Park G10R schematic

[Snowman8]

Thanks from me as well

Also was looking for G10/G10R schematic. I have a G10 and a G10R, both have the noisy pot problem, and I have heard of others with this issue. I have tried cleaning them but it doesn't seem to help for long. Time to replace them. Schematic not really needed for this, but thought it would be good to have in case of some future failure.

I'm planning on converting the G10 to a G10R, since I have a G10R (and now the schematic) to use as a guide.

[J M Fahey]

You should be able to do so easily, since I'm sure the board is the same, even component values silkscreened on top, so you shouldn't even need a schematic.
You'll have to get the matching reverb tank though.

[Brad Litton]

I have a G10R that blows fuses immediately when put in, I'm not familiar with the electronics, but figure that something is shorting out. Does anybody have any idea what may cause that?

[J M Fahey]

Yes, replace the TDAsomething power chip.
Be careful when desoldering and pulling the old one, better yet clip its legs and pull them one by one.
Pamper the PCB.
Remember you'll ned a new mica and some thermal grease, check when retightening the nut that the IC flange stays insulated from the chassis.
Good luck.

[plast]

Hi all, I'm also working on the same thing: converting a G10 to a G10R. Many thanks for the schematic! I'm having a hard time reading what IC3 should be though... doesn't look like the 4558 as on the others, or?

And, the reverb unit, what is that? Is it really a reverb tank? I would have expected some digital circuit, must be much cheaper to make, no? So for those of you who have a G10R, do you know what is in there??

[J M Fahey]

A 4558 should work, as well as a TL072. They often use a 1458 there, don't know if it can supply a little more current or just because they save $0.002 or perhaps they have to use up those 5 Million chips they ordered once by mistake .
The reverb tank is a Belton, don't know the code but it can probably be read on another similar amp, the reverb is *very* generic.

[tpb03]

Hi Thanks for this info. I have a G10 which I want to get going again. Like most people's experiences all my pots are scratchy and I am going to replace them. While I am at it I plan to replace the JRC4558 with a TL072. I noticed there are a few of them in the circuit so I might replace all of them. I also plan to ditch the TDA2030 and upgrade to a TDA2050 for a bit more power. I have a question for soem further mods, I would like to add a dedicated clean channel and a line out. I assume that I can add a line out with a 2.2k resister from the speaker out to ground.

For the clean channel I wanted to have a switch after input which can divert from the existing adjustable gain channel to a clean preamp circuit. I am not sure where I can take the line out of the clean preamp and rejoin the existing board. My electronics is a bit rusty but my gut feeling is that I can run straight into pin 1 (passive input) of the TDA2050.

Can anyone help me out? Alternatively does anyone have a schematic from a Park G25R? I'm pretty sure the circuits would be similar and its more than likely using the TDA2050.

[J M Fahey]

Hi TPB
That G10 won't let you do much, for lack of physical space.
Where would you fit the pots necessary for "a second dedicated channel?"
There is only one 4558.
Replace it, if you wish; the sound will be basically 99% the same, very slightly brighter.
You *will* have noticeably less hiss, that justifies the change.
Try cleaning your pots first, replace only what's really necessary.
You will *not* increase its power by using a TDA2050, because the power supply stays the same.
If you want something better, you'd better build something new from scratch, whatever you like.
The single most important increase in quality would be to build a cabinet with a larger, better speaker(s) and use your combo as a head.

[tpb03]

Hi TPB
That G10 won't let you do much, for lack of physical space.
Where would you fit the pots necessary for "a second dedicated channel?"
There is only one 4558.
Replace it, if you wish; the sound will be basically 99% the same, very slightly brighter.
You *will* have noticeably less hiss, that justifies the change.
Try cleaning your pots first, replace only what's really necessary.
You will *not* increase its power by using a TDA2050, because the power supply stays the same.
If you want something better, you'd better build something new from scratch, whatever you like.
The single most important increase in quality would be to build a cabinet with a larger, better speaker(s) and use your combo as a head.

Thanks J M,

I failed to mention that I had two 12" Celestion speakers which I was going to use in a separate cab. I was going to then rehouse the amp in a new head unit type closure, hence I would have more room for a second clean circuit.

I figured if I could get a simple two channel amp up and running by modifying my park, then I could build something from scratch afterward once I get back up to speed and I am familiar once again with my trusty old multimeter.

Thanks again

Tim

[J M Fahey]

¿ Two 12" Celestions? Great !!
You are starting this with your right foot.
Fully agree with your idea of going step by step.
You may first use that great cabinet driven straight from your G10.
Later on, you can build a 50/70W power stage (LM3886/TDA7294) with its own power supply, mounted inside your cabinet, turning it into a *Guitar* powered cabinet.
With that strong base, you can experiment (protoboard) preamps at will.
When you are certain, you commit to Veroboard or PCB.
You can also build a tube preamp if you wish.
Good luck.

[tpb03]

¿ Two 12" Celestions? Great !!
You are starting this with your right foot.
Fully agree with your idea of going step by step.
You may first use that great cabinet driven straight from your G10.
Later on, you can build a 50/70W power stage (LM3886/TDA7294) with its own power supply, mounted inside your cabinet, turning it into a *Guitar* powered cabinet.
With that strong base, you can experiment (protoboard) preamps at will.
When you are certain, you commit to Veroboard or PCB.
You can also build a tube preamp if you wish.
Good luck.

Yeah I eventually intend to build a platform based system, but to start with I just want to get back up to speed on the old Park. The Park has a pretty good sound for such a cheap unit. Way better than a lot of more expensive amps.

Going back to my original post, if I build a clean channel preamp using an lc386 or similar, where do I re-enter the existing circuit? Do I wire it straight up to leg 1 of the TDA2050?

Eventually I would like to do as you suggest and build a power amp from an LM3886. If I want to use the Park G10 as a preamp, is it ok just to use a line out, or should I scale back the signal with some form of resistance first?

[vhm14u2c]

A friend of mine gave me a park g-10 that had noisy pot issues. I tried tuner cleaner, did not do much good, but when I got ready to replace them, I noticed the component board traces where the pots were soldered to, were broken, and barely touching, so before replacing them, I resoldered them first added solder to fix the open traces to the pots (did all since some seemed a bit "shaky", and have not had any noisy pot issues since. Its best to unmount the component board from the panel completely to see which pots are loose, most likey, those will be the pots that have broken traces.

Vince

[JoeM]

Thanks for the tip Vince. My older son has a G10 with the noisy pot issue. I'll check the traces for bad connections. Not a bad sounding amp actually.

[J M Fahey]

a G10 ..................................... Not a bad sounding amp actually.

Funny that this can be said in this very professional Forum , while on countless others such an opinion would bring instant death to the blasphemous (well, at least a virtual death).
Even funnier is that most (all?) beginner's amps do sound very good, just needing a real speaker cabinet such as a decent sized 2x12" (or 4x12") , obviously loaded with good speakers, which to boot do not cost much more than around 100$ each, and sometimes even less , nothing out of this world.

Oh well.