1958 Grundig 8058 USA
 

I got this for a reasonable amount.

Very nice physical condition.
All the back panels are there.

Mono 3D sound with Multisonic 5 band EQ

PE Rex changer with MAGNETIC cartridge

Came with a schematic. I'll also check Radio Museum

High WAF (it is smallish)

I better open it up and take a look before I power it up

I been inside German radios before

This has EL95 outputs

http://videokarma.org/attachment.php...5&d=1323916160

Nice looking set. I have a much smaller Majestic table radio from that era, and it's a good performer.

Yes! The SKY IR code for Grundig LCD26HDIT is the code used to set your remote control

I suggest contacting the original owner or the manufacturer for info

I got the photofact for it

I pulled the changer and the receiver, de-oxit'ed the volume control which was frozen.

Cleaned the tuner vanes with non-residual QD cleaner. Reset the tubes, which still had the original tape to hold them down on them.

Siemens tubes not Telefunken

No burnt or melted parts, everything looked as it was in 1958 when they closed it up

I fired it up. It works! No hum and it was getting some stations on AM

I need to de-oxit the rest of the buttons and switches

The FM dial string is broken so I get to figure that out now

All the lights work which is great

The EM34 does work but is weak

Ok, its worth investing more time and money

I just spent all day re-stringing the FM tuner, what a PITA

I have all the diagrams

This was my first re-string, both wire and cord

Hard part is holding it all together and getting the spring connected

Works now and I did the clutch also

I did a more thorough cleaning of the tone bank and buttons

I emission tested the tubes on my TC-2 and both EL95 tubes test bad to awful, so I ordered new ones

I tested FM and, like AM, it sounds real garbled in the bass side. I hope that is the tubes

BEAUTIFUL! :yes:

I'd be looking to replace all wax paper capacitors. They will be leaky by now, and that leakage will upset the biasing on the audio amplifier tubes.

Also there's probably a non polar electrolytic or similar cap in the crossover that cuts bass going to the tweeter that needs to be changed.

Yes! I agree. I learned all I know about vintage gear from these sites. Thanks!

I ordered all the caps but I am going to wait till I get the new tubes in before recapping the unit.

It's my Arizona electronics theory of preservation

Jeez, I had to get the EL95 tubes from Bavaria

This would make an awesome looking guitar amp

http://videokarma.org/attachment.php...2&d=1324172535

Nice radio! I have Grundig 4088 and 5088 :)

Checking Radio Museum, It looks like your 5088 and my 8058 both use EL95's

My new EL95 tubes are in the mail

The only thing that did not test out okay was these two tubes, everything else was good

Right now I am making a three pin DIN to RCA adapter to check the tape input.

Looks great, OM. Good luck with it!

Yes, my 5088 uses a push-pull of EL95 :yes:

http://img27.imageshack.us/img27/3997/dsc05085oz.jpg

Full recap complete
 

I completed a full recap on the Grundig 8058. 33 capacitors in all

Almost all capacitors measured about 50% over spec on my capacitance meter

German radios are assembled without consideration to future service, so I had to disassemble parts in order to get to some caps, but not too bad

Most of the caps I change get pigtails which makes it much easier to correctly place the new cap.

I just brought the two 100uf filter caps underneath (zip-tied caps in image)

http://videokarma.org/attachment.php...1&d=1326640371

http://videokarma.org/attachment.php...1&d=1326640371

I fired it up and got a shrill tone, very bad

Obviously something I did since it worked before

So I then went back to my cap list and meticulously compared each changed cap's wiring against the schematic, validating the change

At first I was suspicious of the filter caps because I had to run a ground bus and tie three caps to it and it required the most change, but nope, not it

The C90 .01uf cap that came off of pin #1 of the output tube (EL95) was soldered to the pin NEXT to the correct pin, again, very bad on my part. The schematic review worked.

I remember that I cut this cap out only to discover that I did not have this particular cap on hand so I had to leave the patient on the operating table for 3 days until I could get the new cap. Another mistake on my part

Fixed it.

I fire it up again and NO shrill sound, the unit comes up and starts receiving stations

BUT IT SOUNDS JUST LIKE IT DID IN THE BEGINNING, MUDDLED TONE

Now I am going to pull the receiver and meticulously check EVERY resistor

I also found another very well hidden .0068 500v cap in the tone circuit as well as a 20uf 50v Non Polarized cap on the speaker wiring

Observation on aged caps
 

I noticed on these caps they all showed evidence of expansion and contraction causing the cap to deform

I think this is caused by the cold, expanding the caps

When I see this I automatically make the cap a candidate for replacement

I believe cold weather storage is worst than hot weather storage

Any opinions on this?

http://videokarma.org/attachment.php...1&d=1326641143

Checking B+ and rectification
 

I put a DC meter on my + and - of the selenium rectifier and got a reading of MILLIVOLTS?

Could the lights be on, the tubes heat up and I get some sound and radio if the B+ was so low?

If the B+ was very low could it be the cause of the muddled sound?

Should I measure the ~ AC on the rectifier

I think I will change the original selenium rectifier for a full wave bridge rectifier and a 100ohm 10watt resistor

Lights and tube heaters are AC so wouldn't depend on the B+. Check the plate voltage on the output tube(s) vs. B- and compare to schematic voltage, or if no schematic, compare to typical ratings of that tube from a tube chart. That would be a clue as to the health of the high voltage supply.

On the bench with a proper meter connection the B+ is 264vdc and the schematic calls for 270 so I am now under the impression that the rectifier is working properly.

I am going to check the resistors and change the last two caps, especially the NP 20uf in the crossover circuit

I have to read up on checking plate voltages on the output tubes, since I have not done that before and I like to understand what I am doing.

