Search found 433 matches

by The Defpom
Wednesday 9th Mar 2011, 19:36
Forum: CB Radio Repair and Troubleshooting
Topic: President Lincoln control buttons not working
Replies: 9
Views: 15386

Re: President Lincoln control buttons not working

I should drop in here more often by the looks ! I wish I wasn't so busy with other things, anyway. One thing to try, as weird as it will sound, is swap out the LCD PCB, I have seen instances where a faulty LCD PCB has caused the MPU to appear to be faulty, it is a long shot, but an easy thing to rul...
by The Defpom
Thursday 9th Dec 2010, 22:14
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 2000 stuck in tx
Replies: 2
Views: 5356

Re: Cobra 2000 stuck in tx

Hi,
there are 3 possible causes, listed in likelyhood of failure.

C33 (10uF 16V), TR35 (2SC945), IC4 (MB3756)
by The Defpom
Thursday 9th Dec 2010, 7:46
Forum: Tips and forum usage
Topic: Picture Posting Problem?
Replies: 1
Views: 5600

Re: Picture Posting Problem?

The forum handles images differently, if it is a very large image the forum will link to it instead of displaying it on the page. There is also a button shown under the image name after you have "added" it to "place inline", if you want to have it display on the page then you nee...
by The Defpom
Thursday 9th Dec 2010, 7:30
Forum: CB Radio Repair and Troubleshooting
Topic: Emperor TS-5010 CPU Info
Replies: 1
Views: 5168

Re: Emperor TS-5010 CPU Info

The large IC is not the PLL, it is an MPU, which controls TWO PLL's, along with many of the radios functions, such as the display etc. There are differences between the MPU programs, and this includes the functions of its pinouts. Personally I would just keep the 2510 working, electronically they ar...
by The Defpom
Thursday 8th Jul 2010, 23:28
Forum: Wanted !
Topic: Christchurch NZ stuff wanted
Replies: 3
Views: 8865

Re: Christchurch NZ stuff wanted

I can do radio work via post if you cannot locate anyone down there that knows what they are doing, to be honest, I do not actually know of anyone else apart from me that works on AM/SSB CB's in NZ. As far as getting CB items in NZ, that can be hard, if I need anything I import it from the US or UK ...
by The Defpom
Monday 5th Jul 2010, 11:03
Forum: RadioMods Members Assistance
Topic: Different repeatershift on Kenwoord TM-741 ??
Replies: 1
Views: 5733

Re: Different repeatershift on Kenwoord TM-741 ??

HI,
Sorry, I know little about HAM equipment, all the ham information on the site is what I had collected from other sites and people over the years, I did not write those bits I'm afraid.
by The Defpom
Monday 5th Jul 2010, 1:57
Forum: CB Radio Repair and Troubleshooting
Topic: need help from the 148 gtl experts.???
Replies: 7
Views: 9477

Re: need help from the 148 gtl experts.???

That sounds fine at that point.
by The Defpom
Monday 5th Jul 2010, 0:18
Forum: CB Radio Repair and Troubleshooting
Topic: need help from the 148 gtl experts.???
Replies: 7
Views: 9477

Re: need help from the 148 gtl experts.???

Check the voltage drop across R111 (tell us the voltage on both sides of it, in TX and RX), I have come across issues on this and similar chassis where a capacitor is loading down the DC supply causing a large voltage drop across that resistor, it sounds similar.
by The Defpom
Sunday 4th Jul 2010, 22:38
Forum: CB Radio Modifications
Topic: converting Aussie to NZ am cbs, help please
Replies: 9
Views: 13205

Re: converting Aussie to NZ am cbs, help please

What I have done is move the 10.24MHz xtal to the PLL, break the tripled 5.12MHz output, add a crystal for NZ and then modify the oscillator to allow it to work 4MHz higher for the new crystal. the tricky bit is that sometimes this can load the oscillator when on SSB and the clarifier is turned full...
by The Defpom
Sunday 4th Jul 2010, 22:23
Forum: CB Radio Modifications
Topic: converting Aussie to NZ am cbs, help please
Replies: 9
Views: 13205

