Old 96er
New Member
I recently did a full restoration on my 1250 sans tuner board. The bill of materials I used does not cover the tuner board, and I understand a lot of folks are reluctant to mess with the tuner. I understand, and I would have left it alone without any further thought if I didn’t have an FM tuner problem.
First of all, I almost never listen to FM and couldn’t care less about AM, but here in Tucson, AZ we surprisingly have a few actually local FM stations worth listening to. After I completed my 1250 restoration I decided to listen to FM and it sounded amazing. Then, an intermittent problem cropped up after several hours of flawless operation. The FM Stereo beacon would blink off following a crackle and pop sound, the volume would drop with mono audio, then the stereo beacon would sometimes come back on with stereo audio (at reduced volume). Then the volume would go back to normal, sometimes for hours, sometimes not. I knew the problem had to be related to a dirty switch, loose connection, a bad transistor, or bad capacitor.
Controls and switches re-checked, all good. So, I just decided to order replacement capacitors for the tuner since I saw a few of those notorious and often-condemned light blue Sanyo caps on the tuner board. Plus a handful of tantalums that just needed to go. The board is easy to access, so why not? I ended up replacing all aluminum electrolytic and tantalum capacitors. All capacitors 4.7uF and under were replaced with Wima MKP2 or MKS2 film capacitors. All CEA caps were replaced with Nichicon UPW. The CSZA, CEANL, and CSSA caps were replaced with low-leakage Nichicon UKL (Wima film if 4.7uF and under). I replaced Q7, a 2SC1312, which is on the list of problematic transistors. I used a KSC1845FTA in its place.
Refreshing the tuner board solved my problem and the tuner sounds noticeably more clear than before. I left the tuner going all day while doing stuff around the house. No problems. Tuner works great and all stations line up with the pointer on the nose. Out of curiosity, I tested all the old caps. A good half of them tested outside of 20% stated value. Some were more than 50% off value, and the Sanyos had high ESR readings indicated by my cheap component tester.
That being said, it’s worth changing out the tired old caps and Q7 on the tuner board.
First of all, I almost never listen to FM and couldn’t care less about AM, but here in Tucson, AZ we surprisingly have a few actually local FM stations worth listening to. After I completed my 1250 restoration I decided to listen to FM and it sounded amazing. Then, an intermittent problem cropped up after several hours of flawless operation. The FM Stereo beacon would blink off following a crackle and pop sound, the volume would drop with mono audio, then the stereo beacon would sometimes come back on with stereo audio (at reduced volume). Then the volume would go back to normal, sometimes for hours, sometimes not. I knew the problem had to be related to a dirty switch, loose connection, a bad transistor, or bad capacitor.
Controls and switches re-checked, all good. So, I just decided to order replacement capacitors for the tuner since I saw a few of those notorious and often-condemned light blue Sanyo caps on the tuner board. Plus a handful of tantalums that just needed to go. The board is easy to access, so why not? I ended up replacing all aluminum electrolytic and tantalum capacitors. All capacitors 4.7uF and under were replaced with Wima MKP2 or MKS2 film capacitors. All CEA caps were replaced with Nichicon UPW. The CSZA, CEANL, and CSSA caps were replaced with low-leakage Nichicon UKL (Wima film if 4.7uF and under). I replaced Q7, a 2SC1312, which is on the list of problematic transistors. I used a KSC1845FTA in its place.
Refreshing the tuner board solved my problem and the tuner sounds noticeably more clear than before. I left the tuner going all day while doing stuff around the house. No problems. Tuner works great and all stations line up with the pointer on the nose. Out of curiosity, I tested all the old caps. A good half of them tested outside of 20% stated value. Some were more than 50% off value, and the Sanyos had high ESR readings indicated by my cheap component tester.
That being said, it’s worth changing out the tired old caps and Q7 on the tuner board.
