[EdHolland]

Thanks for the very detailed post palegreenthumb.

I'll follow up on the leads - that's really helpful

[EdHolland]

I found some more info on-line. Grillecloth had a vague reference in one of their archives, and showed the correct lineup. I then searched and found Mallory repair guides online (I'll post the link when II find it again). Of those, one included the 388 set, indicated it has a 460 kHz I.F. and also control circuit and part details.

Back in the UK, I have a Riders manual. We're heading there next week so I'll pull it out and try some more detective work. It would be good to have more circuit info.

Ed

[Ron Ramirez]

Aside: Truetone was the house brand of Western Auto Supply Co. (of Kansas City, KS).

Kansas City, Missouri. (How do I know? KCMO is my home town.)

Their old headquarters building has been turned into loft condominiums, and the building retains its landmark yuuge Western Auto sign on top.

http://www.kc-lofts.com/bldgs/westauto.htm

[palegreenthumb]

Thanks, Ron! I appreciate the correction!

[EdHolland]

Now I'm here in the UK, there was a chance to look it up in the literature I have here. I remembered incorrectly, it is a Mallory service encyclopedia, stating "All Pre-War Receivers"

Our 388 appears as hoped for, and the info matches previous details presented in the thread. 1938 model, 8 tubes/valves. Alas, there is no circuit diagram, or reference to one in Riders.

None of this should get in the way of the early health checks or basics of restoration.

Ed

[EdHolland]

OK, time to resurrect this thread. I put the radio on the bench today, for a first look, and pulled the chassis carefully from the cabinet. It is very rusty on top.

Points of note include

1) There is no back, and it is uncertain if there ever was one. I wonder if it could have had a set-back loop antenna
2) There are two unterminated wires protruding from the chassis, connecting in to the band-switch general area. Presumably antenna/earth connections of some kind - there are no other terminals provided for this on the chassis.
3) Someone has disconnected the old electrolytics and placed replacements under the chassis. This work was quite neatly done, so I will have to decide whether to restuff the old stud-mount caps, or replace the under chassis parts.
4) Lots of paper caps, and a few in tricky places beneath the bandswitch and the preselector switching assembly.

Next up will be a power and o/p transformer health check, and a think about what is needed in general. Also a sketch of the top and underside of the chassis. Still a big question is if/how to deal with the rust. Also to determine where the loose wires connect and their purpose.

The valves look OK, as they still have the last shop test tag on them from the mid forties....

[EdHolland]

Ah, also forgot to mention this radio will provide my first experience working with Candohm resistors. If there is a problem here, it will be interesting since without a circuit diagram and values, I'll be flying blind. Hey-ho-hum.

I need to get some pictures up here next, so there's something for you to look at rather than reading my blather.

[EdHolland]

There was time for a little action on this radio today:

   

   

[EdHolland]

Underneath:

   

[EdHolland]

And a couple of views of the chassis:

   

   

[EdHolland]

And so to work...

The first thing I noticed was that there is plenty to replace beneath the preset button and coil assemblies, so the wires were labelled and desoldered. I had hoped that the two parts could stay soldered together, but there was another connection to the coil frame that was beneath the whole thing. So 12 wires were dutifully desoldered, and then the two parts could be out of the way. This is safer overall, as the preset coils have very vulnerable fine wires.

I cut a circle of cardboard and covered the speaker, also drew out a diagram of the chassis, and checked off which valve locates in each socket.

The three electrolytics were removed from the chassis. I think I will restuff these, and remove the parts added beneath. The wiring looks to be clear enough - remember, I have no documentation to go on whatsoever.

The transformers were checked for continuity, and all test well, also the speaker field coil. The mains switch was cleaned, and with all valves removed, power was applied using the "dim bulb" tester. Not a flicker from the bulb, but the dial lights lit up, and all secondary voltages seemed in order. There's a good 350V AC on each half of the HT winding, so they meant business, feeding the two #41 output valves.

The tuning drive string broke, I've ordered some new cord. The mechanism confused me at first, there are two strings - one connecting the drum to the tuning shaft, the other connecting to the dial mechanism.

Lastly, I tested removal of the rust. It seems this might well clean up better than expected so gentle scrubbing with a kitchen scourer, plus rust removal gel will be pursued first.

Cheers

Ed

[Paul Philco322]

Naval jelly? Or do you have another brand? Always curious. Paul.

[EdHolland]

Loctite brand Naval Jelly.

It's the basic pink gooey stuff that uses phosphoric acid as the active ingredient. I've got about 1/2 the top area and most of the back looking more respectable now, and it will come up OK.

I also stripped the top of the cabinet, and started restaining it to reproduce an interpretation of the original colour. The rest will be left, as there are decals I do not want to disturb. Cleaning has done much to return a presentable appearance.

On the electronics, I'm just looking things over. Many of the paper caps don't appear to have values marked, but have manufacturer codes instead. This will take a bit of detective work. One idea I have is to bake to remove moisture. I tried this on an old, really leaky cap from my Philco restoration. While it won't return safe high voltage performance, leakage at low voltage reduced greatly - enough that the capacitance meter returned a value close to nominal.

More pics later.

Cheers

Ed

[EdHolland]

Here is the cleanup progress at close of business this evening:

   

It is coming along nicely.

Another thing that needs attention, the rubber grommets under the tuning assembly are flat and hard as nails, so that will come out shortly. This will also help provide access for chassis cleaning.

The paper capacitors - what was I thinking, those part numbers "05 - 400" suddenly made sense. 0.05uF 400V maybe   One less mystery!

[EdHolland]

Working from home gets in the way of radio restoration. I did get the top stripped, and experimented with restaining it. I'm not going to strip the whole thing, as the decals are in nice shape, and I value originality.

On the chassis, I was able to desolder the braids attached to the tuning cap bolts, and establish that they will loosen, and disconnected the wires from the antenna and oscillator sections. These are linked by a "gimmick cap" on the other set of solder tabs - something I have not seen before. Tomorrow, I'll remove the tuner assembly, and see what I have in the way of grommets, or rubber to make something for its return. Cleaning of the chassis can also be completed more easily with this stuff out of the way.

Cheers

Ed