Are These Circuit Traces Bad

[Findm-Keepm]

Originally Posted by zeno

You need to be careful with any brand boards in the box.
They are quite often the bad boards. Someone changes it &
never marks it as bad. Many shops were careless about
returning duds for core credit, often loosing track of where they
came from etc. No invoice -no credit.......
Also many put them aside to rebuild themself "when a chassis
comes in & I got time" Needless to say that usually was never &
bad boards piled up. Then someone comes along 30 years
later & liquidates them on E-Bay. No way in hell he knows.

CAVIAT EMPTOR

73 Zeno

I quite agree - when my dad retired back in 2008, he had exactly 7 good Zenith Duramodules and about 30 boxes marked with the symptoms the module had. After the heyday, and after junking a few sets, shops ended up with lots of questionable stuff.

Originally Posted by TinCanAlley

I tried the original transistor again and the set wouldn't fire up. Putting in the one from the old board in again worked. So now I need to find me an NTE171 locally. Not gonna spend a couple of bucks for one and then $7 for shipping.

As far as needing a transistor, post the 121- number, as many of us have stashes of original parts - yours for postage, in my case. Don't default to buying new stuff when we might have what you need, and are willing to give it away!

Cheers,

[TinCanAlley]

Originally Posted by Findm-Keepm

I quite agree - when my dad retired back in 2008, he had exactly 7 good Zenith Duramodules and about 30 boxes marked with the symptoms the module had. After the heyday, and after junking a few sets, shops ended up with lots of questionable stuff.


As far as needing a transistor, post the 121- number, as many of us have stashes of original parts - yours for postage, in my case. Don't default to buying new stuff when we might have what you need, and are willing to give it away!

Cheers,

Thanks. The part # is: 121-755

I bought these off ebay and they were noted as being NOS. They sure don't look used and are a newer cream colored board instead of the old brownish (I'm so bad with any color other than primaries). The boards are the updated versions of the originals, but they can't be much newer as they also have plug in transistors.

[rcaman]

looks like a capacitor has leaked on the traces. steve

[Findm-Keepm]

Originally Posted by TinCanAlley

Thanks. The part # is: 121-755

I bought these off ebay and they were noted as being NOS. They sure don't look used and are a newer cream colored board instead of the old brownish (I'm so bad with any color other than primaries). The boards are the updated versions of the originals, but they can't be much newer as they also have plug in transistors.

Zenith may have had a second production run, as many shops ordered modules but failed to turn in duds. I remember PTS and others would issue a hotlist if modules they would buy at the dud price, to develop sufficient stock. Zenith System 3 modules were that way in the early 80s - some modules were backordered to the factory to get replacements. We fixed all of ours, so we never swapped anything but tuners and tuner controls. Duramodules (the Zenith term for your module) were exchanged, as the modules were cheap, and Time-to-repair was greater.

I'll check in the morning and see if I have your transistor.

Cheers,

[TinCanAlley]

Okay, the new boards aren't cream color (I was going from memory). They're actually white and green. Here's a pic of the one I installed. The bad transistor is the one with the screw hole just behind large orange capacitor.

[DaveWM]

so you still did not look into the horz blanking? that would have been the 1st place I would have checked.

[zeno]

Originally Posted by DaveWM

so you still did not look into the horz blanking? that would have been the 1st place I would have checked.

Yes lets get back to the jail bars ! The filter can was a good learning
experience but as I suspected unneeded..............
The Sams is in front of me & I am redy to rock & roll !

73 Zeno

[DaveWM]

is this the 25dc56? I assume so,

I would look at the diode and blanking transistor, as well as the voltage divider in front of that.

Scope the fly pulse all the way thru the two blanking transistors.

[Findm-Keepm]

Originally Posted by TinCanAlley

Thanks. The part # is: 121-755

I bought these off ebay and they were noted as being NOS. They sure don't look used and are a newer cream colored board instead of the old brownish (I'm so bad with any color other than primaries). The boards are the updated versions of the originals, but they can't be much newer as they also have plug in transistors.

Sorry, I don't have one. I go from 121-500 to 121-758, nothing in between.

Cheers,

[TinCanAlley]

Originally Posted by Findm-Keepm

Sorry, I don't have one. I go from 121-500 to 121-758, nothing in between.

Cheers,

No problem. Just found out there's an old electronics shop a few miles from me that has lots of older stuff sitting around. I'm going to make a list of parts and call to see if they have them.