Author Topic: President HR 2510 CPU/PLL issues  (Read 1193 times)

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Offline Robb

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President HR 2510 CPU/PLL issues
« on: February 14, 2018, 08:46:42 PM »
Howdy, Radio tech and friends!
My first post here:

Have a 2510 that won't play nice.  Radio is TXing on 26.965mhz only - regardless of the display setting.  Using the Service Manual from CB Tricks BTW.  The VCO voltage setting won't change/adjust and is stuck on 7.15v @ TP 303 regardless of the freq setting; supposed to be 6.5v @ 29.699mhz/AM.  TP 306 is supposed to read 6.200mhz @ 28mhz,l but reads ~4.9mhz and won't adjust either.  Seems that none of the adjustments are working. 

Also, where is the ground point for testing on the CPU board? Think this may be my issue testing it and the settings issues.

I've worked on a lot of Galaxy, Cobra, and other CB radios; but never on a Ham 2510.  So I am a newbee to working on this radio.  Gonna test the voltage regs next.  Replaced all of the caps already.

Anything you can toss my way to help get this one in A1 working condition is appreciated.
Thanks!

BTW - the Service Manual does NOT cover all of the adjustment points; it really is lacking in that regard.  But that is the best I can find it seems.  SAMS Photofacts doesn't have a manual for it either? <shrugs>

http://www.cbtricks.com/radios/uniden/hr_2510/graphics/uniden_hr2510_sm_pg01_pg28.pdf

Offline Robb

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Re: President HR 2510 CPU/PLL issues
« Reply #1 on: February 17, 2018, 07:47:55 PM »
Addendum:  Both voltage regs on the CPU/PLL board tested OK.  Voltage reg for the main board also checked OK.

Offline Radio Tech

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Re: President HR 2510 CPU/PLL issues
« Reply #2 on: February 19, 2018, 11:45:08 AM »
The main thing with these radios are capacitors in the CPU board. They are terrible for going leaky. Also any of that old yellow glue needs to be removed.
Buddy kc4umo

Offline Radio Tech

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Re: President HR 2510 CPU/PLL issues
« Reply #3 on: February 19, 2018, 11:45:24 AM »
BTW,
Welcome to the forum.
Buddy kc4umo

Offline Robb

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Re: President HR 2510 CPU/PLL issues
« Reply #4 on: February 20, 2018, 12:09:23 AM »
Thank you Radio Tech for your reply.  Thing is, I replaced all of the caps in the radio including the CPU board.  Even tested all of those caps and only a few were marginal and a few shorted outright on the main board (one in the final bias circuit & two audio caps). Removed the glue too.

Just cannot understand why the voltage and freq adjustments on the CPU board are non-responsive?   The volt regs all tested OK as well.  Kinda stuck w/o a clue.  Have any insights where to look next?

Thanks!

Offline Robb

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Re: President HR 2510 CPU/PLL issues
« Reply #5 on: February 22, 2018, 04:07:45 PM »
I tested the three SMD varactor diodes (D305, 306, & 307) in the voltage adjustment circuit and they all tested OK.  Here is a strage factor: I can hear a change in the static volume level in the speaker when adjusting L317; it sounds like it is working.  But the test point shows no change in voltage at all; still reads 7.15v.  Very odd; wrong ground location for the meter?  Hmmm... 

So at the other side of this equation would be the NJM3404AS or the PLL0305A at fault.  Doubt that the S042P has anything to do with what looks like a short condition in one of these other device (yes; a guess), since it is a mixer chip at the receiving end of this chain.

Going to have to test the NJM and the PLL at their pins and see if anything is amiss.  Gonna have to go with the datasheets, since the schemo doesn't show voltages/signals values.

Thoughts?

http://www.cbtricks.com/radios/uniden/hr_2510/graphics/uniden_hr2510_cpu_sch.pdf

Offline Robb

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Re: President HR 2510 CPU/PLL issues
« Reply #6 on: March 06, 2018, 02:20:02 PM »
I understand thru another source that these CPU boards have their own issues.  Is there a link to any page that has documentation?  Couldn't find anything on the net that was worthwhile or complete.

Thanks!

Offline Robb

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Re: President HR 2510 CPU/PLL issues
« Reply #7 on: March 08, 2018, 05:30:48 PM »
:hearing crickets?:

Offline Radio Tech

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Re: President HR 2510 CPU/PLL issues
« Reply #8 on: March 09, 2018, 05:51:33 PM »
Robb,
Sorry, not much time to internet here. Been so busy with work.
I do not know of any links about the cpu board.  There is not a lot of information out there on these. If I find something I will post it up for you.
Buddy kc4umo

Offline UncleBobo

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Re: President HR 2510 CPU/PLL issues
« Reply #9 on: March 09, 2018, 06:38:23 PM »
If you can get access to a working unit, swap CPU boards to make sure that is the problem area.

Offline sonoma

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Re: President HR 2510 CPU/PLL issues
« Reply #10 on: March 10, 2018, 01:15:15 AM »
have you checked out Rogerbirds site.

http://rogerbird.tripod.com/

Offline Lazarus

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Re: President HR 2510 CPU/PLL issues
« Reply #11 on: March 16, 2018, 12:59:55 AM »
IC306-1/2 (actually the b half of the chip according to the pinout) is half of a dual op-amp acting as an active loop filter (active low pass filter), its job is to take the phase error pulse train signal coming from the phase detector (A) output (pin 13) of IC301 (pll chip), and turn it into a smooth dc control voltage for the vco tank made up of D306, D307, and L317 (best i can make out, its blurry),

i highly suspect that the reason for its output being so high (as high as possible i suspect), is because of the too low freq going into the Fin pin 9 of the IC301, its putting out max voltage in an effort to raise the freq going into that pin up to where it should be,

there are many things that can go wrong in a pll system, especially one as elaborate as this one, but a maxed out loop filter voltage is almost always due to an either missing or too low Fin freq,

NOTE: the other half of IC306 is also an active loop filter for the VCO tank made up of D303, D304, and L302 (best i can make out, its even more blurry), its associated PLL chip is IC302, its associated VCO output, after being divided by 10 while going through IC303, eventually
winds up going into IC304 to be mixed with the previous PLL/VCO, then this newly down mixed signal looks to be what feeds the Fin pin of IC301, so looks like you have your work cut out for you narrowing down where the fault is,

and i just noticed, looks like the first VCO goes through yet another mixer (IC305) before being mixed with that signal, wow there's sure alot of mixing going on in this PLL system,

anyway hope that helps a little, just holler some more if you need anything further, my hope is that my giving a little detail on what things are doing will help you to narrow the problem down,

:)