Re: converting Aussie to NZ am cbs, help please

I have converted AX144 for NZ channels before, it is a bit involved, but can be done by modifying the current circuitry's design and adding a few parts, realistically it can be tricky to get working properly sometimes, which can take a lot of time to convince it to work properly on all modes, as one...
by The Defpom
Wednesday 30th Jun 2010, 8:12
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 77836

Re: Ham Jumbo MK1 - No Swing AM

I would suggest upgrading the Zener, you can use any 10V Zener, but I suggest you get a 5W version, which is less likely to fail again.
by The Defpom
Tuesday 29th Jun 2010, 23:17
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 77836

Re: Ham Jumbo MK1 - No Swing AM

lbcomms posted whilst I was... Definitely worth checking the AVR to confirm it is operating correctly, I have replaced that circuit with a 7809 without any problems (I did add a 220uF 16V Electrolytic cap to it as well to ensure it had good smoothing, just a part I had a lot of, a smaller value woul...
by The Defpom
Tuesday 29th Jun 2010, 23:14
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 77836

Re: Ham Jumbo MK1 - No Swing AM

I am trying to see how pin 6 can be fed with 11V, as it passes through the band switch and returns to the VCO via the VR1/VR2 trimmers, so I am suspecting that there may be a short on the band switch wiring. (unless my diagram is a bit dodgy and is not showing a connection, which I suspect may be th...
by The Defpom
Tuesday 29th Jun 2010, 11:54
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 77836

Re: Ham Jumbo MK1 - No Swing AM

What are the voltages of all the pins on that IC (mid band ch 19).
by The Defpom
Tuesday 29th Jun 2010, 10:03
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 77836

Re: Ham Jumbo MK1 - No Swing AM

There is a Zener diode on that PCB, marked on the diagram as MZ205 (next to C5), it would pay to check that it is OK.
by The Defpom
Monday 28th Jun 2010, 12:09
Forum: CB Radio Modifications
Topic: Board in my old Courier Spartan PLL 40CH
Replies: 2
Views: 5582

Re: Board in my old Courier Spartan PLL 40CH

I think that I only have one set of diagrams for a spartan, I do not know if it is the same as yours, as they do not have the PCB number marked, but it is for a uPD858 PLL, so it may be the same one. According to the diagram AM power is VR6, so if that matches up then it will likely be the right dia...
by The Defpom
Saturday 19th Jun 2010, 11:38
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 77836

Re: Ham Jumbo MK1 - No Swing AM

Thank you very much Sue, that will definitely come in handy !
by The Defpom
Friday 18th Jun 2010, 8:35
Forum: CB Radio Modifications
Topic: Nato FM
Replies: 1
Views: 4342

Re: Nato FM

If you are meaning the Nato 2000 FM then that information is on the website:
http://www.radiomods.co.nz/pcma001salign.html
by The Defpom
Tuesday 15th Jun 2010, 8:21
Forum: CB Radio Repair and Troubleshooting
Topic: President lincoln display/audio fault
Replies: 26
Views: 31195

Re: President lincoln display/audio fault

Hi, What did you find to fix the display ? If there is no audio in all modes then it is something to do with the last signal or amp stages. If you have a RX signal with no audio then at a guess the squelch amp may be shorted out, check IC101 (NJM2902) on the main PCB slightly right of center towards...
by The Defpom
Sunday 13th Jun 2010, 20:23
Forum: CB Radio Repair and Troubleshooting
Topic: President lincoln display/audio fault
Replies: 26
Views: 31195

Re: President lincoln display/audio fault

The MPU PCB is a complex thing, without suitable test gear you stand no chance of locating the fault, at the very least you would need to determine what is working correctly on the PCB (if anything), you need to check the frequencies and control signals of the VCO's, and also the digital waveforms c...
by The Defpom
Sunday 13th Jun 2010, 10:25
Forum: CB Radio Modifications
Topic: K40 microphone
Replies: 7
Views: 14056

Re: K40 microphone

Hi, the upload limit for a post is set to 5MB, so you may be able to post it in another message, would be helpful for people to see it here.
by The Defpom
Sunday 13th Jun 2010, 0:11
Forum: CB Radio Repair and Troubleshooting
Topic: Replace MB8719 with MC145106
Replies: 4
Views: 10458

Re: Replace MB8719 with MC145106

I believe (although I have never tried) that you cannot replace an MB8719 with a MC145106, as they have a different PD output, one is reversed from the other.

