Predicta Princess spare chassis

[DaveWM]

https://www.youtube.com/watch?v=Xi0vF6x4KCM

Part 5 of the series so far.

I picked this up from another forum member, I just wanted a spare chassis since I have a princess and thought it would be a good idea.

I was surprised by how easy it was to pop the pcb off for access, so will now proceed to replace the old film type caps that are always bad.

[bonanzaman]

Thanks, Dave, for the post....I'm starting a princess, and will try the 3 wire release and tilt method and see how it goes. My set, like yours has the older, cotton with color band wire insulation....very hard to tell em' apart unlike the nice bright colored vinyl insulated wires I've seen on other Predictas.

[Rcr1961]

Dave,

I just finished up a restore on a debutant 11L43 chassis, I found that all the caps on
the PCB could be replaced with the board in place.
I did need a longer soldering iron tip for a few of the parts, but I really did not want to
remove the board, thanks to your video I can now see that would not have been a problem.

Bob

[DaveWM]

Yes you can get most maybe even all of the caps, I did that with a solder "gun" with a bent tip to get to some of the hard to get ones.

having done it both ways I would say IMHO its better to release the board, its just easier and less stressful on the pcb (I did not have the best control with the bent tip aproach, ended up doing some minor damage from lifted traces).

Not to mention this is the only way to get at some of the sockets and or traces if they need to repair.

I am about 1/2 thru the cap replacement its just so much easier.

[powerking]

Quote:

"Yes you can get most maybe even all of the caps, I did that with a solder "gun" with a bent tip to get to some of the hard to get ones.

having done it both ways I would say IMHO its better to release the board, its just easier and less stressful on the pcb (I did not have the best control with the bent tip aproach, ended up doing some minor damage from lifted traces)."

This is one more reason I am a proponent of vacuum desoldering stations/hand-held units like the Hakko 808 over solder wick/with burned finger tips using that stuff....




Tom (PK)

[DaveWM]

done

https://www.youtube.com/watch?v=YQumnEkSMbg

[bonanzaman]

Good job, Dave....I had kind of the same idea as you on making the wires pluggable, but went a little further:
The ones without the connectors are for that hard to get to 4 section C2 cap. I realized that I probably should have taken the shrink-wrap all the way down to the bottom of the connector, but they seem to hold really well. I did all 30 some odd wires....really did not take that long, and I can R&R the board in about a minute and a half. I like the idea of being able to completely free up the board for 360 deg access for re-capping and any other work that needs doing. I'm going to rebuild the K5 network, as it is showing signs of rupturing, leave the others for now, and re-installing the board for a power-up test...we'll see if I got all the numbers right!

[DaveWM]

Wow bonanzaman, that looks good. Did you use tube socket pins as well? that is what they look like.

[bonanzaman]

Yes, they are 7 & 9 pin socket connectors, but I have found some that look better and should have full length contact with the PCB lugs:

http://www.ebay.com/itm/261455280078...%3AMEBIDX%3AIT

The lugs on the Predicta board are actually .060" (1.5mm) wide, so these are a little big, but I'm going to keep looking for others that will be closer to the 1.5mm lug size.

BTW, you don't have to break apart the 7/9 pin sockets to retrieve the connectors.....just grasp the solder lug end close to the phenolic base with pliers and give a good, firm push....they pop right out.

[DaveWM]

If you REALLY wanted to re engineer it..

I was looking at mine, it seem like you could flatten out the bottom chassis mounts that stick up, drill them with some pilot holes, glue on some spacers, use some screws and attach the PCB using the top holes that the mounts poked up thru. put some grounding pins under the screw head for some jumpers to attach the PCB stake to and it would be completely removable with out getting out the iron.

I know that's a bit extreme just thinking out loud.