Recapping T-85 Tuner - 10uF Capacitor Selection?

[MarkyM]

Hi,
I'm recapping my T-85 tuner and am wondering what type of electrolytic cap I should use for the 10uF/16 Volt caps. There are 14 of them, none of which are in the audio path.

They all seem to be used for decoupling or filtering to ground.

I have a bunch of Nichicon UKL Low-Leakage but should I be using UPM/UPW Low Impedance/Low ESR instead for this?

There's one in the Divider section of the Front End:

Several in the power supply:

And a few in the AM section:

Thanks,

--Mark--

 

[amr2]

Hello

I used Nichicon FC for all of them

 

[MarkyM]

Hello

I used Nichicon FC for all of them

Hello and thank you.

I don't see an FC series from Nichicon, only from Panasonic. Per the datasheet, they are 105 degree, low impedance, long life like the Nichicon UPM/UPW series.

 

[amr2]

Sorry, I mean Panasonic

 

[amr2]

Yes Panasonic FC is more or less like Nichicon PM/PW. And Panasonic FM like Nichicon HE

 

[MarkyM]

Thanks.

So low-impedance / low ESR is more important in this decoupling/filtering application than low-leakage?

These two traits seem to be mutually exclusive.

 

[amr2]

IMHO low leakage is not necessary, but I'm pretty sure that both types will do the job fine. Any of them have better specifications than the originals. In any case, I'm not a tuner expert...

 

[MarkyM]

Thanks. that's what I'm thinking as well. I'll post this in the general discussion forum to see if I can get some cap experts to respond.
Tuner or amplifier, same thing in this regard.

 

[rcs16]

For dc filtering use low esr types. For the 1000uf in the ps doubler, I suggest highest ripple current. For the o/p use a UES BP type

 

[MarkyM]

For dc filtering use low esr types. For the 1000uf in the ps doubler, I suggest highest ripple current. For the o/p use a UES BP type

Thank you,
I have ordered low impedance / low esr UPW’s for all of those 10/16’s that are circled.

 

[rcs16]

UPW is fine for all polarized ecap positions
You could add c137 in the rf section, a nice red wima fkp, for even more supply filtering
Are you replacing all the ecaps or only that 10uF value?
Show a pic of your results

 

[MarkyM]

UPW is fine for all polarized ecap positions
You could add c137 in the rf section, a nice red wima fkp, for even more supply filtering
Are you replacing all the ecaps or only that 10uF value?
Show a pic of your results

Thanks.

Yes, I'm replacing all of the electrolytics.

And all of them 4.7uF and below I always replace with WIMA or Kemet film caps.

Here's my full, updated cap BOM with the 10uF UPW's:

1 Qty. 1 Nichicon LKG1E472MESZAK 4700uF 25 V RADIAL: C357
2 Qty. 5 Nichicon UHW1C102MPD 1000uF 16 V RADIAL: C259, C260, C261, C262
3 Qty. 3 Nichicon UHW1E102MPD 1000uF 25 V RADIAL: C359, C362, C363
4 Qty. 1 Panasonic EEU-FS0J472 4700uF 6.3V RADIAL: C333 (memory backup)
5 Qty. 1 Nichicon UPM1C221MPD 220uF 16V RADIAL: C344
6 Qty. 2 Panasonic EEU-FR1C101B 100uF 16V RADIAL: C343, C348
7 Qty. 1 Nichicon UPW1C330MDD6 33uF, 16V RADIAL: C132
8 Qty. 6 Nichicon UPM1C470MDD1TD 47uF 16V RADIAL: C253, C329, C330, C349, C352, C355
9 Qty. 14 Nichicon UPW1C100MDD 10uF 16V RADIAL: C130, C215, C285, C291, C303, C305, C322, C340, C342, C350, C351, C353, C354
10 Qty. 2 Nichicon UHE1H220MDD 22uF 50V RADIAL: C347, C359
11 Qty. 1 Nichicon UPW1V220MDD 22uF 35V RADIAL: C346
12 Qty. 1 Nichicon UPW1C220MDD 22uF 16V RADIAL: C356
13 Qty. 7 WIMA MKS2B041001C00KO00 1uF 50V 10% RADIAL: C298, C315, C316, C320, C324, C339, C345
14 Qty. 4 WIMA MKS2B034701B00JSSD 0.47 uF 50V 5% RADIAL: C203, C295, C307, C336
15 Qty. 2 WIMA MKS2B044701K00JSSD 4.7 uF 50V 5% RADIAL: C296, C309
16 Qty. 3 WIMA MKS2B043301H00JSSD 3.3uF 50V 5% RADIAL: C317, C318, C328
17 Qty. 2 Nichicon UES1H100MPM 10UF 50V BP RADIAL: C279, C280

Pics will follow when done!

 

[MarkyM]

The recap is complete. This tuner is exceptionally easy to work on with the 2 circuit boards suspended basically around the edges by the unit's frame chassis after removing the top cover and bottom panel.

Pics:

Here's a mod. I removed the stock ceramic filters for the Narrow and Super Narrow modes, added 3-pin sockets and loaded newer 180kHz Murata GDT filters. More gain and flatter response!

Nicely laid out with a separate Front End board:

As I said before, all electrolytics 4.7uF and below were replaced by WIMA film caps:

Overall top view:

Power supply section:

Next up: Alignment using my trusty Sencore SG-80.

