KenLayton
In Memoriam
Yes it's possible to have a shorted ic.
K7000 Blowing Fuses :(
- Thread starter zenomorp
- Start date
OP
OP
Ok, done everything humanly possible (for this human anyway), so I would like to know if there are any technicians that would like to t-shoot this chassis further for me. Compensation will be provided, of course. Let me know. Thanks - Mike.
modessitt
Volunteer: Encyclopedia Submission Moderator
I could, I guess. i charge $50 + parts (if needed) + shipping both ways...
I would like to know what is the issue with this chassis. I am compiling all sorts of notes in my repair logs for K7000 issues. I hope to some day get photos of differences as well. I've run into several chassis that have the wrong parts installed.
Peale
Active member
Yup, I'm also following along on this. Modesitt, post when you find the cause, please!
modessitt
Volunteer: Encyclopedia Submission Moderator
Dunno if I'm getting it or not. Haven't heard anything...
OP
OP
Well, most likely not. I can get an exact working replacement for around $60, so it's not in my best interest to send it to you. I'll just get a replacement and swap all the new caps and flyback from the bad one to the new one.
modessitt
Volunteer: Encyclopedia Submission Moderator
Ok, then what do you plan to do with the old one?
KevinMullins
Active member
K7000
Sounds like he's going to rob it of all it's new parts to put them on a "working" chassis.
Sounds like he's going to rob it of all it's new parts to put them on a "working" chassis.
OP
OP
That's the plan as of now. I may try and t-shoot a little more, but I can't find a single thing wrong with it. Pathways are all good. I checked, rechecked and REchecked everything listed in all the pages of this thread and they are all good. It is most definitely something that is not normally checked or goes bad. I mean after all, I did direct short the input wire to R301. Who the hell knows what that did? Could be anything.
KevinMullins
Active member
So just to re-cap on stuff checked .....
D19, D20, D21, D22, D23, D24 ( no shorts or opens) ?
IC4 (no shorts between pin 3 and any other pin) ?
Q11 H.O.T. (not shorted) ?
C36 (not shorted) ?
Also the potential of pin 16 on IC2 having been shorted to ground as well.
Flyback replaced before or after the incident?
D19, D20, D21, D22, D23, D24 ( no shorts or opens) ?
IC4 (no shorts between pin 3 and any other pin) ?
Q11 H.O.T. (not shorted) ?
C36 (not shorted) ?
Also the potential of pin 16 on IC2 having been shorted to ground as well.
Flyback replaced before or after the incident?
OP
OP
All good. All checked out of circuit. D13, D14, D15, and D10 are all good as well. Also replaced the B+ pot. No Joy.
Nope. It's been replaced and rechecked after replacement. Pin 3 to Pin 1 reads .995 on the diode checker setting. Pin 3 to Pin 2 reads 1.247. Pin 3 to Pin 4 reads .306. Pin 1 to Pin 4 reads 1.086.
Nope. It's been replaced and rechecked after replacement. Collector to both legs reads .521 on the diode checker setting. Roughly 73K ohms.
C36 was NOT shorted. However, I don't have just one cap there. I also have a C69. Neither of them are shorted when removed from the circuit. Here is a pic...
Pin 16 of IC2 reads roughly 6.5K ohms to ground. I already replaced the chip as well. Replaced IC1 also. No joy.
I replaced the flyback with a brand new one a week or so after I got the chassis nearly a year ago. After this incident, I put the original working one back on (still had it) and it did nothing. So, it's not a flyback either.
Last edited:
SandGunner
New member
When all else fails
Been reading over your saga and only one item comes to mind from field service days. You may have already checked this but are the insulators on your chassis transistors in good shape? If the ceramic casing of the transistors is actually touching to chassis instead of via heatsink compound and an electrical insulator these could cause problems.
It usually was the case after going through the laundry list of common failures as you already have. Check all chassis transistors. Failing that a good bottle of wild turkey helps!
Sandgunner
"And now we just clip the wire from the flyback and ZZZZZZZzzzzzt......"
Been reading over your saga and only one item comes to mind from field service days. You may have already checked this but are the insulators on your chassis transistors in good shape? If the ceramic casing of the transistors is actually touching to chassis instead of via heatsink compound and an electrical insulator these could cause problems.
It usually was the case after going through the laundry list of common failures as you already have. Check all chassis transistors. Failing that a good bottle of wild turkey helps!
Sandgunner
"And now we just clip the wire from the flyback and ZZZZZZZzzzzzt......"
OP
OP
Unfortunately, I have ruled that out as well. I unbolted the transistors from their respective housings and moved them away from them a little. Essentially "free-floating" them. Turn everything back on and, nadda. Neither of them are shorting to the frame.
R3LL1K
Well-known member
This is a pretty sad situation and it's the same one I found myself in. I ended up making the same decision. I applaud you for having spent more time on yours than I did on mine Zenomorph.
KevinMullins
Active member
Were you holding your tongue on your left cheek while squinting with your right eye while powering it on ?
OP
OP
No, I am fearless...
OP
OP
Ok, new developments. Yesterday, I called up a local vendor asking if they had any spare K7000s laying around that I could get from them. They said, "No, we are using all the working chassis' we have." I said "Ok, do you have any non-working ones?" They said "We have a U5000 you can have for free." I said "Ok, I'll come get it tomorrow." (because I just wanted to get a replacement for this K7000 that I blew up so I could get the machine up and running again) After work today, I stopped by to pick it up. I found out why it was free. It had no neck board. I said "Hey man, you didn't tell me it had no neck board. How am I supposed to use this?" He said "Oh yeah, sorry about that. Let's go see if we can find one." After looking, we couldn't. I did walk by what looked like an excellent condition K7000 sitting on a shelf with what looked like 100 other chassis' that were supposedly "non-working". I said "Hey, here's a K7000. That's what I am trying to replace." He said "Hell, just take that one then." There was a tag on it that said "Good picture, but too small. 19"?" I could immediately tell it was not. The neck board was definitely a 25". They let me have it for free instead of the U5000 because the technician was out on a call and the guy I was dealing with had no clue about chassis'. Man I got lucky. I got home, fired it up, and it works great. The problem of the "picture too small" was simply due to a broken Vertical Size pot. I replaced it and everything is great. The chassis is in remarkable condition. Not even hardly any dust on it. I am going to rob all the new caps and fly from the non-working one and put them on this new one. Sorry I couldn't find a fix for the other one, but I tried everything. Thanks for following along and to everyone who tried to help me. It's really appreciated. - Mike.
