Hi Reed,
Per your suggestion I disconnected the wire from the secondary of T1320 to the voltage tripler and powered up the scope. The waveform at TP1318 immediately snapped to 32 volts p-p at about 70Khz without any persuasion via the 1K resistor trick. I also checked the oscillator over at the junction of CR1329 an C1326. It measures 320 volts p-p so it looks like I need to order a voltage tripler module.
Thank you so much for your help. Obviously, you know your way around these scopes.
Ripley
Sent from Mail for Windows 10
From: SuddenLink
Sent: Sunday, March 3, 2019 8:27 PM
To:
[email protected]Subject: Re: [TekScopes] 475 with no Display and no HV
Hello Again,
I went back to the circuit around Q1306 and Q1308 this evening. The resistors are all within specs. C1305 was pulled and checked. It is also fine. C1304 is good and so is C1302.
By the way I am checking the capacitors with a DE-5000 LCR meter. It was never let me down yet.
The only component that I have not replaced or substituted is Q1306. It checks fine on my little Chinse component tester. For whatever that is worth.
Enough for today.
Ripley
Sent from Mail for Windows 10
From: Steph L
Sent: Sunday, March 3, 2019 7:05 PM
To:
[email protected]Subject: Re: [TekScopes] 475 with no Display and no HV
Hi Ripley,
How about C1305 0.1uF.
If open, gain of Q1306 (and whole oscillator loop) will be lower and perhaps not enough to maintain oscillation? (Great suggestion from Don re 1K pull up touch on Q1318 base.)
Steph
PS. Still nubie here and unsure which "Reply" button to click on. I clicked on Ripley's "what the heck?" message "reply" button and see it has been inserted a few messages prior! That is really confusing. I'm in Melbourne Oz GMT +10 hrs. Is this the reason (i mean time difference guys and not quirky)
