About all the parts except for the transformer in the 35 Astron are cheap to buy. I usually buy my parts from Mouser, Digi-Key, or Jameco. For things to be burnt as you say they are, my initial impression would be an extreme power surge. You might find a few parts at Rat Shack if you can muster the will to go in there. I wish they would go ahead and change their name to Cell phone shack. They are at least trying to drop the Radio part by calling themselves the "Shack". Well....enough of that. I can tell you that the guys in the technical department at Astron are very nice and will help you if they can. I have had to call them a couple of times and they have been very helpful. That is one reason I don't mind to spend a little more for one of their supplies.
Randy From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kd8dey Sent: Saturday, June 26, 2010 1:52 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Astron HELP!! (35A) --- In Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> , "skipp025" <skipp...@...> wrote: > > You Emailed me direct, I replied and said I'd help you along > with some instructions... so "guess yes". Someone did answer you > (me) and it's now your turn to reply back to me after reading > my reply. > > s. > > > "kd8dey" <kd8dey@> wrote: > > > > --- In Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> , "kd8dey" <kd8dey@> wrote: > > > > > > Howdy y'all. I came across the repeater builders website looking for information on the Astron 35A. I am in my 4th quarter at ITT and just started Devices 1. > > > > > > I just received a non working 35A from another ham for use as "Study" material for our electronics club. > > > > > > Looking at the 4 different schematics available I Believe that we have the one based on the 1991 schematic. > > > > > > So far we know that the MCR225 is toast. There was enough of it to get a partial number off to help us guess that it was the 1991 version which is the only one to use that specific part number. > > > > > > Also on the cabinet mounted TIP29 there is a brown lead that I believe is coming from the emitter to the top of a resistor sticking up on its end. That resistor is also toast and I am guessing the tip29 along with it. > > > > > > I am not sure if that is the 2.4 ohm resistor that is omitted in some of the other schematics or not. Its too burnt up to tell any color codes. > > > > > > I am curious as to what would have caused this kind of failure along with suggested replacement parts numbers. > > > > > > I also need verification as to the Identification of the "mystery" resistor. > > > > > > Any help would be appreciated. > > > 73 > > > > > Guess not > > > Sorry, I emailed you direct from your address posted in a message on another board. Didn't realize you were also active on this board. thought you responded from my email and not from my post here. my bad. I have been doing some more digging around on the internet and found yet another schematic i somehow overlooked with all the ones listed... I believe that I have now figured out the mystery resistor. I overlooked the 1978 schematic on the website. that one matches the way the "Mystery" resistor is wired into the circuit even though it lists a different SCR part number. so maybe it was made sometime after 1978 but before 87?? R15 2.4 ohm in the other schematics the resistor looks to be either connected in a way that it would have had to be completely mounted on the board instead of the lead coming from the pass transistor or omitted in some versions all together. With all the revisions they really made it a mess to figure out exactly which version you have. I have been unable to find any reference on the cabinet. I still wonder what could have caused all the damage that we found, old age, power surge......I still need to look up substitute parts and locate a cheap source. when finances permit I would like to upgrade the board But for now it will serve it's purpose as a lab project for our electronics club.. BTW I have been pestering our class chair (a former ham) to maybe introduce ham radio to the club. Handed him my old study guide and a hint about how mounting a dipole on the roof would give good coverage from east/west........maybe I will be able to get a new club in the works lol.
