BIG PROBLEM: Radio-tuner volume much lower than phono 8900zdb

[PurPowerPaul]

Traded my G5700 for an 8900zdb today. Hooked it all up to my hefty SP-X7900 speakers, dropped the needle on a Def Leppard record, (I like to use DL 'High n Dry' to test because of the Mutt Lange - heavy on the bass - cannon-fire percussion production) pushed the volume 'til I could hear the slight clicks and pops of the vinyl, the first song's electric guitar intro started to rip, I pushed the volume button, going for broke and... oh my God! The drop ceiling in my basement started snowing tiny white debris, (drop ceiling particles from cutting the tile pieces, clinging for years, finally vibrated down like a snow flurry on a windless day.) It was astounding in an amazing way! My 13 year old son, while cupping his ears, looked up and around with a big smile. A truly remarkable Sansui Kodak memory moment.

Thank you to all who recommended the trade! I was very apprehensive about trading my G, and could have easily been talked out of it. Proud owners, and previous owners of the Z-series stepped up and dished out some great advice. I'm just ecstatically overwhelmed at how cleaner the sound is by way of comparison. The 125wpc marriage to my SP-X7900's is perfect! When taxing the volume to the 8 mark, you'd think I had 6 foot Peavey box cabinets with four 15" woofs and humongous horns on each side. I mean, it was shaking my drop ceiling, for crissakes! It has so much more punch than the G... AND it just sounds so jaw-droppingly cleaner! Cosmetically, the inset lighting with the two LED monitors bounced and twinkled like a Christmas tree! This thing really comes alive visually, and really has an aesthetic charisma that I feel many missed. I think I'm truly set for home audio for awhile, as this was more than I needed. (Save from going deaf!)

THE BIG PROBLEM: After spinning the rude Leppard record, and spinning some Steely Dan, I decided to move onto the FM button. The trade worked well, because the seller let me know the radio isn't as loud as the phono, or aux-CD. My G5700 also had a minor problem where the right side negative speaker wire clip-hook up was broken. The spring to the push-tab was broken making it locked shut. A little finagling with the right tools and you can still get the wire connected. So we both agreed to trade with each unit having a slight glitch. I'm more of a vinyl spinner than a radio guy... (My Classic Rock radio punch-card is tattered and riddled with holes from hearing 'Carry On Wayward Son' a thousand times too many) so I was undeterred.

Back to the low tuner volume problem. I can almost turn it all the way up to 10 and the result is what the volume level should sound like on 2. I know this has to be a common problem... hopefully something that can be fixed with a good cleaning and recapping. Any ideas???

 

[Sansuiman]

Can't say I've run into this one or heard of anyone else with it so far on the big Z models. Since the source selection is done via a bank of mechanically interlinked pushbutton switches, it may be possible the FM switch is suspect. Cleaning these isn't so easy as they are sealed push switches with multiple poles.

If you are tech savvy and have the gear to do so, you can trace the audio from the tuner to the ingoing side of the mode select switch and see if it maintains normal line level signal to that point. If not, then you'll need to drill further back into the tuner circuit. If the signal level is normal up to that point, then either the switch itself or possibly some portion of the control amp is suspect.

Source switching is done directly by the switches, no relays involved. The switches also directly control power to portions of the circuitry that need not be active depending on the mode (i.e. tuner displays being disabled when in AUX or PHONO) thus they have multiple poles to facilitate the switching of both power and audio line level signals for routing to the control amp.

If I recall there is an FM de-emphasis two position slide switch located near the FM varactor front end (silver shielded metal box). I highly doubt this switch getting oxidized and failing to conduct well would affect the audio level output by the tuner, but you could certainly try cleaning and cycling this switch a few times to see if it makes any difference. I expect your problem lies elsewhere unfortunately.

