Pole position monitor issue
- Thread starter Yakama
- Start date
Vertical collapse shouldn't really cause HV shutdown and a 160v B+. Ozone smell often comes from arcing from the lopt. Maybe it's arcing internally? I've sorted loads of MTC900E chassis, on the odd occasion i've had vertical collapse on an MTC900E I don't recall it ever having caused HV shutdown. In fact I had a 900E with vertical collapse recently, it kept blowing the TDA 2653A vertical deflection chip, turned out there was a broken trace round the lopt area (think it was part of the grounding circuit).
That's correct as it is, just checked one of my 900/E's. That pad is there along with the others for a diffirent manufacturer of the lopt that uses a smaller footprint on the lopt's pins. Might be worth changing the vertical chip, you may also have a problem with the vertical size pot. I had similar problems on that chassis I mention above, I even put in a new pot I found in my parts which made no difference, turned out the new pot I soldered in was faulty! Soldered in a used one from another chassis and the picture came back full size (after installing a replacement vertical chip).
Nope, that's a 7812 voltage regulator. Provides 12v if I remember correctly from some higher voltage pin on the lopt. The TDA2653A is the multilegged chip (marked IC3 on the pcb silkscreening) on the front of that heatsink, closest to the image adjuster pots. The spring clip just pings off after moving one end sideways out of the hole. Might break when you remove it, a lot of those spring clips are getting weak after so many years. When you remove it, find the ground pin (pin 8 according to the datasheet) and do a beep/continuity check with the other pins. If any show a short then it's toast.
Thank you @gunblade and @tb2000 after replacing the flyback, TDA2653A and one of the pots it is now working again. Needs a bit of adjustment still but it’s working at least.
Now another strange issue, when I bought it it came with a pi position but it wouldn’t register the steering despite having the replacement sensor. I and the previous owner assumed the pi position was faulty (I tried updating it and a few other things first) but I bought the new p4 position and it’s the same. The cabinet works with the original pcb but the steering won’t register with either the pi or new p4 position. I’ve tried a post on the Facebook group but no joy. Any ideas anyone?
Now another strange issue, when I bought it it came with a pi position but it wouldn’t register the steering despite having the replacement sensor. I and the previous owner assumed the pi position was faulty (I tried updating it and a few other things first) but I bought the new p4 position and it’s the same. The cabinet works with the original pcb but the steering won’t register with either the pi or new p4 position. I’ve tried a post on the Facebook group but no joy. Any ideas anyone?
