Early versus Late 800B Tuning Switches

[Joseph W Strickland]

Today I finished printing out the entire set of Service Manual pages and began reading through them. I read the push-button tuning section with interest. I noted that the early models have a different set of momentary switches used than the late models. The ones in the late models have a double row of contacts that allow user choice of how many buttons may be used for AM and FM stations out of the total number of possible push-buttons.

I recently ordered a late model 800B radio/tuner/preamp chassis that includes the wooden front trim panel complete and will have the double row push-button switch contacts.

I am thinking it will be possible to move the newer push-button switch assemblies to the early model chassis which is in better condition overall. It will require some re-wiring to provide the FM common lead to both sides but I think it can be done. Have any of you ever done this?

Joe

[Joseph W Strickland]

Here are a few pictures of the underneath of the Early 800B Radio/Tuner/Preamp chassis:

[Joseph W Strickland]

Here are a few pictures of the Late 800B Radio/Tuner/Preamp chassis:

[Joseph W Strickland]

Here are a couple of pictures of the Early 800B Ratio/Tuner/Preamp chassis after I replaced the RF cover (having cleaned and polished it with chrome polish), cleaned and polished the FM RF tube shields. It looks more presentable now. I still need to clean and polish the rest of the chassis so it can look its best. This RF compartment cover does have a few small rust pits, but cleaned up quite well. The original RF cover had about a 1 inch diameter spot of rust that had gone all the way through to the base metal beneath. The only cure for it would have been to have the RF cover completely stripped of plating, buffed smooth again and then completely re-plated.

Joe

[Joseph W Strickland]

Today I identified the added relays for the tuning motor. There are two of them and they are positioned below and on either side of the center shaft of the AM Bands switch. They attach to the front side of the lower RF compartment sheet metal. These two relays are missing from any Early 800B chassis.

Joe

[Joseph W Strickland]

In my first reply I made the statement that the Early and Late versions used motors with different voltage ratings. That turned out to not be true and I misunderstood the service manual statement about the two receiver versions. Both the Early and the Late versions use a 24VAC motor. The Early version uses the 36 volt winding of T10 due to extra relay windings in circuit with the feed to the motor. The Late version eliminates some connections and consequently relay coils and so it only needs to use the 24VAC winding of T10.

Joe

[Joseph W Strickland]

I recently printed out all the service information on the 800B and put it in a loose-leaf binder. This has made access to the information in it much easier. I was pleased to find the section showing component locations for the radio/tuner/preamp and FM IF/Audio Output/Power Supply chassis. That is a big help. I went through needless work determining where K4 and K5 relays were and when I found them in the service manual it even differentiates which one is which. E H Scott did excellent documentation compared to some companies.

Joe