Does Changing Out Caps In A Tuner Effect FM Reception

[Mark R]

"TQ" Subject at hand is a Marantz 120 tuner. The tuner lit up but no output. Recapped the entire unit. Before it was working fine tuning in Stereo and Mono. Now it just about tunes Stereo and some of the mono stations are weak. Nothing else was changed. When you do hit a stereo station the stereo lamp will come on but flickers as it's trying to hold the MPX signal.

I don't see how bringing the unit back with new caps checked by my Sencore LC103 would effect the FM section. Every Value is as it was from the factory?

Any Thoughts?

[stj]

tuners work by mixing a signal from a local oscillator with a filter to select the incoming frequency,
if you change the caps related to the local oscilator or the filter/mixer you will need to ajust it after.
a service manual helps

[Mark R]

tuners work by mixing a signal from a local oscillator with a filter to select the incoming frequency,
if you change the caps related to the local oscilator or the filter/mixer you will need to ajust it after.
a service manual helps

Thanks... Yep all caps were changed... If I had known that I would have left those caps along. I don't have any AM/FM alignment equipment. I have everything else but. I was looking to pick up a SENCORE SG80. But they are none around. I do have the Service manual but that procedure is very involved. I was going to spend the money for a Alignment unit but I think I'll pass.

Since I have never done an alignment but have seen it done on Youtube, It's involved. In all my years of electronic repair I have never done an AM/FM alignment. I think I'll pass. The unit is now on Ebay for Repair or Parts.

So now if I have to recap the Marantz 150 tuner... I'll have to locate those caps that work with FM reception.

[stj]

i would just put the display on a known frequency of a station and then tweak each of the variable capacitors for the strongerst signal.
it takes a while because they effect each other, so you have to go over it several times.

[Mark R]

i would just put the display on a known frequency of a station and then tweak each of the variable capacitors for the strongerst signal.
it takes a while because they effect each other, so you have to go over it several times.

Yeah that's one way.. But I rather have the SENCORE SG80....But they are no where to be found for sale in the world.... Real Hens Teeth.

[stj]

or use a mini sig-gen like shango66 on youtube does.
go watch his video's!

[Mark R]

or use a mini sig-gen like shango66 on youtube does.
go watch his video's!

Well I found a Sencore SG165 with the original Box and manual and test leads on Flea Bay. Also downloaded the full manual which has calibration and skids and well as operation ... 71 pages. Looks clean Except it does power up. He had pics of the insides which looked very clean. I'm guessing the power supply is farked. Probably caps or something minor in the supply.

So I gave it a shot and pulled the trigger. When I get it working and calibrated which looks simple I might learn something. I'll put my self thru school and try to do the Marantz 120 and do my first alignment. I know I'll be pulling my hair out trying to make it work. But it'll be fun.

This is the part where you Laugh....L.O.L.

[stj]

how much is the sencore?

the chinese pocket device is 70-130$ and can probably do far more than the sencore
it has a color spectrum analyser and a generator that can do AM/FM and subcarrier etc.

if i did much radio i'd probably get one.

[Mark R]

how much is the sencore?

the chinese pocket device is 70-130$ and can probably do far more than the sencore
it has a color spectrum analyser and a generator that can do AM/FM and subcarrier etc.

if i did much radio i'd probably get one.

Sounds like a winner... Not up on the Chinese devices. But it has to do modulation Pilot freqs and all the stuff that a Standard alignment generator would have to do. I picked the Sencore up for cheap about $140.00 not counting shipping.. I collect old Vintage test gear. I'm still looking for the Digital Version which was the newer model. The SG 80. That unit is sought after by most techs and are like hens teeth.

One went up on Ebay and lasted 10 Min. I missed it as it sold before Ebay could notified me as I have it on my Favorite List and it went fast before I could get the notified.

Check out the SG80...this one sold 6 years ago....
https://offerup.com/item/detail/6ae7...d-0fb3482f6ff8

See if you can pick a unit for me that does what the SG80 does above. Give me a Part Number and Make... I don't know enough about them.

Also..took some pic's of that possible Solder bridge you caught. It's close but not shorted... Unit is still working great.

[Mark R]

Disregard the above pic's I posted them hear by mistake.