Sansui 5000A bulb replacement

[Prathapdan]

Wonderful thread. I came across this a few weeks ago and was inspired to revive my Sansui 5000a. I replaced 6 bulbs and did a thorough clean (compressed air and deoxit). Sounds and looks better than it ever did in the 8 years I have had it. I have used it for the past two years. Now, I am planning to get a learn to solder kit before embarking on some of the mods discussed here. Thanks for the inspiration.

 

[smokinone]

I'm happy that it did inspire you. I also was inspired by the AK community. A lot of great people and ideas here.
I would suggest something like a HAKKO variable temp soldering iron and a Hakko 808 or whatever the model number is now for their desoldering gun, or similar tools. The gun makes the job so much easier and quicker than using the wick and doesn't necessarily create a lot of extra heat on the sensitive PC boards.
Be sure to post with pictures of your progress as we all love pictures, and you may inspire some as well. It's a nice feeling when you finish what ever stage of restoration you're in and get to sit back and listen to the results.

Thanks

 

[DIPO]

Ran across your thread the other day and was wondering if you are still on AK and if so I have some questions concerning bulbs on my 5000a. I took off the face plate and got a bench full of old insulation, It had dried out and was crumbling. All the bulbs work and I thought I had beat the devil, however when I put it back together and turned it on the front panel did not light up. The bulbs are working just not showing very well through the face plate. Was wondering if the insulation had anything to do with it not lighting up properly. Just stumped, thanks..

 

[Sansuiman]

That insulation is just self adhesive cellular foam strip, much like weather stripping. It dries out and crumbles with age, so can be cleaned off and replaced with similarly dimensioned stick on weather strip that can be found at a hardware store.

Its primary purpose is to shield the back side of the front panel from rubbing metal on metal to the front frame panel. It also probably serves to block light leakage around pushbuttons and across adjacent backlit sections of the front panel.

Being deteriorated shouldn't have anything to do with the amount of light getting through panel for legend backlighting.

 

[DIPO]

Got any ideas as to what could be causing this, maybe weak bulbs, do you think new bulbs would help, after all these are 40 odd years old. Also if I went to LCDs will they be brighter than standard bulbs? I recently replaced the F1040 boards, with re-manufactured ones made by bonzoro, removed the remaining insulation, and cleaned the face plate, amp works great just can't see anything on face plate or they are so dim they are not showing through very well. I have owned this amp since 1970 and want it to be perfect. Any help will be greatly appreciated, and thanks.

 

[Sansuiman]

Did the panel illuminate normally before disassembly and cleaning, and this issue only arose after reassembly? Incandescent lamps will lose a bit of their brightness over time, but not so much that they get to half or less of their original output.

I suspect you have some other problem, either the lamp supply voltage (unlikely as it comes right off a secondary tap on the transformer) or perhaps a problem with the source selector switch. The dial scale lighting is switched by the source selector so that they only show when in AM or FM modes. The signal and center tuning meters and dial pointer are also disabled outside of any tuner mode (phono, aux, tape head).

In the non-tuner input modes, only the selected source indicator (along top of dial scale) and the light green legends under the bank of rectangular pushbuttons to the left of the tuning knob will be on.

Is it possible the bulbs were previously changed to an incorrect type? And are they all dim, or just some? Some more details would helpful.

 

[smokinone]

Ran across your thread the other day and was wondering if you are still on AK and if so I have some questions concerning bulbs on my 5000a. I took off the face plate and got a bench full of old insulation, It had dried out and was crumbling. All the bulbs work and I thought I had beat the devil, however when I put it back together and turned it on the front panel did not light up. The bulbs are working just not showing very well through the face plate. Was wondering if the insulation had anything to do with it not lighting up properly. Just stumped, thanks..

Sansuiman is correct about the insulation and also with his other reply on needing more info and the lights not coming on depending on mode. I can't remember if I had to replace the insulation on the 5000A I have, but I had similar dealings with my Luxman where I did go to the local depot and get some insulation (weatherstrip) for replacement. Although the bulbs I had were mostly working at the time, I found some NOS on the bay and decided I would replace them for prosperity. I did put LEDs in the Luxman I rebuilt, but I had to build a small power supply to get the correct voltage needed for them operate correctly, and play around a little with it to get the output I wanted.

I would, as Sansuiman suggested, check the voltage at the bulbs and see if it is correct or maybe some insulation from the feed wires maybe bare and shorting somewhere on the chassis.

I would also add that I am just a novice at this type of thing and there are far more competent AKers that should be able to help you track down the issue. I've had lots of great help here.

 

[DIPO]

thanks to all, will go out to the bench and to the depot re-insulate the panels and go from there. more to come

 

[DIPO]

Well I went out to the garage where the 5000a is used as the shop music machine, turned on the unit and switched it to, AUX let up fine, but the other modes could barely be seen so I squatted down and eureka all lit up fine. A real duh-huh moment for me, as you can imagine, was looking down on the unit not straight at it, go figure. still going to replace insulation, all bulbs come on. Thanks to all for the advice. dipo

 

[spudnut]

Was there a "brightest bulb" in your observation?

 

[smokinone]

I

Well I went out to the garage where the 5000a is used as the shop music machine, turned on the unit and switched it to, AUX let up fine, but the other modes could barely be seen so I squatted down and eureka all lit up fine. A real duh-huh moment for me, as you can imagine, was looking down on the unit not straight at it, go figure. still going to replace insulation, all bulbs come on. Thanks to all for the advice. dipo

It happens...glad it worked out on a positive note.

 

[ghazzer]

Some LEDs can be very directional. I remember that someone on AK had a procedure for drilling a slight cone into the end of the LED "bulb" to diffuse the light.

 

[DIPO]

To spudnut, it certainly wasn't me, but all the bulbs seemed normal. Just the angle I was looking at them. thanks