Connect another known good speaker to the extension terminals on the radio and check if that sounds good indicating radio speaker trouble. Is the "muddled" sound on AM, FM, or both? If you play an external source through the phono input, how is the sound? The external source could be a transistor radio with cable plugged into its earphone jack and patched into the phono input. If sound is good this way would point to the audio/speaker section being OK.

Tube plates will have B+ voltage on them, varying by design of the radio to suit the tube. Your - meter probe will go to common B- and the + probe to the plate pin of each tube (look up tube basing diagrams.) The schematic will show approximate voltage at each tube plate or if not, then a typical range of voltages can be read from a tube chart. If the voltage is way high or low the circuit around the tube needs to be checked.

Determining exactly which pin to connect the DC meter to on the output EL95 to measure plate voltage was surprisingly challenging with my limited mental capabilities.

Finally, Wikipedia showed me that the anode was the plate

After reading up on measuring plate voltage (mostly guitar amps) and looking at EL95 diagrams, all I could do was match the plate symbol to the pdf diagram of the EL95 pinout and determine that EL95 PIN-5 the 'a' pin was the pin that I would connect my probe to

I have those clip probe connectors so I will connect to pin 5 of the EL95 and measure the DC voltage

Target voltage is 260

Does it matter which EL95 I test first?

Why am I seeing no voltage on the anode plate?
 

My first ever attempt at reading plate voltage

I set my DMM to DC ___---

I connected the black lead to the - on the rectifier

I connected the red lead to the EL95 PIN5.

At first I counted wrong but after I figured it out I got the connection correct

http://videokarma.org/attachment.php...1&d=1327767742

http://videokarma.org/attachment.php...2&d=1327776463

From the terminal side of the tube socket, starting at the wide space, and counting clockwise, pin 5 is the plate. You should have high DC voltage between the plate and the negative side of the filter caps. Using the schematic, follow the high voltage from the power supply section through every component until you arrive at the output tube plates. Something is open or shorted keeping power from those tubes.

From the terminal side of the tube socket

The terminal side being the side where the tube plugs in?

Thats how I counted

I was 99.18436572% wrong in calculating the correct pin to test

Terminal side of tube socket, where the wires terminate, counting clockwise from the open space between pins

PIN 5

Now I get it

Makes a big difference

PIN 5 measures 246 on both EL95s


Still sounded too bassy through the regular speakers

So I connected an external speaker and it sound much better, matter of fact it sounds great

A lot of bass but I can control it

The woofer is now suspect. I measured 5.1 ohms from the 10 inch woofer, which is what I would expect

I'll pull the woofer out and check it out. It is wrapped in a sack cloth

Theres your problem right there Vern
 

Nice speaker from Grundig

Looks OK from the back

Total failure of the foam surround

Well, It's a GOOD thing I went ahead and did a total re-cap of the whole receiver AND bought new tubes when it probably just needed a new surround in the first place

yeah... a good thing...

Now I have to pull all the speakers and check them out

Good for you, you got it going! That's a good speaker and it's been matched to the set to give its characteristic performance. You may have replaced foam surrounds before but if not it's not difficult. Here is one source, there are others:

http://www.matelectronics.com/acatal...ories_149.html

Well, It turns out replacing the foam surround/gasket is a manual task that does not include a ready built kit.

I conferred with my pals in AudioKarma and one found this:

http://www.radiomuseum.org/forum/gru...rtschrank.html

So I have to think about this a bit as I want a cleaner solution for the new surround

But Hey! I guess the radio part works Okay and the re-cap was successful.

First time I measured plate voltages

First time I re-strung a tuner

I still have work to do but all-in-all a great experience

You should be able to do this taking a little care and ingenuity. The dealer that I referenced has I believe a $25 minimum which is a lot if all you want is a surround worth a couple of bucks. You could modify one of their surrounds to fit your speaker. Or, I used to re-surround speakers using 1/4" "hobby" foam, cutting my own surround "donuts." You'd want to be careful not to get any debris down inside the voice coil area while working: your speaker has no dust cover there. You could cut a round piece of black felt (fabric store) an inch or so in diameter and glue there first. Get fabric glue while you're there: similar to white glue but stays a little flexible and is waterproof as it's meant to glue patches on clothes that will be washed. When glueing on a surround, I used to glue it onto the cone first and then next day glue the outer part to the speaker frame, all the while making sure that I was not bending the cone to make the voice coil rub on the magnet pole piece. One way to do that is to play a radio low through the speaker while you're working on it and listen to be sure there's no rubbing distortion. Hold down the outer edge of foam with bunches of clothes pins to dry.

Replaced the surround AND gasket
 

I got some thin flexible foam and cut a surround out 9" inner 10.5 " outer.

I used some adhesive from another surround I did (good stuff)

After several hours spent clearing old adhesive off of the cone, I glued the surround onto the cone, using a small plastic ruler to press up from below the surround. This process took a couple of hours as I had to do a little at a time. Let that dry overnight

Next day I hooked up an amp and CD player to the speaker, applied the glue to the outer surround-to-frame edge. Playing the 30Hz test tone allowed me to align the cone as to not touch the coil. Each ten minutes I test again to make sure. Also test in horizontal position as this is the normal position of the speaker

I also cut out a 4mm thick ring of open cell foam to use as the gasket

I'll re-install the speaker after it cures

VICTORY! It sounds fantastic

The multi-sonic control is effective and the base is sweet and controlled

The gaskets are important to flush the speaker against the cabinet

I think I spent 30 hours of labor on fixing the woofer alone

Great! I always figure my own hours on my own stuff are free, as I enjoy doing it and overcoming some problem.