Allwave 15 Voltage

[Doug Faubion]

I am Working on an  ALLWAVE 15 S/N f-303 and I could use a tube voltage chart ie the voltage on each pin of all of the tubes in the set. I do not have the speaker for the radio and had to make a resistor box to lower the voltage that the field coil would have done. The AM band works but the SW is very week.

[Kent King]

Doug -

Unfortunately, Scott never published a voltage diagram for the 15. In fact, many Scot sets do not have this information available. Check the voltages on the B+ divider resistor You should have (roughly) 200-220 at the high end, then 90-120, 50-60 and then to ground. Those have to be fixed first. Once you know the values in your set, it's pretty easy to check plate and screen voltages, except on the oscillator tube. 

You said it plays on on AM but is weak on SW. Do you only get a few strong SW stations, or do you get a lot of SW stations but with little volume? The first problem may be an alignment issue, the second may be a problem with the set, amp or speaker. 

Hopefully others will jump in to help...

Kent

[Doug Faubion]

Thanks for the info.  I have 227-97-56-0 on the divider resister.  Do I need to get bigger voltage dropping resistor for the box I made?   It does play on the AM band but is not too strong compared to other sets in the house ie number of stations.  If I inject a signal on the mixer grid at around 50 uv I get about -.45 of AGC but if I inject the same signal on the AM ANT (red)   post The signal drops off a lot about -.17 or less AGC.  I have checked the switch in the big can that switches the ant from Am to SW and it is ok.  Looks like the RF section is not working at all.  The SW bans do not get anything unless I force a signal into the set at a very high lever.  I have voltage on the plate and screen of the RF amp around 98 on screen and a little over 200m on the pate.  This was an E-bay set and it got damaged in shipment.  The front of the radio got hit and the shaft for the band selector got pushed in about 1/4 to 3/8 inch and broke the top of the gear box into 5 parts.  I had to machine one out of aluminum.  The coils seem to rotate as they should now.  I am going to pull the coil asm off and do some ohm meter work.           Thanks for any help.  Doug

[Kent King]

Well, you may have contact problems with the coils since you had to machine a new gear support assembly. I can probably locate original parts here if you need them, I have a large "graveyard" of chassis to pull parts from. Also, does the AW15 have a rotating contact switch up near the front of the chassis driven from the wave change shaft? I know the AW23 does, can't recall on the 15. If that isn't working right, you will have problems such as you've described.

The voltages on the divider are fine, no worries about that. You'll probably want to align the IF and adjust the tuning. The service and owners manuals are available here in the Scott Info Archive (link above). I think we will want to find you some original parts for the wave change assembly. Can you post pics of what was broken? I"m sure I can locate the required parts.

Kent

[Doug Faubion]

The complete gear box had to be removed and several screws and to be added to make the sides stand up again and the top had to be made (the old one was in 5 parts)  If yo have parts that I could use I would be more that happy to cover the cost and shipping.  I was thinking of getting a junk one on e-bay just for the parts.  Yes I think it has the switch you are asking about.  I don't think the osc is running on the SW bands at all  If I put a signal on the mixer grid at a very high level (about 1 volt) I get a very broad signal on the band about 2 MZ wide.  I wish I had sent this radio back when I had the chance.  Ok on the voltages.  Wish me luck.Thanks for you help Kent.

[Norman S Braithwaite]

If Kent does not have the gearbox available, I do.  I also have a Scott chassis boneyard.  Yes, the AW-15 has a switch above the chassis but it is only a two position switch, BC and all SW.

Norman

[Doug Faubion]

You nailed it Kent,  The problem is in my home made gear box, after some ohm meter work I found out that the contacts where not making, I did some more machine work on the gear box top and now AM and SW-1 and SW-2 work great  I can see the problem with SW-3 and it is that the coil turret is not running true so I have something off center in the gearbox.  Please take a look and see what you can come up with.  I feel that we made a lot of progress tonight.  Much Thanks 

sw-2  

[David C. Poland]

Also important to follow the instructions for dismounting and there re-mounting the coil wheel. This is to protect the switch from damage in the coil can above the gear assembly you rebuilt. Namely, put the band switch in broadcast before dismounting and leave it there until you remount the coil wheel, Since you have already been through the dismounting, remove that can and visually check the action and the contacts - as that coil is the antenna coil as I remember.

 Also, each of the IF cans across the back of the receiver have a wax/paper cap inside to replace. 

The pair of red antenna posts (for the short wave antenna) you mentioned indicate an early AW-15 using a Wunderlick tube 2nd detector. Just use a longwire antenna for shortwave and leave the antenna switch in position for the black antenna switch.  Some early AW-15's have been modified to use a 55 tube because Wunderlick tubes became unavailable.  I can provide a good one at a fair price if you need one.  Riders does not have the Wunderlick tube diagrams. But the Scott site does, as I remember. Scott made a lot of running changes during AW-15 production, so, your set may not exactly match any digram. 

Good luck.  

[Doug Faubion]

Thanks David for the input.  This radio has 4 post for the antenna connections One Black with ANT on it and two red (for SW it looks like) and one  with GND on it.  It does not have the Wunderlick tube.   I have had the coil wheel off and on several times because the set was damaged in shipment ( the front of the set was hit and pushed back the band change shaft and broke the gear box in several places and I had to remake parts of it.  The front vertical side of the box was broken off an dthe top plate was in 5 parts.  Not good news for a first time Scott owner.  Thanks for the heads up on the IF coil caps.  I see my next problem as getting the BFO to work, it does put out a frequency but not the correct one  I guess because I can not here it.  I am thinking that it should be a little off from the IF frequency like about 1 KC or so.  Thanks  Doug

[Kent King]

Good to hear on the progress. I will look tonight on the wave change gearbox assembly, I'm pretty sure I already have one pulled out. I'll let you know this evening after work. I suspect that with an original, undamaged assembly, the contacts will be good and you'll be able to finish the restoration.

[Doug Faubion]

Thanks for the information.  Doug

[Kent King]

I do have the part you need. Send me an email at [e-mail] and we will get it moving.

[David C. Poland]

The Wunderlick tube would have been left side, 3rd tube back as you face the front of the radio. Tube sockets have the tube number embossed - except the Wunderlick socket has no tube number, rather the button in the middle is dark red. With yours having  red antenna posts, I would be surprised if that 2nd detector socket said 55. Curious to know.