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Message |
    
Dale
Advanced Member
Username: Dale
Post Number: 942
Registered: 12-2002
| | Posted on Friday, June 01, 2007 - 9:33 pm: | 
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got a used uniden grant that needs a good
tune up its set up for all dk.i looked it up
on the mods list i found the one coil but not
the other.help
dale/a.k.a.hotrod
cef426
cvc#64
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Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2543
Registered: 9-2004
| | Posted on Saturday, June 02, 2007 - 10:43 pm: |
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what PLL chip is in that radio?
is it a upd858?
or is it an MB8719?
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Dale
Advanced Member
Username: Dale
Post Number: 951
Registered: 12-2002
| | Posted on Sunday, June 03, 2007 - 7:48 am: |
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mb8719 made in philly
dale/a.k.a.hotrod
cef426
cvc#64
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Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2545
Registered: 9-2004
| | Posted on Monday, June 04, 2007 - 12:34 am: |
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great radio!
same radio as the 148gtl, although a few parts on the inside are in different places.
here is a complete, overly detailed alignment process for that chassis for someone that has never done one before.
http://www.copperelectronics.com/cgi-bin/discus4/show.cgi?tpc=34&post=113535#POST113535
might be too much info to sift through, so here is a transmitter tune up that should get you going if nothing is broken.
first, set radio to ch.19 or 20.
clarifier in center.
mic gain all the way up.
using a plastic or wooden tuning tool, turn these coils in this order while saying "ahhh" into the mic. DO NOT tune them with a silent deadkey. they must be tuned for max. MODULATED wattage.
turn them VERY slowly and carefully. make sure the tool fits snugly. (whittled down toothpicks work well for the small coils, as they will usually break before the ferrite core does.)
ok, here ya go:
L47, L48, L46, L45, L38.
set VR10 for the deadkey that you want. (about 3-4 watts is great)
adjust VR11 for max SSB power while in SSB mode and saying "ahhh" into the mic. (dont exceed 16 watts!)
VR7 is the AMC control. turn it all the way up and use the front panel control to lower modulation if need be.
BTW, if the radio has absolutely NO modulation on AM, but SSB works ok, replace TR41 with an NTE152.
or a 2N6487.
dont forget the insulator or the heatsink compound.
i have LOTS of other upgrades for this radio.
best to take these mods step by step though, so figure out what you want to do to the radio first, and we'll go from there.
best of luck,
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Airplane1
Advanced Member
Username: Airplane1
Post Number: 988
Registered: 5-2004
| | Posted on Monday, June 18, 2007 - 9:11 pm: |
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Kid_vicious, can you tell me how to tell which pll chip is in my grant xl?
also can I ask you to pm or email me the mods and other info for the grant xl?
I am getting a grant Lt that has no receive or transmit but looks great and all lights / channel display works,where whould be the first place to start to fix this problem? I paid 35 bucks for it so if it is junk I can use it for parts.
thanks,
Roger |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2556
Registered: 9-2004
| | Posted on Tuesday, June 19, 2007 - 12:32 am: |
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if its a grant XL, its the MB8719 chip. same as the 148gtl and the 2000gtl, also the same as the uniden madison. (the one with the dig. clock)
i will try to find the mods.
they are on here somewhere.
try doing a search on the forum for "2000gtl mods, or 148gtl mods" etc...
or you can do a search to find all the posts made by me in the ASK the TECH section.
ive posted them a few times, and as i learned more about the chassis, i stopped using certain ones and started using others, so you may find conflicting stories.
if and when you find them, just ask me here which ones i use.
all of the mods you will find here posted by me for this chassis have been tried by me and i like them all. just small differences.
have fun,
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Airplane1
Advanced Member
Username: Airplane1
Post Number: 989
Registered: 5-2004
| | Posted on Tuesday, June 19, 2007 - 11:16 am: |
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Thanks, I did a search and found lots of good info.
Do you know anything about and if so Can you help with the grant Lt with no rec. and transmit problem?
What to look for to diagnose it?
I hear they are good radios too.
Roger |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2558
Registered: 9-2004
| | Posted on Tuesday, June 19, 2007 - 10:54 pm: |
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sure, i can try.LOL
"no receive, no transmit" is actually a bit broad of a description to diagnose the problem.
kinda one of those, "could be this, could be that" things.
so, if you have the radio in front of you; maybe you can do a few tests to determine whats working and whats not.
radio powers up?
make sure all controls are set correctly.
sound from speaker?
tried external speaker?
tried different microphone? (use a known good one!)
using known good mic, does the RX/TX light turn from green to red when mic is keyed?
movement on S-meter when mic is keyed in AM mode?
movement on wattmeter set on lowest scale in AM mode?
radio to SSB mode. mic gain all the way up. known good mic. movement on wattmeter when saying "ahhh" into mic?
key another radio very near the grant LT.
any movement on S-meter?
any pops or hisses from speaker?
try radio in PA mode. any sound from PA speaker?
if you can run the radio through these tests, i can make a few guesses as to where to look.
happy to try to help.
