Safe House, 8 Zone fire alarm


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Old 11-25-22, 07:03 PM
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Safe House, 8 Zone fire alarm

I know this is an old system but looking for help with circuit board components Only getting 8volts to the smoke detector terminals on the board and should be 12 volts. I have tested two of the larger capacitors. The burglar side of the alarms work fine.
 
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Old 11-25-22, 09:49 PM
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Welcome to the forums.

A model number of the panel would be helpful.
Pictures are always helpful...... How to insert pictures.

Lots of seasoned pros here but we need to know exactly what you are working on.
 
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Old 11-25-22, 10:52 PM
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8 vdc with no wiring on terminals?
Good backup battery?
Wiring to smoke good?
EOL resistor on smoke while metering voltage?
 
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Old 11-26-22, 06:28 AM
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If you haven't done so already, remove the wiring from the smoke detector power in the panel and check the voltage at the panel.. There may be a high-resistance short in a device or wiring.

AFAIK Safe House is a private label brand. As already stated, pictures of the circuit board in the panel will help in identifying the manufacturer.
 
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Old 11-26-22, 08:16 AM
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Model is SafeHouse 49-485 Every thing was working fine until I by pass the smoke detector from the kitchen area I may of had a SR moment! I can't remember if I killed the power first. I removed the board and now have the EOL resistor at the board. I have replaced the 3300 and 2200 capacitors witch the old showed good anyway. So when first power on I get a little over 9 volts but not long afterwards volts drops with no load.
I will see about getting photos down loaded.

 

Last edited by Detour; 11-26-22 at 08:36 AM. Reason: photos
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Old 11-26-22, 08:40 AM
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I have tested 3300 and 2200 and replaced anyway.

 
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Old 11-26-22, 10:16 AM
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You may have a failing voltage regulator. Look for some version of a 7812 (positive regulator) or 7912 (negative regulator).

My only experience with Radio Shack systems was replacing them.
 
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Old 11-26-22, 11:37 AM
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317T on this one no number on front of the other is there away to test on or off the board


what does this one do? also no part number. is there a way to test
 

Last edited by PJmax; 11-26-22 at 11:54 AM. Reason: resized/labeled pics
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Old 11-26-22, 12:00 PM
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The four pin device is a bridge rectifier. Converts AC to DC. The caps you replaced filter that DC.
The 16.5vac is applied to the center two terminals and you'll measure +20vdc on + and -.

The LM317T is an adjustable DC regulator.
Pin 1 = voltage set - pin 2 = output - pin 3 = input.
You may see 20-25vdc on the input and probably 12vdc on the output.
LM317T spec sheet - pdf

What are you measuring on the battery line with battery connected ?
BE CAREFUL - shorting semiconductors will blast them.
 
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Old 11-26-22, 12:58 PM
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seams I can't reply by mobile! Im getting 13.5 AC 17.25 DC on bridge. testing the others two meme to tricking for me to test. if need be Ill replace.
 
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Old 11-26-22, 01:35 PM
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Ok... the voltages on the bridge are fine as that uses a 12vac transformer not the typical 16.5vac.
Not sure the problem testing the regulator.
Takes some smaller and sharp probes.

Where are you getting the 9v.... on # 36 and # 38 ?
 
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Old 11-26-22, 02:05 PM
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Yes on 36 & 38 when I test the detectors on the battery it self
They work fine. When this first happened I did smell an Oder at
the board but see no evidence if that helps what to look for.
 
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Old 11-26-22, 04:15 PM
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What are the input-to-negative voltages on the regulator on battery and on AC power? If the output voltage is OK on AC, you probably have a weak battery; 3-5 years is the life expectancy of a SLA battery.

If output is not OK on AC, look at the drive to Pin 2 of the regulator.
 
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Old 11-26-22, 04:19 PM
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Are all the fuses ok ?
One looks to supply the power to the smoke alarms.

You didn't confirm you had good charging voltage on the batteries.
What do you get on #25 and #26 ?

You take good pictures. Take a picture of the back of the board near the #36-38 area.
 
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Old 11-26-22, 05:29 PM
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Terminals 25 & 26 12.6 volts

This checked out to 13.5 AC and 17.25 but I noticed looks to be some hot stains? and noticeable flux


 

Last edited by PJmax; 11-26-22 at 09:41 PM. Reason: labeled pic
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Old 11-26-22, 09:38 PM
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The diode bridge checks ok.
It runs quite warm which is why it's on the heatsink. Runs hotter when battery is older.
That brown stuff is flux leftover after board cleaning. No problem.

Terminal 25 and 26 are the 12vdc ACC terminals and check out ok which means the primary regulator is working.

Red marks are + power
Blue marks are in/trigger
Q7 is the B+ switching transistor for smoke detector power.
Q7 may be bad.

While noodling around I spotted this..... Q9 has exploded.

 
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Old 11-27-22, 08:42 AM
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That funny because Q9 looks nothing like the photo. looks has good as others. Im getting 12.5 at your white 12.5 on your red to ground 6.3 6.5 but! when i push the rest button for fire alarm it sends 12 volt to your red for a few seconds
 
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Old 11-27-22, 10:21 AM
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That is a problem.
It's either a bad transistor or the support components around it.
I'll look the board over again.
 
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Old 11-27-22, 10:45 AM
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Didn't see this little bump until you said could be bad. I see a #151 and on top #202 Not sure what to order.
 
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Old 11-27-22, 08:08 PM
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Look at the other transistors on the board. See if you can find one that uses similar markings.
Based on what you posted.... not enough info.
 
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Old 11-28-22, 05:17 AM
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Removing markings from components was an attempt to keep others from pirating a design. Also done to discourage service. One of the things that made come to dis like board work.
 
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Old 12-07-22, 08:52 AM
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Finally got the new transistor in and everything works. Thanks for all the help.
 
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Old 12-07-22, 01:17 PM
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Wow, good job!
 
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Old 12-07-22, 01:33 PM
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I agree..... definitely a good job.

 
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Old 12-08-22, 07:27 AM
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