Grundig Sat 800 too much audio!

[nanZor]

Got hold of a seemingly perfect Grundig Satellit 800 refurb and everything works as it should, except for one thing:

The audio goes into distortion when the pot is advanced beyond about 2 for am/fm, and about 1.5 in ssb. No crackles, smooth operation, it seems like it *wants* to go loud, but it can't do so cleanly.

I knew what I was getting into, and this is neighbors rig given to me that has sat dormant for about 12 years. Bummer, this could be a showstopper, and yes I've read all the reviews over the years.

Pulled the back cover, and noticed nothing unusual, like blown / leaky caps, loose wires etc.

Before I tear this this thing totally apart in anger, has anyone had this problem and a smoking gun fix for it?

Disappointing - but I knew going in that this is no Drake quality rig, but a cheap facsimile. Nice concept for it's time, but shoddy implementation and QC ruled the day.

 

[NDRADIONUT]

Tuner cleaner on the pot....

 

[Blackswan73]

There is a yahoo group for the 800, and the head honcho of the service department is there. Also he has quite a bit of NOS parts for the 800, since he bought Drake's entire stock of spare parts when Drake closed. Most likely it is the synthesizer board, about $50.

 

[nanZor]

Took it fully apart (getting the back clamshell back on was a lot of fun...)

Cleaned up some cold solder joints, cleaned the rf/if connectors etc, but still the same distorted audio above about 1 or 2 oclock.

I don't know how much I'll put into it now, but will do a couple of hail-mary cap substitutions - but in fact it might be power regulation and not really an audio issue at all. We'll see.

I'll have to check out that Yahoo group, although their forum software drives me insane. Instead of keeping it all secret, sure wish one could at least *read* the posts. Oh well.

 

[majoco]

Get a good look at the volume control potentiometer and check that the ground/chassis terminal actually goes to ground and is connected to the wiper when the control is turned down to minimum volume. I have had a problem with those small potentiometers where the rivet that joins the terminal to the track has come loose or the track is cracked.

Could also be an AGC problem - is it equally too loud for weak or strong stations?

 

[Boombox]

I'll have to check out that Yahoo group, although their forum software drives me insane. Instead of keeping it all secret, sure wish one could at least *read* the posts. Oh well.

It wasn't broke, so Yahoo tried to "fix" it.

I never go to Yahoo eGroups anymore. Like you mention, too difficult to pull up threads, posts, etc.

Last time I checked, several previously popular groups were dead. No wonder.

RE your problem. Does it react the same on batteries as well as AC power supply?
I had a boombox that would distort on batteries. Took a while for me to realise in that case that it was the batteries didn't have enough juice to drive the audio. The radio, although a slimline, was 3W or so. It needed more power.

Not that you would have this problem, but sometimes the power supply to an audio chip can be a culprit in these cases. A bad electrolytic is usually blamed for stuff but I've found that most radios I've had built since the mid-late 1970's had no electrolytic issues, unless there was obvious damage.

But then, parts can be faulty.... You just never know until you nail it down.

Good luck. Hope you're able to figure it out.

PS, don't forget to check the speaker. If it's fine through headphones at reasonably high levels but crappy audio through the speaker, there could be an issue with the speaker.

 

[nanZor]

FIXED my Grundig Satellit 800 audio!

Found the culprit:

A 2200uf electrolytic cap just to the right of the antenna connectors and easily reachable when the back cover is taken off.

Although I should have used a non-counterfeit Nichicon, I did the impulse Radio-Shack thing. Works fine now, and even went ahead and replaced the other large cap, a 1000uf and the surrounding little 10 and 100uf's surrounding the original 2200. Hoping to get a few more enjoyable years of use out of it.

Other then the easily reachable 2200uf cap, the others really need to have the case covers and board disassembled to get to, but if anyone has a symptom like mine, replacing the 2200uf is pretty easy.

