The OFFICIAL MSM5540RS/M5540 Sansui Gx700 40pin IC Thread! NUDIES
- Thread starter trueno92
- Start date
trueno92
Active Member
Thanks for all the supportive suggestions, everyone.
With Brad egging me on to "gitter dun", I picked up a test xtal of 6mhz, a wee bit off of the 6.5536 that is spec'd in the schematic.
I was doubting it would do anything as I completely figured it was for the quartz lock, but from Brad's understanding, the quartz lock is totally transistor-driven. Call me crazy but "Quartz" and "crystal" just seem to go hand-in-hand.
In trying the 6mhz crystal, the display kicked in immediately. Altering frequencies between the FM and AM bands. The quartz lock seems to depend on the continuity through the xtal, but not specifically dependant on the xtal frequency.
Seeing as there was a deviance of 10mhz between the analog and digital tuners (analog shows 98, digital shows 108mhz) I decided to adjust TC06 as per the manual, but it looks like TC06 allows for only 5mhz adjustment. Once dialed down to 105mhz, it jumps back to 109.9 and continues cycling - no matter how much you wind down the TC06.
[youtube]_ngHdZ5x3A0c[/YOUTUBE]
https://www.youtube.com/watch?v=ngHdZ5x3A0c
So, now to spend the $0.70 cents on the correct xtal and $8 to have it shipped. Should be all good by midweek.
With Brad egging me on to "gitter dun", I picked up a test xtal of 6mhz, a wee bit off of the 6.5536 that is spec'd in the schematic.
I was doubting it would do anything as I completely figured it was for the quartz lock, but from Brad's understanding, the quartz lock is totally transistor-driven. Call me crazy but "Quartz" and "crystal" just seem to go hand-in-hand.
In trying the 6mhz crystal, the display kicked in immediately. Altering frequencies between the FM and AM bands. The quartz lock seems to depend on the continuity through the xtal, but not specifically dependant on the xtal frequency.
Seeing as there was a deviance of 10mhz between the analog and digital tuners (analog shows 98, digital shows 108mhz) I decided to adjust TC06 as per the manual, but it looks like TC06 allows for only 5mhz adjustment. Once dialed down to 105mhz, it jumps back to 109.9 and continues cycling - no matter how much you wind down the TC06.
[youtube]_ngHdZ5x3A0c[/YOUTUBE]
https://www.youtube.com/watch?v=ngHdZ5x3A0c
So, now to spend the $0.70 cents on the correct xtal and $8 to have it shipped. Should be all good by midweek.
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trueno92
Active Member
I have read about it happening quite often on ROOMBA vacuum robots, recently.
But for a 30+yr old radio, I suppose it wouldn't be unheard of.
BKTHEKING really has to take credit for this, as he noticed a really important point early on:
DO AM AND FM both have a locked digital readout of the exact same digital figures?
If so, then it points at the clock as the scaler is responsible for FM and AM go thru a different circuit. (BKTHEKING can correct this if I remember it wrong)
IF the FM is locked and the AM still operates correctly, then the issue lies with the tuner section as with Dr*Audio had highlighted.
I think a few more threads on AK that point to the MSM5540RS chip are actually issues with the scaler or signals to the scaler.
BONUS ROUND: The thread where the poster had transplanted an F-3220 in place of a F-3000 and changed around the wiring matching color codes for the transplant can revise their work and run the wiring right off of the tuner board, removing the scaler F-3010 right out of the circuit.
also, another vid, since, I'm from the late 70's and Digital was all the rage of my childhood.
http://youtu.be/3IDC6PSzlCs
THANKS AGAIN AK. GOOD KARMA for all!! Will update thread with the official spec crystal install - later this week!
trueno92
Active Member
SHE LIVES!
Looks like swapping out the xtal to the appropriate 6.5536mhz as per spec was the ticket!! My tuner is now displaying the correct readings, matching the scale! Its responsive and instant, and doesn't exhibit any of the 10 second delay to sync as I have read in a couple of other threads (digital display starts at a high number range and then eventually syncs down to the actual signal value)
Since the unit was apart, decided to do a few caps on the amplifier board and power supply. I know I didn't get them all and apologies if the work looks a bit tardy!
its all buttoned up, and sounding better than ever.
http://youtu.be/q4BWSr1HkOE
I did a lot of critical listening over the last couple of weeks and to compare - the re-cap made a very noticeable difference. Similar to upgrading speakers to something a model number or two up the food-chain. Like a veil has been removed, the imaging between instruments on a stage sound more uniform and the center imaging is much more planted. Same goes for vocals.
THANKS FOR ALL YOUR HELP AND GOOD - KARMA FOR ALL!!!!!!!!!!!!
Looks like swapping out the xtal to the appropriate 6.5536mhz as per spec was the ticket!! My tuner is now displaying the correct readings, matching the scale! Its responsive and instant, and doesn't exhibit any of the 10 second delay to sync as I have read in a couple of other threads (digital display starts at a high number range and then eventually syncs down to the actual signal value)
Since the unit was apart, decided to do a few caps on the amplifier board and power supply. I know I didn't get them all and apologies if the work looks a bit tardy!
its all buttoned up, and sounding better than ever.
http://youtu.be/q4BWSr1HkOE
I did a lot of critical listening over the last couple of weeks and to compare - the re-cap made a very noticeable difference. Similar to upgrading speakers to something a model number or two up the food-chain. Like a veil has been removed, the imaging between instruments on a stage sound more uniform and the center imaging is much more planted. Same goes for vocals.
THANKS FOR ALL YOUR HELP AND GOOD - KARMA FOR ALL!!!!!!!!!!!!
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trueno92
Active Member
Thanks for the encouragement and shout-out to BKTHEKING for calling me up and walking me thru this. First time for me, so I guess BKTHEKING is my Mrs Robinson hahaha
GHAZZER: let me know if you want any further pics. I have the unit buttoned up and I have to say the new caps have made the high-hats and cymbal crashes much more distinct and clearer - Miles Davis, ALL BLUES has Jimmy Cobb strutting a few different cymbal transitions between solos and they are much more defined. Piano tones are silky with loads of body behind them. I am really tempted to pop her open again and just change out everything I can get the iron on to.
GHAZZER:
BKTHEKING identified IC02 AS THE SCALER!!! its not the same IC02 from the F-3000!!!!
Sorry for turning the pics into a jigsaw puzzle. I'm hesitant to keep touching this thing cuz ever since i was a kid, I keep trying to fix it, and I just end up breaking stuff!!! - I think this goes for all of us here in the sansui forum!!!!!
Now im just so curious to see the ratio of F-3000 to F-3220 IC failures!!
GHAZZER: let me know if you want any further pics. I have the unit buttoned up and I have to say the new caps have made the high-hats and cymbal crashes much more distinct and clearer - Miles Davis, ALL BLUES has Jimmy Cobb strutting a few different cymbal transitions between solos and they are much more defined. Piano tones are silky with loads of body behind them. I am really tempted to pop her open again and just change out everything I can get the iron on to.
GHAZZER:
BKTHEKING identified IC02 AS THE SCALER!!! its not the same IC02 from the F-3000!!!!
Sorry for turning the pics into a jigsaw puzzle. I'm hesitant to keep touching this thing cuz ever since i was a kid, I keep trying to fix it, and I just end up breaking stuff!!! - I think this goes for all of us here in the sansui forum!!!!!
Now im just so curious to see the ratio of F-3000 to F-3220 IC failures!!
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