Panama Loco 15 Watt Head Schematic Request

[dhuber]

I'm looking for a schematic for a Panama Loco 15W Head.

I bought the X version used. Way over the top gain, unusable for me. I opened the amp up and it looks like it's going to be easy to revert back to a regular non "X" amp. I bought the amp used but I have to believe Panama did the mods to make this a X version. It does not look like they removed the circuit board, just jumpered components across the top of the board. They installed a single stage transistor circuit board at the front end of this amp and used hot glue to attach it to the chassis. Looking at the main board I can pretty much guess what needs to be removed as it's obvious where Panama modified it. If no one posts a schematic I'll post one when I'm done.

[dhuber]

Loco.pdf I have the schematic drawn out and saved as a PDF. If it does not appear I will rescan it and save it as a GIF. The LOCO X version has all the potentiometers bypassed with 330PF caps from the top to the wiper. These were soldered in from the top side of the board so I'm wondering if this only occurs only on the X version. I'm also curious about the value of CXX, C5, C7, C9, C10, C11, C12, C14, C18, R20, R21, R24, and RX on the regular LOCO model.

[Enzo]

Node: R27,28,29 lacking path to ground. Power tube cathodes lack a ground connection, I assume a cathode resistor.

Caps on the volume pots are brightness caps, eliminate them if you like. I'd leave them until I determine the amp is too bright or not.

RX can be anything. It is a high value resistor to keep C11 charged. I don't know what a minimum might be, 47k maybe? I'd use 470k or 1 meg myself. The value doesn;t matter. When the switch is open all it does is keep the cap charged, it has no audio effect. When the switch is closed, it is shunted across and has no effect.

No reason to think R20,21,24 would be different.

[dhuber]

Yep, R26 47K ohm should be just left of R27 with one end at ground

Node: R27,28,29 lacking path to ground. Power tube cathodes lack a ground connection, I assume a cathode resistor.

Yep, R26 47K ohm should be just left of R27 with one end at ground. It may take a week but I'll correct the schematic. Thanks for the feedback!

[Dave H]

Yep, R26 47K ohm should be just left of R27 with one end at ground.

If the 47k is between the junction of R27,28,29 and ground it will need a capacitor between the effects return and V2 pin 2, R29.

R1, R2 should be connected to the screen supply.

[Bass 300]

dhuber,

Forgive me for resurrecting an old thread but I can't contact you directly for some reason.

You're schematic is the only one of the amp I can find online. I've emailed Panama about my Loco and Conqueror head but haven't heard back.

I have a regular Loco and, as I received it, it's too dark and muddy when distorted no matter what guitar/cab combo, power setting, or voicing I use. I have to put an eq pedal in the loop and take lows out to get it where I want it.

I haven't open it yet but was hoping you could help me figure out what I need to change. I'm proficient with an iron and should be able change any components involved.

The QC sticker is still on the back under one of the screws so i assume it hasn't been opened or modified.

Thank you

[dhuber]

Bass 300, I'm sorry I can't answer you outright as I buttoned up this amp a little over a year ago. I added a bright switch to my amp but I don't have the bright switch on the schematic and I can't remember how I'm accomplishing the brightness. Off the top of my head I think I might just be putting C xx in and out of the circuit. I can't remember why I have this capacitor labeled as C xx. Maybe it was never mounted to the circuit board. I agree the amp is too dark without the bright switch and too bright with the switch. This is on my to do list but I don't know when I'll open this back up. I think I need to put a larger value capacitor in C xx. I think I'm using a 300 pF right now. I'll post my values once I finish this up.

[Bass 300]

Thank you sir. I can post pictures of the board in my amp for comparison if it'll help.

[dhuber]

I pulled my amp out of the cabinet today. Disregard what I stated on my previous post. For brightness I’m taking C10 in and out by an added switch. C10 is covered by hot glue and I can’t remember if it’s 680 pF or 330 pF.
Don't take C10 out of your amp because it's dark with C10 out and bright with it in. They have C10 in place to let the highs bypass the first gain potentiometer. The higher you turn the gain the less affect C10 has.

I previously changed C9 from 1 uF to 22 uF. This won’t do anything for treble but it should add more mids and bass. I changed C11 from 10 uF to 2.2 uF. At lower volumes I prefer the voicing switch on (adds C11) which gives me mid boost.

I also noticed I previously took C18 out. I don’t know what its purpose is except that it would cut high frequencies or noise.

C10 and CXX are ceramic capacitors. As a general rule prefer my signal passing through film capacitors as opposed to ceramic capacitors. At some point I may change these out with film capacitors. I apologize as I have no easy answer for you to add treble. CXX and R19 make a high pass filter. Increasing the value of R19 should cut more mids and lows. Increasing the value of CXX should start adding mids.

My schematic is incomplete and I noticed I have R 28 & 29 labels swapped. My amp was an X model. I’m pretty sure the values for C: 5, 7, 9, 10, 11, 12, and CXX are the same is on your model but I'd like confirmation on that. I'm by no means an amp expert that's why I posted a schematic request and would also like confirmation on what the component values are on the plain LOCO model.

I spent a lot of time playing this amp today. I actually played with C10 in place, tone set at 12:00 and the Stratocaster tone slightly rolled back. I thought it sounded fairly decent. I may put C18 back in and permanently put in C10. Looking back I should have just cut the added components off with a pair of cutters because it was obvious what Panama or whoever did to make this an X. I thought the X sounded like crap, but I'm not a high gain player. I'm also thinking there might be a component failure or a bad solder joint somewhere on your amp causing the dark tone. When I switch C10 in, which is the regular stock setting for this amp, the tone is bright. If you're complaining about the tone with the gain full on I think you're asking too much from this amp. With gain full on the tone is non distinct fuzz tone. I don't care for the tone of this amp once the gain is rolled past 12:00, YMMV.

[Bass 300]

Sorry taking so long to get back. Tore mine open today to find C10 and C18 missing....so much for the tamper sticker.... sounds like this could be why mine sounds so dark.

C5 is 22uf 450v
C7 is .22uf 250v
C9 is 10uf 50v
C10 ?
C11 22uf 50v
C12 .001uf 1200v
CXX 715P 600v 222j Orange Drop

C18?

[Bass 300]

[Bass 300]

For anyone who finds this thread in search of circuit support, it would appear that the Orange Tiny Terror 15 is essentially the same circuit and its schematic can be used as reference. My Loco even has "TT15 Combo" printed on the circuit board next to the input jack.