EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

My recently acquired Allwave 23 is now working. Had a new power transformer made, and replaced all the paper bypass caps in the tuner chassis. Ran fine for a couple of hours, then quit. Checkout found a bare wire from the antenna circuit above the chassis. Was able to replace the wire without taking it too far apart, then the grid cap came off the RF tube. Resoldered the cap and now working well. 

Beware 70 year old rubber covered wire. Also, support the grid cap while removing the connector.

My thanks to all who offered help and directions. Also thanks to Heyboer transformer co. in Grand Haven Mi. 

This should probably last for another 70 years. 

Thom

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Hi Thom:

 I will be starting on my AW23 shortly and was wondering if you have any pointers. What problems did you encounter and what to watch out for. How is yours working as expected, better??

Greg

Greg:

The only thing I would suggest you do is first, download the service info that is on this list. I did most of what it recommends, but not everything. You will need to replace all the rubber grommets on both chassis if they haven't been.

I removed the tuning meter to get to the dial lamp. The insulation on the rubber covered wire is brittle and will break off at the slightest touch. You can cover it with sleeving or replace it as needed. The wire from the center antenna coil to the terminal strip between the tuning cap and RF tube on mine had to be replaced because of this. I used all .1 uf bypass caps except where the schematic called for .05s. Radio seems to work ok, but I need an outside antenna to find out for sure. I have a lot of noise on all bands, but we have dimmers on several lights and several flourescent lamps as well. 

It is interesting to work on a chassis where your tools can get lost if they fall in!! I used a pair of 2X8 boards cut a little longer than the chassis height for support at each end with the chassis upside down. Most of the caps can be replaced with out much disassembly, except for the 8 going into the IF cans. That was a little extra work, since the covers have to be removed and that requires unsoldering the grid cap connectors. The covers on mine were very tight and needed to be gently pried to come off. I used a long length of wire  soldered to the grid wire to feed back thru the cap to reinstall. You may decide to simply replace the wires and cut them to length. I simply clipped out the old caps leaving as much of the original lead, bent it into a u and cut the new caps leads to length and soldered them in.  I ordered the caps from Antique Electronic Supply in Arizona. The yellow ones work fine. You have probably done this before, so use what you feel is best or available. 

There are still a few things I should do. The dial scale is off by about a .25 inch and needs to be mechanically reset. Didn't find that out until I had it back in the cabinet. Haven't cleaned the dial scale or the colored display. 

While I had the IF covers off, I shot the trimmer caps with cleaner. Haven't attempted an alignment. This is apparently one of the 'transitional' chassis, as some things are different from the schematic. It has the air trimmers and they are original to the chassis. Also the BFO doesn't seem to work, but that is a minor detail. 

I spent a couple of days doing this work. Taking a break every couple of hours helps. For mine, the power supply had been rebuilt  at some point, so finding a burned power transformer was something of a surprise. It all came back to life with the variac. 

Thom

Tom  & Greg,

My first AW-23 (early 5 knob) many years ago also had a shorted primary on the power transformer that appeared the first time I tried to power up after I had recapped it.  Replaced the blown 3 amp fuse. Powering it up on a Variac, the fuse glowed red at about 40 volts, and then it blew.  Took awhile to get another power transformer from a rough amp. A year later, during a several hour duration play, the fuse blew - primary of that transformer had shorted !!!.

 

Ultimate problem was in the speaker, where I discovered the B+ wire to the field coil was resting on the point of a screw. Old insulation had allowed a low grade short . Not enough to blow the fuse, but enough to cook the transformer that day.

 

So, I suggest you check the current drain of the high voltage circuit .

 

I also replaced the dried out original rubber low loss wire. Took a lot of time. Used black test lead wire.

-Dave Poland

Thanks for all of the pointers! I have Norman B's list, the AW23 service manual, the schematic and what have you out of Riders, I should have all angles covered. Thom, I do have a good outside antenna that gives good reception on my other radios so should do really well with the AW23. I really do dislike that rubber covered wire, causes more trouble than I care for.

Greg

 

Good tip David, do have the spec for the aprox B+ drain?

 

Greg

David C. Poland said:

Tom  & Greg,

My first AW-23 (early 5 knob) many years ago also had a shorted primary on the power transformer that appeared the first time I tried to power up after I had recapped it.  Replaced the blown 3 amp fuse. Powering it up on a Variac, the fuse glowed red at about 40 volts, and then it blew.  Took awhile to get another power transformer from a rough amp. A year later, during a several hour duration play, the fuse blew - primary of that transformer had shorted !!!.

 

Ultimate problem was in the speaker, where I discovered the B+ wire to the field coil was resting on the point of a screw. Old insulation had allowed a low grade short . Not enough to blow the fuse, but enough to cook the transformer that day.

 

So, I suggest you check the current drain of the high voltage circuit .

 

I also replaced the dried out original rubber low loss wire. Took a lot of time. Used black test lead wire.

-Dave Poland

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