The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

KC7NOA

That's ok .... its an AM radio anyways .... it works, just no display ... think i'll use it for parts ....

KC7NOA

Looks like X301 or the transistor near it ....

KC7NOA

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...

KC7NOA

Radio Make and Model: Sears Roadtalker 40 PCB Number: PLL Number: Test gear available: Symptoms: no display What is working: every thing else What has been tried: compared to another Did it suddenly happen ?: unknown Anything else that may be of help?: just looking for schematic.... or common proble...

KC7NOA

Any luck?

KC7NOA

This is an old thread ...

But just bought one with a pair of CD2545'S installed ... looks original...

Two watt drive keys 45watts ....

Probably replace the output transformer with something longer and a pair of mrf454's ...

KC7NOA

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

KC7NOA

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

KC7NOA

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 ...

KC7NOA

Hey otter ... you wrote some code for the Lincoln for picMicro?

KC7NOA

Radio Make and Model: ht2510/lincoln
PCB Number:
PLL Number:
Test gear available:
Symptoms: no lcd

What is working: lcd

What has been tried: lcd

Did it suddenly happen ?:
Anything else that may be of help?: ok, skip

Im just wondering if the HR2510 and the Lincoln used the same exact lcd?

KC7NOA

Good deal ... hope radio was cheap! !!

KC7NOA

Ok ... ill go that route .... it seemed that the thermal bias diode is.in the way big time ...

KC7NOA

If not bought new ... sounds like Rf getting into the displays Vcc .... supply voltage ....

There is an amp on that thing right? Disable the amp and see if it still does it.

KC7NOA

It is easy to add FM to most radios using a 455 KHz IF. You just need a 455 Mod-demod module which can be obtained from Spectrum Communications http://www.spectrumcomms.co.uk/cbkits.htm#FM455 If you have any trouble, obtaining one from Spectrum, let me know as I think I still have one in stock. Sti...

KC7NOA

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?

KC7NOA

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 ...

KC7NOA

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 ) ....

KC7NOA

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 m...

KC7NOA

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 me...

KC7NOA

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...

KC7NOA

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

KC7NOA

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 ...

KC7NOA

Doesn't seem like your getting much help so I'll throw my thoughts in....

I would start by bypassing the lowpass filter and inject signal to the first stage ... try to devide and conquer ...

KC7NOA

Well I just got my 2510 up and working -.. poof I smoked a Mrf497 - god im a fool ... I know darn well my match is bad around 26.965!!!

Where to get the pcb for useing an mrf455??

KC7NOA

warhorse wrote:http://rapidshare.com/files/125848670/H ... _.zip.html

2nd time lucky..

Long gone .... still somewhere??

KC7NOA

Hi, all these replies spoiling me you r'' J34 is on the main president lincoln board its a wire link that supports the rx circuit to the 1st mixer i.e. q101. like u say using a sig gen and a scope for component checking should find the fault as of yet i have not located this annoying fault with thi...

KC7NOA

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...

KC7NOA

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

KC7NOA

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?

KC7NOA

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 ...

KC7NOA

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

KC7NOA

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 ....

KC7NOA

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

KC7NOA

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 --recover...

KC7NOA

Where did you get a replacement CPU?

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