M K L
Well-known member
Checking heater voltage at the flyback is OK but to get a proper reading the meter needs to have an AC bandwidth that covers the 15KHz frequency. Most portable multimeters don't do that. Some bench ones do.
K7000 static, but no neck glow after shorting.
- Thread starter msdstc
- Start date
msdstc
Active member
Ok thanks for the updates all! I'm gonna try to get back to it tonight when I free up and will update afterwards.
msdstc
Active member
Hey, so I'm getting roughly 4 ohms of resistance a to j. How do I check the volts?
M K L
Well-known member
Check voltage at R90 (in front of the flyback). If you don't have +12VDC there, the flyback isn't working so the lack of heater voltage/neck glow is due to this. If you have 12V, set the meter to AC and measure at point C of the pic in my previous post. In both cases put the black probe on the big heat sink (ground).
msdstc
Active member
Awesome thanks a ton. I'll check this later.
msdstc
Active member
I have 1.3 volts at r90
M K L
Well-known member
Do you have 130V in (any of) the points here?
And 12V on this side of R56?
And 12V on this side of R56?
msdstc
Active member
Getting 173 DC on those 3 and then 1.3 AC on r56
M K L
Well-known member
B+ (130VDC) is missing probably because the voltage regulator is bad.
msdstc
Active member
Sorry I'm awful at all of this. Does that mean there's a chance the flyback is alive? Is the voltage regulator the HOT? Should I order a part? Thanks a ton for walking me through this.
M K L
Well-known member
The flyback is most likely good. It's possible to isolate the VR circuit from the rest of the chassis and test it with a light bulb as a dummy load if you want to make sure it's bad before ordering a new one.
msdstc
Active member
alright awesome, I'll go with just ordering the voltage regulator. Should I get that and the HOT to be safe?
M K L
Well-known member
A spare HOT (2SD1398) is always handy to have around but the current one can be tested easily:
msdstc
Active member
Thanks a ton. I put in the orders with the extra hot to be safe as well. I'll get to testing it later, but if it's good I'll just add the extra to my parts. I'll report back when the parts are in and hope it hangs in there! I remember reading about this years ago now with the k7000a and the non-existent flyback replacements, so if we can save it that would be good. As always you guys are the best thanks so much for the help.
msdstc
Active member
Getting 12v at r56 now that I replaced the voltage regulator but still no neck glow.
Also have 130v at those 3 points on the neck board.
msdstc
Active member
If it helps I'm losing voltage right before the heater pins but I'm not sure what I'm supposed to be seeing around that area. The first short I had was on the neck board itself so I'm hoping one of the pieces there is no good
Have you examined the chassis closely for cold solder joints and cracked traces? As in, checked everything in the relevant circuit(s) for continuity where appropriate?
msdstc
Active member
I've looked at it pretty good, but I could possibly go over it again. My thing right now is I'm curious about tracing that voltage from the 3 resistors over to the heater pins.
M K L
Well-known member
12V on R90?
msdstc
Active member
Yes got 12 on r90. Is there a way to trace th voltage from th 3 resistors to the heater? I tried tracing it and got to a cap, after that th voltage numbers made no sense.