You can replace the MB8719 with an RCI8719-99, which can be obtained from various places online.
by The Defpom
Monday 7th Jun 2010, 11:06
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 77836

Re: Ham Jumbo MK1 - No Swing AM

The Cybernet chassis (which the Jumbo is) is known for having poor AM power, I have come across many radios that could not do 4W on AM because of the audio problem, in reality your probably best to just set the AM power at 2.5-3W so that you have some swing on AM, if you need more power just drop a ...
by The Defpom
Sunday 6th Jun 2010, 11:34
Forum: CB Radio Repair and Troubleshooting
Topic: HMV Roadhound TX77 Repair
Replies: 3
Views: 6427

Re: HMV Roadhound TX77 Repair

Check TP1 first, if the voltage is at one extreme (close to 0V or 5V) all of the time then the PLL is trying to compensate for the frequency being incorrect, if the voltage is 0V the first thing you should do it try replacing C3, C4 and C5 (they smooth out the voltage feeding the VCO), if one has sh...
by The Defpom
Sunday 6th Jun 2010, 11:13
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 25ltd st
Replies: 2
Views: 5522

Re: Cobra 25ltd st

L20 is the 54MHz filter, it is tuned to limit RF output on 54MHz (1st harmonic), you need a spectrum analyser to adjust it properly.

Your probably best to just adjust it back to about 3/4 (towards the top), that should at least be approximately correct, certainly closer than where it is now.
by The Defpom
Sunday 6th Jun 2010, 11:01
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo Alignment Problem
Replies: 4
Views: 10352

Re: Ham Jumbo Alignment Problem

If it were me, I would undo everything and return it to original first (apart from the EPROM board), and then go from there, possibly re-modding anything that is needed.
by The Defpom
Sunday 6th Jun 2010, 0:18
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 148-GTL issues
Replies: 7
Views: 9429

Re: Cobra 148-GTL issues

Hi, You would still need to align the radio after the conversion to AU, not only the frequencies, but you would also need to align the TX and RX sections as well, as they will likely be tuned for best performance on NZ. You would need a 7 digit frequency counter to correctly align the frequencies, i...
by The Defpom
Saturday 5th Jun 2010, 23:54
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 148-GTL issues
Replies: 7
Views: 9429

Re: Cobra 148-GTL issues

That is funny, I get people giving me Cobra 148's to convert from 27 to 26MHz, it almost seems a waste to convert one back ! Basically the NZ mod involves changing a crystal (X3) to drop the radio down by 635KHz (from 11.325MHz to 11.1125MHz) , however, once that crystal has been changed, all you ne...
by The Defpom
Saturday 5th Jun 2010, 23:35
Forum: CB Radio Repair and Troubleshooting
Topic: President lincoln display/audio fault
Replies: 26
Views: 31195

Re: President lincoln display/audio fault

There should not be a connection from the MPU (the large chip) to the speaker, are you sure it is soldered, and the wire has not just come off and lodged between a couple of pins ? Lincolns can be hard to troubleshoot, I have repaired many of them, it usually requires a frequency counter and oscillo...
by The Defpom
Tuesday 27th Apr 2010, 15:47
Forum: CB Radio Modifications
Topic: Adding TX/RX LED to Lincoln
Replies: 7
Views: 15818

Re: Adding TX/RX LED to Lincoln

You could just use a flip flop type transistor switch pair, and feed that directly from the mic TX line, which is 0V when in TX, nice and simple. Yes there are points you could connect to, in order to pick up the RX and TX only voltages, off hand I cant name them, but there is a PNP switching transi...
by The Defpom
Saturday 20th Mar 2010, 20:45
Forum: CB Radio General
Topic: Kudos - Dave Zodiac
Replies: 6
Views: 11528

Re: Kudos - Dave Zodiac

here here!
by The Defpom
Monday 8th Mar 2010, 7:49
Forum: CB Radio Modifications
Topic: MC145151 PLL
Replies: 15
Views: 22808

