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2245 help needed.

 

Hi, I am repairing a dead 2245 . After recap all the power supply, I get all the normal tensions with the PS board out of the scope, when I connect it it doesnt want to start up. i discovered that disconecting the output of the HV transformer to the multiplier and the 2.7Kv, keeping connected the heater , the scope turns on normally but obviosly no CRT. after disassemble the crt shield ,I dont see light from heater(5 volts on) and i dont see the vaccum plated in the neck of the tube(I dont know if all the CRT has it). the tube dont show marks of cracks in the glass. heater resistance measurement= 27 ohms. It seems to me that its bad the CRT. Its possible that this make a short to the PS?
Thanks in advance, Carlos
 

I do not think the CRT can short the power supply but the high voltage
multiplier sure can.

On Mon, 26 Mar 2018 07:51:27 -0700, you wrote:

Hi, I am repairing a dead 2245 . After recap all the power supply, I get all the normal tensions with the PS board out of the scope, when I connect it it doesnt want to start up. i discovered that disconecting the output of the HV transformer to the multiplier and the 2.7Kv, keeping connected the heater , the scope turns on normally but obviosly no CRT. after disassemble the crt shield ,I dont see light from heater(5 volts on) and i dont see the vaccum plated in the neck of the tube(I dont know if all the CRT has it). the tube dont show marks of cracks in the glass. heater resistance measurement= 27 ohms. It seems to me that its bad the CRT. Its possible that this make a short to the PS?
Thanks in advance, Carlos
Bob Koller
 

Bad multiplier? Not an uncommon problem in general on Tek scops.
 

On Mon, Mar 26, 2018 at 09:26 am, David Hess wrote:


I do not think the CRT can short the power supply but the high voltage
multiplier sure can.
Actually I think it can but it would be rare because that would mean a dead short in the CRT. It can happen but usually there is some sign of the HV trying to start.
 

On Mon, Mar 26, 2018 at 01:31 pm, Bob Koller wrote:


Bad multiplier? Not an uncommon problem in general on Tek scops.
Or on anything that uses them. We changed tons of them in TVs way back. Actually when Sony used them they fed them with sine waves to supposedly go easier on them.
 

Bad news, I took out the CRT and has chips of glass inside , no plated. I did not make short measurements between electrodes. It must be kicked.. I ll try to get a donor CRT scope . Thanks All for the suggestions. Carlos.
 

Friend of mine has a 2215 and a 2225 I think. One of them is pretty much parts for some reason and we took the knobs for the other one. If the CRT will fit I can ask if he is willing to part with it.

But then you might find one elsewhere anyway with all that unobtaimium in there.

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