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Airplane1
Advanced Member
Username: Airplane1
Post Number: 990
Registered: 5-2004
| | Posted on Wednesday, June 20, 2007 - 7:32 am: |
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thanks very much Kid_vicious,
I will do these tests and let you know what I find.
Roger |
Airplane1
Advanced Member
Username: Airplane1
Post Number: 995
Registered: 5-2004
| | Posted on Tuesday, June 26, 2007 - 8:16 pm: |
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Ok Matt,
I hooked up a known good mic, powered it up, all lights work. I have no sound at all, no needle movement at all in receive. I key mic and no meter movement or light change to show transmit. It is the same in am,LSB and USB.
It is acting the same as if there is no mic connected, you know like if you have a grant xl and unhook the mic the lights stay lit but no sound or meter movement.
the only thing I did not try is an external speaker as I dont have one right now. I will get one soon and try it.
thats what I got for now, any ideas so far?
Thanks,
Roger |
Airplane1
Advanced Member
Username: Airplane1
Post Number: 996
Registered: 5-2004
| | Posted on Tuesday, June 26, 2007 - 8:46 pm: |
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got some more info, I opened the top cover and seen a black burn mark on the inside cover, looked down on board and sloder looks a bit burnt on a spot on the board so I took off the bottom cover and speaker wires are unsoldered and the burnt piece I found looks like the small diode D44. there is also a small board with components on it wraped in foam and black tape. with a sticker saying ********** and Install Preset/ align 4/28/01.
I dont know what a preset is unless it is the board taped up inside.
Any info for me to know whats up? Is this fixable? I sure hope.
Thanks,
Roger |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2564
Registered: 9-2004
| | Posted on Wednesday, June 27, 2007 - 12:49 am: |
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i have some ideas, but no time to type now.
will post tomorrow.
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Airplane1
Advanced Member
Username: Airplane1
Post Number: 997
Registered: 5-2004
| | Posted on Wednesday, June 27, 2007 - 4:09 pm: |
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I can also post some pics of the inside in the pic area if needed to see the board and burn mark.
Roger |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2565
Registered: 9-2004
| | Posted on Wednesday, June 27, 2007 - 11:03 pm: |
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pics are always good.
the add on board has me worried.
there is no telling what it is, and whether or not it is the culprit.
also, if you remove it, the radio may still not work after being repaired, because it was tuned while the device was inline.
so, i would say, if you want this radio to work, and dont mind putting a few buck into it; you should send it to a tech.
along with the repair, you will get an alignment, which is worth its weight in gold if the tech has the right test equipment.
now, if you just want this radio to mess with and see if you can do it, then i would say, first remove whatever that board is by unsoldering all the wires from the board.
if its an echo board, you may need a schematic of the radio to put the mic wires back after removing it. (this kind of thing gets very frustrating)
by what you are telling me, it sounds as if the voltage regulator has shorted out.
its IC4 and its an MB3756. not too hard to find, but an NTE1271 will work just fine.
after replacing the voltage reg. DO NOT turn the radio on until you have also replaced D44 with an 18.2 volt zener diode, and added a 1N4001 diode from pin 1 to pin 2 on the MB3756 voltage reg.
on D44 the UNBANDED end goes to ground.
on the 1N4001 diode the BANDED end goes to pin 2, and the UNBANDED end goes to pin 1.
there still might be other problems. see, when the voltage regulator shorts out, one of the symptoms is a very high AM deadkey, like around 10 watts, with little to no modulation.
if someone were to key the radio for more than a few seconds like this, they could blow the final, the driver, and/or the AM power regulator which is TR41. also the audio amp which is next to TR41 could be blown.
remove the board, replace the voltage reg. and diodes, and try the radio.
hopefully the light is turning from green to red now when the mic is keyed, even if there is no power output.
maybe, maybe not.
now for some more bad news.
even if you replaced all the IC's and transistors ive mentioned, the radio STILL may not work at all due to being mistuned.
many a CB'er has stared at a broken radio until they feel like its their only hope to start turning coils and VR's.
i think you can see why i recommend this one go to a tech.
still, if you like a challenge, you may want to try what you can, and then send it to a tech if you cant get anywhere.
best of luck, feel free to ask any more questions you may have.
