Marantz 18 scope not Working how to check if scope is faulty

[Widzew83rts]

There is also dioda CR5 conected to red/grn

 

[Widzew83rts]

Results C11= 13,60UF
CR5= 2.844v

 

[Widzew83rts]

took out one leg before i messure

 

[Widzew83rts]

I replaced c11 and cr5 and still it doesnt work

 

[bktheking]

What is the voltage reading now? There may be other issues here besides that -500 v.

 

[Widzew83rts]

I disconect 12K and 12K and two yel to check whats the voltage is with no scope, and voltage on red/grn dc goes to 400V that goes down to 190V right away.

C11- - 50v

 

[bktheking]

Leave everything connected and measure, then after 10 minutes disconnect the scope tube from the socket and measure without the tube connected.

 

[Widzew83rts]

c11 200v dc
red/grn ac 170v ( it goes to 400v than rigt away go down to 170v)
12l dc -180
with no lamp same think but red/grn 0v but when i touch a few times goes to again 400v and go down

 

[Widzew83rts]

its crazy no i measure 12l and its 170v widouth -

 

[bktheking]

Check other caps connected to that 500v feed, one of them is likely shorted brining that -500 down or perhaps a failing resistor but I’m thinking a shorted cap.

 

[Widzew83rts]

Can you tell me wich one i have to check?

 

[bktheking]

C12/13/14/17 - there’s also some sort of ground going to the chasis on the positive side of those caps- make sure the ground is there and making contact.

 

[Widzew83rts]

I cant faind c17

 

[bktheking]

Top side perhaps? Manual doesn’t show. That’s an old pic cause you replaced the one cap already correct?

 

[tonebells]

I cant faind c17

It's to the right of the tone board I do believe.

Tony

 

[Widzew83rts]

I took this marantz to profesional repair man and he said reg/grn line500v is destroyed in transformer
Any sugestion?

 

[bktheking]

That's strange cause when that tap goes bad there's zero volts. Only solution is to do what tonebells did and add a secondary transformer.

 

[Widzew83rts]

Yes its confuse becouse voltage goes to c11 from 12j

 

[Widzew83rts]

Can i get link to this?

 

[bktheking]

Tonebells is an AK member, look at this thread, he posted.