Superstar 3900 problem

[Robb]

Put the rig into the AM mode. Scope the output (pin 7) of the AN612. It should show a carrier of about 1 vp-p. Check the voltage on pin 1 of the AN612. It should be about 1.3vdc. Switch to ssb mode. The voltage on pin 1 should now be approx 2.8vdc, and there should be no carrier at pin 7. If there is a carrier but at a reduced level, it should be completely suppressed by adjusting the balance VR. If the balance VR has no effect, check the continuity from pin 5 to the VR, from the VR to Ground, and from VR to pin 1. If these check OK ... chances are the AN612 is bad.

When I tested the AN612 (see post #42), the pin #7 voltage of IC3 was 6v instead of the 4v that the voltage chart gave:
http://www.m0ysu.com/SS_360FM___Cobra_148GTL_DX.bmp

I am going to replace it and see what happens. I ordered a AN612 from RF Parts in San Diego CA for $4 plus shipping (bought some other parts too; as there is a $25/min when ordering).

I noticed that VR7 had a couple of bad traces on the board from previous soldering/desoldering. Those traces are OK now; but the AM carrier on SSB still exists. Hmmmm; seems that this particular radio had a problem in this area once before. Are there any circumstances that would help to mediate the failure of the IC3/AN612?

Seems that the previous owner of this radio swapped out the R174 & R187 (10k resistors) for 1k resistors (they look like 1/2w resistors too; not 1/4w resistors as the scheme calls for). These parts are found in the Mic Preamp/IC4 circuit. No doubt they were replaced for the purpose of boosting the audio/modulation output higher. Could this mod have contributed to the failure of the IC3/AN612 by over-driving it? As the scheme shows, the mic audio IC and the AN612 are tied together. Gonna replace these 1k 1/2w resistors with 5.6k 1/4w resistors. In this way, I hope this resistor choice will allow for some modulation boost w/o hitting the AN612 too hard. Thoughts?

 

[Robb]

Found the fault with the 4w carrier on SSB . . .

I replaced the AN612. But that didn't do it.

Turns out that the VR7 trimmer pot/10k was warped. In its location, it is very crowded and has no real room to sit flush against the board. There is a capacitor there that it jams up next to. Perhaps that board wasn't engineered as well as it could have been.

I had taken that pot out before and tested it and it was fine. But back on the board, it was being warped (because of that capacitor) and did not allow the wiper to fully contact the resistance material on the pot. I put another pot in and didn't force it to the board - as I did before - before soldering it in place. It worked and adjusted properly.

Well; I now have a spare AN612 IC in my parts bin if I need it for another radio in the future. It is used in most of the SSB Uniden chassis as well, so it will be fine as a spare. I can now give this radio back to its owner. Hope another "whack-a-mole" doesn't pop up again . . .

Learned a bunch; and I thank God I fixed it for the owner!



In the mean time, I bought a SuperStar 3900 radio on eBay for $65. It was a real dirt bag. The owner sold it for cheap because the receive sounded really bad and control pots were pretty rough - like the rest of the radio was.

Turns out that the speaker was shot. Replaced it and no more rough receive. Cleaned all of the pots on the front panel with some pot cleaner and they are fine. Had to put a bulb in the meter - as well as fix the meter too. It was locked up. Replaced the receive diodes with some Schottky diodes and then gave the radio a full and much-needed alignment. Used a lot of elbow grease to clean this dirty little bugger up too. The previous owner had the modulation limiter removed and a resistor was cut to maximize output on AM. Didn't want that! So I put in another transistor and re-soldered the clipped resistor. SSB and AM are both xlnt now. In addition, I also unlocked the fine clarifier control before alignment.

It is a real gem now, and a fine performer too.

 

[jazzsinger]

Found the fault with the 4w carrier on SSB . . .

In the mean time, I bought a SuperStar 3900 radio on eBay for $65. It was a real dirt bag.

your a glutton for punishment Robb, pmsl.

It is a real gem now, and a fine performer too.

they certainly work well when you spend a bit of time on them, i've got a 3900 and a 3900 eghp (reminds me of all you guys over the pond , need to get that astatic flag mike for it for maximum U.S.A bling) and quite honestly despite having many other so called better radios (several jacksons,lincolns,grants,706,ts50 etc) over the past 12 years or so since i came back on radio, i would say the humble ss3900 has been the best workhorse of them all and its still taking a beating, they rarely let you down when run within their limitations, pound for pound i doubt you'll find a better value radio anywhere, except maybe a good condition pb010 chassis if you get it at a sensible price

if it wasn't for the ss3900 and its uniden pb010 predecessor i doubt 11m would be half the band it is/was. it allows worldwide contacts with a modest set-up at a price most people can afford. they are simplicity to use with very few useless gimmicks, they hold their resale value surprisingly well too. for a beginner or someone who doesn't want to f@ck up their pride and joy taking it in and out of vehicles, its ideal.

