1. Home
  2. Electronics Design
  3. SAC722 Motorola ?

SAC722 Motorola ?

I think this is a SCR, due to the circuit it is in.. Can any point me to a data sheet telling me what this is?

This is small circuit that is part of a water pump system. There are only 3 heavy snap in contacts where #1 and #3 passes the AC current through 2 turns of wire around a Reed switch envelope.

Another spade connection made from the start circuit that passes through a SAC722, which looks to be a SCR, of the Gate and cathode, through a 1k R and then through the reed switch, which then hits the gate of the other assumed scr. On the other SCR, the cathode passes through another coil that is wrapped around on just one end, not the middle, like the first one, and then goes back out to #2 terminal where it holds the circuit in the run position..

It looks like if you short #2 lug, which will create much more current, the secondary coil will generate enough flux to work against the main coil so that the reed switch will open and thus unlatch this mess.

If need be I can create a ASCII schematic of it, if any one is interested?

The strange thing about this is, I am having a hard time getting my head around this because the anodes of assumed (SCRs) are both joined together and go no where? That is like putting 2 diodes back to back.

So, if any one has a data sheet site for the "SAC722" or, just confirm my suspicions of it being so, It would be much appreciated. Thanks.

Jamie

Reply to
Jamie
Loading thread data ...

"Jamie the Fuckwit Radio Ham"

** Motorola used to ( maybe ON still does) offer custom selected parts.

In the case of their famous " MJ " series power transistors, the "M" was replaced with an "S" and the 4 digit number was a code known only to Motorola and the customer - ie, SJ1234.

Motorola also made a series of triacs and SCRs that used the prefix " MAC" followed by a 3 digit number.

EG:

formatting link

This leads to "SAC" followed by a 3 digit code for custom selected versions.

One can only make educated guesses at such a part's real identity.

... Phil

Reply to
Phil Allison

it turns out these units are TRIACS. 2 in series.. Not sure why there? Maybe to up the voltage handling or a redundancy ?

Anyway, this board was designed to switch in the starting capacitor for a single phase 230 volt pump motor and uses a REED switch to monitor current. When current from the motor drops down, the REED switch opens and thus, no longer supplies a gate signal to the TRIACS. The motor's starting cap is connected to one side of these triacs while the other end of the string goes to the motor winding.

There was a failure due to insufficient voltage while operating under emergency power. Apparently, the hot water heater was on and there wasn't enough to keep the well pump at full RPM's. TRIACS are not heat sink mounted. The motor is still ok.

What this all comes down to is, I was asked by a dealer that sells and services these items and tells me this unit is no longer offered and a voltage sensing type kit is put in its place, however, the replacement apparently does not work as well. They would like to use a current sensing type instead.

Btw. Thanks for the inside info on what Motorola does or did.. Kind of a sneaky trick..

Jamie

Reply to
Jamie

What's sneaky about giving customers 'House numbered' parts? It is a common industry practice. As a so called 'ham' you should have already known about their SRF numbering.

Reply to
Michael A. Terrell

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.