Callins electrolytics

[ppppenguin]

How bad are the little blighters? The Thorn 2000 I'm restoring is full of them: http://golbornevintageradio.co.uk/forum/...p?tid=6396

I know they all will need to be changed but is it worth doing a mass replacement before I apply power to a board? Or should I just power up and wait for things to happen. I know that mass replacement can introduce extra faults but I'm pretty careful and reckon to be able to trace the faults if I make a mistake. I don't see the pont in trying to diagnose faults one by one when there are a load of dubious caps. It's not like mending a fault on a basically working set where mass replacement of parts is the sign of an unskilled repairer.

There's a very strangely rated one on the PSU regulator. C6 on the regulator PCB is a 1uF 350V Callins electrolytic. (Manual in archive if anyone wants to look). It's a decoupler on the output of the line timebase power regulator. The normal maximum voltage at this point is53V and it would never be more than about 65V even with gross misadjustment. Even under nasty fault conditions with the series pass transistor short circuit it won't go above 75V or so. I fitted a 1uF 100V electrolytic. Probably should have fitted a 1uF 100V polyester.

[pwdrive]

Thorn/BRC loved them, service engineers found them unreliable, at least I did.

Lawrence.

[Murphyv310]

Absolutely brilliant capacitors, never had an issue with them....... They failed constantly and kept me gainfully employed so no problem for me.

[Crackle]

I have had one or two still work ok, out of about 20 .
Look for a beige deposit around the base. I have even had some pop the plastic case of altogether.
Mike

[Murphyv310]

It's all down to your perspective. If the manufacturers used components that went on and on there would be no repair engineers.... agreed?
So if the components and designs were crap then we would be busy.
Today the components and designs are crap and prices low, plus the mindset you don't repair. So no matter what you think the Radio & TV trade is finished, gone forever. At least Callins and others kept us working.

[ed731pdh]

It's strange that capacitors from certain eras stand the test of time. When I restore a home computer, normally I recap the unit before attempting a power up, but there are a few exceptions. Capacitors from the early 80s seem to hold their own reliability wise and very rarely are found faulty in operation. However, capacitors from the mid 90s onwards I instantly tag as suspicious, they are just not to be trusted. As for 70s capacitors, well, enought of that.

[Aerodyne]

To mass-change or not - that is the question, right? Trouble is, Jeffrey, how reliable would any new replacements be?
On balance, I would change the lot, given the age of the receiver, but I'd want to find the opinions of others on the longer-term reliability of the make I chose to use.
Tony

[ppppenguin]

I'm thinking of changing the lot before running up the relevant boards. They'll all have to be changed anyway so why not just get it out of the way. The risk of introducing new faults by making mistakes is small for PCBs as against hard wired chassis. If I don't change them there will be a ragbag of odd faults, totally unlike a repairer would ever have to deal with back in the day.

I've got a lot of NOS good quality electrolyitcs of various makes. Mostly from redundant manufacturer's stock that was used for building professional equipment.

[Murphyv310]

If you have the required capacitors Jeffrey then you'd be daft not to replace them. Remember what I said, I used to love Callins caps as they kept me gainfully employed.

[ppppenguin]

The only question is whether to do a bulk change or diagnose the faults one by one. Either way they all have to be replaced (even if they're not causing an immediate problem) and on balance the bulk change is easier and quicker.