 

[Robb]

your a glutton for punishment Robb, pmsl.

George, I really am trying very hard to learn how radios work.
I wouldn't call it 'gluttonous' though; howabout saying 'earnestly'?

they certainly work well when you spend a bit of time on them, i've got a 3900 and a 3900 eghp (reminds me of all you guys over the pond , need to get that astatic flag mike for it for maximum U.S.A bling) and quite honestly despite having many other so called better radios (several jacksons,lincolns,grants,706,ts50 etc) over the past 12 years or so since i came back on radio, i would say the humble ss3900 has been the best workhorse of them all and its still taking a beating, they rarely let you down when run within their limitations, pound for pound i doubt you'll find a better value radio anywhere, except maybe a good condition pb010 chassis if you get it at a sensible price

if it wasn't for the ss3900 and its uniden pb010 predecessor i doubt 11m would be half the band it is/was. it allows worldwide contacts with a modest set-up at a price most people can afford. they are simplicity to use with very few useless gimmicks, they hold their resale value surprisingly well too. for a beginner or someone who doesn't want to f@ck up their pride and joy taking it in and out of vehicles, its ideal.

I run a Galaxy DX 99V in my mobile for the last three years, and I think it is a fine radio. Same basic chassis as the 3900 - just with more bells and whistles.

Two days after I bought that SS 3900 from eBay and got it all spruced up, I tried it on .555 with the beam antenna. Talked to more than a few stations in the UK, France, Austria, Denmark, and even got a station on Corsica. Not bad for a barefoot radio with decent skip conditions from the West Coast/California (just 18w on SSB). Got decent reports - too.

West coast of Scotland was in this morning as well; you should have been on George!

 

[Zman]

i like mine!

 

[jazzsinger]

George, I really am trying very hard to learn how radios work.
I wouldn't call it 'gluttonous' though; howabout saying 'earnestly'?


I run a Galaxy DX 99V in my mobile for the last three years, and I think it is a fine radio. Same basic chassis as the 3900 - just with more bells and whistles.

Two days after I bought that SS 3900 from eBay and got it all spruced up, I tried it on .555 with the beam antenna. Talked to more than a few stations in the UK, France, Austria, Denmark, and even got a station on Corsica. Not bad for a barefoot radio with decent skip conditions from the West Coast/California (just 18w on SSB). Got decent reports - too.

West coast of Scotland was in this morning as well; you should have been on George!

not long moved house Robb, haven't got round to setting up an antenna, still doing it up, haven't been out mobile in ages.

the ept3600 chassis ain't perfect by any stretch of the imagination, much like the uniden pb010 it was cloned from, but underrate them at your peril, its nice owning 100w hf sets, but if you just want the job done on 11m then a 3900 and a kl203 will sound nearly as good as any hf set,unless your actually talking to somebody who can actually hear subtle audio differences (bob85 or .00000000000001 % of the radio world) then i doubt anyone would even notice.

if you/know someone who can align your radios then they are one of the best buys you'll ever make. once aligned (factory alignment is generally poor) they do the job, its that simple.

infact if it wasn't for being bored out shopping one day back in 2000 and picking up a radio magazine for a browse (the first time in 15 years) and seeing a 6 band cobra 148 gtl dx (crt ss3900) lookalike openly on sale in the republic of ireland and only a visa card and phone call away from satisfying my curiosity i might never have came back to radio. it arrived weeks later.

back in the good old days my favourite weapon was a modified 4 band cobra 148 gtl dx that could drop to super lows and opened up 26.285 for me, my favourite hunting ground, how could i not be curious at a six band off the shelf model that also had the bleep switchable and +10 khz as standard, both mods i'd have performed as necessity on 148's back in the early 80's here in the uk, bleep switchable meant no-one knowing what illegal radio you were using whilst on the legal uk40, and +10khz to let you access the channel skips as even with 120 or 160 channels it was very crowded in my city back then.

ironically a 3 ch radio would suffice here these days.

 

[Robb]

Oh yeah George, I do all of my own alignments. I have/use some decent gear to this end. I found that learning to align the receive on the ept3600xxx chassis was a bit different than a Cobra 148 . . .

