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[AMXoldhack]

 
I've found links to modify the old pitch on the original SC546 chime module.
What I can't find is anything on the newer SC546A module- note the "A" suffix.
the newer versions have 6 transistors and no separate "chime chip".
any leads/ideas anyone?

[Brian H]

Like you I have not found any information on the later version.
I will see if I can find some data even a schematic may help.
Yours probably has a output transformer driving the Piezo element. Like mine is.
X10WTI was trying to replace older hard to get parts with surface mounted parts. So you may find a completely different surface mounted controller in yours and powered by around 3 volts. As mine are not current Date Code units.
I have a feeling the Ding Dong tones are generated by the controller chips firmware and not easily modified.
The small power horn SH10A/PSH02 basically looks the same internally. Just responds differently to X10 commands. I did modify one of those to close a small relay when the Security Console sounded an alarm.

[AMXoldhack]

I guess I'll try to hack it myself. just didn't want to re invent the wheel if some one has already found a hack on the newer chime moduals. I'll probably start with modifying out board resistors by 5% and see if I can hear a alteration of the "ding dong"

[Brian H]

Let us know what you find out.

I may look inside one of mine and see if can get more data.

The main DC Supply. Is a typical line derived supply X10 liked to use.
It is 29VDC in the ones I measured. 2SD667 output transistor to a tapped transformer. Driving the piezo element.

I have seen the same board in the SH10A Small Siren module.

My information was from an RSC15A Date Code 02E19. Retail version of the SC546A.

Around the middle of 2007. X10WTI redesigned some modules to use easier to find parts. Like the SONiX SN8P2501B surface mounted controller. Has a 2.4VDC to 5.5VDC specification. So if yours are a presently sold revision. You may find a completely different design. Like around 3.5VDC on the controller chip.

[AMXoldhack]

I also believe the sound generator has been moved into the main IC. the two or three I disassembled are standard IC chips. not surface mount. If I can't modify the pitch by resistors, I'll try more brutal methods on the chip audio output. If I can't change the pitch I'll try distorting the audio wave form. I don't really care if the end result sounds like s__t. just need to tell them apart.

[AMXoldhack]

I took the easy way out. Picked up 3 of the older models. I recognized them by the older style case.
modified to 1.4 meg from 820k ohm to be able to tell the sound from the more recent ones.
Haven't given up on modifying the newer version, just put it on the back burner.