What is an FTZ Coil?  - Page 1
Forum section: electronics / repair

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 08, 2018, 06:18:24 pm
content: I am repairing Nad 402 AM/FM tuner and I want to replace this part. Trouble is I can't find it.It has the following info:From the manual:Part number N56002296-S Coil FTZ Filter 10DFE01From the partSumida 10DF E01 S443 H023Any ideas ?Well, I am going to give this up for awhile. I cant figure out what's wrong and dont want to spend another frustrating minute on it until after i do another project or 2 with more of a chance of success.Thanks again for all the help.

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 08, 2018, 06:26:28 pm
content: http://www.ftz.pl/index.php?

author: Gyro
author_rank: Super Contributor
timestamp: September 08, 2018, 06:35:41 pm
content: Picture?It might just be short for filter. Hard to say without seeing it.

author: Terry01
author_rank: Frequent Contributor
timestamp: September 08, 2018, 06:41:57 pm
content: Quote from: Hextejas on September 08, 2018, 06:18:24 pm

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 08, 2018, 06:48:44 pm
content: Sumida is the brand, 10DF says something about the housing (see pic), the rest I have no idea.https://products.sumida.com/ProductsInfo/

author: Gyro
author_rank: Super Contributor
timestamp: September 08, 2018, 06:59:11 pm
content: Ah, ok.In that case it could be an IF transformer (coil is a pretty 'broad' term in a parts list), a local oscillator inductor or a filter. Physical location might provide a clue.Why do you want to replace it? It's not the sort of part that usually dies. As it's adjustable, you'd need to do some alignment after replacing it. I'd start by trying to figure out its pinout. as it will have have low resistance windings, you ought to be able to do it in-circuit if you're careful.

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 08, 2018, 07:10:41 pm
content: Physical location and the color of the adjust 'screw' can tell you which one it is, MW OSC is usually red, 10.7 IF orange etc. One reason I can see why it needs to be replaced is a bit too much adjusting where the ferrite breaks in half... been there, done that

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 08, 2018, 07:18:50 pm
content: Interesting, in the schematic it looks like a dime-a-dozen ceramic 10.7 filter but on the pcb it looks like a IF coil.So there goes my adjusting theory… I'd go with ceramic filter anyway.

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 08, 2018, 08:52:05 pm
content: Ok, here's the picture. And the reason that I am thinking about replacing it is that for this tuner, I got the AM working but not the FM. So I was replacing all the capacitors in the signal path (as best as I can discern it), and this thing is also in the path.

author: Gyro
author_rank: Super Contributor
timestamp: September 08, 2018, 09:06:35 pm
content: Ah ok, already out.In that case, I'd check for continuity map out continuity of the pins against the PCB footprint.If it's a 10.7MHz filter then it's probably an LC configuration.Bypassing in-out pads on the PCB might give some clue,otherwise try a 10.7MHz ceramic filter as PA0PBZ suggests (not sure how lossy they are in comparison).Hang on, checking the IC datasheets, aren't we past the IF strip by now - that's all handled in the LA1266, the LA3401 is the AM / FM switching and stereo decode. I don't think FL5 is 10.7MHz. Also leaky or reversed C56 would screw up the internal biassing of LA3401 pin 2. Worth a try. Have you checked that the AM/FM select pin (10) of the LA3401 is being driven correctly?

author: emece67
author_rank: Frequent Contributor
timestamp: September 08, 2018, 09:28:10 pm
content: .

author: Gyro
author_rank: Super Contributor
timestamp: September 08, 2018, 09:32:29 pm
content: Hmm, whatever is going through FL5 is then going through a 10uF non-bypassed electrolytic, the frequency can't be that high.

author: Gyro
author_rank: Super Contributor
timestamp: September 09, 2018, 11:04:02 am
content: I didn't realize this was part ofhttps://www.eevblog.com/forum/repair/i-am-trying-to-fix-this-fm-tuner/Please don't do that!

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 09, 2018, 11:30:54 am
content: Thank you Gyro, but I was just trying to make things easier on you good folks. The reason for a separate post is thatI didn't want to make you wade through all the "already fixed" issues I had with this tuner.Just a simple parts identification question.Maybe a mod could tell me if I did wrong.73

author: Gyro
author_rank: Super Contributor
timestamp: September 09, 2018, 11:59:09 am
content: Not so much a matter of 'doing wrong', more a matter of trying to work out what a part is in isolation, without datasheet and context.... followed by what does it look like, where does it fit in the circuit, oh, it's between these ICs, look up the datasheets, followed by....Time and effort and a bit of good will wasted. An in context reply in your other thread would have achieved an easier response from those already 'in the loop'.[EDIT: Actually, I see now that it's yourthirdthread on this tuner repair....https://www.eevblog.com/forum/repair/is-this-feasible-and-i-apologize-for-the-vagueness/, so maybe veering much closer to the 'doing wrong']

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 09, 2018, 12:59:03 pm
content: Quote from: Gyro on September 08, 2018, 09:32:29 pmAh yes, it is audio, so it probably is some kind of low pass filter with a 40KHz cutoff.

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 09, 2018, 01:41:49 pm
content: Quote from: PA0PBZ on September 09, 2018, 12:59:03 pmIt seems that I ruined the part while taking it out so I am going to wire a jumper in its place and see what happens.The last time that I had the tuner plugged in and working with AM I took some voltage readings with these results.LA3401Pin 2 = 2.9VI replaced capacitors C40 and C56I had it tuned to 91.7FM, a local C&W station. There was another light on the panel that was on and it was "Center Tune".

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 09, 2018, 01:47:28 pm
content: One more thing is that I have an oscilloscope that I am testing and I was wondering where in the schematic I would put it in order to see the FM signal ?thanks

author: Simon
author_rank: Unknown
timestamp: September 09, 2018, 07:59:41 pm
content: Quote from: Hextejas on September 09, 2018, 11:30:54 amHaving multiple threads about the same thing will lead to confusion and frustration. If it's a large topic and things change over time the best thing is to post updates on your initial opening post which you can do by editing the post.