Sansui G-6700 Surprise Capacitor
- Thread starter geode
- Start date
Well that's good news
Finished the board and getting ready for a listening session. Thanks all for the help so freely given to the electronically uneducated. 
So I've been playing the receiver for some days now. It does sound wonderful. Played em for a while on some little Bozak Sonoras, then switched to a nice pair of OLAs. To be fair, the little Bozaks didn't give up much to the Advents in sound. Mostly I've been listening to the radio. This tuner picks up most of the local to me stations without an antenna. We're talking about 35 miles or so to the towers. Nice. So far the F-2898, F-3000, and F-3060 boards have been recapped and trimmers replaced. Bias is pretty rock solid at 3.3 mv and DC at 1 mv or so. Replaced one of the panel bulbs with the 8V 300 ma wedge bulb. I've noticed that there is an adjustment for the tuner power board F-3060. The schematic states 5V DC at the emitter of TR601. I would like to measure this voltage and set it to proper voltage if needed. I'm guessing the measurement at the emitter is with respect to ground? I will out it on a DBT before I turn the trimmer to see how it reacts. If good, then full mains and let it warmup for about 10 minutes and adjust. Does this sound like a plan or should I do something else. I've been really lucky so far so don't want to screw the pooch now. just a thought, should the selector be set to tuner while measuring and adjusting or no signal using the aux port. Anybodys feedback again appreciated.
kevzep
Its all about the Music
Have you recapped and re-transistored that board?
They get a lot of heat damage under the chassis, silly place for Sansui to put the board in all honesty.
As long as the voltage is about 5V its all good.
Yes ground to the voltage measurement.
No need to put it on DBT, you'll be limiting voltage and current for no reason.
Yes the board shows some heat. Not bad but it is there. I put in new caps but didn't change transistors. They show no signs of stress, blackened leads etc. So, does the input need to be set to tuner while measuring/adjusting. Thanks Kev.
Edit: I was wondering if desoldering those cement resistors and putting them on the foil side
would help with the heat problem. The heat generated would rise into the chassis instead of rising into the board?
kevzep
Its all about the Music
Its a regulated supply so wont make any difference or not if the tuner isn't running, but you can run it if you want totally up to you.Yes the board shows some heat. Not bad but it is there. I put in new caps but didn't change transistors. They show no signs of stress, blackened leads etc. So, does the input need to be set to tuner while measuring/adjusting. Thanks Kev.
Edit: I was wondering if desoldering those cement resistors and putting them on the foil side
would help with the heat problem. The heat generated would rise into the chassis instead of rising into the board?
I always put new resistors in those circuits, the heat stress isn't great for them, and the new ones, you can stand them off the board when you solder them in to reduce the scorch marks and so forth...
Kev, I'm thinking of replacing the transistors with the ones you suggested. Will replacing the cement resistors from the current 3 watt with 5 watt help with the heat. I found non-inductive resistors at Mouser. Also, the zener diode RD15E from what I can tell can be replaced with a 15 volt 1/2 watt zener or should it be 1 watt. I'm looking at this one https://www.mouser.com/ProductDetail/onsemi-Fairchild/1N5245BTR?qs=jumAldekxNAufOthuRVeGQ== Also, the VR601 Trimmer rated at 4.7K ohms 1/2 watt with Bournes multiturn. The small carbon film resistors are 4.7K ohms and designated as non-inflammable types. Can metal oxide be used here or just metal film or... After finishing the F-3060 board, the only thing I have left is replacing the big filter caps with the Nichicon Gold Tunes I have on hand. Thanks for all the help and info.
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kevzep
Its all about the Music
The caps, I would use the BW series Nichicon which are 135˚ caps, it gets hot in there.
5 watt resistors is a good call, they will dissipate the heat better.
Just put the same value Zener in, it wont help anything increasing wattage.
I normally use metal film, just because its mostly what I have in stock but you could use metal oxide.
The Gold Tune caps are great but I do feel they are a "luxury" item, quite expensive. I have been using Kemmet lately, they have some great options and for a fraction of the cost.
Alrighty then. Time to order some parts. The voltages on the F-3060 board are all spot on. Thanks again, Kev.
