RIP.... sniff-sniff. Just checked a 477 out of another parts chassis...... he's.... he's dead Jim!
I understand all that. SO, a solution occurred. Why not put them all in a box and sell them here on the forum? Surely there are a few of us that like to restore old radios - provided that your price is amenable and would be glad to relieve you of them.I have eight (maybe more) 2510's here in various states of customer didn't want to pay to have fixed.
Two are obvious , a crater in the middle of the 477
One was a modified clarifier, output of a regulator in the mezzanine to the top of the RIT and the bottom directly to ground.
Two smoked the audio chip, easy fix, replace the audio chip only to have them come back with a smoked audio chip some time later. Quoted a recap and here they sit.
One has the 477 replaced with a 455 stud mount. it was installed with base and collector reversed.
One has a dead chip, clock, regulator, who knows?
One was lighting struck, or, as hearsay goes it got tazered because the owner was a complete ass. Aside from the possible active device damage I found most of the receiver transformers open.
I have less than no interest in fixing them. I keep my several running but as they fail it's a case of diminishing returns. Do I really want to clear my bench (or dig it out of boxes even) just to spend hours with a 25 year old radio's voltage charts ? For what ? A 10, 11, 12m 30 watt multimode radio ? Keep in mind I have "several" general coverage radios with and without VHF/UHF so my opinion may differ from some.
Thanks.Say Robb... I have an original Blue dot MRF477 here that is a pull from a dead rig that shows hfe of 27 if you're interested?
As old as that beauty is you normally have to rewind the ferrite with fresh wire. If you get it back together and have issues with it those are likely the cause. I have known some guys to coat them with fingernail polish to get around rewinding them but that is hit and miss at best. That is a known problem. That and the glue on the CPU board under the voltage regulators becomes conductive and also causes problems freq. I seem to remember a delayed keying release fix as well that often needs to be done on those older radios. I think Rogerbirds site makes mention of this. I think it is just the addition of a cap to fix that.I don't normally get to work on these fine, old radios. But one came to me just the other day from a local trucker op that brings me his radios from time to time.
The amount of glue that holds the toroids in the back of the radio is daunting to remove. However, I have found that using the soldering iron will soften it up really fast and w/o damaging the board or the parts themselves. Makes removal from the board much easier. Problem is: what do I use to remove the glue from the toroid after it is out? Another problem: what kind of glue can I use to refasten it to the board that won't become conductive? Epoxy? Certainly not hot glue?!? I know; old clewing gum obtained from the bottom of a restaurant table?!?
lol . . .
Also had a problem with the heat sink getting too hot And something I have NEVER seen before: the speaker was getting so hot you couldn't keep your hand on it - and still worked!.
Turned out the MRF-477 had perished. Could it be because the person that installed it left out the mica insulator?!?
No doubt that it will need to get re capped. But there are nearly ~70 electrolytics on board. Figuring that replacing 15 caps/hour/average would mean close to/exceeding four and a half hours labor. Not to mention the fact that the cap kit will be nearly twice the price. Doesn't add up to a cheap bill. Gonna have to break the news to the customer. Guesstimate the bill will be $40 for the caps, $90 for cap replacement/labor, another $45 for a MRF-497MP (replaces the MRF-477 and can be purchased from 'RF Parts'). Then alignment will be another $50. That's 225 buckereenies w/o anything else it might yet need. If I charge for glue removal (I should); that will be another $30.
Nice old radio; but not a cheap date by any means!