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Model Eighteen Resurrection...(I hope)

hirscwi

hirscwi

AK Subscriber
Subscriber
I beginning the rebuild of a Model 18 sitting around for quite a while. I bought it from the original owners. He was in the navy and it cost a large portion of his salary.
But it was used and enjoyed for many years --- and then went into storage. I thought it would be great to resurrect it. It was absolutely filthy. Not as bad as some that I've seen displayed by BKtheKing and BLHagstrom, but very dirty:

Note: There is a happy ending to this saga - but you have to skip over some self-inflicted diagnostics.
 

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These are great receivers. The phono preamps are very good for their age. I enjoyed restoring mine. Good luck with the resto and keep us in the loop.
 
I spent quite a bit of time cleaning the unit with vacuum and brush. Some rust but not too bad. I repainted the case. The faceplate was not bad - all lettering was present. Same for the glass - all lettering present. I knew from previous AK threads that the lettering on the glass was easily destroyed so I cleaned it with a dry, soft cloth - and it worked.

My objective was to replace all the capacitors. All caps in my 18 were axial, so choices were limited. AK member Leestereo was extremely helpful in determining the replacements for the caps. I'm sure he spent several hours poring over the schematic to make his recommendations. If you are interested in the parts list, just drop me a PM and I will send it to you.

The primary replacement capacitor is the Vishay 138AML with some Nichicon VX also. The mylar "box caps" will be replaced by Kemet (RIFA) polypropelene film caps if they are in the signal path.

I have had good success replacing key diodes in the power supply (based on information here in AK (BKtheKing and Patfont). So I wanted to do the same to get the reduced background noise from soft recovery diodes. Again Leestereo generously helped me find the correct replacement s(actually he did all the work).

Now I'm off to start the replacement process...
 

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Many of these 18s (perhaps all) have a cut-out switch designed to prevent someone form electrocuting themselves if the case top is removed. It is activated by the screw in the center of the top/rear.

Also, it was clear that this 18 had been home to many spiders over the years (some carcasses remaining...
 

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First up - driver boards

I first tackled the driver PCBs because I didn't like the looks of the power supply (discrete, not PCB). They are easy to gain access and have only a few caps to be replaced.

C1010 gets bumped from .47mfd to 1 mfd - Kemet (RIFA) film cap, same form factor as original
C1004 stays at .47 - RIFA same forma factor

c1002 and c1005 stay at the same value but converted from axial to radial Elna Silmic II (RFS). This was against Leestereo's recommendation but I wanted tro try the Silmics in this unit. We'll see...

Before and after pictures:
 

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Sorry this post is out of sequence, but here are a few photos of the chassis after cleaning. Some portions still need to be cleaned after the parts are removed, but I'll do that as I proceed. I didn't want to remove all the caps, especially those not on a PCB, to make sure I got them back in the correct orientation.

Also a photo of the restored case bottom.
 

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Should have mentioned this at the start...

I'm sorry but I should have prefaced this thread with the following:

I am no expert at this. I no just enough to be dangerous (hopefully only to myself...)

I would greatly appreciate any and all suggestions. I have already researched as much about the Eighteen as I could find on AK. I do know that there's some serious voltage on the scope and will treat it with healthy respect (fear?).

I've heard fantastic things about the Eighteen's sound and want to experience it for myself. I like the idea that this is a one owner unit and had some real enthusiastic usage (read that "parties"). It's in such rough state that true historical restoration isn't the route I've chosen (not that I have those skills, anyway).

Please let me know if you have suggestions, criticisms, laughs, etc. I'd like to know if anyone has a desire to follow this thread or if I'm just sending my thoughts into the ether...
 
Nice job. Be very glad your glass is as nice as it is. I had to buy a repro glass for mine. Oh - the on/of switch on mine went. I understand it's a weak point. So be wary of yours.
 
I can only offer luck and encouragement. I'm pretty fond of my 18 and think you will really enjoy it when you are done. It's worth saving.
 
I did not fire this up prior to recapping because it was in such bad condition. So I don't know if the scope works or not - but hope springs eternal...
 
The caps that are currently in the 18 are Sprague, but I don't have a good source for those so I'm using the Vishay. They are reputed to be very nice. We'll see in a couple days...
 
Thanks, Ben. I got way-laid with a 2325 that I finally gave up on (took it to the professionals for the non-working FM).
 
Yes, I'm lucky about the glass. I seem to recall reading that the original Eighteen switches were red - and mine is black. So I think it's already been replaced. Time will tell.
 
There were two switches that came with the units- they are red and black. The red switches were on early unit, if you look at the 18 literature they were red. They had a habit of going bad and were eventually replaced with black ones, which are also garbage. My unit had the black switch- mine now has the red one and it's been fine , fingers crossed. Not all units came with the safety switch under the cover, Ed's did not, mine does. Does the scope work on your unit?
 
Disappointed to hear that both red and black switches are crummy. Mine does seem to cycle on & off (according to ohmmeter at least).

I don't know if the scope works because when I started it using dim bulb tester, both 25 watt and 60 watt bulbs burned brightly and stayed lit, so I didn't proceed any further. Will try again when it's rebuilt. I did look at the scope tube and it was silvery where I think it's supposed to be silvery. And I seem to remember that is a good sign, but not sure.
 
Just means the tube isnt gassy. Before you proceed and dump a whole pile of time and money check to make sure the scope tube is getting voltage, if the winding is shot its 200 plus shipping to get it rewound. An 18 without a working scope is worth half of its value.
 
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