There are slight differences between the 29 and 25 - or 78 versus 68 series.
The parts and layout may look similar, but it's with the Parts PLACEMENT that makes one mod that works well on one type, fail in being tried on the other...
Here. Read this
Thread about the PC-66
Note the layout and PARTS placement - how it's wired in.
Then go here...another spot for the 29
Both look similar and you'd be right, but the values need fixing.
So,
@NZ8N has the better way - at least it's more universal.
When the MOD limiter clamps too hard, it means the section is TOO sensitive to changes - so you'll have to tame it - use a 1KΩ or even 560Ω ohm resistor ACROSS C71 or C91 to lessen the filtering - those caps "Sample and Hold" until the limiter transistor bleeds it down - and there is nothing else there to lessen those spikes. When the cap stores that charge - there is only the BASE of the limiter to drain it off - so do what NZ8N and many others do, just strap a resistor of some low values across the two legs of that sample cap and run with it.
In the above, the 29 graphic, you can keep or remove C70 - but just solder a low-value resistor in across C71 or C70 (whichever is convenient) - to reduce the effectiveness of the caps charges that hold the limiter engaged longer - by draining it faster.
C91 of the '29 76/78 series and C71 of the 66/68 / 25 series of the older units, don't know of the newer SMD ones if those are even still using a similar design.
Many simply "pull the limiter". But in doing so - remove any chance to keep the signal from entering into stereos and amps and speakers - of your neighbors.