Re: MC145151 PLL

Hi Dave, Hopefully we can get to the bottom of it. Pin 28 should be connected to 0V through a 220pF ceramic cap to help load down the LD output (minor detail) You have the 8V and 0V markings back to front on pins 2 and 3, pin 2 is 0V, pin 3 is 8V. For 10KHz spacing you want RA0 and RA1 to be low, an...
by The Defpom
Sunday 7th Mar 2010, 9:13
Forum: CB Radio Modifications
Topic: MC145151 PLL
Replies: 15
Views: 22808

Re: MC145151 PLL

Hi Dave, I have used that PLL with an EPROM, only I moved all the inputs over by 1 bit, and set it for 5KHz steps, then the lowest bit can be manually switched to give a 5KHz shift. It is a very versatile PLL, and is able to be configured for many different situations, negative and positive going PD...
by The Defpom
Saturday 6th Mar 2010, 8:55
Forum: CB Radio Repair and Troubleshooting
Topic: Midland 76-900 internal PSU fault
Replies: 6
Views: 8821

Re: Midland 76-900 internal PSU fault

The usual culprit that dies in that power supply is the main current regulator, Q201, sometimes I have found the Zener diode dead (ZD1, ZD2), or Q1. To answer your question, you could use a different diode there OK, as long as they can handle the current they will be OK, as the voltage is low anyway...
by The Defpom
Friday 5th Mar 2010, 14:12
Forum: CB Radio Repair and Troubleshooting
Topic: Galaxy 98vhp deadkey 250 watts on ssb???
Replies: 9
Views: 12954

Re: Galaxy 98vhp deadkey 250 watts on ssb???

Good to hear that you found the fault.
by The Defpom
Thursday 4th Mar 2010, 10:39
Forum: CB Radio Repair and Troubleshooting
Topic: Galaxy 98vhp deadkey 250 watts on ssb???
Replies: 9
Views: 12954

Re: Galaxy 98vhp deadkey 250 watts on ssb???

Then it is likely to be something around the BM, I would start by checking the power supplies and switching, Q34 does the switching, it may be leaky so it is not switching off properly, also check C149, C144, C146, C145 after that you will just have to check each resistor around the IC, R172, R174, ...
by The Defpom
Wednesday 3rd Mar 2010, 11:08
Forum: CB Radio Repair and Troubleshooting
Topic: Galaxy 98vhp deadkey 250 watts on ssb???
Replies: 9
Views: 12954

Re: Galaxy 98vhp deadkey 250 watts on ssb???

I would be looking at the balanced modulator first (IC6), to make sure that it is filtering out the sidebands and only providing an audio carrier, and then go from there.
by The Defpom
Friday 19th Feb 2010, 22:08
Forum: Scanners
Topic: pro 2006
Replies: 7
Views: 43157

Re: pro 2006

I know this is an old thread but in case anyone finds it searching for the same symptoms, I found the cure. Simply replace the batteries, then RESET to Factory Defaults - Both Realistic Pro's I've owned are reset by holding the 2 and 9 buttons down then turn on - you will lose all stored frequencie...
by The Defpom
Friday 19th Feb 2010, 22:03
Forum: CB Radio Alignments
Topic: SWR meter
Replies: 1
Views: 6093

Re: SWR meter

It is not really needed, FS stands for Field Strength, it is used to check the radiation pattern of the antenna, I have never used one, and am not really sure it is of much use anyway, personally I think it was just a bit of a gimmick.
by The Defpom
Thursday 18th Feb 2010, 7:17
Forum: CB Radio General
Topic: Am I slowly killing my radio?
Replies: 2
Views: 7439

Re: Am I slowly killing my radio?

