Thanks for the reply, Bob. It sounds like the 50a bridge rectifier may be my best bet. Same with the newer style caps.
I'm admittedly somewhat of a perfectionist and neat freak, and my motto has always been "use oem parts for proper repair", but this appears to be one of those cases of "do you want it fixed or not?", and I guess an ugly working TPN1110A is better than a junk TPN1110A! I will hit eBay and pick up a few of the bridge rectifiers. A screw, nut, and some thermal grease and that part should be good to go. The caps, well some heat shrink and wire ties should fit the bill. I have a second TPN1110A that works but has horrible voltage sag and ac hum under load. So I guess I will be rebuilding two of them at once. Maybe a few pictures and RB article are in order when I'm done. Eric KE2D --- In [email protected], "Bob M." <[EMAIL PROTECTED]> wrote: > > Other diode alternatives: consider replacing the two diodes with a bridge rectifier. You can get a 50A 1000V unit (I've used these in Astron RS35 supplies) on eBay for about $5 - KBPC5010. One single #8 machine screw holds it to the chassis, and 1/4 inch quick-disconnect terminals let you connect it to just about anything. There are also 60A and 70A versions on eBay. You'll need to add your own ground wire to the negative terminal, but it's probably easier to deal with in the long run. > > Stud diodes come in both anode-to-case and cathode-to-case, but they're each about the same price as the bridge rectifier, and you need two, plus some means of mounting them (bracket etc). > > I guess you have to decide if it's worth replacing just the press- fit diodes to maintain the original Motorola configuration, or finding a current component that will do the job and be readily available if it ever fails again. > > Bob M. > ====== > --- On Thu, 9/18/08, Bob M. <[EMAIL PROTECTED]> wrote: > > > From: Bob M. <[EMAIL PROTECTED]> > > Subject: Re: [Repeater-Builder] Re: Micor TPN1110A power supply parts ID > > To: [email protected] > > Date: Thursday, September 18, 2008, 1:02 PM > > Those big aluminum electrolytic caps with screw terminals > > are getting extinct, and if you DO find one, it'll > > likely be expensive. You can get something quite smaller in > > size but the same or larger electrical value. Go with that. > > Stuff some stiff foam rubber or even some wood slats around > > the bottom so it will fit into the original clamp. > > That's what a lot of the hi-fi repair guys are doing > > now. A lot cheaper for something that has much better specs. > > > > The diodes are probably very similar to what an automobile > > alternator uses. Of course, finding the exact replacements > > could still be difficult. They're probably (minimally) > > 50V, 50A, but I'd look for something a bit bigger. The > > supply is good for 25A at 14V nominal. According to the > > schematic, the anodes (the ends with the arrows) are > > connected to the case and ground. Push-in diodes came both > > ways, mainly because many alternators use three of each > > inside, and they can only ground the case of three of them. > > > > You could also replace the diodes and bracket with a piece > > of aluminum heatsink material and use stud-mount diodes. > > Again, observe polarity otherwise you'll have to > > insulate the cases or the heatsink (probably not a good idea > > to have that sitting at +15V). > > > > Bob M. > > ====== > > --- On Thu, 9/18/08, kk2ed <[EMAIL PROTECTED]> wrote: > > > > > From: kk2ed <[EMAIL PROTECTED]> > > > Subject: [Repeater-Builder] Re: Micor TPN1110A power > > supply parts ID > > > To: [email protected] > > > Date: Thursday, September 18, 2008, 10:10 AM > > > The diodes CR1 and CR2 are compression-fitted style > > > rectifier diodes > > > that are pressed into a rectangle stock of aluminum, > > and > > > the aluminum > > > is then secured to the chassis via two screws. The > > diodes > > > have one > > > solder lug terminal. > > > > > > The service manual only lists the Motorola part #; no > > specs > > > or > > > industry-standard part # is given. Same on the caps. > > Only > > > spec given > > > is 27,000 uf @ 20wvdc. > > > > > > I did a quick search of Mouser and DigiKey, and was > > unable > > > to find > > > any chassis-mount style caps. Anyone find something > > > suitable that can > > > be re-secured to the ps's chassis via new rivets > > or > > > screws? I know I > > > can just solder in any cap that meets electrical > > specs, but > > > I would > > > like the caps to be secure and not have the ps become > > a > > > fire hazard > > > waiting to happen! > > > > > > The power supply was still sitting in my truck last > > night. > > > When I get > > > a break today I will take it apart further and see if > > I can > > > find a > > > part # stamped on the diodes and caps that might > > indicate > > > what the > > > real part # is. While I was at the repeater site > > yesterday > > > I thought > > > I saw a 1Nxxxx stamped on the diodes. > > > > > > I would have thought that there would have been > > someone > > > here on the > > > list that has repaired one of these supplies before, > > so > > > that is why I > > > asked. > > > > > > Eric > > > KE2D >