First of all, I start the receive alignment on this chassis by turning the core slug of L7 all of the way to the bottom - and then turning it one full turn up. From there, I tune L6, L7, - and so on - in AM mode. This method will keep the receive meter from 'ghosting'. As you well know, ghosting is a false meter reading. On SSB mode, the meter will show a strong signal with no signals present - even at night. This is a result of an improperly aligned receive. IF L7 is adjusted the way I metioned - with L7 just one turn from the bottom of that coil first - and then moved/adjusted no more than one more turn upwards during the alignment, the results are xlnt. No more than two and a half turns from the bottom - tops! No ghosting on the receive meter and a clear signal with little static noise if this method is used.

In addition, I use a germanium diode/1N60P instead of a 1N4148 at D12. As you know, these diodes have a lower turn-on voltage and allows the receive meter to be far more accurate and quite a bit more linear as well. I use the 1N6263 Schottky diode mod in D1 and D2 and first take out the 1N60P's that are in that position. I then take one of these removed 1N60P's and pop it into the D12 position and then re-align the receive meter. Simply by recycling that one part, the radio meter works better. More response and a more accurate reading.

Another useful mod for this chassis is shortening the leads of C47 thru C50 - IIRC. If the leads to these caps aren't as short as you can make them; they can and will pick up excess static in the receive. Not a huge difference; but some.

Same goes for TR17; the first receive transistor.

These are a few tricks that I learned about this chassis along the way.

But I'm sure you know this already, as you have been doing this far longer than me!
All the best, George.

 

[jazzsinger]

Oh yeah George, I do all of my own alignments. I have/use some decent gear to this end. I found that learning to align the receive on the ept3600xxx chassis was a bit different than a Cobra 148 . . .

First of all, I start the receive alignment on this chassis by turning the core slug of L7 all of the way to the bottom - and then turning it one full turn up. From there, I tune L6, L7, - and so on - in AM mode. This method will keep the receive meter from 'ghosting'. As you well know, ghosting is a false meter reading. On SSB mode, the meter will show a strong signal with no signals present - even at night. This is a result of an improperly aligned receive. IF L7 is adjusted the way I metioned - with L7 just one turn from the bottom of that coil first - and then moved/adjusted no more than one more turn upwards during the alignment, the results are xlnt. No more than two and a half turns from the bottom - tops! No ghosting on the receive meter and a clear signal with little static noise if this method is used.

In addition, I use a germanium diode/1N60P instead of a 1N4148 at D12. As you know, these diodes have a lower turn-on voltage and allows the receive meter to be far more accurate and quite a bit more linear as well. I use the 1N6263 Schottky diode mod in D1 and D2 and first take out the 1N60P's that are in that position. I then take one of these removed 1N60P's and pop it into the D12 position and then re-align the receive meter. Simply by recycling that one part, the radio meter works better. More response and a more accurate reading.

Another useful mod for this chassis is shortening the leads of C47 thru C50 - IIRC. If the leads to these caps aren't as short as you can make them; they can and will pick up excess static in the receive. Not a huge difference; but some.

Same goes for TR17; the first receive transistor.

These are a few tricks that I learned about this chassis along the way.

But I'm sure you know this already, as you have been doing this far longer than me!
All the best, George.

Ghosting, rotflmao, a word with many meanings Robb
Urban Dictionary: ghosting

the first in that link being my particular favourite

yeah its a good chassis, can be tweaked here and there if your into perfection, i gave up seeking that out a long time ago, i'm happy if i can talk skip these days, which even a standard realigned 3900 will do well, only thing i add is a sirio antenna and an amp, as long as i've got 80-150w i'm happy i'll work anywhere in half decent conditions.

one thing i learned a very long time back is your equipment counts for about 20% of your success rate whilst dx'ing, the other 80% in my experience comes from confidence in your voice and belief in your equipment. if you don't believe me get a local cb'er who has never or seldom dx'ed before to use your equipment,

i guarantee he lacks your success, the reason is very simple, you see it everywhere, people naturally avoid monotoned, nervous, scared, boring, those struggling with foreign language, those who go on and on, etc voices. most people listen before they join a conversation and will pick up on these things, its human nature to take the easy option.

i bet you do them all yourself, lol, even if subconciously.

tell me you don't, the next time an oversplattering Italian calls you with shite English,pmsl. in that situation i'm off faster than a whores knickers at a gang bang, just like most folk.

i'm just too old in the tooth these days too be dicking around with soldering irons for a small percentage of 20%, f@ck i grudge getting the iron out for essential jobs nowadays,

 

[Robb]

Yeah; surprising how slang works. Ya gotta be careful what words you use or someone could take it the wrong way - lol!

