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Ept360015c Dirland Superstar 3900 xmit repair...

Hawkeye351

Well-Known Member
Jun 27, 2021
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I had such great luck getting the other radio straightened out on this site thanks to Handy Andy, it's now time for me to jump to the next radio and try my luck with it.

It's old, and possibly been in some dirt at some time in its life. It belongs to a long time friend of mine who had it in a stash of radios that didn't work but there are a few he does want to try and get going. This is one of them.

It's a Dirland Superstar 3900 (EPT360015c) with a single final (1969). It's issues are listed below:

1. No xmit (fixed by replacing final)
1. Carrier on SSB (fixed by readjusting bias)
2. Regulator gets hot (fixed by above)
3. AM carrier fluctuates between 2.5 watts to 3 watts with no audio applied, carrier jumps, erratic. (Not fixed, it's what I'm asking for help on)
4. Clarifier out of line and off frequency (fixed by realigning the clarifier circuit and adjusting xmit frequency)

Nothing in the radio is getting hot, getting 25 watts swing on peak and 10 watts swing on rms. Audio sounds great on listening station. Only issue with the radio is the am carrier fluctuating (flickering, jumping up and down).

Anyone have any suggestions?
 

Forgot to add:

Carrier flickers .5 watts to 1 watt up or down regardless of where the carrier is set at internally (radio has no external RF control).

Swing does not flicker up or down at all, stays dead on 25 watts with a constant tone.

I did stress test it to locate heat issues:

Deadkey results (2.5+- watts, flickers) - 4.25 minutes before regulator got hot. Final/driver cool to warm. Everything else cool to warm.

Cooldown results - 3 minutes

Audio results - 9.45 minutes before regulator got hot. Final/driver cool to warm. Everything else cool to warm.

Internal carrier adjustment has a smooth transition, as does the bias adjustments.

There is a strange parr number in the place where you'd find a 473, 1819, a1012 or ecg153 in front of the am regulator. This part is a transistor also but half the size and marked as a1282. Is that the right transistor? I've never seen that one in that location on these style boards.

Any advice is greatly appreciated.
 
"Flickering" could be many things - and combinations thereof...

I've got an oldie SS3900 EPT360011Z board - so I know of some of the issues you'll have.

First things to check?

Locate the riveted tabs that hold the board to the back panel - reflow solder around on the pad, and investigate how well the tab is mounted to that rivet. There are several spots that use RF bypass caps that can open up because the rivet that holds the tab to the rear panel - that little nub, can loosen or oxidize - causing an open antenna for RF currents to circulate.

Also, might want to remove and refresh the dielectric insulator pads - either new or clean up and reapply new dielectric grease and reassemble - the check here is to locate any cracked insulators and replace them with new. The older silicone goo can harden and get contaminated so if it can be cleaned up and reapply some new grease can help isolate problems you don't want creeping in.

But while you have the pieces out - the rear panel should be checked and reburnished for fresh aluminum to help with the older oxide and anodizing that can get affect the way the insulators can do their job.

Any ideas as to how old the PLL chip is? There's a Date code on it so if it has been a decade or more - you might want to look into the reasons that the power fluctuations and this may mean replacing older caps that are picking up stray charges and act more like Resistors.

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Date Codes...
RED ARROW - Last 2 digits of YEAR
GREEN ARROW - Week of Year Made

The thing is (if it's the one I fear) all aluminum chassis case and its a PITA for open and oxidized RF bypass lands - so care is needed to clean up and improve the many groundling lands that thing uses.
 
I can only get a pic of 1 of those IC's due to the encoder board being in the way of the other one.
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Notice all that wax?
Yes, I had to readjust the vco cause someone had been screwing around in it.

Here are some pics of the inside so you can look them over. Yes the regulator area looks like some hodge bodgery has been tried out.

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I know it looks rough. Not my work, I'm just trying to get it back to working order for this guy. Only issue with it working is the carrier (deadkey flickers/fluctuates). Receives good and xmit audio sounds good. Just carrier jumping.

