It keeps blowing fuse 3 amp on circuit board any ideas? I already replaced t stat

Blowing fuses, was caused by many thing.
Short of rectifier,resistor,elco,tube heater,tube pin, and also trafo itself (primary or secondary winding). It must check step by step.
CAUTION :
THIS IS HIGH VOLTAGE AREA.
RISK OF ELECTRIC SHOCK THAT CAN KILL.
DON'T DO THIS IF YOU ARE NOT TECHNICIAN OR NOT FAMILIAR WITH VACUM TUBE CIRCUIT. THE CIRCUIT MAY STILL CONTAINS ELECTRIC SHOCK EVEN IF IF THE AMP IS NOT POWER PLUGGED.

The simple steps (see picture) are:

1. Disconnect all connection from secondary of power trafo (PLV,PDCH,PACH and PHV).
   Power ON the amp. If fuse is not blowing,trafo is good.
2. Power OFF the amp. Unplug the cord.
   Connect PLV1-PLV2-PLV3 (this are Bias voltage,+/-15VDC and Backlight PCB voltage) to power trafo.Power ON the amp. If fuse is not blowing,PLV circuit is good.If fuse blowing,there are parts is damage (dioda,elco,7815/7915,resistor) in this PLV circuit.
3. If step 2 is good,go to next step.
   Power OFF the amp. Unplug the cord.
   With PLV circuit stay connected,connect PDCH 1-2 and PACH 1-2 to power trafo. Power ON the amp.
   If fuse is not blowing,PDCH and PACH circuit is good and all tubes heater/filaments are lights after a few seconds.
   If fuse blowing,there are parts is damage (dioda,elco,tube heater pins) in this PDCH/PACH circuit.
4. If step 3 is good,go to next step.
   Power OFF the amp. Unplug the cord.
   With PLV,PDCH,PACH circuit stay connected,connect PHV 1-2 to power trafo.
   Power ON the amp. CAUTION: HIGH VOLTAGE AREA is ON.
   If fuse is not blowing,PHV circuit is good.
   If fuse blowing,there are parts is damage (dioda,elco,tube pins) in this PHV circuit.

.
Notes:

• Steps had to be done sequentially from 1 to 4, not upside down.
• If tube/heater pin is short,it can't be repair. The tube must be replacing.
• PDCH circuit is voltage for V1-2-3-4 heater/filaments.
• PACH circuit is voltage for V5-6-7 heater/filaments.
• Always replace fuse with same type.

check thermostat wire to outside unit. replace contactor coil in outside unit.

the contactor on the condensor if it blows on a call for cool.

Hi, when you lost power, it may have taken out a fuse to the indoor unit if this is the kind of system you have, I don't know. As far as the stat going blank when you hit run, it may be the 24 volt circuit board fuse, I would need more information on the system you have. See if your stat has batterys also.If nothing is running at all, check all breakers, fuses and so on. If you do have a split system, the indoor unit will have a circuit board where the stat wires are terminated. The fuse looks like a auto fuse, 3 to 5 amp. This may be blown. If so, replace and your back in business. Like I said, if I new what kind of unit you have, it would be very easy to trouble shoot. It may have taken out the transformer also. Just make sure all power is restored, no breakers tripped and fuses blown at the indoor unit. This should be very easy for you to take a good look at this unit. The display on the stat runs off batterys most of the time, but some are powered from the transformer. Try what I have said, as you will need to have 24 volts to the stat to fire up the unit, and if you do and the stat still goes blank, you have a faulty stat board. Keep me posted. Best of luck to you.
Shastalaker7
A/C, & Heating Contractor

1 blink is ignition failure check that the gas valve is in the on position make sure you have gas at the gas valve if it is not that then its the flame sensor it could be dirty . the only way to blow a fuse on the circuit board is through the t-stat wiring ? hope this helps

you only need a common wire at the t-stat if you are using a digital t-stat.

Your wiper motor is about to go out, if it hasen already, wiper motor pulling to many amps will cause the fuse to blow.

if it keeps blowing the fuse you have a short in the wiring

if the fuse is blowing then this is generally indicative of a short in the low voltage wiring, isolate the wires on the thermostat and the unit ends, use an ohmmeter to verify that there is no path for continuity with no wires touching, if there is then you must pull new t-stat wire to the thermostat, (a guess would be that the green and red are shorted, by the symtoms you gave.

if this is a split system unit look for a short in the stat line weed eater damage! mark all wires on stat wire and un hook if still blows board bad if not short in stat wire hope this helps

Hi,

when a fuse blows, its telling you that theres a fault. this could be a loose or broken wire.
or alternatively, the fuse rating is too low. you could check the wires are tight. and also possibly try fitting a 5 amp fuse. check first that the fuse is rated correctly for the appliance. usually 3-5 or 13 Amps.

Mike @ compurepair.