That word was 'coined' by the techs at Galaxy radio to describe the condition.

Sure hope you get your station up and running while we still have some decent conditions. Wanna get you in the logbook here. Been getting a lot of Ireland, N.Ireland, Scotland, Wales, and England the last few days. Catch me on .555 if you can.

Going to be getting another radio similar to the Superstar 3900. Bought it from a forum member here. It is the Superstar 360FM. In addition, it has some serious issues too. The symptoms are that it has no TX or RX.

 

[jazzsinger]

you can't whack the ss360fm, i have 2 very similar president richards. those and my 3900's are the only radios i use outside grant,lincoln and jacksons. i like reliability.

no rx/tx on the ss360fm can be as simple as the chassis screws aint tight enough, although many other things could cause it too, once you get hold of it you'll have a better idea of the cause. first thing i'd check is the 2sa473 regulator.

when up and running they are hard to beat.

yeah slang can easily be misinterpreted, ie, fanny on your side of the pond is the exact opposite that it is here.

 

[Robb]

you can't whack the ss360fm, i have 2 very similar president richards. those and my 3900's are the only radios i use outside grant,lincoln and jacksons. i like reliability.

no rx/tx on the ss360fm can be as simple as the chassis screws aint tight enough, although many other things could cause it too, once you get hold of it you'll have a better idea of the cause. first thing i'd check is the 2sa473 regulator.

when up and running they are hard to beat.

yeah slang can easily be misinterpreted, ie, fanny on your side of the pond is the exact opposite that it is here.

Seems to be a popular design. The Galaxy 99 I use has been reliable.

Thanks for that tip on the 2SA473. I'll be pulling that transistor out first and testing it. I have a few of these parts; so popping one in if it is faulty won't be a problem. I have a TIP42C that will work nicely there, as they are rated at 100v/6A. That should give this chassis a very sturdy voltage supply.

The other thing I will check is the VCO. Could be a bad 10.240mhz crystal too. So many parts that can be bad that will make it difficult for me to troubleshoot. If it isn't the voltage regulator, I will start at the top of the oscillator chain and work my way through it.

Any other typical problems these radios have that I should look into?

 

[jazzsinger]

Seems to be a popular design. The Galaxy 99 I use has been reliable.

Thanks for that tip on the 2SA473. I'll be pulling that transistor out first and testing it. I have a few of these parts; so popping one in if it is faulty won't be a problem. I have a TIP42C that will work nicely there, as they are rated at 100v/6A. That should give this chassis a very sturdy voltage supply.

The other thing I will check is the VCO. Could be a bad 10.240mhz crystal too. So many parts that can be bad that will make it difficult for me to troubleshoot. If it isn't the voltage regulator, I will start at the top of the oscillator chain and work my way through it.

Any other typical problems these radios have that I should look into?

its a very popular design, nearly every modern multimode is based on the uniden pb010 ss360fm/cobra 148gtl dx/president richard chassis.

don't pull the 2sa473, check it has 8v on the centre pin, if i recall. if not its probably failed.

of late the clone typical problems were many,usually down to poor soldering, but older models/clones were far more reliable. could be any number of things, but my prime suspect would be tr41 the 2sa473 or its surrounding components.

try googling Cobra 148 gtl dx no tx/rx,

should take you to uk forums where this chassis and its faults will be well documented, as its probably the most used radio on 11m in the uk.

 

[doffo]

i bought a Cobra 148 GTL off ebay for about $40ish dollars. Seller said it had no tx/rx. I bought a Fairchild TIP42C thinking it might of been the problem. When I received the radio, I switched it from PA to CB and hooked up a MIC.... It receives/transmits great!

Guess now I have a spare TIP42C incase one blows up on my either my Grant XL or Cobra.

 

[Robb]

i bought a Cobra 148 GTL off ebay for about $40ish dollars. Seller said it had no tx/rx. I bought a Fairchild TIP42C thinking it might of been the problem. When I received the radio, I switched it from PA to CB and hooked up a MIC.... It receives/transmits great!

Guess now I have a spare TIP42C incase one blows up on my either my Grant XL or Cobra.

The Cobra 148GTL or Grant XL doesn't use a TIP42C or 2SA473 regulator. The Cobra 148GTL-DX does; but that radio is completely different design of circuit board and nothing like the Cobra 148GTL. The older model Cobra 148GTL's use the MB3756 8v IC to regulate voltage. The newer Cobra 148GTL's use a LM7809 9v regulator in a TO-220 case.

Congrats on finding the problem.

 

[doffo]

Thanks for clarifying... Christ I guess I better double check stuff before I end up putting a wrong part!