Products > Test Equipment
Tektronix 7633 Scope, Can anyone please help Old64goat!!!
finom1:
Here is another update from the Old64goat:
"David, I know you had mentioned you did not know how to get out the HV board but do you know if I have to remove the Z-AXIS and the other board on the side of the HV box?
You had asked me if I had a capacity bridge, yes I have a SPRAGUE Telo-Mike TO-5.
However I do not own a transistor tester so all I can do is use my SIMPSON 260 to test the transistor for shorts.
I was getting some sine wave oscillation so could that mean the 2N3055 is good?
If so I do not have to remove it, I need to buy some heat sink compound and a mica washer for the 2N3055.
IF I can get the HV board "box" out I will replace C1198."
Thank you for all your help!!!
finom1:
More pictures from the Old4goat:
Does anyone know how to pull out the HV Board?
finom1:
Few more pictures:
Looking for any help removing the HV Board!!!
Thanks again.
David Hess:
--- Quote from: finom1 on May 04, 2017, 09:38:06 pm ---"David, I know you had mentioned you did not know how to get out the HV board but do you know if I have to remove the Z-AXIS and the other board on the side of the HV box?
--- End quote ---
I took a quick look at my 7603; it uses the same enclosure over the high voltage board. The enclosure is held on by two side facing screws along the top where the z-axis board is and one down facing screw on the bottom. In order to gain access to the bottom screw, the power supply has to be pulled out from the back.
You might be able to leave the z-axis board connected and only have to temporarily unmount it to get to the top two screws.
--- Quote ---You had asked me if I had a capacity bridge, yes I have a SPRAGUE Telo-Mike TO-5.
--- End quote ---
That is one cool piece of test gear however I was reading the manual and:
2.1.2 CAUTION. The TO-5 should NOT be used to measure the capacitance
of small transistor electrolytic capacitors with low doc voltage
ratings, or to check the I-R of transistor ceramics rated 50 volts or less.
Such capacitors require special test equipment to avoid damage during
testing.
--- Quote ---However I do not own a transistor tester so all I can do is use my SIMPSON 260 to test the transistor for shorts.
--- End quote ---
That is usually sufficient because most transistor failures are shorts or opens; I always use the diode test function on my DMMs to test the two transistor junctions separately and then do a base shorted to collector test. Do not use the Rx10,000 range on your Simpson 260 for testing transistors; the 7.5 volt potential is enough to cause reverse base-emitter breakdown damaging the transistor.
--- Quote ---I was getting some sine wave oscillation so could that mean the 2N3055 is good?
--- End quote ---
Yes, I think so.
--- Quote ---If so I do not have to remove it, I need to buy some heat sink compound and a mica washer for the 2N3055.
--- End quote ---
The mica washer should survive. The high voltage board is mounted to the inside of the enclosure so the TO-3 transistor goes with it. Possibly you will not have to remove the 2N3055 but that can be determined after you have the enclosure pulled back.
--- Quote ---IF I can get the HV board "box" out I will replace C1198.
--- End quote ---
Replace C1198 and test the other transistors.
Looking at the schematic again, I now think Q1190 may still be good but test the transistors anyway. Possibly the only failure is C1198 and that capacitor is known to wear out in this design.
finom1:
--- Quote from: David Hess on May 04, 2017, 10:40:46 pm ---
--- Quote from: finom1 on May 04, 2017, 09:38:06 pm ---"David, I know you had mentioned you did not know how to get out the HV board but do you know if I have to remove the Z-AXIS and the other board on the side of the HV box?
--- End quote ---
I took a quick look at my 7603; it uses the same enclosure over the high voltage board. The enclosure is held on by two side facing screws along the top where the z-axis board is and one down facing screw on the bottom. In order to gain access to the bottom screw, the power supply has to be pulled out from the back.
You might be able to leave the z-axis board connected and only have to temporarily unmount it to get to the top two screws.
--- Quote ---You had asked me if I had a capacity bridge, yes I have a SPRAGUE Telo-Mike TO-5.
--- End quote ---
That is one cool piece of test gear however I was reading the manual and:
2.1.2 CAUTION. The TO-5 should NOT be used to measure the capacitance
of small transistor electrolytic capacitors with low doc voltage
ratings, or to check the I-R of transistor ceramics rated 50 volts or less.
Such capacitors require special test equipment to avoid damage during
testing.
--- Quote ---However I do not own a transistor tester so all I can do is use my SIMPSON 260 to test the transistor for shorts.
--- End quote ---
That is usually sufficient because most transistor failures are shorts or opens; I always use the diode test function on my DMMs to test the two transistor junctions separately and then do a base shorted to collector test. Do not use the Rx10,000 range on your Simpson 260 for testing transistors; the 7.5 volt potential is enough to cause reverse base-emitter breakdown damaging the transistor.
--- Quote ---I was getting some sine wave oscillation so could that mean the 2N3055 is good?
--- End quote ---
Yes, I think so.
--- Quote ---If so I do not have to remove it, I need to buy some heat sink compound and a mica washer for the 2N3055.
--- End quote ---
The mica washer should survive. The high voltage board is mounted to the inside of the enclosure so the TO-3 transistor goes with it. Possibly you will not have to remove the 2N3055 but that can be determined after you have the enclosure pulled back.
--- Quote ---IF I can get the HV board "box" out I will replace C1198.
--- End quote ---
Replace C1198 and test the other transistors.
Looking at the schematic again, I now think Q1190 may still be good but test the transistors anyway. Possibly the only failure is C1198 and that capacitor is known to wear out in this design.
--- End quote ---
David,
Thank you for all your kindness helping the Old4goat "Bill" out fixing his scope!!!
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version