--Mark--

 

[Blue Shadow]

56 caps, wow. Regular receivers have about 85 and 100-watters maybe 20 more. That is a lot of caps. I've opened a few pieces and just closed em back up when I saw the piles of caps. The Citation 25 preamp is one. The Yamaha C-4 had over 80 but a bunch were on a board that comes out easily.

Glad you got it done. I don't see anything special other than the use of films at low capacitance and the bipolars. Let us know how it goes after the alignment.

 

[rcs16]

Good job, they are a well designed and easy to work on tuner.
I wonder if the new filters change the thd numbers or improve the selectivity.
Over on the fmtuner forum they are experimenting using the smt ones you can get at mouser. They report the filters have better characteristics than the older leaded ones. There is a small pcb made available

 

[MarkyM]

Good job, they are a well designed and easy to work on tuner.
I wonder if the new filters change the thd numbers or improve the selectivity.
Over on the fmtuner forum they are experimenting using the smt ones you can get at mouser. They report the filters have better characteristics than the older leaded ones. There is a small pcb made available

Thanks! Yes, the 2 180 GDT filters have less loss than the stock 230’s and adjacent channel selectivity is now excellent. I’ll check the THD when I do the alignment but it sounds pretty darn good even in super-narrow.

I saw that! I’ll have to get a few of those boards and some of the new smt filters.

 

[rcs16]

You left in the original opamps (later model using the 2068S) and it sounds good.
I have an early production unit that uses the op-amps they show in the manual.
If you are into op-amp rolling I made up a smt adapter pcb that has the soic-8 to 9-pin sip pattern on it. The link to the cloud for pcb fab files is on the fmtuner forum

One has a bad or intermittent RCA o/p jack, they should be replaced with something of better quality.
They all need a proper "F" jack. I used some spare F jacks for some, for another I bought a T/E 5-1814826-3, it is for RG-6 which I have a crimper for. Still to be done.
The front-panel switches can go intermittent, I have one in the loft with this problem, not sure if it is that glue goop on the wires (another job) or the switch contacts themselves are going south
There you go, my experience with the three that I own

 

[MarkyM]

You left in the original opamps (later model using the 2068S) and it sounds good.
I have an early production unit that uses the op-amps they show in the manual.
If you are into op-amp rolling I made up a smt adapter pcb that has the soic-8 to 9-pin sip pattern on it. The link to the cloud for pcb fab files is on the fmtuner forum

One has a bad or intermittent RCA o/p jack, they should be replaced with something of better quality.
They all need a proper "F" jack. I used some spare F jacks for some, for another I bought a T/E 5-1814826-3, it is for RG-6 which I have a crimper for. Still to be done.
The front-panel switches can go intermittent, I have one in the loft with this problem, not sure if it is that glue goop on the wires (another job) or the switch contacts themselves are going south
There you go, my experience with the three that I own

Thanks for the info!

 

[amr2]

Here's a mod. I removed the stock ceramic filters for the Narrow and Super Narrow modes, added 3-pin sockets and loaded newer 180kHz Murata GDT filters. More gain and flatter response!
Next up: Alignment using my trusty Sencore SG-80.

Thanks for the tip!. I'm very happy with my unit, one of the best tunner I owned. I will try the filters mod.

 

[MarkyM]

OK, the alignment went very well except for one problem. Moral of the story: Don't touch the "IF Offset Adj" pot (Step 19) if you don't absolutely have to! (see below)

All circuit boards should be as well marked as this one. Nice!

It has 4 controls for nulling distortion in the Super-Wide mode! There are 2 more controls for Wide mode distortion and 2 controls each for separation in Super Wide and Wide modes (L into R and R into L).

It easily beats it's specs. In Super-Wide mode at 1kHz 100% modulation, I am getting 70dB of separation in both Super-Wide and Wide modes! 35dB in Narrow and 30dB in Super-Narrow. (with the 180kHz GDT filters)

Distortion is super low! THD, stereo, both channels driven, 1kHz, 100% mod: S-Wide: 0.06%, Wide: 0.08%, Narrow: 0.12%, S-Narrow: 0.15%
19kHz pilot leakage is in the noise. Which is -80 in stereo!

This is my favorite tuner, by far right now.

Short version about the center-channel and CSL adjustments (thanks to Bob over at FMtuners@groups.io):
You find the true channel center, using various methods. I like to reduce the generator signal to very low level, and change frequency slightly while listening for signal break up. You adjust the tuner in either mode to channel center, and note the Vt voltage there, the varactor tuning voltage. Then you adjust both CSL and nonCSL tuning modes to give the exact same Vt for that channel (frequency). CSL mode is adjusted via the ratio detector transformer slug (T204 in the T-85), and non-CSL mode adjusted by the IF offset pot next to the LC7210. You need to turn the tuner off and on again to see changes made when adjusting this pot.

I threw those controls way off to the point where CSL mode didn't work at all and non-CSL mode was off frequency by over 100kHz. The service manual instructions make no sense.
Through trial & error, turning the tuner off & on each time moving that pot, I finally got non-CSL mode on frequency. Then it was much easier to force CSL mode (by grounding Pin 17 of the IC) and tuning T204 until the Vt voltage matched the voltage noted in non-CSL mode. Whew!