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Airplane1
Senior Member
Username: Airplane1
Post Number: 1000
Registered: 5-2004
| | Posted on Thursday, June 28, 2007 - 2:46 pm: |
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Thanks Matt, I bought it to tinker but did not know it had some thing added to inside like the board. I am looking inside right now an thinking how complicated it looks, SO, I dont know what to do. Is it worth the money for a tech to fix it, I dont know, the radio is pretty nice cosmetic wise.
I will let you know what I do, If I need anymore help I will ask.
Roger |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2566
Registered: 9-2004
| | Posted on Thursday, June 28, 2007 - 10:22 pm: |
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cool.
i would say that if you have the equipment and ability to give the radio an alignment after it is repaired, then you should go ahead and try to fix it yourself. you'd need a signal generator, a wattmeter, and a good frequency counter at the very least.
IMO that is one of the only old radios that IS worth paying to have fixed.
the parts in that radio are very sought after by the guys who build custom radios out of this chassis. (of which i am one)
if nothing else, put it aside, and get another one.
then you'll have a parts radio to fix whatever goes wrong with the new radio. (except the voltage regulator.LOL)
best of luck to ya,
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Stepchild
Intermediate Member
Username: Stepchild
Post Number: 157
Registered: 11-2002
| | Posted on Friday, June 29, 2007 - 10:42 pm: |
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Hey Kid
What kind of signal generator do you use? There aint to many people around here that work on ssb radio's so I guess I'm giong to have to learn how to do some of this myself. Also,What do I need to look for in one and were.
Stepchild
CEF-187
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Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2567
Registered: 9-2004
| | Posted on Saturday, June 30, 2007 - 8:51 pm: |
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hi stepchild.
i use a LEADER LSG-16.
not the best out there, but it serves its purpose well.
it is good enough for testing and aligning receivers, but it does not have a calibrated output, so i cant properly adjust S-meters, or squelch circuits.
luckily, these adjustments are rarely messed with, and if they are, i can get them, very, very close just using another radio.
i beleive that the best piece of test equipment that someone can invest in is a test radio.
with it, you can fake alot of things that test equipment is for.
as far as what to look for in a signal generator; well, that depends on what you want to spend.
mine cost me about 70 bucks on the internet. basically new.
to get one with a calibrated output level would probably be 300+ dollars.
the design of my LEADER LSG-16 is copied exactly by many other manufacturers, so if you can find a pic of one online; any other brand that looks the same will be about the same.
i like leader because they have been in the test equipment game for a while now.
have fun, just for fun, here is a sample alignment for the MB8719 dual conversion SSB chassis.
it will give you an overview of what a basic alignment consists of.
remember though, that every chassis is different.
http://www.copperelectronics.com/cgi-bin/discus4/show.cgi?tpc=34&post=113535#POST113535
later,
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Stepchild
Intermediate Member
Username: Stepchild
Post Number: 158
Registered: 11-2002
| | Posted on Monday, July 02, 2007 - 11:00 pm: |
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Thanks KV
Serving the purpose is all I need. I don't need anything to complicated for my little peanut shaped brain. As far as a test radio just a cheap am/ssb radio is all I need for that right? I'll do some searching around the net for one and if I can find one I'll get you to tell me how to use it! LOL !!! Thanks again
Stepchild
CEF-187
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Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2571
Registered: 9-2004
| | Posted on Wednesday, July 04, 2007 - 1:01 am: |
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cool.
the main things about a test radio are that it is aligned properly, and is in good working order.
yes, ssb is a very useful feature to have.
if it had extra channels thats good too, but not really necessary, unless the radio you are working on does.
so, the thing to do is get a decent radio, and have it aligned by a real tech.
shouldnt be more than 30-50 dollars.
then you can use this radio as a referrence. as long as you keep your hands out of it.LOL
here's a simple way to use your test radio to tune the receiver of the radio you want to work on.
you need a dummy load for the test radio.
you can make your own.
hook the dummy load to the test radio, and put it in another room.
put the mic next to a TV set tuned to "snow". this will give you some white noise to modulate with.
key the mic with a rubber band. make sure that the test radio is on the same channel as the one you are working on.
now go to the radio you are working on, and look at the S meter.
if the reading is any higher than S-5, you'll have to decrease the wattage on the test radio or move it further away.
as you can see, you now have a steady signal with which to tune your receiver.
later,
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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