Jim hi,
Check the BC transistors and the LEDs with the DMM's diode mode. Without removing them.
Check the BC transistors and the LEDs with the DMM's diode mode. Without removing them.
Hi Salas -
DMM = UNI-T UTI39C Diode mode
BC transistors on negative reg:
Q1 B:E 0.059 B:C 0.559 / reversed leads B:E 0,059, B:C 0.597
Q2 B:E 0.266 B:C 0.634 / reversed leads B:E 0.266 B:C OL
Q3 B:E 0.691 B:C 0.634 / reversed leads B:E OL B:C 1.134
Q4 B:E 0.323 B:C 0.591 / reversed leads B:E 0.396 B:C 1.022
Continuity between E:C, checked out, no shorts on all 4 BC transistors
Measurements made w/ M2 installed, M1 is out of circuit at the moment.
LED's tested correctly.
Thanks again,
Jim
DMM = UNI-T UTI39C Diode mode
BC transistors on negative reg:
Q1 B:E 0.059 B:C 0.559 / reversed leads B:E 0,059, B:C 0.597
Q2 B:E 0.266 B:C 0.634 / reversed leads B:E 0.266 B:C OL
Q3 B:E 0.691 B:C 0.634 / reversed leads B:E OL B:C 1.134
Q4 B:E 0.323 B:C 0.591 / reversed leads B:E 0.396 B:C 1.022
Continuity between E:C, checked out, no shorts on all 4 BC transistors
Measurements made w/ M2 installed, M1 is out of circuit at the moment.
LED's tested correctly.
Thanks again,
Jim
LEDS check, OK.
Those are all NPN transistors. The red probe was always on B pin (as it should) when you measured the junctions against C, E, pins?
Those are all NPN transistors. The red probe was always on B pin (as it should) when you measured the junctions against C, E, pins?
Re-measured post video, changed to Extech DMM:
Q1 B:E .020, B:C .541
Q2 B:E .096, B:C .578
Q3 B:E .580 B:C .610
Q4 B:E .543 B:C .122
Double checked I got it right. What say you as to what to replace?
Q1 B:E .020, B:C .541
Q2 B:E .096, B:C .578
Q3 B:E .580 B:C .610
Q4 B:E .543 B:C .122
Double checked I got it right. What say you as to what to replace?
I changed out Q1 and Q2. Re-powered briefly. No light from LEDs and R1 immediately hot with a wisp of smoke, same fault as prior.
Thank you, Salas. I took at close look relative to the schematic per your advice. The offending negative rail M1 = FQP 3P20. Schematic calls for FQP 3N30.
M2 has IRF530. Schematic calls for IRF9530
On my 5VDC working UB, M1 if FQP 3N30. M2 neg rail has IRF9530. And the other TB supply kits on the neg side have those, too.
Could this be the cause of the fault?
M2 has IRF530. Schematic calls for IRF9530
On my 5VDC working UB, M1 if FQP 3N30. M2 neg rail has IRF9530. And the other TB supply kits on the neg side have those, too.
Could this be the cause of the fault?
After the tests carried out M1 defective but Q2, ok, do I have to check something else?
On the other hand, I don't know how I'm going to get this FQP3N30, what equivalent can I have? Or, if someone has one who can sell it to me, I'm a taker.
Hi, IRF610PBF should substitute FQP3N30. The LEDs or M2 or JFETs are seldomly reported broken, but you can check.