Amp doesn't let up at all and show high swrs at radio.didn't see or smell smoke...in fact just turned it on
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Did my palamar die
- Thread starter hotrod
- Start date
Palomar?
Not very specific.
1970s Palomar?
or 80s?
90s?
Or is it too young to buy a drink?
Keying circuits can do this. Does the standby switch shut it down? Or the power switch?
Tubes?
Transistors?
Base?
Mobile?
All important clues to zero in on an explanation or a fix.
Kinda like "My Ford won't start".
More than one kind.
73
Not very specific.
1970s Palomar?
or 80s?
90s?
Or is it too young to buy a drink?
Keying circuits can do this. Does the standby switch shut it down? Or the power switch?
Tubes?
Transistors?
Base?
Mobile?
All important clues to zero in on an explanation or a fix.
Kinda like "My Ford won't start".
More than one kind.
73
Hmm. Itty-bitty DIP-package relays. Probably a failed relay. An amplifier that's turned off should act like a barrel connector in the coax. The amplifier's failure to act like a barrel connector suggests this. That amplifier had the mixed blessing of double-sided plate-through circuit board. Makes it more rugged, and more trouble to remove small parts. Each component-lead hole has a metal sleeve in it, to join the top-side foil to the bottom-side foil at each hole. Commonly called a "plate-through". More trouble to desolder. Just wants to stick the pin to the inside surface of that sleeve. Heating the pad repeatedly to extract enough solder risks heat damage to the glue holding the foil pad to the board. Tugging on it can pull the sleeve out of the hole altogether. That relay is best removed destructively. It gets clipped into pieces until only the pins remain where you can grab one of them at a time. Grip each pin from the top, melt the solder from the other side and remove each pin with no stress to that sleeve. The remaining solder will be easier to remove from the empty hole than it was when there was a pin in the hole.
No way to do this without removing the circuit board. No need to unsolder the RF transistors. Just remove the two bolts on each. The one I remember has outer edges of the circuit board captive in a track on each side. Has to slide out. Usually best to unsolder the wire from each coax socket. and slide it out the front. Tricky part is to smear heat-conducting compound onto the heat sink so the transistor doesn't scrape it all off sliding the board back into place after the relay is replaced.
Not fun but doable. It's the only way to find out how much of the rest of the amplifier is dead or alive. Everything goes through that relay, so when it breaks you can't tell what else is or isn't broke.
The original relay is most likely rated at 2 Amps. If you can find it, the 3-Amp version should be a bit more stout. Pretty sure that's the highest Amp rating you'll find in that physical package.
The pin pattern layout is not the same for every relay that size. The replacement relay has to match old relay's pin layout to line up with the holes in the circuit board.
What are the brand name and type number on the top of the relay? Would help to nail down a compatible replacement.
73
No way to do this without removing the circuit board. No need to unsolder the RF transistors. Just remove the two bolts on each. The one I remember has outer edges of the circuit board captive in a track on each side. Has to slide out. Usually best to unsolder the wire from each coax socket. and slide it out the front. Tricky part is to smear heat-conducting compound onto the heat sink so the transistor doesn't scrape it all off sliding the board back into place after the relay is replaced.
Not fun but doable. It's the only way to find out how much of the rest of the amplifier is dead or alive. Everything goes through that relay, so when it breaks you can't tell what else is or isn't broke.
The original relay is most likely rated at 2 Amps. If you can find it, the 3-Amp version should be a bit more stout. Pretty sure that's the highest Amp rating you'll find in that physical package.
The pin pattern layout is not the same for every relay that size. The replacement relay has to match old relay's pin layout to line up with the holes in the circuit board.
What are the brand name and type number on the top of the relay? Would help to nail down a compatible replacement.
73
If you want another one the works I've got a "Magnum" 4 pill blue. 1=1/2-2 watts in is swinging 3...
Had to take a relay off a board from a power chair before. The relay pins were tight enough to keep solder from sucking out easily due to capillary action and the solder they used laughed when i tried 400°F. They had SMD parts under the relay and all around it too. Tried ChipQuik low MP solder and the highest setting on my iron. Didn't work. I thought destructive removal was my only option until I got on an electronics forum and found out what my errors were.
Remove as much of the solder from the pins as you can. Low MP stuff like ChipQuik is good for that if the solder they used has a high MP. Then, add a little regular solder, but not much. Just enough that the iron tip makes thermal contact to the solder in the hole.without having to travel through the relay pin to get there.
You absolutely must preheat the board. You dont have to get it hot enough for other parts to fall off, but get it at least too hot to touch. Hair dryer is better than nothing here.
Then take a monster half inch copper tip propane soldering iron, get it good and hot, wet the tip with some regular solder and hit all the pins as fast as you can. You absolutely NEED a huge thermal mass in the iron tip or by the time the solder melts in the last pin, the first resolidifies as the iron wont keep up. Preheating helps big time here.
If you did use ChipQuik or something low melting with bismuth or indium, flush the pads/holes with regular solder and clean off a few times so the low mp metal dont cause problems down the road.
Preheat and a huge thermal mass are absolutely necessary. I wouldnt worry too much about the iron being too hot. The goal is to get the pin and surrounding solder melted before the heat can spread out, so playing it safe below the trace delamination temp isnt going to work. The pads wont lift off anyhow since its through plated and they are mechanically fixed in place. Give it the business, just be quick about it.
Remove as much of the solder from the pins as you can. Low MP stuff like ChipQuik is good for that if the solder they used has a high MP. Then, add a little regular solder, but not much. Just enough that the iron tip makes thermal contact to the solder in the hole.without having to travel through the relay pin to get there.
You absolutely must preheat the board. You dont have to get it hot enough for other parts to fall off, but get it at least too hot to touch. Hair dryer is better than nothing here.
Then take a monster half inch copper tip propane soldering iron, get it good and hot, wet the tip with some regular solder and hit all the pins as fast as you can. You absolutely NEED a huge thermal mass in the iron tip or by the time the solder melts in the last pin, the first resolidifies as the iron wont keep up. Preheating helps big time here.
If you did use ChipQuik or something low melting with bismuth or indium, flush the pads/holes with regular solder and clean off a few times so the low mp metal dont cause problems down the road.
Preheat and a huge thermal mass are absolutely necessary. I wouldnt worry too much about the iron being too hot. The goal is to get the pin and surrounding solder melted before the heat can spread out, so playing it safe below the trace delamination temp isnt going to work. The pads wont lift off anyhow since its through plated and they are mechanically fixed in place. Give it the business, just be quick about it.