Capacitor replacement

[bulgin]

Hi

I have found a supplier for two 10'000mfd 63vdc electrolytics I've been advised to replace on my 405. The replacements' dimensions are almost identical to the originals (only 1mm taller) and the supplier claims they are 'good quality - no comebacks' ever. (Most likely Chinese...)!

The replacements' are however rated @ 100vdc. Will it be OK to use these?

At this time, I don't want to disturb the looms and connecting wires to the caps and just want to unbolt the clamprings and desolder the wires. No cutting. Is it safe to desolder incircuit capacitors which will carry a charge of some kind? Obviously observing polarity on replacement and no shorting between + and - !

I'm also replacing two brown caps on each circuit board marked '100/16'. Would it be OK if these are substituted with same value replacements?

Thank you for any advices.

bulgin

[mrshow4u]

Hi Bulgin, pardon my ignorance, is this a Quad 405?? If so, I'll see if I have that schematic.

[AndrewT]

Hi,
the electrolytics of higher voltage will not come to any harm when you swap over. But 100V caps are usually twice as expensive as 63V caps.

Allow some time after switch off before opening up. The amp will partially discharge the caps for you.
Have you got some resistors? Any value from 1k0 to 10k will do.
Use them to CAREFULLY discharge the caps. Be very careful you do not short the cap terminals together.

Once discharged you can safely unsolder.

BTW 10,000uF =10mF


The brown 100/16 are likely to be polarised 100uF 16V. Can you identify any more information? or use the schematic that Mrshow is trying to find/post.
I think the 405 sch is allready on the Forum, have you tried searching?

[anatech]

Hi bulgin,
Your email is not turned on. Anyway, the 405 schematic and complete mods are all out on the web.

All the information Andrew has given you is correct.

-Chris

[bulgin]

Guys, Guys Thank you!!!

I'll reply later and let you know what's up. I've got 2 big caps branded 'Kendeill Made in Italy' . Hope they fit as (as usual) the supplier quoted me with solder tags but they have screw terminals on top. All black 'n gold and each have a peculiar soft rubber button on top.Would this be for discharge or a plugged hole through which they p## in your eye if you treat them wrong?

I bought the 4 smaller ones too (2/per pcb) and of the correct replacement value.

I'll be here later to let you know the outcome!

bulgin

[anatech]

Hi bulgin,
The soft rubber is the safety vent. If the cap gets overheated, that seal will blow. Capacitors are not good anymore after they have vented.

-Chris

[bulgin]

Hi Everyone

It is 9.50pm here in Cape Town and I'm about to start. Thanks too, to MrShow4U. I'll post a bit later. I'll try do fix my mail.

Thanks

bulgin

[mrshow4u]

Hi Bulgin, I looked but couldn't find that schematic. I found this link. It might help. The last page has the schemo. Apologies if somebody else has posted the same link <http://quad405.com/405mods4.pdf>

[bulgin]

Hi mrshow4u, anatech

The job is done! Thanks for all the help here!!! It took longer than expected (finished at 5.30am this morning) but I worked carefully and everything looks nearly like Quad made the 405.

The big electrolytics I replaced were the same dia as the old items but the height was a few mm more despite the screw terminals and JUST clears the lid.

I also re-fitted the small pcb behind the speaker posts, for better or worse...

I even had a chance to shamelessly copy an esteemed diyaudio member's idea - I changed the red led 'on' indicator to blue. The only trouble here is it's far too bright and I will have to change the led's resistor to another value. I measured the resistor's value as 2.69Kohm? and hope to get some advice for a higher value to dim the blue led a bit.

I also did not know the second small caps' value on each pcb. I replaced only the 2 100/16's and found the other two's value is 47/40 and will have to get these today and fit them.

@ The problem with my email? Is it my email at DIY or at listen@blueangelaudio.com?

It could be that draconian spamblockers and Norton could be causing the problem.

I'd love to send some pics for those interested and will check again how to do this later.

I again would like to thank all here at DIY for advice and your interest. Thank you all!!

bulgin

[bulgin]

Hi

Sorry I forgot AndrewT! Thanks Andrew!!

bulgin