Proco Rat 2 USA made OP07DP little to no variance in gain and filter

[DMZ]

Hoping for some advice on these 2 x RAT 2 pedals I have. Both are the slant box USA models with the OP07DP Op Amps. Basically identical and both behave in the same way.

I am wondering if these pedals are meant to behave this way or if there is something faulty with them? With the Volume pot there is a smooth increase and range from 8 O'clock to 4 O'clock. Not so with the Filter and Gain pots. There is no variance from 10 O'clock to 4 O'clock on either of the pots.

I have earlier 90's Rat 2 and have used the later Chinese made models and it only seems to be with these 2 that there is no variance in the Filter and Gain as I have suggested.
Both pedals are stock. Is this normal for these type of Rat 2 pedals?

Thank you for your help in this problem.

DMZ

[antonis]

Open enclosure and check for proper Pots connection..

[DMZ]

Hi Antonis.

Thanks for the reply. The pots are surface mounted onto the PCB so I dont think they have been wired incorrectly.

Thanks again for the input. Its appreciated.

DMZ

[antonis]

Are pots properly soldered on respective pads..??
(not just placed/populated there..)

[GGBB]

The pots are surface mounted onto the PCB so I dont think they have been wired incorrectly.

The board is sandwiched between the pot body and the enclosure - but RAT pots are through-hole soldered - not surface mounted.

It is possible that those solder joints are failing, as Anotonis has suggested. If you take the board it out of the enclosure you can look at the solder joints to inspect them. Post pics if you can.

In any case, it sounds like something is probably wrong with your units. Did you acquire them used? Were they ever damaged/repaired/modified? Are the pots worn or dirty or noisy? Are all of the pot and component values correct?

Here's a RAT schematic for verification:

[Chugs]

Check the taper of the pots. They should be Log but I have seen OPO7DP Rats with Reverse Log pots instead. The use of Reverse Log pots would make the controls seem they like are not doing much.

[DMZ]

Hi Antonis, GGBB and Chugs.

This forum is great, the members are always so helpful and willing to impart their collective wisdom.

I love learning and get alot out of asking questions from the group.

Thank you all for your great input and advice

In answer to your various questions:

They were purchased used and look to be completely stock.

The solder points on the pots look very clean and shiny.

The pots were not noisy or scratchy or looked worn, Its all very clean inside.

However, what I have now discovered thanks to you all is that the pots are C100, which means they are Reverse Log pots as Chugs suggests?

And this would mean that they behave the way they do because of this?

So they are not faulty, its just the way they were designed to operate with the C100 pots?

Regards

DMZ

[willienillie]

Wow, major screw up at ProCo!

So they are not faulty, its just the way they were designed to operate with the C100 pots?

They were designed to operate with A taper pots.  I bet your volume comes on quick!  The Filter control makes a good Tone control with a C100K, but you would need to swap the connections to the two outer lugs, much easier with wires than PC mount.

[DMZ]

"...I bet your volume comes on quick!.."

yes it does Willienillie

[ElectricDruid]

Gah, they just stuck in any old thing, didn't they?

Maybe the work experience kid got put on parts ordering that day?

[GGBB]

Gah, they just stuck in any old thing, didn't they?

Maybe the work experience kid got put on parts ordering that day?

I think it might have been an episode of Undercover Boss.