Electronics > Beginners
[Closed] Flyback transformer testing and replacement
Ian.M:
For Q10, frequency does't really matter. Any small signal NPN with min. hFE>200 will do. To get you moving forward today, you can probably pull one off a random scrap board and all you need to check is that the pinout matches, its Iceo leakage is too small to read on an ordinary transistor tester, and its hFE is high enough.
gkmaia:
Thanks Ian. I just got one more question before buying the parts. I want to get some spare Q9s.
For Q9 service manual refers as "PNP Chip 2sd1623T-TD"
The attached Datasheet the 2SD1623 is a NPN, while the PNP is the 2SB1123.
If you look at the schematic it is treated and seems to behave as an NPN.
On the tests I've made current from B+ to C- and E-, which is NPN.
So I think I the service manual may be wrong...
Ian.M:
--- Quote from: gkmaia on January 06, 2019, 05:14:56 am ---So I think I the service manual may be wrong...
--- End quote ---
Trace enough of the actual circuit round it to confirm the schematic is correct then you can safely assume the error is in the BOM.
TheNewLab:
--- Quote from: Ian.M on January 05, 2019, 06:13:05 am ---Ass you have it our of circuit,......
Check the ESR and capacitance of electrolytics C24, C26, C27 (or replace if you don't have an ESR meter and cap meter). If no faults are found, put it back and measure the voltages in the part of the circuit to the right of T1 on the schematic, at each component pin and look for any discrepancies that may indicate a cracked track or dry joint. If you've got a scope, check the signal at the base of Q9 when DMMP transitions from high to low to see if its attempting t start oscillating.
--- End quote ---
OOPS! typo in the first sentence. LOL :-DD
I tend to be writing post challenged.. :-//
Now I am really password retarded....my friends fall over laughing when I have to enter a password to access some site.. |O Too often, the site blocks me out after making so many tries
( i know, off topic)
Ian.M:
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