Tuner problems are a nasty breed due to the complexity and special gear needed to test and align them (scope, FM signal generator) so chances are good you'll need the services of a good tech to whip this one if it isn't a simple signal path issue like a flaky switch. Just be careful not to tweak something that will knock the alignment all out of whack and require that much more effort to correct.

Kevin

 

[PurPowerPaul]

Can't say I've run into this one or heard of anyone else with it so far on the big Z models. Since the source selection is done via a bank of mechanically interlinked pushbutton switches, it may be possible the FM switch is suspect. Cleaning these isn't so easy as they are sealed push switches with multiple poles.

If you are tech savvy and have the gear to do so, you can trace the audio from the tuner to the ingoing side of the mode select switch and see if it maintains normal line level signal to that point. If not, then you'll need to drill further back into the tuner circuit. If the signal level is normal up to that point, then either the switch itself or possibly some portion of the control amp is suspect.

Source switching is done directly by the switches, no relays involved. The switches also directly control power to portions of the circuitry that need not be active depending on the mode (i.e. tuner displays being disabled when in AUX or PHONO) thus they have multiple poles to facilitate the switching of both power and audio line level signals for routing to the control amp.

If I recall there is an FM de-emphasis two position slide switch located near the FM varactor front end (silver shielded metal box). I highly doubt this switch getting oxidized and failing to conduct well would affect the audio level output by the tuner, but you could certainly try cleaning and cycling this switch a few times to see if it makes any difference. I expect your problem lies elsewhere unfortunately.

Tuner problems are a nasty breed due to the complexity and special gear needed to test and align them (scope, FM signal generator) so chances are good you'll need the services of a good tech to whip this one if it isn't a simple signal path issue like a flaky switch. Just be careful not to tweak something that will knock the alignment all out of whack and require that much more effort to correct.

Kevin

Thanks again, Kevin.
The guy told me over the phone that he keeps all his sound gear covered that he collects. Upon arrival, I was told to, "use the garage door", and as I walked to the door, I could hear the 8900zdb rocking the garage. Once inside the tiny garage, I noticed speakers stacked to the ceiling and many receivers. The first thing that hit me was the intense heat from a wood burning stove in the corner. It had to be over 100 degrees in there. It was an average to small size wood burner... but still far bigger than you'd need in such a small, one car garage that doubled as his audio lab. If you've ever burned wood, you know that when opening the door to stoke the fire, or throw a log on, a lot of smoke can escape into the room. After I got the unit into the truck, I noticed it reeked of wood smoke. Not only that, but the on side of the silver face plate... which is like 3/4 of an inch... seemed slightly stained with an orangie haze. He kept a towel over the top of the unit, but the face was still exposed.

I'm wondering if smoke could be the culprit. If so, a good air blowing to remove the dust, and then some careful and strategic application of circuit cleaner might do the trick... try cleaning up the varactor switch as you suggested. I'm worried about all those lights when spraying the circuit board cleaner.

Other than that, she works like a charm.

 

[Sansuiman]

Whatever you do, don't spray it with anything while powered on. And make sure the cleaner you use is fully dry and/or evaporated before powering up again. Also make sure the unit is unplugged as there is standby power present inside the unit any time it attached to the mains.

As to cleaning switches, I need to clarify. The varactor is not a switch, it is a metal encased module on the circuit board that forms the basis of the tuner front end section. Do not clean this part with anything, there is nothing inside of it to clean. There is a small slide switch near it that should be labled on the board with something like "FM DEMPHASIS" and should also have two numbers in uS (microseconds), one for each position. Clean this switch; but again I don't expect this will do much to help the symptom you are getting.

The other switch to try cleaning is the pushbutton used to select the FM mode on the front panel. I more suspect this one is a potential issue. Cleaning the smoke residue from the outside can be attempted safely with 90% isopropyl. Avoid anything with abrasive in it as the texture on the finely striated aluminum parts can be easily damaged on these. I suggest microfiber cloths as many paper towles contain fibers that can scratch finished surfaces, especially the plastic window on tbe front panel.

Kevin