The Electronics Universe

Well.  One problem I have found is that the downloaded manual isn't the exact one for the model I've got.

I noticed mine uses power transistors on the output for the speaker but the manual I've got shows the circuit using an IC.

Also the rec board is not the one I've got a diagram of - though it's close.  I know I can find some info on the ones I've got on Youtube and here tho'.

Last night I observed that the aerial makes no difference.  It still picks up a few stations, but this is irrespective of whether or not the antenna is inserted.  I thought that was interesting.

Eventually I'll get some progress done.

The first step on the fault-diagnosis tree says to check the voltage on the rec board (1076B).  Well they are all quite a bit over 10% of spec.   Approaching 50% on a couple and 20% over on the 600V pin. I was using the earth on the board as the common.

So with that information I see I need to fix board 1076B as a first step - but I can't find anything in the service manual explaining how I might go about correcting the variance.  I assume the most likely components to go out of spec would be the caps.  So I suppose I should find some newer caps from my 'box-o'-circuit boards' and see if this sorts the problem out.

Though experience tells me things working at voltages well in excess of how they were intended can easily wreck semiconductors.  That worries me.

Yeah!  I'm obviously a bit slow at this.  I'm a bit out of my depth.  Though at least I can see some improvement in my knowledge of this beast.

I just want to receive on it.  I don't intend to transmit with it.  I posted a bit about it in the 'introductions' forum.  Now I've migrated here hoping to  get some advice and and learn ways to get the thing to work properly on receive.

It was given to me by someone who used to use it but I'd say by the look of it and clues in what he said, that it hadn't been fired-up for a decade and maybe two!

I kinda like listening to SW, and it's one way of finding something in English.  I live on a small island in Japan and English is hard to come by. I use a few radios to try to find something rather than the local stuff, but I thought the Yaesu must be better at it.  And it was!  For two days it was quite fun to use.  Then I noticed the volume and/or sensitivity was becoming weaker, and after another day or so it only picked up the odd squeak with indecypherable speech mingled therein.

This post was something I intended to do tonight, but I got side-tracked for too long and it's time to sleep - so I'm not going to do much at the moment except begin this thread.
I downloaded the instruction manual, and a short while ago I separated it into sections.  It's huge!  Some 221 pages.

The FT-101 that adopted me is pretty early I'd say.  I've seen a few Youtube vids about the FT-101 and none of them has actual transistors in the speaker output board that I saw.  Well that's the age of the thing I've got.  It has two large heatsinked transistors with what must be thermistors neatly glued on top.

I shall now try to abandon the introductory thread I started and try to work it out here. 

I'm not an expert with electronics, but I can basically navigate my way around a circuit board and I'm no stranger to fixing electronics and adapting them - allbeit on a pretty basic level.

I found that Yaesu had thoughtfully sealed the most dangerous voltage inside the box with the two output tubes.  But I discovered my forearm is quite capable of reaching a live part when I'm trying to check something else.

I'd love to get this going.  I intend to use this thread to speak of my progress, and also someone might have some great idea I can try.  Hopefully someone can say with confidence where I should start looking.

I've already changed a couple of cracked caps - but that didn't do it.  So I shall now try to digest the 221 page manual and follow what the author says.

Last night I took out a few caps.  I chose them because they happened to be in the  poorest physical shape.  Unfortunately I see one problem with re-capping as it's virtually impossible to decypher the remnants of the printed values.  If changing those three caps made a difference, it wasn't obvious.  Still the same low output.  Two of the caps I replaced had cracks all around and you could see the film inside.  The other one was physically sound.  I might put the OK looking one back and try to find some more I can change.  I haven't got all that many old boards to get components from these days.  Maybe I should try to order the 'cards' as one unit instead of trying to fix problems within each 'card?'

Not a huge problem though because I am going to try once again to download a circuit diagram and hopefully find something in the service manual which can point me in the right direction to solve the lack of volume and the apparent lack of sensitivity - along with the intriguing lack of proper response when trying to tune in the pre-select.

Hmmm???  Could there be something with the unresponsive pre-select and it's associated circuit?  I just hope it isn't FET because I haven't a clue where I might find one of those and I'm sure it will be a lengthy process to get one.

Well off to go and find something to download.

Yes.  I know I can edit without making a new post.  Actually I hardly ever post anywhere on the 'net, and I only use English here.  It's nice to practice English sometimes.

Thank you for the welcome.   

I've got quite a few things going on at the moment, so I haven't had time to swap some caps - which is what I hope the problem is.  I sometimes go cold when I wonder if it's a component that I can't replace..

Several days ago when it became clear the radio was getting quieter and quieter and apparently less and less sensitive, I reluctantly put it all back together with the aim of digging it out at some time in the future when I  (might) have the time and peace of mind to spend some serious time on sourcing the problem.  Trouble is I never did manage to control myself when it comes to a sickly electronic device that needs fixing.  So after a couple of days I got it back on the bench and fiddled with it some more.

What I've done so far is to clean the switches somewhat - wondering if this might improve matters.  It didn't.  Then I cleaned the relays on the antenna and the one inside the box for the tubes.  Unfortunately this didn't bring it back to life.

I periodically remove the sound board thinking this might be worth re-capping.  I say this because there are a few caps that look dodgy.  The dark browny-red caps appear cracked and split - but not much.  The other caps appear OK.
One reason I haven't replaced even one suspicious looking cap is because I see Yaesu fitted the components properly to the board by bending the wires over before soldering.  That's a bit lazy because I can just use some braid and suck the old solder up then bend the wires straight and replace.

The radio as it is actually works.  It's just at an extremely low level.  I only have a few metres of wire as an antenna, but I was picking up quite a lot before it slowly faded away.  Now, I can get a few whines, and I can detect a voice in the middle of them.
I put a signal into the input of the volume control by way of holding the metal shaft of a pick, and there is certainly some amplification.  I can't say whether it is enough  or not because this radio is a mystery for me - less of a mystery than a week ago, and especially since it gave me a several-hundred volt bite when I erroneously touched some tuning bits just below the protective case of the HV box with my arm when I used it as a resting point.

The FT-101 is on the bench now, and now the case is removed, also the protective covers for the high voltage are off.

I find I spend hours mostly just looking at it and trying to think of where the problem might lie. I certainly want it to work.

I asked an acquaintance who has some tube gear about a professional repair.  He said it wasn't so expensive to ship it, but the repair would likely cost a lot.  I live on a small island and the set would have to be shipped to the mainland. 

Well I'll meander my way back to the bench in a short while and I will ask myself where do I start with changing some caps?  I tried to download the service manual and circuit diagram a few days ago but it was taking forever so I gave up.  But I'll need the circuit diagram if I am going to start swapping bits from the boards.