And this guy is fine with the alc/amc being put back in and any swing mods removed.
 
There are several areas that will certainly need attention - nearly immediate.

The rear section by the output final - starting at about the center panel - towards the SWR riser card - all appear to have some kind of residue or "wax" mess - that discolored the output coils burned off the varnish/enamel - exposing the copper which has now tarnished.

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The Final and Driver got replaced BEFORE the incident that trashed this occurred.​

If someone did the work on the rear final and driver - good job, if not, they tried to get it working - that work is newer than the radio itself's own OEM date - with was about 1993 to 94' thereabouts - the Date code on the PLL is 9320 - so the earliest this thing was produced was in 1993.
  • Did this thing catch fire? Might be a lost cause - for if it was only that area, you could restore it - but looking over to the AM regulator side - lost quite a bit of foil to the experiments one of the previous owners did to it.
  • No, I've had my share of fun with these - and unless you are VERY passionate about radio - many of these turn into donors.
The wax over a lot of the parts is due to some type of heat exposure - which if this was in a truck that caught fire - or part of a salvage from a place - the wax wets the surface it touches which permeates and collected dirt, body hairs - bunny dust and who knows what else.

Although the wax doesn't hurt MOST components - the debris that sticks to it does, so this will have to be a clean and go, and clean and go and clean and go.... type of scenario. One step at a time

This will be one that takes time - for you have to depopulate the board around that area - get the parts off of it - so you can clean it.

IT looks like most of this problem is in the area where that discoloration is.

This radio got some kind of exposure to water or elements - so the speaker jacks and nearly all the rear panel by the coax connector - looks like it got soaked in water - left alone hooked up in a shed type of install. Water dripped down the coax into the rear panel - it explains the corrosion.

This one will take time.

Are you up to it? That alone can be and is only answered by, the one willing to tackle this one to rebuild it and get it working.
 
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Not sure if it ever caught on fire. It does look like a lot of golden screwdriver (or should I say golden soldering iron) mess has been done to it, lol...

I did notice that coil in the RF section, I figured I would have to locate another exact one or wind one myself.

I'm thinking someone has replaced the final before. Hell, if you notice, they even installed one in the extra final slot without adding all the needed components to make it work, lol...

I felt like it would take some time on this one. Even though it works, it's still not up to par like I would want it. I may put this one aside and pull one of the others out.

Still got a galaxy saturn (ept360014b) dual final that the lights dim severely and freq counter goes nuts when modulating, along with low power.

Still got an emperor ts5010 (shogunn) that came in with no xmit. Popped covers off and looks like a few caps have leaked. This radio sat on our local techs shelf for 6 years before he recently passed. Now everyone is getting their stuff and bringing it to me, dear God, lol...

Good news is I just got another radio to add to my personal collection. It's a galaxy dx 11b. Only issue is the cb band drops out, all other bands continue to work as normal. I can't start working on any of mine until I fix these other people's radios, customer comes first you know, lol...

I'll just put this 3900 on the shelf for now and start on one of the other ones. Which one do you prefer Andy?
 
I'll pull the 5010 out. Should be a simple fix on it, but it's Old so there's no telling what I'll run into.

Prolly have to go with a 2sc1969 since I can't find any mrf477's around. I do have some caps though.
 
Still waiting on parts for another radio, so I decided to pull this 3900 back off the shelf. After removing the junk mods and cleaning up some of the sloppy soldering, I tried to figure out the qwerk in the xmit circuit. After hours of messing around with it and going over solder joints, I found the entire problem.

The main issue was the chassis ground tab on the pll side of the radio not making good connection to the board. After fixing that issue, everything fell right into place.

3 watt key swinging 18 to 24 watts peak on am, ssb is about 18 watts. 3 watts swinging to about 8 watts average. No carrier fluctuations, no overheating issues, no garble, etc...

Another happy customer.
 

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