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A question about a Madison upD858 early unit

Wulff777

New Member
Feb 9, 2016
7
0
1
Mesa, AZ
I picked up a 858 Madison SSB/AM off fleaBay and the kid that sold it thought the clock was keeping it from starting up because he said when he messed with the clock knobs, it would sometimes come on.
I did a little troubleshooting when it came in and found it was the switch that was on the 115 VAC input (instead of the AC/DC switch on the later ones) when you unplugged the AC cord it activates the DC input.
I soldered a jumper wire on it to disable it and it fired up, looking it over I was happy to notice it wasn't hacked or modded.
Well, to make a long story even longer, right after I bought it I was recapping a President Washington (858 as well) and I used one of the power transistors that plug-in for the early President Washington to get it going.
Well, I went and got Stage 4 liver cancer and have been going through Chemo for about a year and my chemo-brain (plus my wife's clean-up) I can't locate the schematic so I don't remember if those 2 transistors are regulators or what!
I know with the transistor (on the right, looking from the front) missing, the channel selector LED isn't working (the only thing that lights up is the LED's under the meter that show what mode you are in.)
can any of you Madison gurus help so I don't have to search for a schematic that is buried in my closet?
Once I replace it, I am going to solder/w shrink the plug-in wires leading to those transistors, it's kind of strange they plug in.
Just what the heck are those transistors? Are they they the same numbers or different?
By the way, my radio daze goes back to high school in 1969 when I had tube radios with plug-in Xtals, I can still build tube-type linear amps if anyone needs info, I used to buy the color tv sweep tubes for $2 each new, now they cost a fortune!!! I built a mobile-4 tube and used a surplus Dyno-motor (motor-generator) for the high voltage...... those were fun days!
I couldn't afford these old Madison's and Washington's when they were new so I am making up for it now!
Any help, I would appreciate it.. Thanks
 
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according to my sam's, there's 2 transistors on the power board. tr301 and tr302.

tr301 type numbers are 2sc945, 2sc945a, 2sc945ap, 2sc828, 2sc1740, 2sc458, 2sc900, 2sc372.
tr302 type numbers are 2sc1419b (20W @ 2A), and 2sc1419.
 
howdy,

with the top cover off of your madison, front of the radio facing you, component side up, you will notice that the vertical metal "wall" on the left right behind the clock makes a weird curve. the two transistors that are mounted to the wall there are your driver and final.

do not mess with those.

every other transistor in that radio that looks like the driver and final is either a 2SC1419, or a 2SD1135, and are the same. (interchangeable)

those two parts are hard to find these days and the NTE152 or the 2N6487 are popular replacements.

be sure to replace all the electrolytic caps in that radio, and give it an alignment afterwards.
they are really great radios, but are so old now that you will be plagued with problems unless you re-cap it.
there are kits on ebay for this radio to do this.
once you replace the electrolytics, and align the radio, it will work like new again.
LC
 
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...there are kits on ebay for this radio to do this: once you replace the electrolytics, and align the radio, it will work like new again.LC
LC, how can you recommend a kit that includes 10v capacitors? Shame. My kit includes +25v capacitors plus detailed installation instructions. I'm also a member here if you recall, whereas the other is not.

Note to OP: $1 discount for all worldwidedx members, send me PM for details. If you order from eBay, no discount.

http://rover.ebay.com/rover/1/711-5...0001&campid=5336136228&icep_item=141433856683

$(KGrHqZ,!hYE1fq8ePqqBNc,sNLoBg~~_35.JPG

 
Last edited:
LC, how can you recommend a kit that includes 10v capacitors? Shame. My kit includes +25v capacitors plus detailed installation instructions. I'm also a member here if you recall, whereas the other is not.

Note to OP: $1 discount for all worldwidedx members, send me PM for details. If you order from eBay, no discount.

http://rover.ebay.com/rover/1/711-5...0001&campid=5336136228&icep_item=141433856683

$(KGrHqZ,!hYE1fq8ePqqBNc,sNLoBg~~_35.JPG
shoot Mike. i thought that was your kit!!! oops!
that link is outta here!

guys, buy from Mike, he is the man when it comes to recap kits.
sorry about that Mike!
LC
 
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Thanks guys, you remind of the guys when I was younger and into CB's always willing to help!
I checked a few other sites that seem to have very young users that just says stuff like "why do you want to run and old radio like that for?"
I said "If you have to ask, you are never going to understand!
I started recapping it before I got sick and I see I still have some caps to replace, I hit the tops of the replaced caps with a marker so I know which ones have been replaced.
I don't have my o-scope and various tools anymore so I have to try to find a reputable shop in the Phoenix area to align it afterwards.
Thanks again for all the help,
73's
Phil
 
howdy,

with the top cover off of your madison, front of the radio facing you, component side up, you will notice that the vertical metal "wall" on the left right behind the clock makes a weird curve. the two transistors that are mounted to the wall there are your driver and final.

do not mess with those.

every other transistor in that radio that looks like the driver and final is either a 2SC1419, or a 2SD1135, and are the same. (interchangeable)

those two parts are hard to find these days and the NTE152 or the 2N6487 are popular replacements.

be sure to replace all the electrolytic caps in that radio, and give it an alignment afterwards.
they are really great radios, but are so old now that you will be plagued with problems unless you re-cap it.
there are kits on ebay for this radio to do this.
once you replace the electrolytics, and align the radio, it will work like new again.
LC

I bought a bunch of NTE152's last year but need to make sure they are good.
The two I was wondering about is on the aluminum 'wall' towards the back of the chassis, and is connected to the main PC board with wires about 5-6 inches long. for some reason I am thinking they were both the same and was marked 2SC1419 but not 100% sure.
Thanks,
Phil
 
LC, how can you recommend a kit that includes 10v capacitors? Shame. My kit includes +25v capacitors plus detailed installation instructions. I'm also a member here if you recall, whereas the other is not.

Note to OP: $1 discount for all worldwidedx members, send me PM for details. If you order from eBay, no discount.

http://rover.ebay.com/rover/1/711-5...0001&campid=5336136228&icep_item=141433856683

$(KGrHqZ,!hYE1fq8ePqqBNc,sNLoBg~~_35.JPG
Its critical you add the tantalum's to that kit.
Ticking time-bombs for sure.
 
there are different schools of thought on tantalums, but back in the 70's they were not as good as they are now.
definitely a subject worth reading about.
we are running out of tantalum though, and they are thinking that vanadium will be the next big thing.
LC
 
from memory I think C179 in the final area is one that will cause a lot of problems with SSB and even it will blow the fuse at times when it is bad.over the 16 years I have messed with radios that is one that has caused a lot of problems. when I worked on radios all the time if one came in I would changed that one just for future possible problems.
 
I use an electrolytic in that spot and it works fine and never had one to fail. radionut 63 started me on that one years ago. do not know what happened to him his site closed down about 1 year ago. he had a lot of info on the 858 radios. those were his specialty.
 

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