Vintage Asylum

restoring a Pioneer F90, is this component bad?

68.108.173.65

ltman

A

I like the sound of the F90 but every 20 minutes or so it produces a medium loud "popping" sound.
So I went ahead and purchased a cap/transistor replacement kit from a guy in Australia(!). Although I haven't checked the kit, I doubt it includes the component shown in the pic, which is the only component that looks bad visually to me.
I guess that will be the first test for my new Hakka desoldering vacuum.
Diode I guess? I have the service manual but I am not trained in electronics and this schematic is a bit complicated for me, I am really just a DEOXIT technician :)
Can anyone advise? Certainly looks bad. It is not broken or crumbly, just has that ugly crust on it.
I do have schematics in the sm I could photograph...

Edits: 01/14/24

Follow Ups:

Funky Looking Component - Triode_Kingdom 07:09:10 01/15/24 (1)
The pictorial in the service manual refers to that as L7, a 100uH choke. However, the schematic denotes L7 as a 2.2uH choke. This part feeds DC tuning voltage to the FM oscillator varactors D1-4, so I'm not sure which value is correct. Mathematically speaking, the XL of a 100uH choke provides greater isolation between the RF at the diodes and the DC tuning voltage. OTOH, it's possible the higher SRF (series resonant frequency) of the smaller value choke is being utilized. A 2.2uH Bourns axial molded choke (part no. 78F2R7K-RC) is specified with a SRF of 95 MHz, which would be about right. In any event, I suspect this isn't the problem. The odd appearance is likely only aging of the varnish used to protect it from humidity and such.

FWIW, I've stopped working on vintage digital tuners due to the large numbers of proprietary ICs and other components that are now unavailable. It's simply not worth the troubleshooting time and effort, so when mine fail, they go in the trash and I buy a replacement. I've discarded a Luxman and a Fisher in just the last few years because of this. The latter was a superb performer with a sound quality that's rare in PLL designs. My current tuner is a Denon TU-660. It needs a new memory capacitor, but otherwise works well. I seldom use FM broadcasts as a source, so I live with this minor inconvenience. My advice in your situation would be to look for a replacement.
- RE: Funky Looking Component - ltman 10:24:47 01/15/24 (0)
  thank you, point taken re:obsolete components. this unit is mostly an exercise for me in practicing my component R&R technique, so if it does end up in landfill I won't be too disappointed. I finally sprung for a Hakko desoldering station and what a difference vs. the plunger types.
  
  I am emberrassed to say I do have 6 other tuners - two Sony XDR-F1HDs (one with the full monty mods by the XDR guy and one where I simply removed the undesirable filter caps that kill the HF response), two Sony JT-75s (one needs an alignment, one sounds perfect), one Scott 112B that sounds very musical but has a small amount of hiss in stereo reception on my favorite relatively weak station), and one Dynaco FM-3 that I did some work on,eliminated all the hum,sounds great, but I will do more restoral including pec upgrade.
  
  The F90 sounds fine except for the "popping". If I can fix it I will see if I can give it away to another poor retired guy like me who loves classical music.
  
  Ping me in a month or two if feel you qualify ;)
RE: close up of the part - ltman 15:51:47 01/14/24 (2)
wire resistor?
- Given that it's a tuner... - 1973shovel 03:13:21 01/15/24 (1)
  I'd suspect that it's a coil of some sort, with glue applied to secure the coils. I'm speculating, of course, without the schematic.
  
  Doesn't your service manual show drawings of the individual circuit boards? For example, my Marantz service manuals contain drawings like this
  
  ...in addition to the schematics, which makes identifying individual components easier.
  - RE: Given that it's a tuner... - ltman 10:08:26 01/15/24 (0)
    it's one massive board. I can understand simple schematic circuits but this one makes me dizzy.
    
    I will check continuity and if good will leave it alone.

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable