Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Grunow 654
#16

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

Thanks
Skip...
#17

(06-24-2015, 02:23 PM)vecher Wrote:  Ok Next problem .. Does anyone know how to remove the IF Cans??  See picture..

[Image: http://i292.photobucket.com/albums/mm38/...mlhiri.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
#18

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

[Image: http://i292.photobucket.com/albums/mm38/...mrtjji.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...
#19

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...
#20

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
#21

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

Skip...
#22
Big Grin 

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/...szm6qw.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...
#23

(07-04-2015, 10:37 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/...szm6qw.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
#24

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...
#25

(07-05-2015, 09:51 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
#26

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

Skip...




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Correct model 84 Ac plug an cord type
From what I read Philco went to using brown rubber power cords in 1936, so cloth was used in the 1935 and earlier models...Arran — 11:25 PM
Correct model 84 Ac plug an cord type
Hi Bruce, I have not worked on an 84, but in general, power cords for almost any radio prior to 1938 was cloth covered...MrFixr55 — 08:34 PM
Restoring Philco 38-14
OK, well, so after staring at the sch again, I realized the problem had to be the #12/12A padder. I put a scope on the o...morzh — 08:15 PM
Correct model 84 Ac plug an cord type
Hello Bruce, I mostly use brown far as my cloth powercords go ! Here is the plug that I have used bakelite Acorn style...radiorich — 08:05 PM
Correct model 84 Ac plug an cord type
Looking for as correct as can find the right Ac plug an the correct colored cloth line. Ive seen many old photos but mos...Bruce — 04:13 PM
Restoring Philco 38-14
Rod Two Y-caps make sense if you use them from L/N to the chassis; this is only makes sense in the transformer radios...morzh — 10:11 AM
Restoring Philco 38-14
Mike, I'm curious about a specific use of he Y cap. Lately I've seen a single cap across the power transformer primary. ...RodB — 09:01 AM
Restoring Philco 38-14
hello morzh , That sounds like a plan ! Sincerely Richardradiorich — 07:45 AM
Restoring Philco 38-14
Richard, It helped some, but I still had the whining when engaging the rear power strip (I did not realize it was fro...morzh — 07:07 AM
Restoring Philco 38-14
Hello morzh, Yes , that dreaded hum in my room where i do alighment I have my cable modem and router plus desktop plus ...radiorich — 11:25 PM

[-]
Who's Online
There are currently 3894 online users. [Complete List]
» 1 Member(s) | 3893 Guest(s)
Avatar

>