SBE Console II necromancy

[TM86]

Picked up a Console II from eBay dirt cheap. It's worth what I paid for it, that's for sure.



This was after I threw the knobs in soapy water to remove the nicotine crust and scrubbed the brown ring away from around the channel selector. Cosmetically speaking, not that bad.

But then I found that I'll probably have to replace a fuse.


Maybe a cap or two.


And probably undo a small channel mod.


But I'm pretty sure caps never came with powdered sugar as part of the package.


I can't tell if that's just the caps getting fuzzy from age or if they're actually growing mold on them.

So, yeah, this thing's going to be a project. Or an addition to the local landfill. One of those.

As it stands today, though, this thing is dead. So is bringing it back making it live again? Or just making it undead?

 

[walterjn]

Picked up a Console II from eBay dirt cheap. It's worth what I paid for it, that's for sure.

View attachment 64885

This was after I threw the knobs in soapy water to remove the nicotine crust and scrubbed the brown ring away from around the channel selector. Cosmetically speaking, not that bad.

But then I found that I'll probably have to replace a fuse.
View attachment 64886

Maybe a cap or two.
View attachment 64887

And probably undo a small channel mod.
View attachment 64889View attachment 64890

But I'm pretty sure caps never came with powdered sugar as part of the package.
View attachment 64891

I can't tell if that's just the caps getting fuzzy from age or if they're actually growing mold on them.

So, yeah, this thing's going to be a project. Or an addition to the local landfill. One of those.

As it stands today, though, this thing is dead. So is bringing it back making it live again? Or just making it undead?

If it's is mold, spray white vinegar on it. That will kill the mold, bleach will not kill it, and it'll come back with a vengeance.

 

[TM86]

If it's is mold, spray white vinegar on it. That will kill the mold, bleach will not kill it, and it'll come back with a vengeance.

I'll probably just swap out the caps and not worry about it. Who knows how long that stuff has been there and what damage has been done.

I will use your vinegar tip if I find that white crud anywhere else in the radio.

 

[TM86]

Finally figured out what's going on with those powdered sugar looking caps. They're mica caps with a plastic coating, and that coating is breaking down. I guess that can happen after almost 50 years of abuse and neglect.

Ordered replacements. Like a car guy I'm putting more into this thing to get it running than I can ever get out of it. Next guy will probably butcher it anyways, but that's his problem.

 

[TM86]

Made some progress on this thing. Finished swapping out the fuzzy mylar caps while I wait on the backordered micas to show up. Decided to smoke test it. It didn't smoke, so I know it's concerned about it's health.

This was off an external power supply. The internal one is going to require a bit more work as the pictures above showed.

What it does do: Receive in AM, blow fuses in sideband.

What it doesn't do: Transmit in AM, work in sideband.

Mind you the channel selector is dirty as heck and sometimes it requires a bit of wiggling to go, but when everything lines up I get a signal.

So now I have to track down what's shorted on the sideband side of the house. Then I can start looking at why it doesn't TX.

It's not much but at least now I know there's a chance of saving it, and it may be worth fixing the internal power supply.

 

[nomadradio]

track down what's shorted

I suspect that a very bright light and the biggest magnifier you can find will reveal a solder splash, or bridge between foil traces.

73

 

[TM86]

I suspect that a very bright light and the biggest magnifier you can find will reveal a solder splash, or bridge between foil traces.

73

I looked and I looked, but I couldn't find one. I did isolate the problem to where the mode switch feeds 8.7 volts or so towards the base of the final by pulling the wire. Looked on both sides of that connection and could not find a short. Connected it back up to confirm that the problem remained, and the radio no longer blows fuses in any mode. So there probably was a bridge, and I accidentally fixed it.

Still doesn't transmit, and I think at least one crystal may be dead, but at least with the power staying on I have a chance to figure those things out.

Oh, and I don't know if it's common for these, but it's got a 2SC1306 for the final. Not what's in the Sam's, but the heatsink it's attached to matches the transistor type. So this may be a factory mod, or it may have been a kit someone was selling as an upgrade. All I know is the mounting holes all line up correctly, and there aren't any extras.

 

[nomadradio]

Seems to me the factory final was in a metal TO-5 can with a flange holding it to the heat sink with two screws. I would adapt a modern (!) TO-220 transistor to one mount screw on the old heat sink. Had to add the mica washer. Looked awkward, but worked okay. The 1306 is either a final for AM-only radios, or the driver in a SSB radio. Sounds like someone used it to replace the final because it's what they had.

Wouldn't be the first time.

73

 

[TM86]

And the weirdness continues. Found a "dead" socket. No crystal works in X5. Also found a dead crystal at X7. OK, I can live with both of those until I figure out the problem that's really throwing me for a loop.

