🔴 President Lincoln Repair - Processor Reset Experiments - No.887

[@sleeve8651]

Although your idea seems much more sophisticated, my display on a Uniden HR 2600 would go blank, sometimes of powering up, and sometimes just setting stationary ! Would lose ability to transmit, and functions would stop ! I read where the chassis screws can become loose over time, as they develop a poor connection to Ground ! This means pulling out the CPU to expose the hidden PCB screws that lay underneath ! After loosening and retightening them, the display came back to life ! Just thought I would throw this out for consumption ! Thanks for your interesting post ! 👍😉

[@TheDefpom]

@@sleeve8651 yeah that wasn’t the issue this had, checking screws are tight is something I do on every radio I work on as they can come loose, have found many radios with loose screws on the PCB mounts.

[@sleeve8651]

@@TheDefpom So glad you responded, as the video said 9 years ! Was the resistor the one tied to ground off the transistor to pin 56 ? I think my schematic on the HR 2600 , shows 100k ? Guess I should ask, did you just tie a 10k in series with it, or replace the larger value altogether ? Thanks !

[@TheDefpom]

@sleeve8651 sorry I don’t remember

[@fredflintstone1]

Nice find:-)

[@davidv1289]

Nice repair, Scott. An interesting problem that appears to be designed into the radio. The only concern with changing the value of the pull-up resistor would be the ability of the M51953 to sink the current when pulling the line low - it's rated at 6 mA so that shouldn't be a problem.

[@M0HKB]

Love to see more radio videos

[@hallpet45]

Nothing like a"Bug"in ya,life😊.Is that more, Patrionts..I hope so..4got too say.Thx for Freebie(DefpomCup).

[@TheDefpom]

Yeah I have Patreon setup to give a free sticker or cup after a period of time, depending upon donation level.

[@621ELECTRONICS]

Love these radios, still have a couple 2510’s and a few parts 2510 chassis. I was on your forum years ago, remember Rick’s “Test your knowledge” game on the forum for the Lincoln / HR2510? I participated in the first one trying to sort out the no transmit problem. I learned a lot from your site years ago, enjoyed it when I was big into radio! Seeing the Lincoln here made me think of that. Nice video on this.

[@TheDefpom]

The forum was certainly very popular back in the day, not so much these days, not helped by the spammers trying to constantly create accounts on there, it got so bad that I have turned off registration on it.

[@621ELECTRONICS]

@@TheDefpom Yeah I miss the days it was really active, loved browsing there. The spammers are really bad these days it seems! Great site / forum though, had gotten a lot of information there from 2004 or maybe 2005 and up until I kind of fizzled out on radio stuff maybe 5 to 8 years ago. Seen the forums slowly drop on activity through the years, all forums really, even the car audio ones which use to be really popular too, sad as I liked the forums.

[@TheDefpom]

@@621ELECTRONICS - if you decide to get rid of those parts chassis’s let me know, I’ve built a few radios out of junkers.

[@621ELECTRONICS]

@@TheDefpom Will do, but I'm a bad hoarder with things!

[@Niels.OZ3NO]

Hello And thank you for doing this video. I had the same problem so I did what you said Putting A 10 K Resistor paralle. AND Now The display is working again. But I have Another problem The Radio Will not Transmit. I have had it in my closet for 5 years. And it got the display fault while being in the closet. Do you know if the TX problem is related too the CPU Board everything els is working Prefect besides TX I can key the radio but nothing is happening Thanks in advance

[@TheDefpom]

@@Niels.OZ3NO at this age they need a full capacitor replacement, it is likely that one of the PLLs are unlocked (common issue), it is quicker to just recap the whole whole radio than try to figure out which ones are giving trouble, they will also get audio issues and other subtle issues, even with the display showing a signal constantly etc.

[@Niels.OZ3NO]

@@TheDefpom now I just have to find A service manual for my Uniden 28 30. Do I don't have to finde the valves on the Capasitators in the radio. When I am going to order them. Because It would be much easier to look in the parts list 😊

[@franciscolopez3229]

Hello sir, I have a 2510 that was made in Taiwan. May I ask sir, how do I disable the talkback, and would it be easy? If not, I'll just let it be. It's just that I get annoyed every time I transmit. Sure would appreciate it sir.

[@apollorobb]

Had this very same issue with a 2510 about 15 years ago. Same problem same solution. There was an article about this on some Ham forum years ago it apparently was a common problem. Great Video sir

[@franciscolopez3229]

Oh yes, may I add, it is off 1.3 to 1.5 KHz. I do have a frequency counter, if it is possible and safe, what do I components do I have to tweak to have it alligned? Or should I just transmit say for example at 27.556.4 instead of 27.555.0 MHz so as not mess things up with the radio. All the best.

[@IanScottJohnston]

On-the-edge design from the manufacturer....oh dear! A 100k pullup on the IC's open collector output is a bit too high IMHO and is compromising the signal via the AC coupled cap C388. Not a great pulse eh! The PNP transistor is a series pass setup with the NPN just driving it's base from the pulse. Note: C392 is the programmable delay cap on the M51953 IC. This delays the open collector output of the IC after the correct supply voltage is reached. Nominal 10nF seta a 3.4mS delay......Not sure what size you have there but I guess you could play with that delay also.

[@TheDefpom]

If the rise time improvement didn't solve the problem the next thing I was going to look at was the delay time to give the MPU more time to settle before the reset turns off, it could even be that the rise time improvement is effectively increasing the delay time, maybe next time I will play with the delay instead to see if that also works.

[@dan2226kv]

Great video, Scott! I have a couple Lincolns that have both suffered this issue in the past...always bugged me! Can I ask you the value of the parallel resistor you added? Would like to carry out this fix...

[@TheDefpom]

I think I ended up using a 10k

[@dan2226kv]

@@TheDefpom Thanks mate, appreciate it!

[@Recoils-electronics-repairs]

will have to drag my Lincoln out of the cupboard and do this mod as it has the same issue

[@videossimon4288]

I have a 2519 and the radio shack version

[@videossimon4288]

2510