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ft101b HELP with power supply removal

 

All-
I bought a cheap Yaesu ft101b to learn about tube HF.? Based on guidance from this board I started it on a dim bulb tester (receive worked), tuned it per manual and service manual (they do not agree, but both tuned it).? Set it for 1/2 power and transmitted into a known resonant 20m dipole.? Got about 60w out. Groovy!? Next day it only received!!!?? Stopped and pulled the case to look for c13 and c125 to replace them if still the originals per instructions here and elsewhere. I found sources saying? this is what happens if C13 fails open.If it fails shorted, fire ensues.? I have had no fire, smoke, or evil smells from the 101.

Opeed case and found this inside (see photos of rectifier board PB1076B.)








This is PB1076B, the rectifier board.? That stuff is not spray on insulation, the components are partially carbonized. And it still receives.? Tough radio.

How do you remove this board?? It appears to have been born in this position and cannot be removed without explosives. Most everything else looks accessible, but not this.? No other damage evident anywhere.

How can I get this board out? Anyone have one to sell? And while I'm asking, where are the C13 and C125's I need to replace?? I have found several with those numbers.

Thanks for any help available.? I think I made or bought a mess.

73,

Tom
KO4HNB
 

Tom

It is possible to remove it. It's not easy but I did that.? Probably it is necessary to verify all components.
take a picture and note the position of all the wires

You can loosen the screws on the other side where the plate is fixed. To do this, you have to remove the speaker to access the screws on the support.

Now if I remember correctly these burned resistors belong to the inverter circuit. In other words, the ft101 can work without them.

good luck

Emerson
PP6EW
?


Em seg., 25 de mar. de 2024 às 00:17, Tom KO4HNB <alnath14308@...> escreveu:

All-
I bought a cheap Yaesu ft101b to learn about tube HF.? Based on guidance from this board I started it on a dim bulb tester (receive worked), tuned it per manual and service manual (they do not agree, but both tuned it).? Set it for 1/2 power and transmitted into a known resonant 20m dipole.? Got about 60w out. Groovy!? Next day it only received!!!?? Stopped and pulled the case to look for c13 and c125 to replace them if still the originals per instructions here and elsewhere. I found sources saying? this is what happens if C13 fails open.If it fails shorted, fire ensues.? I have had no fire, smoke, or evil smells from the 101.

Opeed case and found this inside (see photos of rectifier board PB1076B.)








This is PB1076B, the rectifier board.? That stuff is not spray on insulation, the components are partially carbonized. And it still receives.? Tough radio.

How do you remove this board?? It appears to have been born in this position and cannot be removed without explosives. Most everything else looks accessible, but not this.? No other damage evident anywhere.

How can I get this board out? Anyone have one to sell? And while I'm asking, where are the C13 and C125's I need to replace?? I have found several with those numbers.

Thanks for any help available.? I think I made or bought a mess.

73,

Tom
KO4HNB
 

Thanks for your reply, Emerson.? I have the board out and am currently removing and testing components.? Surprisingly the badly charred resistors test right on the money.? Some of the smaller components outside the charred area are dead as doornails.? Go figure.? I will replace everything with obvious damage or that tests as marginal. We'll see how it goes!

73,

Tom. KO4HNB

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