Wells Gardner K7000 Blows Fuse

jjfin

Member
Joined
Jan 9, 2022
Messages
42
Reaction score
20
Hi,
Installed cap kit to Welss Gardner K7000 and new flyback transformer. After few weeks and only few games played, monitor blows fuse.
Chassis is P447. Checked all diodes (out of circuit) and all are ok.
Main suspect is IC4 STR3123 regulator. R301 and R302 are parallel with IC4 pins 1 and 4.
Measured both resistors R301 and R302 and those are ok.
Diode testing (in circuit testing) IC4 pins 1 and 4 multimeter shows 0.002 V (both ways). Resistance over pins 1 and 4 are about 2 ohm.
Is that IC4 the reason why fuse blows?
When I removed resistor R103 and put power on then fuse stays ok, degaussing coil was disconnected during this test.
Q11 2SD1398 transistor changed, but not tested to play the game after that, because need to be sure that everything else is ok.
I don't have new IC4 yet, so can't make comparison. What is the correct resistance between IC4 pins 1 and 4?
 
Hi,
Installed cap kit to Welss Gardner K7000 and new flyback transformer. After few weeks and only few games played, monitor blows fuse.
Chassis is P447. Checked all diodes (out of circuit) and all are ok.
Main suspect is IC4 STR3123 regulator. R301 and R302 are parallel with IC4 pins 1 and 4.
Measured both resistors R301 and R302 and those are ok.
Diode testing (in circuit testing) IC4 pins 1 and 4 multimeter shows 0.002 V (both ways). Resistance over pins 1 and 4 are about 2 ohm.
Is that IC4 the reason why fuse blows?
When I removed resistor R103 and put power on then fuse stays ok, degaussing coil was disconnected during this test.
Q11 2SD1398 transistor changed, but not tested to play the game after that, because need to be sure that everything else is ok.
I don't have new IC4 yet, so can't make comparison. What is the correct resistance between IC4 pins 1 and 4?
Your new fly back is defective more than likely. Could have taken those components out. If it was working for a bit then died and worked before you did it I'd bet money it's questionable. Did you get it from security001 or someone else?
 
If you're blowing fuses, you need to go through the power section completely. Mike has a ton of videos on this subject, but here is a really good one:


This is basically the procedure I go though on every K7000 that I work on. Don't skip any steps.
 
STR3123 (IC4) can be tested with a meter by looking for a short of each leg to any other leg. Remove it from circuit to test it. It sounds like it is shorted but remove from circuit to test.

With the D1398 in circuit is there a short between the chassis frame and the collector of the HOT (middle leg)? If yes, remove it and see if there is a short from the middle leg to any of the other 2 legs. If shorted, then replace. If not, see if there is a short from the frame to the collector's solder pad. If yes, then start looking for the short. 2 common causes of this are bad flyback and bad retrace cap C36. You can remove those components and see if the short goes away.
 
STR3123 (IC4) can be tested with a meter by looking for a short of each leg to any other leg. Remove it from circuit to test it. It sounds like it is shorted but remove from circuit to test.

With the D1398 in circuit is there a short between the chassis frame and the collector of the HOT (middle leg)? If yes, remove it and see if there is a short from the middle leg to any of the other 2 legs. If shorted, then replace. If not, see if there is a short from the frame to the collector's solder pad. If yes, then start looking for the short. 2 common causes of this are bad flyback and bad retrace cap C36. You can remove those components and see if the short goes away.
don't forget C38. and 4 leg C36 you test the legs kitty corner, not left/right across from each other.

also highly obscure, had one of these blowing fuses and it wound up being D10 was shorted

I don't know how the voltage regulator would cause the fuse to blow, like on a scientific level, but I think I've seen one and zeno has too. lol
 
don't forget C38. and 4 leg C36 you test the legs kitty corner, not left/right across from each other.

also highly obscure, had one of these blowing fuses and it wound up being D10 was shorted

I don't know how the voltage regulator would cause the fuse to blow, like on a scientific level, but I think I've seen one and zeno has too. lol

Bad VR blows the fuse for sure. I've seen it more than a couple of times.
 
Back
Top Bottom