CRT Oscilloscope repair
I received two GW Insteak GOS-622G 20Mhz Analog CRT oscilloscopes to repair. both have shorted transistors and fried resistors in Y plate drive circuit.
since both have same issue, I want to find if this common issue with this scope or any other cause. here I attached schematic of Y output circuit.
C2570 Transistor. this is Gigahertz range low power transistor (VCBO-25V, VCEO-12V, 50mA) for use in VHF/UHF range. but, that transistor here in the circuit of 160V supply. both scopes have both this transistor fried.
Transistors with heatsink - 2SB648A, 2SD668A. each pair. one scope has one pair shorted and other with another side. not same (channel)
2SA1206 transistor also shorted in same side.
Could C2570 transistor cause issue?
Anyone experienced with these type of scope repairs... ?
in the circuit, I checked all other parts. resisotrs within value. caps, diodes. everything fine.
since both have same issue, I want to find if this common issue with this scope or any other cause. here I attached schematic of Y output circuit.
C2570 Transistor. this is Gigahertz range low power transistor (VCBO-25V, VCEO-12V, 50mA) for use in VHF/UHF range. but, that transistor here in the circuit of 160V supply. both scopes have both this transistor fried.
Transistors with heatsink - 2SB648A, 2SD668A. each pair. one scope has one pair shorted and other with another side. not same (channel)
2SA1206 transistor also shorted in same side.
Could C2570 transistor cause issue?
Anyone experienced with these type of scope repairs... ?
in the circuit, I checked all other parts. resisotrs within value. caps, diodes. everything fine.
Attached Files