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Old 31st March 2014, 04:09 PM   #3081
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best
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Old 31st March 2014, 06:12 PM   #3082
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it ´s back up on regular supply now...
running bias procedure
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Old 3rd April 2014, 09:03 PM   #3083
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Hi

Had my regular F5 now for a year. Sound is great, however this evening I turned it on and heard a crackling sound. Took the lid of and saw a small spark coming from the + terminal of one of my Fairchild bridge rectifiers. I guess the part is fried on the inside and needs replacing?
My heatsinks are only 4" tall by 14 long, which mean the amp is hot to touch 50deg C and pretty warm inside. The rectifiers are screwed on to the bottom aluminium plate of the amp chassis.
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Old 5th April 2014, 05:37 AM   #3084
auxie22 is offline auxie22  Australia
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Default FQA12P20 and FQA19N20

Hi All,

I am not sure if people know of this company that do end of life parts but I found that they stock the FQA12P20 and the FQA19N20. here is the link:
Active and Obsolete Parts and Semiconductors - Rochester Electronics

According to the site they have 1000+ of each. I'm getting a quote as we speak for 25 of each.

Last edited by auxie22; 5th April 2014 at 05:38 AM. Reason: spelling
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Old 5th April 2014, 07:59 AM   #3085
Liliya is offline Liliya  Norway
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Price? It is always an interesting matter.
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Old 7th April 2014, 12:49 PM   #3086
generg is offline generg  Germany
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Mind that they offer only the FQA19N20 L

The L type has a much lower Vgs threshold and a very high transconductance value than the type without suffix or the C type.
Matching them with the P type could give a very high 2nd harmonic distortion.
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Old 7th April 2014, 02:04 PM   #3087
Tea-Bag is offline Tea-Bag  United States
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I use the TO-220 FQP because they are still in production.
Me being paranoid and anxious of fakes.
Quote:
Originally Posted by auxie22 View Post
Hi All,

I am not sure if people know of this company that do end of life parts but I found that they stock the FQA12P20 and the FQA19N20. here is the link:
Active and Obsolete Parts and Semiconductors - Rochester Electronics

According to the site they have 1000+ of each. I'm getting a quote as we speak for 25 of each.
Quote:
Originally Posted by generg View Post
Mind that they offer only the FQA19N20 L

The L type has a much lower Vgs threshold and a very high transconductance value than the type without suffix or the C type.
Matching them with the P type could give a very high 2nd harmonic distortion.
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Old 7th April 2014, 02:18 PM   #3088
generg is offline generg  Germany
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Default FQA19N20 L

look here can you see the difference between the L types left and the C type right side…

:-)
Attached Images
File Type: jpg FQA19N20 L und C im Vergleich.JPG (384.8 KB, 246 views)
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Old 12th April 2014, 04:00 PM   #3089
SRMcGee is offline SRMcGee  United States
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Join Date: May 2004
Location: Wynnewood, PA
Folks:

I'd appreciate your advice regarding fuses on an F5T V2. The amp includes the following:

120 VAC mains
diyAudio soft start board v2, with four 75R power resistors and a 1uF X-class cap in the C9 position
1000 VA SumR toroid with 24 VAC secondaries
Dual bridges, sixteen 10,000 uF Nichicon KG caps in the power supply
diyAudio F5T boards, MOSFETs biased to .9 A
diyAudio speaker protection board v2
DC offset of under 2.0 mv

I've been using 4 Amp slo-blo fuses and every once in a while they blow. Should I be using 5 Amp slo-blo fuses or is there a problem that needs addressing?

Regards,
Scott
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Last edited by SRMcGee; 12th April 2014 at 04:07 PM.
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Old 12th April 2014, 04:02 PM   #3090
6L6 is offline 6L6  United States
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Scott, are they failing at power-up or just randomly?

Regardless, if there is nothing seeming to be wrong, use the 5A slow-blow.
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