PT-80 repeats

[mmaatt25]

Hi,

Finished and had fully working PT-80, but now the repeats pot doesn't change the amount repeats?? I get 6-7 clear repeats constantly.
I've measured the resistance of the repeat pot as follows: between lugs 1&3 48.3k (fully open/fully closed), lugs 2&3 48.3k/99.4K (fully open/fully closed) and lugs 1&2 50.8k/0.00K (fully open/fully closed). hope that makes sense??

So the pot appears to be working?? If I understand this right the repeats pot bleeds of to ground the repeats (regenerated from pin12 of the ne571), so giving less repeats when fully grounded. Over simplified???

Level pot and time pot working fine.

Whats going on??

Many thanks

Matt

[mmaatt25]

Just need one clever person to help me!!

Matt

[Galego]

Lugs 1&2 should have the same results as 2&3 but reversed.

Does the delay level work?

[mmaatt25]

The delay level works fine.

The pot measurements are measure in situ, so any that would would explain the differing values, other compents having any effect etc.

Matt

[KazooMan]

I am not certain just what is causing it, but you have a problem (you already knew that  ).

I just measured the resistance on the repeats pot of one of my working PT-80 builds.  I get 26K across the entire pot (lugs 1 and 3) and from 0 to 25K or 25K to 0 between lugs 1 and 2 or 2 and 3 depending on the rotation of the pot.  This is with no battery in place and no plugs in the pedal.

If you look at the schematic this makes sense.  The repeats and level pots (both 50K) have their number 3 lugs connected and their number 1 lugs are both connected to ground.  They are in parallel so you would expect to measure 25K across either pot. 

[mmaatt25]

Thanks KazooMan, I took the repeats pot out completely and am getting some strange readings between lugs 1&3 way over 100k?? yet 50k sweep to 0k between 1&2 and 1&3 as expected.

Anyway solder in a new 50k pot and everythings fine.

I'm getting loads of runaway feedback/oscillation, so I think I'll solder in Mark Hammers fix on pin 12 of the NE571.

Many thanks

Matt