Hello All,

Another project has arrived & is under the "knife"---Sony TR-818...

Wanted one quite awhile ago, but gave up until what seemed to be a really good deal showed up last weekend... But pic was a little fuzzy & seller not "radio minded", so got a few surprises...

Worst of all was that someone had poked many holes in grille cloth with what looked to be a ball-point pen---looks like the aluminum front panel is glued to case and would be next to impossible to remove to allow replacement... Looked like dirt specks in seller's poor pic... Thankfully speaker is okay...

Batteries had leaked at one time and a lot of dried residue in bottom of case... Again, bottom edge of speaker frame has some corrosion, but speaker alright...

Concentric tone & volume control shafts are frozen together & very stiff---but radio does work...

Noticed adhesive residue below dial as if a label was there at one time---don't think I've ever seen one with it... Anyone have one with this label ?

Anyone have experience removing front panel without damage ?

As always comments welcomed... Will post pics & progress as soon as able...

Thanks.
John

Another challenging project...

Had quite a bit of battery leakage residue to clean---some a rusty/crusty mess... Fortunately no damage.

Took a bit of time & care, but removed glue residue below dial where a label had evidently been---sure improved appearance... Still hope someone will have info on what it originally looked like & said. Have not noticed a single one of these which still has it intact...

After cleaning & drying with compressed air, the holes in grille cloth are less noticeable since threads moved back closer to original position.

Removed volume/tone ctl, hung it on edge of small container & soaked shaft in isopropyl alcohol which freed up concentric shafts bind---went through three cycles of soaking & stop to stop rotation. After thorough drying, lubricated with a few drops of Faderlube allowing each one to soak in---cleaned off excess & both shafts now turn very smooth & easy...

There were several dead spots on dial accompanied by loud scratching sounds---disconnected ground connection to tuning cap & with meter found that the "antenna" section plates were shorting at several locations---after a tedious period of time carefully shifting rotor plate positions, got it working correctly...

The tuning needle is off about 30 kHz across dial & radio appeared to have been open before, so think someone may have pulled tuning knob and got gear position in tuning mechanism one tooth off---radio is no fun to diasassemble, so will "tackle" this at a later time...

And lastly, noticed an unusual component mounted on PCB---mounted with a long screw, it looked like a tubular ceramic cap with a small tubular ferrite "bead" above it... Didn't take time to trace connections to see where it connected---need to find the Sony schematic for this one...

Radio performs very similar to TR-84, but the gear drive tuning is much more stiff... Audio is better & tone control has fairly wide range... And it is a neat looking, well-made set...
Getting the normal Grand Ole Opry "burn-in" as this is posted...

Here are the pics:

Nice looking radio there John.

Wish I could send you a schematic, but I'm missing TSM-27.
I'm curious about that mystery part there.

~ Mitch ~

How about a closeup of the component?

Posted for a limited time only:

http://img31.imageshack.us/img31/6598/img0002gd.jpg

http://img715.imageshack.us/img715/9093/img0003ph.jpg

http://img151.imageshack.us/img151/142/img0004wlr.jpg

http://img560.imageshack.us/img560/9117/img0005av.jpg

.

Thanks much Mitch & Wiscojim...

Below is enlarged pic of "mystery" part---not that great, but no time right now to get out camera & disassemble radio... The "head" of screw is at lower left of pic, the yellow sleeved wire attaches to a lug between ferrite & ceramic looking pieces...

Edit: Wiscojim's Photofact scans D/L'd fine on Firefox---excellent quality ! Thanks very much !

"Mystery part", C21, is actually a 3-12 pF adjustable cap between RF amp transistor input ( base ) and anode of mixer diode M4

And---pic of radio on first page shows label below tuning dial, marks volume "window" and has "Super Sensitive" script...

John

I have the factory service manual, so if there's something the Sams doesn't have, PM me
and I can send scan with higher res than be posted.

Thanks much Steve---sending PM... Would like to know Sony's factory alignment instructions including that adjustable cap ( C1 ? )...