Discussion in 'Exclusively Sansui' started by P.Bear, Jul 3, 2018.
Hey Lee, thanks for your comments. Funny you should mention Silver Mica caps. In my searches I came across a site selling 2 & 3pF (+/- 0.5pF) 500V Dipped Silver Mica Capacitors, and 22pF 5% 500V Dipped Silver Mica Capacitors:
Would these work in the CA & Ba-F1's? And do you think it might be worthwhile as they are apparently on sale right now?
Yep, those ones as long as they are new, they would be fine, just check the lead spacing to make sure they're not big...
Well now you guys got me to dig out my amp and pull the covers to see if I still have the black flags. I do, I see a few of them on the two left and right boards on the bottom. Is that the only place they are at?
You really do want to get rid of those, and I would also hedge a bet that there is that corrosive glue in there as well, and that suff is even worse!!
It's a original amp, the cap glue is minimal from what I'v seen on amps and doesn't look like it's doing any damage,,,, yet.
But my question is, is the only location of the black flags the two small boards on the bottom?
Hey kevzep, the page doesn't give any size info except that the leads are 35mm long and based on that and judging by the pictures they are probably similar body sizes to the Black Flag caps.
Smart Ass [sorry it's all I had to work with], there are 5 on the F-2965 board and the same on the F-2966 board [2x 2pF, 2x 3pF, & 1x 22 pF on each for a total of 10]. Based on the schematics and parts list that should be all for the BA-F1. For the CA-F1 there appear to be10 more BLACK FLAG caps [4x 3pF, and 6x 22pF all 125 volt].
Well those Silver Mica at $0.89ea are certainly cheaper than I paid (around $2.70ea) - so they are only twice as expensive as the ceramic NP0/COG.
Thanks for the complete shopping list as I didn't know they where also in my CA-F1. Sorry to highjack your thread with my questions.
Just in case, very nice info about those little caps.
I just ordered the Silver Mica caps from www.justradios.com. With a few spares of each value the total w/shipping came to $30.04 USD [enough for both the BA & CA-F1]. I'll post here my experience with these when they show up.
The Silver Mica caps from www.justradios.com arrived today [ordered on the 9th, shipped on the 10th]. Turns out they are in Ontario Canada. I've attached a picture to give you an idea of relative sizes. Will have to set aside some time to swap them out. They appear to be perfect for the job.
Nice one, thats what you want. Good Job!!
I've used the same caps from justradios on several jobs and found them to be lovely, but have had it raised to me that in the long term silver mica might not be reliable. Is there are verdict on whether that old problem was really batch/geographic specific?
Depends, yes the silver does migrate over time and can cause the caps to short out. This was a problem in the Crown Macro-Techs, but it depends on quality and what sort of stress the circuit they are in is under.
So the question is: is a pre-amp or amp circuit considered stressful?
Here's the description from www.justradios.com :
"Silver Mica Capacitors made by "brand name" SIMIC. Simic Electronics is a world renowned producer of high quality ISO certified silver Mica Capacitors. SIMIC Mica Capacitors are designed to meet the exacting physical and electrical requirements of the MIL-C-5 and RS-153 specifications. SIMIC silver Mica Capacitors were MIL approved and QPL listed as early as 1985 and all capacitors are manufactured under strict ISO 9001:2000 quality systems. These dipped silver Mica Capacitors work well in the signal position, RIAA equalization/networks, feedback networks and tone control networks. Silver mica are also often in tube radios, TVs, Juke boxes, guitar amps and guitars. Two of the key benefits of silver mica are reliability and capacitance stability."
And the claimed specs:
Premium quality - manufactured from selected Indian ruby muscovite having optimum electrical characteristics.
Copper-clad steel leads are finished with a solder coating for excellent solderability. Long 35mm (1 3/8") straight radial leads for easy "under-chassis" installation in tube electronics.
Excellent capacitor replacement where tolerance & capacitance stability and high reliability are required, such as in oscillator circuits; logic and transmission circuits, DC voltage blocking, filters, delay lines and pulse forming networks.
Rated Working Voltage: 500 Volts and 1000 Volts DC.
Epoxy dipped for superior heat, moisture, humidity, shock, vibration and solvent resistance.
100% RoHS Compliant
Stability over full life of equipment
Low capacitance change with temperature.
Wide operating temperature range:-55C to +125C.
Capacitance tolerance +/- 5%, 2% and 1%. (1pF to 11pF are +/-0.5pF)
Available in "hard-to find" pre WWII MMFD sizes for tube based electronics.
Separate names with a comma.