Nice little Martel FAX-200C receiver... early Rotel!

[Primotubes]

I tried out a 4.7uF 450V cap. Negative side to ground and she smoked and popped when I got the variac up to 80V.
There's another picture of it (looks original) in the first post in this thread but I can't zoom in and see what the value is and exactly where she goes.

The AC line noise capacitor is usually of a value around .01 to 0.1 uf of an AC rated voltage.

 

[gadget73]

If thats from power line to chassis, I'd go with an 0.01uf 250vac Y rated capacitor. An XY is also fine.

 

[Primotubes]

If thats from power line to chassis, I'd go with an 0.01uf 250vac Y rated capacitor. An XY is also fine.

Hiya, Gadge, thanks for clearing that up. I finally recall that this type of cap is called a "safety" cap, which is designed to not energize the chassis if it fails. In other words it fails in the "open" position. Which is not true for the vintage "death" cap encountered in many classic tube amps. Cheers.

 

[laborer75]

If thats from power line to chassis, I'd go with an 0.01uf 250vac Y rated capacitor. An XY is also fine.

I know I have to replace the two 100mfd 150V can caps. You can see them bubbling up on the bottoms. I did find a schematic for a FAX-150C which indeed shows 0.01uF for the missing cap.
Time to order some stuff. Thanks guys!

PXL_20220520_202140057

• laborer75
• May 20, 2022

 

[Primotubes]

I know I have to replace the two 100mfd 150V can caps. You can see them bubbling up on the bottoms. I did find a schematic for a FAX-150C which indeed shows 0.01uF for the missing cap.
Time to order some stuff. Thanks guys!

Hi. You should also upgrade the 2 rectifier diodes in the voltage doubler circuit that are shown in your picture. I like to use a fast recovery epitaxial diode which is better, less noisy, than the silicon diode that is used in your unit. They are available at Mousser for only a few dollars each.

 

[bgp83]

Old thread but does anyone have a good copy of the fax-200 schematic?

 

[jerrysstereo]

Here's the best resolution I could upload

 

[jerrysstereo]

If you DM me I can send it in better quality.