The PHILCO Phorum
Grunow 654 - Printable Version

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Pages: 1 2

RE: Grunow 654 - vecher - 06-24-2015

Ok , That's a good idea.. I didn't really want to remove the IF cans anyway..

Thanks
Skip...

RE: Grunow 654 - Arran - 06-25-2015

(06-24-2015, 03:23 PM)vecher Wrote:  Ok Next problem .. Does anyone know how to remove the IF Cans??  See picture..

[Image: http://i292.photobucket.com/albums/mm38/wb4yvo/grunow%20oo%20004_zpslwmlhiri.jpg]

Looks like you could compress the tabs but I was afraid of breaking them  .. Any thoughts??

Skip...

Skip;
  You won't break those tabs from compressing them, they are quite tough actually. A pair of duckbill pliers will do the job quite nicely. I would not sleeve the wires, the cans are easy enough to get open and it's also an opportunity to inspect the coil inside, and replace any resistors, and a grid lead.
Regards
Arran

RE: Grunow 654 - vecher - 06-26-2015

Ok, I removed the Cans.. Glad I did because the insulation was gone from one of wires..

[Image: http://i292.photobucket.com/albums/mm38/wb4yvo/grunow%20654%20more%20009_zpsgxmrtjji.jpg]

The wire going to the Grid cap was also frayed.. Did the 1st can already now will work on this one. Also found most of resistors have changed value.. The Mica caps were OK.. The dogbone resistors one that was 20K was reading 70K other was 5K reading 6.5 K..

So I will Keep moving Forward..

Skip...

RE: Grunow 654 - vecher - 07-04-2015

I tried to re-stuff the Caps on this.. However didn't go very well. So for now I just went with the right replacements under the chassis.. radio works very well. Performed alignment..

One question.. I did not replace the bias cell. How can you tell if its still working.. I pickup lots of stations on both bands and volume is load with no distortion..

Skip...

RE: Grunow 654 - Radioroslyn - 07-04-2015

Measure the voltage at the control grid at the 1st audio. If battery is good (haha) should see -1.5vdc. Watch batteries make good replacements.
Terry

RE: Grunow 654 - vecher - 07-04-2015

Terry, Ok thanks I will go out now and check..

Skip...

RE: Grunow 654 - vecher - 07-04-2015

I measured -.5 volts using my Old Military VTVM TS-505.

According to schematic it should be -.2 Volts..

[Image: http://i292.photobucket.com/albums/mm38/wb4yvo/R390%20016_zpsxhszm6qw.jpg]

These radio were run on 110 Volts AC I think so with my voltage higher it should be more?? The B+ should be around 250 Volts I measure about 330 volts.. I have a transformer I use on my 390's to step down the voltage .. I guess I will hook it up to radio to see what I get..

Anyway Radio work great..

Skip...

RE: Grunow 654 - Arran - 07-05-2015

(07-04-2015, 11:37 PM)vecher Wrote:  I measured -.5 volts using my Old Military VTVM TS-505.

According to schematic it should be -.2 Volts..

[Image: http://i292.photobucket.com/albums/mm38/wb4yvo/R390%20016_zpsxhszm6qw.jpg]

These radio were run on 110 Volts AC  I think so with my voltage higher it should be more??  The B+ should be around 250 Volts  I measure about 330 volts.. I have a transformer I use on my 390's to step down the voltage .. I guess I will hook it up to radio to see what I get..

Anyway Radio work great..

Skip...

Skip;
  I think that the discrepancy may be explained by the different readings you get from using a DMM/VTVM verses an old fashioned Volt-Ohm meter which was what they typically used in the 1930s, the types they used loaded down whatever they were trying to measure. Radios from then were designed around a working line voltage of 117 Volts, except for 25 cycle versions which were designed around 115, the only power grids that were a true 110 volts were the DC power grids in some major cities.
Just out of curiousity, have you checked the tubes? One thing that can cause a higher then normal B+ voltage is a weak power output tube, a weak tube conducts less current.
Regards
Arran

RE: Grunow 654 - vecher - 07-05-2015

I did check the tubes. All were Good. However when checking them against schematic I noticed that I have a 6K6G in the place of a 6F6G. I believe it is a direct replacement but how it affects the voltage No clue..

I lowered the input voltage to 117 volts. The B+ now reads + 330 volts using a VTVM.. The bias reads -.68 volts.. Radio still works great.. So I guess its good for now.. I guess I will put it back in cabinet and back to living room..

Thanks all

Skip...

RE: Grunow 654 - Arran - 07-06-2015

(07-05-2015, 10:51 PM)vecher Wrote:  I did check the tubes. All were Good.  However when checking them against schematic I noticed that I have a 6K6G in the place of a 6F6G. I believe it is a direct replacement but how it affects the voltage   No clue..

I lowered the input voltage to 117 volts. The B+ now reads + 330 volts using a VTVM.. The bias reads -.68 volts..  Radio still works great.. So I guess its good for now..  I guess I will put it back in cabinet and back to living room..

Thanks all

Skip...

Skip;
  I think that we have found the answer as to why the B+ voltage is higher, lower current output tube. Find either a 6F6 or a 6V6 to replace the 6K6G, the 6K6G is not a direct replacement, the plate and screen current is lower then the 6F6 or the 6V6, and the heater current is also lower, the plate impedance is also wrong.
Regards
Arran

RE: Grunow 654 - vecher - 07-06-2015

Arran, Ok thanks . I will check to see what I have..

Skip...