jsteiger

Re: [BUILD] CAPI FC526~500 Series~FET Limiter Kit~Official Support Thread
« Reply #460 on: November 06, 2019, 03:15:34 PM »
Hey guys!

I'm building two FC526 and both are measuring really well on the different test points, compared to Test Points Guide Rev_2 and Calibration Guide Rev_1 until ** Gain Reduction Meter Calibration ** where I have reached. However, I do measure -10.05 on TP9 which is a bit more than the guide prescribes (between -9.98V DC and -10.02V) Is that ok?

And a bummer.. After I finisted building these two, I saw that there was this visual guide, at the beginning of this thread, and discover that there is a certain polarity side to the diodes!
..I got those in there 100% random on those meter boards. doh..

Is there a way I can test which side of a diode is what, or is it easiest to just order 2 new batches of diodes?
-10.05 is OK

The arrow on the PCB silkscreen points to the end of the diode with the line around it. The part #'s are also written on the side of the diode's body. Pics at this link will help you identify the parts properly.
https://capi-gear.com/catalog/Build_LC25-40_Rev_A.php#Sec2A
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CAPI is not affiliated with, endorsed by, or sponsored by API.


Thunbo

Re: [BUILD] CAPI FC526~500 Series~FET Limiter Kit~Official Support Thread
« Reply #461 on: November 07, 2019, 02:21:35 PM »
The arrow on the PCB silkscreen points to the end of the diode with the line around it...

Hey Jeff!

Sorry! I meant the LEDs.
I was so focused on having them sitting nice on the front panel, I just went total autopilot - mounted them randomly.
I read somewhere that if one in the string sits wrong, the chain of light stops. The first device lights up as far as PK, 0, .05 and 1. The other does not light at all.
Mathias Thunbo - Denmark

jsteiger

Re: [BUILD] CAPI FC526~500 Series~FET Limiter Kit~Official Support Thread
« Reply #462 on: November 07, 2019, 02:48:36 PM »
Yes they are in a string so the a backward LED will stop the flow to the rest that follow it.
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CAPI is not affiliated with, endorsed by, or sponsored by API.

jsteiger

Re: [BUILD] CAPI FC526~500 Series~FET Limiter Kit~Official Support Thread
« Reply #463 on: December 16, 2019, 08:42:00 PM »
So, an interesting story that I thought I would share. A customer bought 2 kits and had a "tech" build them. One worked fine and the other he could never get the meter to calibrate. I guess the "tech" messed with it for a while charging the original buyer but never fixed it.

The 2nd "tech" had it and said it was hard to bias the VVR FET. He got another pair of FET's and still never got the meter calibrated.

The 3rd "tech" noticed that the 2.5V reference voltage on the meter PCB was around 2.78V. He was the first to mentioned this issue. I sent him a new 2V5 precision reference IC as well as three new LM339's. He said he could not replace the comparators because his hot air rework tool was melting the LED's.

All of this was happening and the original buyer swore up and down there was a "bad part" supplied by me on the build. For the first time ever I said "send it to me".

30 seconds into looking at the build I noticed that the original builder apparently swapped the 2k2 bias trimmer with the 100k meter range trimmer. Once we righted that wrong...everything was A OK.

So folks, don't forget to check ALL of your parts if you are having trouble with this build.
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CAPI is not affiliated with, endorsed by, or sponsored by API.


 

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