Out of town for the long weekend visiting family, back at it on Tuesday!

 

Ok, got the coil and diode removed and board cleaned up.




I soldered the coil back in NP, have not soldered the diode in yet. Checking it with the DVM I only read continuity one direction, normal right? Just need to make sure and resolder back in the correct/same direction. My DVM has diode tester, what value should it read?

 

Continuity in one direction only is the only test you need to do. So, you are good. Pretty much all other testing would be destructive testing, so...don't do that.
Reinstall in the corret orientation and you are good to go. The band on the diode goes at the point of the arrow.

 

Hi.
Now the label L801 shows up where mine failed to conduct from top trace to bottom trace trough those vias.



See my arrowhead. ? Scrape that trace from under the arrowhead upward to around the hole to be able to apply solder on that trace around the hole and solder the right side of the coil to the trace. The blackened hole via where the coil fits is burned off, and to make connection, that trace must be scraped to bare copper so a blob of solder or a small wire can connect the coil pin to that scraped trace.

The hole where the blue end diode fits should also have the trace scraped around the hole it fits-in as appeared not healthy. The intention is to solder the blue end of the diode to that same trace.

When the coil gets soldered-connected and the diode too, check continuity from terminal power4 to the vias we found by the label L801, underside.

To be continued... but not much longer.

 

OK, all of mine had continuity from pin 4 on the harness connector to all the solder points, even the bottom of the board via the L801 vias. I have continuity all the way out to pin 7 although it pauses for a minute and then reads 5 kohms and starts counting up as long as you hold it there.

 

That's normal. You are charging a capacitor. It'll keep creeping up until it's fully charged, then you'll show open circuit.

 

Set the board in its chassis or on an insulated table. Connect the front panel, no cassette unit. Time to power up applying (-) Gnd to chassis (alligator clip Ok; +12V to Power4 and to Power7. Push the on ****. If the display is alive, chances are resurrected. Disconnect and reassemble to retest in a safer assembled way.
To be continued...

 

Ok, tested both, continuity all the way to pin 7 on the back of the front board, but once power is applied I have no power past the diode.

 

There is two separate +12V paths. Follow the voltage presence to the point where interrupts

+12VRearPowerPin4---------->triplevia-------->outerblueendofdiodeD807--------->L801coil----------->Nichiconcapacitor-------->doulbleviabylabelL801-------->circuitry-------->

================================================== ================================================== ======

and +12VACC path on vertical board :

+12VRearPowerPin7------------>Label7--------------->hiddendoublevia----------->hiddenzenerdiodeunderblackplastic---------Arrowtipbelow--------circuitry------>


This arrowtip is also from my fading memory...
Power7 has nothing to do with the diode blue end. It follows other path.

Only the blue end of the diode can have +12V. Its other end is ground
The installed again goldish coil L801 has two terminals. One next to the diode and one next to the big black capacitor ---> Both must have +12V on the traces they are soldered to.

 

Ok, I am back on this now. One unit powers up and seems to be happy, the other does not. I have voltage at pin #7 and many of the surrounding (22, 21, etc) on the unhappy unit but no voltage at the arrowtip, the happy unit measures 6v at the arrow tip. Any ideas what to check next?