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Broken down.
- Thread starter Wayne clevenger
- Start date
Check wall power. device fuses, power strips, and the on/off power switches. Power cords fail too.
1973 Chevy Nova. Drove it to work for 40 years.
All of a sudden it's giving me trouble.
I'm not quite snarky enough to add "What could be the problem?"
Oh wait.. I just did.
What's wrong will be some combination of 40-year maintenance issues.
Issues. Plural, not "issue".
Relay contacts wear out. And on the original version in the pics, the high/low relay will burn up the black insulation on the contact-point block. This is the relay that's between the driver sockets and the final sockets.
Pretty sure that's why this third relay was not found in all the later versions. All later versions had only two relays.
Mileage counts. If the mileage is low, cleaning relay contacts may help. And if the mileage is high, the contacts will be burned. Smoothing the rough surfaces of the points will not fix this when it happens. Sometimes a relay lasts for over 40 years. But not often.
The filter capacitors are decades past their 'use-by' date. If they worked at all in the recent past, it's because the mileage was REALLY low. This doesn't prevent them from going bad, only postpones it a little.
A little.
And we haven't even mentioned the tubes yet. If the mileage is low *AND* it was operated conservatively they could still be good.
Could.
And just one night keying it a little too long, or with a radio that was too big can result in a partial death toll among the eight tubes.
But it's not just the years it's the miles, too.
Now that I've gotten all wound up over stuff that can go bad in an old amplifier, you did say "won't come on".
Like the man suggested, have you checked the power switch for continuity? And there is a fuse in a clip near where the power cord enters the rear of the chassis.
Worth a look. Just don't touch any of the filter capacitors that want to store hundreds of Volts after the cord is pulled from the wall.
Can hurt.
73
All of a sudden it's giving me trouble.
I'm not quite snarky enough to add "What could be the problem?"
Oh wait.. I just did.
What's wrong will be some combination of 40-year maintenance issues.
Issues. Plural, not "issue".
Relay contacts wear out. And on the original version in the pics, the high/low relay will burn up the black insulation on the contact-point block. This is the relay that's between the driver sockets and the final sockets.
Pretty sure that's why this third relay was not found in all the later versions. All later versions had only two relays.
Mileage counts. If the mileage is low, cleaning relay contacts may help. And if the mileage is high, the contacts will be burned. Smoothing the rough surfaces of the points will not fix this when it happens. Sometimes a relay lasts for over 40 years. But not often.
The filter capacitors are decades past their 'use-by' date. If they worked at all in the recent past, it's because the mileage was REALLY low. This doesn't prevent them from going bad, only postpones it a little.
A little.
And we haven't even mentioned the tubes yet. If the mileage is low *AND* it was operated conservatively they could still be good.
Could.
And just one night keying it a little too long, or with a radio that was too big can result in a partial death toll among the eight tubes.
But it's not just the years it's the miles, too.
Now that I've gotten all wound up over stuff that can go bad in an old amplifier, you did say "won't come on".
Like the man suggested, have you checked the power switch for continuity? And there is a fuse in a clip near where the power cord enters the rear of the chassis.
Worth a look. Just don't touch any of the filter capacitors that want to store hundreds of Volts after the cord is pulled from the wall.
Can hurt.
73
Thanks for the info ,it was on I had talked some skip ,then put it back on standby ,then a few min I took it off standby pushed the mike and noticed the watt meter did not swing looked up at box it was off , checked powerstrip it was good the fuse n the back of box is not blown ,thanks for the info I will research further or take it to doc 73s machine gun Kelly.
Thanks for the info got it back up and going it was the fuse it looked fine but it checked continuity and it was blowed in the end of it,Now for 1 more question how to unload the electricity out of it so I can clean the points or contacts in it. Thanks
Thanks for the info it was the fuse it looked fine but I checked continuity and it was blown in the end of it where I could not see it,Now 1 more question how to unload the juice out of it so I can clean the relays or contacts in it it is a phantom 12 tube with 3 transformers in it .thanks
Some will say simply short out the filter caps with a screw driver against the case but that could damage the caps.
Its best to buy or build a tool to discharge the caps properly.
Try this
https://www.instructables.com/id/Safe-Capacitor-Discharge-Tool/
Its best to buy or build a tool to discharge the caps properly.
Try this
https://www.instructables.com/id/Safe-Capacitor-Discharge-Tool/
The filter capacitors are arranged in two sets of three caps. Those three capacitors are wired in series.
This means that if you discharge all three of them by grounding the "hot" side of the high-voltage point, the caps will NOT all empty out their stored charge. You can never fully discharge one capacitor by dumping its charge into another cap. Wiring them in series was done to obtain a voltage rating high enough for what the circuit demands. But it creates this hidden hazard.
This is why we won't work on one unless it goes home with a separate bleeder resistor wired onto each filter cap. So long as each one has its own bleeder, the charge will bleed away in a few minutes.
Can't find any pics of this on file, but you get the idea.
The alternative would be to use a gator-clip lead to discharge each of the three caps in each set one by one.
Not fun.
73
This means that if you discharge all three of them by grounding the "hot" side of the high-voltage point, the caps will NOT all empty out their stored charge. You can never fully discharge one capacitor by dumping its charge into another cap. Wiring them in series was done to obtain a voltage rating high enough for what the circuit demands. But it creates this hidden hazard.
This is why we won't work on one unless it goes home with a separate bleeder resistor wired onto each filter cap. So long as each one has its own bleeder, the charge will bleed away in a few minutes.
Can't find any pics of this on file, but you get the idea.
The alternative would be to use a gator-clip lead to discharge each of the three caps in each set one by one.
Not fun.
73