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

Vol control ?
#1

I have an American Bosch 04 http://www.nostalgiaair.org/pagesbymodel...022251.pdf 
the second print is the one. 
The vol control is open and there is nothing on it besides I'm pretty sure it is not original. I have tried pots from 5k to 500k and all I get is a whisper out of it with it at max. I have about 25' of wire strung in my garage for an antenna. What am I missing? #7 is 48k and #5 is .1uf . Thanks

Eric
#2

Eric Have you changed the caps in it and tested all the tubes? If not that, I would check the antenna coil. I would also ck R7, C3 and C5 not saying its the problem but where I would start. Also did you do voltage checks on the tubes?
If I'm not close on my advise someone will see this and get you in right direction. Good luck.
#3

Hi Eric,
The volume control is going to be a fairly low value as it is in the ant circuit. Probably 10K to 20k should be about right. As Mike said it important to replace the caps and then you can measure voltages to figure out what going on. Without replacing the cap you run the risk of burning up the power transformer which you don't want re replace. It special cause it has a 2.5v filament winding very hard to find.
If you have done the replacements measure the voltage on the plate of the 47. That would be on pin 2.

Terry
#4

(07-26-2015, 06:21 PM)Radioroslyn Wrote:  Hi Eric,
The volume control is going to be a fairly low value as it is in the ant circuit. Probably 10K to 20k should be about right. As Mike said it important to replace the caps and then you can measure voltages to figure out what going on. Without replacing the cap you run the risk of burning up the power transformer which you don't want re replace. It special cause it has a 2.5v filament winding very hard to find.
If you have done the replacements measure the voltage on the plate of the 47. That would be on pin 2.

Terry

Thanks guys, 
Probably should have posted all I have done so here is what I have
All tubes tested and are good.
Re capped all.
I have replaced the resistors ( not that many and the dog bones were mostly way over)
2.5V filament ?  The 25z5 and the 43 have 25 volt filaments. the ballast tube the 185R8 checks out also.
The voltages are as follows
            screen     plate    cath     Fil
25Z5       ----       118     -----     61
43         120        122     35       37 
6c6         52         40        5         6.3
6d6        122        120     .6        12
Some are off not sure why. I have checked the RF coils and there good tomorrow I 'll do the ant.  
 
#5

Sorry I was looking at the 1st schematic, it has 2.5v tubes.
As you may know this is a TRF set consisting of a RF amp a detector, and audio out. The plus is it's pretty simple the down side is poor sensitivity.
The cathode voltage on the 43 seems a bit high but it does use a 600 ohm resistor in the cathode. Most I've seen are a bit lower around 300 ohms.
Double check your ant coil and then use a good ant read long and high up.

Terry
#6

(07-26-2015, 08:51 PM)Radioroslyn Wrote:  Sorry I was looking at the 1st schematic, it has 2.5v tubes.
As you may know this is a TRF set consisting of a RF amp a detector, and audio out. The plus is it's pretty simple the down side is poor sensitivity.
The cathode voltage on the 43 seems a bit high but it does use a 600 ohm resistor in the cathode. Most I've seen are a bit lower around 300 ohms.
Double check your ant coil and then use a good ant read long and high up.

Terry

Found my mistake it was on the 43 tube part 13,14,15 had these wired wrong. To be fair I started this radio when I first started the hobby ran into the dead end and put it on the shelf thinking I need to get more experience. The 5k pot works fine but I need to get one with a longer shaft, not a big deal!. thanks again for helping!

Eric 
#7

Glad to be of help. Depending on how long a shaft you need I've used a piece of 1/4" hose has a coupler to another shaft. If it slips use a tieraps to secure it.

Terry




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
trying to identify this wire type
...and modern wire of the appropriate gauges and insulation V-rating (300V minimum, usually shown right on the wire) is ...morzh — 05:47 PM
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
I have a question about this radio, is there anyone that has access to this radio that has an intact unmolested speaker ...captainclock1988 — 04:28 PM
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
Well what makes me confuse all of those companies is that all three of those companies (Setchell-Carlson, Stromberg-Carl...captainclock1988 — 04:21 PM
trying to identify this wire type
The red wire is rubber covered wire. The others are cotton braid over rubber often in colors or a tracer, also strand...Chas — 02:43 PM
trying to identify this wire type
Greetings Phorum members, Hope you can help me identify this type of wire in the photo I have attached.  I am not sure ...georgetownjohn — 01:53 PM
Philco 60 Squealing
All correct shields must be in place, all tubes correct no subs of any kind. Check any soldered, riveted ground conne...Chas — 01:24 PM
Philco 60 Squealing
I have recapped and replaced out of tolerance resistors and so on. Radio plays nicely on fairly strong stations. The pro...dconant — 10:55 AM
Philco 46-420 Code 121 Reception issues
Welcome Eric, I agree with Bob and far as the two main electrolytic filter capacitors did you change them yourself or w...radiorich — 11:43 PM
Philco 46-420 Code 121 Reception issues
You mentioned the Philco manual and going through the check points...just to be sure we're on the same page here's the m...klondike98 — 08:13 PM
Philco 42-1008 conversion kit
Interesting. I haven't seen that before.klondike98 — 07:02 PM

[-]
Who's Online
There are currently 3120 online users. [Complete List]
» 1 Member(s) | 3119 Guest(s)
Avatar

>