Mag mounts are not ideal, as they are really meant for temporary installations, or ones that require the antenna to be removed frequenctly (such as places that have low height access etc. that said, as long as they are tuned then it will work just fine, it wont be a performer, but it will work. You ...
by The Defpom
Saturday 13th Feb 2010, 23:39
Forum: CB Radio Repair and Troubleshooting
Topic: SUPERSTAR 360FM EPROM
Replies: 38
Views: 46662

Re: SUPERSTAR 360FM EPROM

You will just have to adjust it and watch the voltage, like I said in my earlier post, aim for about 7V on the highest channel the radio has got, and check that you have at least 1V on the lowest channel the radio has got. The slug could need to be turned either way, as it depends on where it is set...
by The Defpom
Saturday 13th Feb 2010, 15:52
Forum: CB Radio General
Topic: Sound Module Pre-Keyup info required Please.
Replies: 9
Views: 17405

Re: Sound Module Pre-Keyup info required Please.

0V, zero volts, the earth trace.
by The Defpom
Saturday 13th Feb 2010, 15:35
Forum: CB Radio General
Topic: Sound Module Pre-Keyup info required Please.
Replies: 9
Views: 17405

Re: Sound Module Pre-Keyup info required Please.

It may be possible, but it would require that the switch design currently uses the 0V line, the only way to know for sure would be to open up the unit and see if one of the wires goes to the 0V trace inside it, if it does then you could connect the other wire to the TX line and see if that does the ...
by The Defpom
Saturday 13th Feb 2010, 13:50
Forum: CB Radio General
Topic: Sound Module Pre-Keyup info required Please.
Replies: 9
Views: 17405

Re: Sound Module Pre-Keyup info required Please.

The switch may need to be replaced using ONLY the wire connections provided, using another source of supply may damage the unit, or the radio, it is best to keep them completely separated from the radio wiring unless it can be clearly seen that one wire is just the 0V rail. The other three wires are...
by The Defpom
Saturday 13th Feb 2010, 11:57
Forum: CB Radio Repair and Troubleshooting
Topic: SUPERSTAR 360FM EPROM
Replies: 38
Views: 46662

Re: SUPERSTAR 360FM EPROM

Yep, you need to adjust it, make sure you use the correct size screwdriver to avoid breaking the core.

Monitor the voltage on CH40 and adjust the VCO until it reads 7V, then recheck on CH1 of the lowest band to make sure you have at least 1V there.
by The Defpom
Saturday 13th Feb 2010, 10:13
Forum: CB Radio General
Topic: Sound Module Pre-Keyup info required Please.
Replies: 9
Views: 17405

Re: Sound Module Pre-Keyup info required Please.

You didn't exactly wait very long... 11 hours is hardly enough time to expect a response, maybe people were asleep, or at work, or out. In my case I was fixing a radio, then a I went to sleep... My guess for your requirment would be to make a small relay switching circuit, to replace the push button...
by The Defpom
Saturday 13th Feb 2010, 9:55
Forum: CB Radio Repair and Troubleshooting
Topic: SUPERSTAR 360FM EPROM
Replies: 38
Views: 46662

Re: SUPERSTAR 360FM EPROM

The easiest way is to just pick it out with a small screwdriver, put it to one side, once adjusted, put it back in a remelt it.
by The Defpom
Sunday 7th Feb 2010, 23:47
Forum: CB Radio Repair and Troubleshooting
Topic: SUPERSTAR 360FM EPROM
Replies: 38
Views: 46662

Re: SUPERSTAR 360FM EPROM

I would actually say to check the voltage at TP2, watch it when you go from CH10 through to CH40 on the UK band, and see if the voltage stops changing once you get to the channels which are not working, the voltage you see is used to control the VCO frequency, and comes from the PLL, it can only pro...
by The Defpom
Saturday 30th Jan 2010, 14:16
Forum: CB Radio Modifications
Topic: new cobra 25/channel mods?
Replies: 7
Views: 10307

Re: new cobra 25/channel mods?

Yes, he has authored a few books, and service manuals.

For more info about the mixer, if he still has it on his site, go to :http://www.cbcintl.com
by The Defpom
Saturday 30th Jan 2010, 9:14
Forum: CB Radio Modifications
Topic: new cobra 25/channel mods?
Replies: 7
Views: 10307

Re: new cobra 25/channel mods?

The PLL generates different internal N codes for its frequency divider between TX and RX, so the board to replace the PLL must do the same. Lou Franklin designed a mixer circuit which switches the radio from low side to high side injection (or vice versa), and allowed a conversion my by mixing in a ...