HF85 schem error?

[ferninando]

What is the error in the schematic of the HF85.?
Iv read it's in the loudness ckt., or the vol ckt.
How to fix it?
Thanks.

 

[jaymanaa]

Damn, I can't recall either. Tom B knows I think. IIRC it's a resistor and cap that go to ground which are in parallel and should be series, but I can't remember what they hook to control wise.

 

[ferninando]

well its going to be awhile bofore I tear into it.
no hurries no worries.

 

[dcgillespie]

The Yahoo Eico group has the loudness modification in its files section I believe. As for there being a schematic error, actually, the original design works as Eico intended it to. They just had a very different belief in how the loudness switch should operate as compared to most other brands out there. In fact, virtually all of the loudness switch installations used on various Eico models are just plain weird in one way or another. At the time, there was no standardization for how such controls should operate.

Dave

 

[jaymanaa]

The Yahoo Eico group has the loudness modification in its files section I believe. As for there being a schematic error, actually, the original design works as Eico intended it to. They just had a very different belief in how the loudness switch should operate as compared to most other brands out there. In fact, virtually all of the loudness switch installations used on various Eico models are just plain weird in one way or another. At the time, there was no standardization for how such controls should operate.

Dave

Talk about weird volume controls, have you ever played with a Hafler Iris pre. There is a circuit in there, that changes the volume that is flat out weird. If my understanding of it is correct, it was designed that way to keep the signal completely out of the volume pot. It works really strange; you turn the volume down just a hair, and it seems to drop a ton, but it just takes a second for it to come back up to just under what you started with. You would have to operate it to really understand what I'm trying to say. I love my modified Iris, and it has been in my main for a long time, but I'm still not used to that weirdness.

 

[ferninando]

well Im scrapping the ldns completely and puting in new vol and tone pots and making it just a CD/phono pre with no tape stuff. and Ive built new tone boards from discrete parts. All to be done in futuer, just getting all the glitches ironed out first if possible.
thanks all for input.

 

[jaymanaa]

Hopefully Tom B will chime in as I need to do this fix on mine too.