K7000 b+

brokentoken

Well-known member

Donor 6 years: 2019-2024
Joined
May 20, 2007
Messages
2,357
Reaction score
1,470
Location
North Carolina
I have a 19" K7000 that is doing a slight hula after a tube swap. I measured B+ at R301, and got 123.5vdc on the blue side and 174vdc on the red side.

Any suggestions on why this might be?
 
123vdc, that should be correct i believe?????? if you have a v reg that ends in ***123, id say thats dead on. I forget which end of the resistor you test at for b+ let me actually get what i need to get done here at home and i will mull this over a little, brain is not working right now..

has the chassis had a capkit done lately?
 
Wow--thanks for the fast response! The thing that has me confused is that the flowchart says the readings should be 123v and 145v on the other side...I'm wondering if the extra 30v could be a symptom as to why the picture is wavy.

I did cap it a couple months ago--the picture looks amazing other than the slight wave.
 
Check the filter cap. Feel on the top of the bubble to see if it is doming inside. You probably need to replace it, although sometimes a bad VR (IC4) can cause this...
 
Crud--just fired it up again, and now I'm getting an immediate shutdown. I can hear it start to warm up, then "click" and off. B+ is now in the 170vdc range...something must've been on its way out when I was getting the funny reading earlier.

Mod, the filter cap feels flat on top. From your recommendation, and the flowchart, it looks like I should try the voltage regulator next. I'm bad at troublshooting circuits...so If I'm jumping to a bad conclusion please let me know!
 
still not too with it, ready to head off to bed. COuld very well be someething was on its way out. THrow a vreg at it and see what ya get... also nows the time to capkit it if you havent already. visit the k7000 stick and check some basics man..


now when you tubeswapped this did ou use the k7000 yoke or did you use the tv yoke??

If you used the tv yoke, do us a favor and ohm the windings between the two and post results here..
 
I've been reading the stickies--that's great stuff you've posted there!

The chassis is capped, and that all looks good.

I kept the TV yoke for the tube swap. Here are the readings:

Original:

2.3 ohms, 13.2 ohms

Donor Tube:

3.0 ohms, 14.5 ohms

Looks like I need to send bob an order. I'll get the VR, and might as well get a new flyback and HOT while I'm at it...
 
Back
Top Bottom