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David, Albert, I will make some more measurements later on. My unit never had that issue you both experienced. It started up right away when it was working. I remember measuring between R55 and

It will almost certainly be a shorted blue-drop (or yellow-drop) tantalum capacitor. That's what usually brings down a 465/466/475 and various 7K series and TM series plugins with the symptom of a

David, I noticed the same in my 106. Stephen, just for comparison: Setting 10 kHz, "A" = Vk = -40 V, output in 50R is 2 Vpp . Then Vgk is almost square wave between -1.5 V and -15 V. Albert

ok, the standard way of testing scope power faults is as follows: 1) determine if you have a linear or a switching supply.? For the 466, I think it's going to be linear. 2) 0 volts or fuses blowing

Looking back through the earlier replies, I shall probably disassemble the verticle board in the morning. It is midnight here now. zzzzzzzzzzzzz

On Mon, Dec 13, 2021 at 02:39 AM, James55 wrote: Hi all, please excuse the lack of input, however I became deflated and just put a cover over the scope and walked away. Thing is, I really do need

The EL84’s should be getting plenty of drive on their control grids. Go back along the signal chain from there to the multivibrator. On my own instrument, after power-on, sometimes it doesn’t

Albert, You’re probably right. Hence the zero volt output measured on all 3. The question is why did they stop conducting all of a sudden, whereas the unit was working perfectly the day before,

Stephen, the ripple sizes in your pictures are only a fraction of what I see in my working 106. Perhaps they are so small because the 4 tubes never conduct. Even with almost exhausted tubes you should

Greetings I sent you an email offlist as I may have some resources willing to help ID this. Let me know if you want me to ask them for help. -ls-

Hello-- I'm offering FS one only? Tektronix 02-1004-402 (s/n 27694) power supply for the 4957; it's untested but in VG cosmetic condition. graphics tablet. The power supply sources +12 VDC @ 0.3 A

I get it. Sorry if I misunderstood you.

Stephen, I mentioned the socket mod as a PSA. I wasn’t exhorting you to do it. Sent: Tuesday, March 01, 2022 1:02 PM To: [email protected] Subject: Re: [TekScopes] Type 106 Saga (Again) I’ve

I’ve rechecked all the tubes, and they still read very strong on my HealthKit tester. Since a I had a quad of EL84’s laying around, I replaced all of them as precaution. They’re not brand new,

Ideally if you have "diode check" mode on your DVM that is what you need to use with the transistor off but all indications point to a faulty A2Q9. For now you can use widely available 2N3906 to get

To work with 6BQ5/7189, a minor wiring change is needed. Pins 1 and 6 are “unspecified internal connection” while the corresponding 7189A pins are explicitly G1 and G2 respectively. On all four

I was thinking about the 475A, but I really don't need it. -Dave

Hi Ozan, I checked both A2Q8 and A2Q9 with my checker and they both gave B of about 78 and uG at 752. I'm guessing that these show the transistors to be OK, but I am definitely rusty on this stuff - I

Hmmm. I have left it on a few times for quite a long time… Mine doesn’t have 7189A’s. It has old Philips EL84’s which read very strong. But I’ll check them again when I get back. I’ll

In Fast Rise mode, the output tubes provide base drive to the Fast Rise circuit. See SW242A on the schematic. SW242B bypasses the AMPLITUDE control in Fast Rise mode, jamming it to maximum. So