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Madison ( u858) lost AM

C

cwk

Member
May 15, 2012
54
15
18
South Central Pa.
Friend stopped over with a rather gone over Madison that lost AM and USB. At first it started to break up then finally dropped out all together. LSB works but that really isn't much help. Honestly, this thing has seen more cheap screwdrivers than a drunken whore in a Philly bar. It's where I really have to resort to shotgunning just to get it back on the air. Any way ,I was wondering if anyone might have an idea or has had an issue that could give a little guidance. I know it will need to be recapped very soon and reflowed. All schematics I find are great until I try to read them- very poor quality. My first suggestion would be to get rid of the toys and expo but I have nothing to go on to restore the wiring properly. Oh, speaking of wiring, this thing has everything from speaker wire to peices of phone wire thrown in. A real chestnut. As I said it was working fine (hard to beleve) but started to distort when I heard it then finally peel off.

Thanks! and sorry for the winded question.
 

Thanks. I have the alignment specs for after recapping. Any idea where I could find a readible schematic online? The only ones I could find quite the resolution to make out values and part #'s.
 
if you go down to the radio modifications section and click on the page and go to radio service manuals it has the trc-457 and 458 service manual which is the same as the madison and the lower part of the manual has a list of electrolytic caps you can get it from. I have the sams for the madison and will hunt it down and post what it shows on it for you.
 
just compared the specs for the 457- 458 radio and the parts are the same for the madison so you can use the parts list for it. only thing is make sure all the 10 volt caps you put 16 to 25 volt caps in for replacements. the 10 volt are bare minimum for what the radio needs as why they go bad so easy.
 
Thank you!

I would just outright pick up a sams but this is a one time deal and I'm doing it for free to help out a friend. I should snap a few pics as a public service and title them "When to run".

Thanks again and I'll keep all posted.
 
the book I told you about here on the site is the sams book and basically the same as the madison. the 179 sams book is very hard to find. it only took me about 3 years to find one on ebay.
 
I was just looking at it. I think this will be a great help. Like I said this poor thing has been "worked on" and has the noise toys,expo board and some sort of freq counter added which of course anly complicates matters. Thank you again and I will pay it foward- sorta doing that now :) .
 
Usually a small Tantalum capacitor bites the dust on these, it is right near the finals and is blue in colour. Almost one of a kind in this transceiver.... Can be replaced with a normal capacitor is no Tantalum can be found.

73 mechanic
 
C179, a tatulum cap. put a 2.2uf 25 volt electrolytic in place of it.when this one is bad it will blow the fuse most of the time , mainly when it is in SSB
 
Bless your heart. Thanks. I am going to let the owner that it realy needs to be re capped. This band aid is only postponing the inevitable...but it's got to be.
 
a recap may not solve your problem but that will have to be done 1st due to the age of the radio. last year I had to refurb some of my 858 chassis radios and 2 8719 radios. 3 president washingtons and 2 cobra 142 radios plus my moble radios that are old also. the radios were degraded so bad I could not use them until I did the recap of them. a couple of them I had some trans that had gone bad but could not find them until I did the recap. takes about 1 hour to recap one when you have done that before. some guy's it takes longer due to them not having done it before. a few months ago I did my old teaberry 40 channel mobile that was made in 1977. now that was a job due to it having the same board as a 23 channel and they just added a pll box to give it 40 channels. it is now like new with ssb also. my buddy borrowed it a few months ago and I have not been able to get it back from him since he likes it so well.
hope you come out on this radio after you get started.

forgot to tell you if you look at the service manual for the 457-458 radio it has the parts marked on pages so you can find them a little easier.. when you do the recap mark all the old caps on the shinny side with a black magic marker, as you remove them you will be able to tell which ones you have pulled and which are new since the new ones will not be marked. only change 5 or so at a time and then power the radio up to make sure it is still acting the same as it had or getting better. sinced the caps have to go in one direction it will help you to know you did not put one in backwards.worked on one awhile back a guy did his and put 2 in backwards and like to never found them due to close quarters of some of the parts.
 
I was just looking at your post and assumed it was a 858PLL unit. you never did say for sure. is it a 858 unit or a 8719 unit. this makes a difference as to what caps it takes and the repair and alignment procedure. just noticed in the heading you say it is an 858 unit.
 

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