K7000 safety questions

sfluter

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A couple of things. I purchased a K7000 chassis, and along with it a replacement flyback and a cap kit (twisted quarter). Nothing dangerous there, I hope.

In truth I didn't check the board out all that closely before I replaced the flyback beyond cleaning up the flux on the solder side, but when I did the cap kit I noticed the board was stamped with P538. Does this automatically mean it is the Zenith version of the K7000? Everything seems to be working fine with the new flyback, but I thought that particular model's flyback was obsolete and could not be replaced.

I also noticed that the B+ adjustment was not factory sealed. After reading a few threads on the subject of how dangerous it is to adjust this, should I be worried about x-rays? I don't know if it has been played with/moved before it got to me. B+ voltage is reading 154 vdc, but again, everything appears to be fine. I will replace IC4 when the parts come in to hopefully get the voltage down under 135.

Any input appreciated. If I am setting myself up for something down the road I would rather ask now than after I sterilize myself....
 
538= usually 25" chassis.. the zenith version is a k7000a, and theres no way you could put a standard k7000 fly on a zenith chassis anyways as they have a different footprint.
 
also whats the part# on the voltage regulator on the chassis? I cant believe its running with the b+ that high. usually they shut down if b+ is too low or too high. Are you sure you are testing b+ at the correct location? If your checking it at the big resistor check voltage on each side and report back.
 
STR30130 is the # on the regulator.

I get 129 vdc on the near side (closest to back of the machine) of R301, and 154 vdc at the end closest to tube. I also get a reading of 154vdc at R103. I can take a reading across c57 if that helps.

I'm a little confused as well on this one. Before I capped it the monitor had a slight hula that I thought might be a bad IC4 (Randy Fromm flowchart). After I capped it, it went away.
 
Thanks!

I did a little more reading on identifying K7000a's. Unfortunately it looks like I own 2 of them. So at least I'll have some spare parts at some point in the future...
 
I am really starting to hate the K7000.

Everything was working fine on the monitor, the only problem was the horizontal width need to be adjusted. So I turned off the monitor, moved the chassis to where I could get at the coil and turned it slightly in to see if it would make a difference. Hooked everything back up and turned the machine back on. The width improved, but within seconds there was smoke and the monitor lost vertical deflection. I shut it down and cursed a blue streak.

I have checked B+, still at 130. IC4 is not shorted across 1 and 4. I checked the HOT for shorts, it is good. Fuses are not blowing. The only reading I would like to ask about is the VDC on pin 6 of IC3. It is supposed to be +24 VDC and I get a reading of 33 VDC, is this in the right range? If it is then I am not sure where to go from here.
 
No, if it should be 24, then an acceptable "range" would be 22-26. Where did the smoke come from?
 
I don't know where the smoke was coming from. I was in the front of the machine looking at the horizontal width when I got the bad electrical smell and then the vertical collapse occurred. I have looked to see if anything looks overheated, and as far as I can tell the only thing I can find is D25 looks like it got really hot. It tests good. Okay, I am literally looking at R101 as we speak and one of the solder pads has lifted, I will repair it, but I won't be able to test it until tomorrow. I am out of 2A fuses, sadly

I am going to assume IC4 needs to be replaced at the very least.
 
You need to get one of the circuit breaker fuse savers from BobRob. Once I have a chassis that is a known fuse-blower, I connect that up and save my fuses until it's fixed...
 
Everything is working well. I repaired the lifted pad on R101. R91 and R92 were both open (I guess this is where the smoke was coming from. They looked like hot dogs left on the bbq too long). I replaced D25 and it fired right up. IC3 seems to be okay.

Only remaining issue is the horizontal size. The coil is not moving smoothly, and I can't even get it turn 3/4. So its time to yank some more parts off the spare chassis. Just for info sake, does Bob Roberts have a replacement coil? All I seem to come across is a replacement for the G07.
 
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