Short of recapping the whole board with Nichicon's, I stopped before I tried to fix what isn't broken.

Never thought of it before, but perhaps Tecsun / Grundig / Drake got caught up in the bad-cap fiasco. I'm going to be nice and say it was just aging in a hot garage.

At any rate, the fix cured the distortion when attempting to travel past 2 oclock, although the box is so loud anyway, I won't be going to spinal-tap volume levels! But good to know the distortion was fixed by a simple cap replacement.

AWESOME now! First enjoyable qso will be to monitor the Vintage SSB roundtable on 75m with it.

Thanks for the help and ideas everyone!

 

[Blackswan73]

Glad you got it working. It is an excellent radio, designed and serviced by Drake, built by Tecsun.

 

[NDRADIONUT]

How did u find it ??

 

[nanZor]

Part of that was good luck being the sole capacitor that is serviceable by only removing the back cover and also the largest on the board, which in my experience, tend to fail more often than smaller capacities. And the larger ones tend to be a bigger part of the "bad cap" fiasco, although I can't say for sure here.

When I thought about it, it did seem like the radio wanted to go to higher volumes, but was starved of power somehow, (AC adapter or batteries) rather than being an audio issue outright. I was thinking cold solder joint but all seemed good.

Since that 2200uf cap was right next to a 3-pin regulator, easily accessible at the edge of the board, I figured I'd take the chance on a replacement since I had already touched up the solder joints just in case. The touch-up didn't make any difference, so that spurred me into a total replacement.

Basically, the cap went to a high-ESR state. The regulator measured out ok, and in fact the cap when taken out of circuit and tested, rated at normal capacity, about 2195uf on my Fluke.

But under hot / aging conditions, the big ones are usually the first to go high-ESR (internal resistance), although yes small ones do too. I don't have a meter for ESR, but just doing a capacitance test is often not enough.

So I took a shot and bingo.

One option for those who don't have the necessary desoldering skills to do it right and muck up the board itself might consider cutting the existing old leads very close to the old cap, and leaving the old capacitor leads soldered to the board. Now solder your replacement to those bare leads sticking up from the board. Do this upright so you don't drop a big blob of solder down the board if you tilt it over. Use a drop of cement or at least make sure it isn't touching the board itself as the booming audio can make it vibrate against it if you crank the volume.

So without a schematic or service manual, I just went for the most likely suspects first, and got lucky. Someday I'll tear it apart again for some bipolar audio cap mods, but learned to at least have a little fun if I end up breaking it by going too far too fast.

 

[nanZor]

Glad you got it working. It is an excellent radio, designed and serviced by Drake, built by Tecsun.

It IS a really nice radio and I am so glad I got it working. Will Drake still service these radios in 2016? I think I saw a listing for tech's they actually farm service out to, but not sure if that still covers the 800.

One can see how it is a meld of Grundig's older 600/650 series married to a Drake SW8. I want one of *each* now!

I totally understand the logic of the time, with price vs features. Rough time though for ANY poor componentry and qc to crop up, which it did.

My version is a refurb, which has the copper vfo collar and whatnot. Why they did not include this stability for the vfo knob at the outset is beyond me, when the first human sense you have is one of touch! Why this wobbly issue carried over to the early Grundig/Tecsun 750 boggles my mind too - I thought they would have learned their lesson.

 

[Blackswan73]

Drake is out of business, but the man who was the head of their service department still services them. I forgot his name, but he sells NOS parts for the 800 on eBay. And he is a member of the Yahoo group. Lives in Ohio, where Drake was located.

Edit: His name is John R. Kriner
www.eham.net/reviews/detail/4412

 

[nanZor]

Great tip about Mr Kriner and nos parts!

Now that it is fixed, I actually spent more money on it since it is such a joy to listen to and operate.

