TCC electrolytics

[ppppenguin]

I have been given a quantity of NOS TCC electrolytics which I will be selling at Retrotech to raise funds for the Broadcast Engineering museum. The cans are about 11cm long and just over 3.5cm diameter.

They are 100uF + 400uF + 32uF all at 300V. I'm trying to work out where they might have originally been used. The values are rather high for a radio so I'm guessing a TV. The 32uF section seems a bit odd. Could it have been intended as a cathode decoupler, though it wouldn't have needed a 300V rating.

The 300V rating seems a bit low for a halfwave rectifier directly from the mains though once load current is drawn it should be OK.

Any ideas as to their original use?

I will test a few to check that they will reform well. Then I'll work out a price for Retrotech. There will be generous quantity discounts.

[`FRANK.C]

Hi Jeffrey
I would think they are for TV. Maybe silicon based TV rather than Valve.
See photo below of NOS RS TV can. 100 + 400 + 16uF It is rated at just 275V.

Frank

[ppppenguin]

Hi Frank, I'm sure you're right. 100uF is the reservoir, 400uF is the smoother but what's the small one for?

I've now reformed a few and they've all been good.

[Mike Watterson]

Hi Jeffrey
I would think they are for TV. Maybe silicon based TV rather than Valve.
See photo below of NOS RS TV can. 100 + 400 + 16uF It is rated at just 275V.

Frank

I had a vague memory that the old TVs I worked on used only 275V rating rather than 350V.

I also thought those seemed like TV types. They'd also be useful for a custom new valve amp build as long as unloaded HT was less than 300V, though that would be 212V AC max.

The big TV cans exploded nicely when a BY127 failed short...

[Mike Watterson]

Hi Frank, I'm sure you're right. 100uF is the reservoir, 400uF is the smoother but what's the small one for?

On a TV looked up randomly on R&TVS, it decouples the ECH84 (multivibrator), which drives the PL36 LOPT.
Pg 344 & 345, 1964-1965 models, a range of Defiant TV models (i.e. Co-op?). It claims the 1st section at rectifier (BY100 or S10AR2) has 235V, but it's fed by 7, 9, 18 and 20 Ohm taps for 200V to 240V mains.
100, 32 & 400 sections. No voltage rating mentioned. Oddly a fuse between L1 choke (on 100uF) and 400uF section rather than at rectifier. However there is a main fuse for entire set just after the on/off switch.

[Murphyv310]

Hi.
The 300v rating is the peak working voltage "NOT" the surge voltage that of course is higher, the surge volts was gradually withdrawn from TV caps. 100 x 400 x 32uf was common the 32 often to decouple line osc or audio stages.

[ppppenguin]

Thanks, Trevor. You (and Frank) have worked on many more TVs than the rest of us.

When I was reforming, I tried one of the capacitors at about 350V and it was fine. My Solartron SRS153 is good for this. It can get to almost 600V on light loads if needed. My recently acquired Farnell E350 only goes to 350V though it's properly regulated - the SRS153 isn't.