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Radio Make and Model: 2510 lincoln
PCB Number:
PLL Number: 1201
Test gear available: 100mhz scope dvm mfj259
Symptoms: intermittent Tx/Rx .. no display .... bar graph recently quit

What is working: all buttons dials

What has been tried: lots of repairs ....

Did it suddenly happen ?: stolen --recovered with conex echo removed (I installed it-part reason it came to me for repair)
Anything else that may be of help?: PTT is consistent to cpu board ... have not verified pin on cpu is correct when Tx is non-fuctioning ... hope its just transistor under board that buffers cpu Tx out...

Im checking sources for any functional CPU for possible replacement ...

Still need to check D318/D322 and Q315 ...... im hoping Q315 is the real problem ...

Pull and clean every plug on the mpu pcb, also pull the display pcb and resolder it all. Especially the through holes as I have seen those fail killing the display and confusing the mpu.

If you have another radio you can pull the display pcb from it helps, as that can eliminate that as the problem.

I would suggest checking the voltage regulators on the mpu pcb and the one on the side of the chassis too.

Also remember that to confirm if the mpu is going into tx all you need to check is the tx output pin from the pcb, if that is working then you need to check the dc switching transistors on the main pcb.

I can't give you part numbers because I am away at the moment and am sitting in a field.

The display lines for the frequency have all had the connectors removed - now direct hard wired ....

Ill check the regulator on the case ... the 8v and 5v on cpu pcb checked fine ...

Can't hurt to resolder the through hole/Via's ....

Well .... must recant. The 7805 on MCU pcb is 6v at cold turn on .... how falt tolerant is the MCU to over voltage ?

Replace it, as it effects the serial communications with other device such as display and plls, I have also come across issues with the factory glue causing shorts to the traces underneath them, so it might pay to clean original glue off, and replace it.

Dang it .... it might of been ok ... with D311 in series with the ground pin ... raises output to 5.7v when using the case as a ground ...

While I'm on the subject - I still have a problem with a howl / squal when L104, L105, L114 and L115 is peaked for max sensitivity.... any one seen this?

And yet another question .... when the frequency expansion is performed ... what is the nominal voltage on pin 35/34?

KC7NOA wrote:And yet another question .... when the frequency expansion is performed ... what is the nominal voltage on pin 35/34?

Well I dug the epoxy looking stuff off of a 2510 and checked for my self ....
I was hesitant to do it, I didn't wanna cut any traces ...

The 2510 has 4.6v on the pair and my Lincoln had 2.5v. That level seems really bad to me since I'm fairly sure it'd a TTL level device ... so I dug out a 1.5K resistor and added it to the radio ... I now have 4.5v there on the Lincoln and un time ill know if it solved the random "no turn on" issue ..

Am finally home (for today anyway!) had any more progress with this radio ?

Not really ... iv noticed that when it will not Tx .... the Tx out from the MCU is not functional .... and its not actually receiving anything.. ... also display is still dead - have a line on a replacement, just no source for any possible MCU ... Really wish the guys that made the chipswitch would released the codeif their not going to make any more ...

Just dawned on me to check Y301 .... probably ok ,but ....

I got a bunch of used mcu from the guy that was doing the chip switch installations in the USA, you might be able to get some from him, you need to specify the exact mcu number you want, as there are a few variants.

If only I could remember who it is...

Think hard .... the radio shop local to me went out of business at the beginning of the last solar minimum .... they did some but everything's gone to the scrap heap years ago...

Hello, first off, KC7NOA I hope you get the radio sorted out. Wish I had the knowledge to help, but I do not.

My question is, is it possible to read the code from a Chipswitch & what would one need to do that? It would be great if someone could start making new ones.

It seems like there are quite a few people that would be interested in the Chipswitch, but have a heck of a time finding one. I know I would like to get one for one of my 2510’s. One of them already has it & I love it! I just wish I could figure out the 15 meter password system so I could open it up all the way for additional reception as I do not have anything that gets that low.

I thought there was two maybe three guys that installed chipswitch’s in the USA?

Anyway, seen the thread & thought I would post as I have always wondered what chip you would need & if the code from a chipswitch could be read to program other chips. Again, hope you get it figured out.

I would hope it was writer in C or C++ ..... then its some what easy modifying it to current production Mu's ..... the hard part would be making the first prototype pcb to fit where the old MCU is now .....

I might try to tackle this problem in the future .... MCU's with lots more power and flash memory --is and way cheaper are on the market now.

I wondered about it. I wish I had the means & the knowledge to do it as I would. Be cool if someone could, it was a nice chip for sure. And sorry for jumping in on your thread, just seen you mention about the code for the chipswitch & thought I would pop in as I have wondered about it for a few years.

KC7NOA wrote:I would hope it was writer in C or C++ ..... then its some what easy modifying it to current production Mu's ..... the hard part would be making the first prototype pcb to fit where the old MCU is now .....

I might try to tackle this problem in the future .... MCU's with lots more power and flash memory --is and way cheaper are on the market now.

Any one have an idea what serial data is sent to the PLL0305A and SM5152A from the MCU .....
Still need to also investigate what is sent to the display for frequency display ..

Hope iv found my intermittent Tx/Rx on turn on .... found a solder splash between pins 5&6 of the PLL0305A Ic .... still no display (frequency ) ....

It would pay to have a close look at the reset circuit which does a reset every time the radio is powered up, I have seen them fail to produce a sufficient reset pulse time, causing the MCU to not correctly reset.

The MCU reset pin is 49, the circuit consists of Q316, Q317, IC314 and a dozen other minor parts. if you have a diagram for it then it is all on the lower right corner of the diagram.

The easy way to test is to monitor pin 49 with a scope to see how long the reset pulse comes on for, it should be about 5V, and last about a quarter a second or more.

Ok will check that .... connector 301when pulled and reseated .....even tilted so that 13vI is pulsed usually get it going .... but its not the connector contacts .... let's hope for a short reset..

On a side note .... I seem to have lost one of the screws to the finals/driver .... any one know the size thread?

Well ... looks to be about 5v and I can't measure the pulse time .... but its long enough for me to see it ... id guess its almost 1/2 second.

Should/will pll0305a output lock be high without serial data sent to it?

Ok ....

Iv got display frequency now ... still random tx/Rx ....

The "locked" output pin of the pll030A is low during this occurance ....
but since the display shows frequency that must mean that the MCU and resonator is functioning.

Seems that pulling plug on connector 301 brings it back up -to usually on the first plug back in ... its not the contacts of the plug .... I verrified that the voltages are getting through it.
Oddly ... the reset is not triggered when its plugged back it .... need to look at the schematic to verrify that 301 is the main voltage supply.

Its been over 4 hours since I worked on it and im going by memory again...

Also
.. almost every time I touch pin 17 of the pll0305A makes it work practically every time.

Any tips on trouble shooting the PLL0305A
.. so I don't haft to hold the pcb out?

So ... might be a 2sc2814f5 on the underside of the cpu board -.. Q308.

Im getting closer ... its hard to determine what's the root cause of the intermittent oscillation...