Has anyone rebuilt a Scott fm tuner?

[nervous novice]

If so, I have some questions.

1. I would like to know how to replace the selenium rectifier.

2. Does anyone know where I can get the 4x40/250 volt and 2x40/250-25-25 electrolytics? Or is there a more modern alternative?

3. Are there any suggestions on which type of resistors to replace the carbon comps, (metal film etc. )? Or should I replace them with more carbon comps?
I am not necessarily interested in keeping it stock , I just want it to sound as good as I can get it.
 Any advice would be greatly appreciated.

Thanks in advance.
N.N.

[Grainger49]

No, I haven't rebuilt a tuner, ever.  But I can answer some of your questions.  

1) The selenium should be disposed of properly, it is toxic.  You can put in a diode.  Just verify the voltage rating and the current rating.

2) Try Antique Electronic Supply (http://www.tubesandmore.com/) or Angela Instruments (I couldn't get the link to open) for the caps.  An alternative is to leave the can and put modern electrolytics under the chassis.  DO use a slightly higher voltage rating than specified.  The tuner was built when 110V was the norm, 125 is close to the norm today.  That is a 13% increase.

3) Carbon comp resistors are notorious for noise and changing their value with heat cycles.  These are a bad thing in tubed designs.  But that is what was available when the tuner was built.  There are people who like the sound, but it is more the circuit becoming out of spec than anything else.

Metal film is a good replacement.  If you can determine what resistors are in the signal path you can substitute "designer" resistors.

[howardnair]

i won't say i have rebuilt a Scott- but yes i have replaced the can caps and selenium rectifiers/coupling caps and a few other things on several--be careful what you do!! fm tuners are sensitive creatures-i have  a couple of the scotts  a LT 110- a 350-and a winter project a 330b fm am simulcast--the hh scott site has schematics and the audio asylum has people to help-when you change the selenium rectifier you most likely will need to add a resistor in the circuit to compensate for the more power the diode will pass
tube depot
tubesnmore and
http://stores.ebay.com/CTech-Electronics?_trksid=p2047675.l2563
these guys i use often
let me know which tuner you have iand i will point you in the right direction you may email me direct

[Wanderer]

While we are talking Scott tube tuners:

I have a 370 tuner that a buddy gifted me with. It is in lovely visual condition but I am thinking it needs realignment as the reception is not very good. 

I can handle cap and resistor replacment and power supply updates but alignment is beyond me. Any suggestions on a Tech who is a Scott tuner specialist? 

[nervous novice]

Grainger,
Thank you for your response.
I see that some of the carbon comps are not measuring what the schematic calls for and some of them I get continuity when I touch both sides of them , with my meter set on diode. I thought that I would start replacing those first with metal films. These are

[Grainger49]

N.N.

I wouldn't increase the wattage.  Metal film resistors are inexpensive today and sound very clean.  

I didn't mean to completely run down carbon composition resistors. Bottlehead uses them for grid-stopper and plate-stopper resistors.  Their characteristics are perfect for that application.  

The whole changing value thing is what truly drives me crazy.  Those were mostly 10% tolerance, 5% in critical positions.  Carbon comps were completely unavoidable when Scott built the tuner.

Today's metal film can be had with higher temperature ratings and higher tolerances. 

Kevin you have a PM.

[howardnair]

http://hhscott.com/cc/tuner_tips_FM_stereo.htm--here is a little help before you send a tuner off for alignment--also make sure your tube pins are clean and if you can open the actual tuning capacitor-dust that with a clean soft paint brush-and a tiny tiny bit of grease on the bearings on each end will also help as it gives a better ground-be careful changing resistors in the radio circuit-thats when its gets fussy-you can fool with the adjustments a little bit on the actual tuner-but the other ones are also fussy --

[2wo]

NN,

Replace the can caps and the selenium rectifier. Then have a listen, before you start replacing resistors, not saying you won't have to but its a lot of work and plenty of chances for things to go wrong...John