrange actually works.
That's why I love my PhAbbtone so much as the mid control is very potent.
Humm, maybe he has been reading the forums and found my circuit.   ;D   Phil.

I'm don't know that amp but Short of reprogramming the chips it's unlikely you can alter volumes. Some digi amps have the ability via software interface to alter parameters so maybe check the manual/ website. If it has a USB port there might be a software app to alter the presets.
You can of course just leave it on one preset and just use OD pedals for more grit.
Great to hear it worked out well, thanks for the feedback as it will give others clues as to how to do such things.
Welcome Hutch,
IIRC, there is an FX loop or Preout/Pwramp input.
Send a signal to return only which should disconnect the Preamp from power amp and see if that resolves the Buzz and over heating.
I know they run those LM chips at the voltage limit and they can fail if driven hard enough, especially if driving 4 Ohms.

Quote from: Loudthud on May 11, 2023, 02:45:12 PMYou learn how to apply Ohm's Law to calculate Voltages, currents and equivalent resistances. If you skip this step or don't know how to do it, you can look pretty stupid on an internet forum.

Yep,  I'm laughing cause That describes me very well.  :-[ :D
Yes I do have times when I get stuck and have to go back and refer to books to recall even basic ohms laws.
I figured I was too old to go back to school so I cheated and just use sims to workout most of the maths.

I use sims and the breadboard to design build my own circuits.
Being able see a graphical plot on the screen at any point in the design makes it so much easier to work out just where you win or loose the mojo.
I can't afford scopes and other fancy teck bench gear and as most of the gear I build is fairly straight forward it's not worth spending on gear that will not get much use.
Hey chum, unless you intend to build the next space shuttle leave that really hard stuff till later.
If all you want to do is understand Analog Audio Amps then you will learn faster by reading stuff on pages like this;

Open up Articals.
Learn some basics first mate, such as transformers and rectification then move on to basic transistor circuits.

Scroll down to *Beginners Luck*, a lot of good stuff to find there.
Stuff there will help you get your head around the basics.

Be warned you will need weeks to absorb it all as it's a massive site with heaps of good info.
Good work, Glad to hear it's working again. ;)
Re speaker, Either way is fine, it only matters when you have more than ONE speaker THEN you have to make sure the polarity is IN Phase.
When more than one speaker the sound still works and no damage is done while out of phase but you tend to notice a loss of Bass.

When I met my wife years ago she had a stereo unit and she said her friend had the exact same unit but it had much better bass so I checked and sure enough the speakers were wired out of phase,, swapped the wires on ONLY One and bingo she then heard the Bass that was missing.

Yes adding a slip on heat sink can't hurt.