When the radio is keyed in any mode, the 9.38 V source, 9.35 AM source, and the 9.22 V SSB source all die. These are, as far as I can tell, all supposed to be constant between RX and TX. They're all fed from a common point, so it would be more of a surprise to lose only one of them.

I suspect that something could be backfeeding from a receive only voltage source, but I can't see where that would be coming from. I'll have to pull R601 to see if that's even possible.

It's also possible that something is shorting only TX. But not enough to blow a fuse. If this is the case it's going to take a long time to hunt it down.

Final possibility that comes to mind is someone attempted a mod and wired something to the wrong point on the relay.

Until that problem is solved, though, no point in looking at the others.

 

[nomadradio]

I suspect that something could be backfeeding from a receive only voltage source,

Find every diode connected to the receive-only rail.

73

 

[TM86]

Found the source of my voltages dying on transmit, and it makes absolutely no sense. Bad electrolytic cap at C160. It wasn't shorted and it tested good on the multifunction tester, but it killed voltages in transmit. And yes, I did check both leads for shorts to surrounding traces on the board before I pulled it. Replaced it and not only do the voltages remain, the darn thing now transmits where it has good crystals/sockets. All modes, too.

So remember, kids, new doesn't always mean good.

So now I'm waiting on the mica caps I ordered that Mouser assures me will be off backorder and on their way to me soon. Although I've gotten used to them, that powdered sugar look on the ones in the radio just seems like trouble waiting for an excuse to happen.

I also need to order some safety caps for the AC input side. You can see that one of them was blown out in the pics at the start of the thread, and I don't trust either of them at this point. I did check the AC input transformer and the DC resistance matches what Sam's says it should be, so hopefully it's good and doesn't develop a short when it's hot. I have a feeling whatever blew up the AC fuse also killed the safety cap, and I'm hoping that's all the damage that was done in the power supply.

And I still need to figure out why that one crystal socket doesn't work. Could be a hangover from the channel mods that were done, could be something unrelated. I think the socket itself is OK. I at least get continuity when probing the top of the socket and the board below it. My crystal-fu is weak, though, so this may be a bit of a challenge.

Once again, my hat is off to you pros who do this day in and day out. The fact that you can deal with problems like this and not launch a radio in to the nearest wall every now and then is quite impressive.

 

[nomadradio]

The fact that you can deal with problems like this and not launch a radio in to the nearest wall every now and then is quite impressive.

Takes practice.

73

 

[TM86]

Upon further review...

Found that I was wrong about the X5 crystal not working, it was X2. AKA 7.5025 MHz. This was a fun one. There was no wire connected to switch that crystal on. Looking at the channel switch I thought I found a terminal that I could attach to that seemed to be switching on and off at the right times. Nope.

I had hit something with the meter lead that I could not see, the stubby remains of where the wire went originally. No eyelet, just a tiny bit of copper hanging out over the edge of the channel selector.

Yeah, I soldered a wire to it. This whole thing is a questionable repair anyways, so what the hell. It worked! I've got channels 4, 12, 16, 20, and 23 working now. Not perfectly on frequency, but that can be aligned.

Now I need to see if I can find a 11.750 MHz crystal for X7. That sucker's definitely dead. Put another crystal in the slot and it works. Wrong channel, but it works. So everything but the crystal seems to be OK.

 

[TM86]

Got into the power supply today. Yanked the "safety" caps and put an inline fuse holder in place where the old 1 Amp fuse exploded. Just to see if it would go boom, plugged it in and turned it on.

Output voltage after about a half hour was fairly stable at 14 volts, close enough.

I did find and order the 11.750 MHz crystal. Should be here by... Oct 10th?

Next up, lights. Thinking of maybe doing a tri-color or RGB LED behind the channel indicator. Have it light up a different color for each mode. Not sure if that would mess with the lighting for the meter, though.

 

[walterjn]

Got into the power supply today. Yanked the "safety" caps and put an inline fuse holder in place where the old 1 Amp fuse exploded. Just to see if it would go boom, plugged it in and turned it on.

Output voltage after about a half hour was fairly stable at 14 volts, close enough.

I did find and order the 11.750 MHz crystal. Should be here by... Oct 10th?

Next up, lights. Thinking of maybe doing a tri-color or RGB LED behind the channel indicator. Have it light up a different color for each mode. Not sure if that would mess with the lighting for the meter, though.

Depending on the colors of the meter, and the colors of the led, it might wash out certain colors. It's a cool idea! Be really easy to tell what mode your in that way!!
Depending on how you are switching the led, it might be possible to run 3 different leds that wouldn't interfere with the meter colors...