Ditched the unregulated oem power supply, and am now using a regulated Enercell 9V / 1500mah dc supply. Radio Shack #2730356 international adapter. The white coaxial "M" adapta-tip with blue ring at the end fits fine. Although it already has a large ferrite on the leads, I still needed to wrap about 5 turns around a large MFJ 700C snap-on ferrite for hf use.

Works great, and makes me wonder how many people smoked their 800 with a bad supply or one with too high of a voltage....

Invested in a nice Maha / Powerex C808M nimh charger, using either 8000mah Tenergy "Centura" low self-discharge D cells, or some higher drain Powerex 11000mah D cells. Tested 2500mah Sanyo / Panasonic "Pro" (formerly "XX") lsd AA's inside D-cell spacers, and got about 5 hours from it as I expected. Of course the real D nimh's last quite a bit longer!

So hopefully I'll get a few more years use out of it. Definitely worth spending a few bucks on better power for it..

Also recycled the oem headphones.

 

[tiger65]

This has been a most interesting discussion concerning the Grundig 800. After over a year I left SW and my 800. I wanted to get back into SW and turned the 800 on and the text on the Displayis garbled and unable to read. It appears that everything works, sound light, AM-SW etc but it is worthless being unable to read the display. I am just a novice in trying to trouble shoot electronics. I did take it apart to check connections. The inside was in mint condition. (I bought it new years ago). I did put in batteries to see if that would help just in case a low voltage PS. Same problem with batteries. Now that Drake no longer repairs radios I could find no help. I did obtain a phone number from Universal Radio from the name alluded to in this forum but the number did not work. Any ideas what might be the problem would surely be helpful.
Thanks,

 

[nanZor]

Yikes - you could do a microprocessor reset by removing BOTH the batteries and dc adapter input for 30 minutes to an hour and try again according to the manual. Apparently a reset occurs when no power is attached for this long. You won't lose any memories as this is not a memory-reset.

Perhaps you have a static charge built up inside fooling the soft switch logic? I know pulling mine out of the box built up quite the static charge when removing it from the box...

The thought here might be to just ground the radio to bleed off static and then fire up. Attach 10 feet of wire or so to the black high-impedance antenna connector jack, and throw it on the floor, wait a bit and fire up. Or actually connect the wire *SAFELY* to a grounded waterpipe for example and try again.

Of course this is assuming you don't actually have a hardware issue ...

I noticed I could force what *looks* like a reset (at least the display seems to do it), when having both batteries and the dc adapter installed at the same time, and pulling the dc adapter coaxial plug out of the jack leaving it running only on batteries. Seems like the sudden change in voltage between the two, or the make/break of the 9v dc input connector makes it do this. Do this at your own risk, as I don't see this mentioned anywhere as a way to do a reset...

Other longshot attempts - maybe exercise the buttons to make sure none are dirty / pressed down when firing up - that may confuse it possibly at powerup....

 

[tiger65]

Thank you for all your helpful suggestions. Unfortunately the problem persists with no change. At least I do receive all bands but I can't read any of the frequencies are what mode I am in. I can figure out if it SW, FM, AM but not sure where I am in each band. This was a good radio while it lasted. I suspect it is bad hardware or voltage problem going to the LCD. I went ahead and purchased the Grundig 750 and will give it a try. I am sure it is not as good as the 800 but it should meet my needs.

Thanks again for your help.

 

[nanZor]

Bummer - it might be worth it to see if any of these guys are still active who might repair it:

Vintage Amateur Radio Product Repair - Drake

I also have a 750 (3rd one!) and yep - very different animals. Quick tip for airband: Unlike the 800 which is happy with a fully extended whip for airband (high-z input), the 750 likes a low-z input with the internal whip, so pull it fully out, but collapse it to about 22 inches.

You'll be riding the rf-gain like a cowboy, since Tecsun does not REALLY understand ssb agc, other than just the heavy-hammer approach. The 800, designed by Drake, performs quite a bit better!

Still, the 750 is a start, and perhaps you can get that 800 fixed. I think they are worth it.