Should I power this thing up?(I HAVE NO VARIAC)

[rhomanski]

Re: Should I power this thing up?(I HAVE NO VARIAC)

Several ways. If you can get a pair of lock pliers on it, turn it out. If you have an easy out. use that. Or drill the head off. Use a drill bit bigger than the head of the screw and drill off the head. Just be careful and take your time.

[ReeceyBurger123]

Re: Should I power this thing up?(I HAVE NO VARIAC)

Carefully....and as my gran used to say "good manners cost nothing"

The way I was taught was a smack round the head sounds like someone never got that

[TechGeek]

Re: Should I power this thing up?(I HAVE NO VARIAC)

could I use a Dremel to make a solid line all the way across the screw and then use a flat-head screwdriver to remove the screw?

[dmill89]

Re: Should I power this thing up?(I HAVE NO VARIAC)

I have a 1995 and I think it's a Sanyo, too...

It is, Fisher was owned by Sanyo from 1975-2010 (prior to that it was owned by Emerson from 1969-1975, Fisher was an independent company from 1937-1969) when Sanyo itself was purchased by Matsushita/Panasonic (Matsushita officially changed their name to Panasonic Corporation in 2008), Panasonic still owns the rights to the Fisher brand but phased it out in 2012.

[dmill89]

Re: Should I power this thing up?(I HAVE NO VARIAC)

could I use a Dremel to make a solid line all the way across the screw and then use a flat-head screwdriver to remove the screw?

Yes as long as you are careful.

[diif]

Re: Should I power this thing up?(I HAVE NO VARIAC)

no, they make a mess....tiny metal shards everywhere, high speed, to much risk of damage if you slip.
Follow the advice of the man that's been dealing with stripped and cross threaded fasteners IIRC longer than you've been alive. I know I have, and his list is sound and of course in order of ease/mess/time.

[TechGeek]

Re: Should I power this thing up?(I HAVE NO VARIAC)

OK, I've come up with a repair/partial restoration plan:

1. Remove stripped screw
2. Remove low-level tone control board
3. Remove/Loosen all boards to be recapped
4. Obtain list of caps to replace
5. Obtain list of caps to replace WITH
6. Obtain a proper soldering iron
7. Obtain solder wick
8. Recap what needs to be recapped
9. Obtain a capacitance meter
10. Obtain an ESR meter
11. Check capacitance and ESR of old caps(just for fun)
12. Blow up old caps that have high ESR/low capacitance
13. DONE

Is this good? Also, what caps should I use on the low-level tone control boards? Thanks.

[rhomanski]

Re: Should I power this thing up?(I HAVE NO VARIAC)

Don't bother checking the old caps unless you just want to. They are 40 years old and due for replacement. Use Nichicon KL and PW series. KL in the audio path, usually those caps will be sky blue or orange. PW for everything else.

Since Mouser has them in almost every size you can replace them with same size in most cases.

You can check the schematic for any problems. One of mine was designed for 117 volts and uses a zener diode in the feedback circuit to the power supply. When the voltage gets too high the zener reverse biases and bleeds off the excess to ground. With a 124 volt line here and now they work pretty hard so I went with a bigger diode.

Look for 2SA726 transistors, replace with ksa992's, replace 1313's with 1845's.

Change the heat sink grease with gc chemicals z9, it's silicone base and mil spec.

Don't touch any pots on the tuner board. You'll need a full alignment if you do.

Some manufacturers put a temp sensing diode on the heat sink. They are unobtanium now so look for them and be careful with them.

That's about it with a good cleaning of course.

By the way, the service manual is here http://www.hifiengine.com/manual_lib.../rs-1056.shtml . Just join up and the download is free.

[kaboom]

Re: Should I power this thing up?(I HAVE NO VARIAC)

is it bad when I can drive intercom speakers that use a transformer and not have a problem?

Drive the VC directly.

Also, how can I remove the non-soldered wires from the boards w/o cutting them?

Those wire-wrap posts? Desolder them, much easier. All too often when unwrapping them, the wires break. If there's not much to begin with, you'll be in for a treat stripping them. And you won't be able to wrap the posts w/o a wirewrap tool. Just heat the posts on the solder side and pull them out.

You need a good temp controlled iron. Even a weller magnestat will do. And some small needlenose pliers. Be gentle, or you'll be ripping traces.


Ignore anything about "audio grade" caps- you want hi temp ones for the life of the unit. The ones I specified are just fine. I've used tons in Yamahas, Sansuis, Kenwoods, etc.

hello?

Not all of us "play computer" all day long...

[rhomanski]

Re: Should I power this thing up?(I HAVE NO VARIAC)

Looking at the schematic it does have the varisters on the heat sinks. SV-004. They haven't been made since the seventies and the supplies have been used up. They can be replaced with three diodes in series but it's best just to be careful and don't hurt the ones you have. Their wires are solid not stranded and very fragile.

[kaboom]

Re: Should I power this thing up?(I HAVE NO VARIAC)

Looking at the schematic it does have the varisters on the heat sinks. SV-004. They haven't been made since the seventies and the supplies have been used up. They can be replaced with three diodes in series but it's best just to be careful and don't hurt the ones you have. Their wires are solid not stranded and very fragile.

Those are thermistors, not varistors.

The other ones are STV-3s. Just use 3 1N4004s in series, but be careful mounting them! Shorts to the heatsink are bad. As in "blow the amp up" bad. Had to do this in a Sansui 4000 a few years ago. Unit was "gotten to" and both channels blew up. Had to rebuld both driver boards with modern components. Only one board had a blown trace- a simple jumper fixed that. I used thermal epoxy to mount the bias diode assemblies to a heatsink on each driver board.


The Sanyo 1056 does not have thermistors in the amp, only STV-3s. Look at the schematic.

If you realize a problem is a challenge and not the end of the world you'll do fine in life. Or at least better.

It's actually one of the easier units to work on, just maybe not the thing for a beginner. Finished a Fisher 500T recently- what an adventure... Those stupid "flat pack" (think SIP TO-92) transistors on the autoscan board were bad.

Shotgunned all of them, autoscan repaired.

Was a bear to align, since the trimmer caps in the front end module were this close to coming apart- got lucky and got it much better.

IF alignment wasn't too bad, but had to "improvise" with sig gen and 2nd harmonic of xtal oscillator- remember, front end was slightly off, even after I got it better. MPX was okay, thank goodness- I don't have an MPX gen.

Power amp board pulled, resoldered, washed. Driver transistors got new thermal compound, new zener for derived voltage, larger/safer resistors for driver transistors- originals were marginal. 21195/96 output transistors.

Power supply upgraded- bigger diodes, larger caps, and minor-rail reg transistor replaced with one having greater SOA, and put on a larger heatsink. Entire board resoldered, cracks epoxied, board washed.

Tone control and autoscan boards also resoldered and washed.

All controls cleaned, all caps replaced. The only thing in that unit untouched was the AM RF board. The ferrite loopstick was "lost" years ago; decision by owner was made to abandon AM.

Also cleaned up wiring from AC socket to switch/transformer, and from transformer to PS board- also added the full compliment of PS fuses.


TG- yours is an easy unit to work on, but if you get frustrated and/or "make do" with the wrong tools, you'll only make things hard for yourself.

Obtain a proper soldering iron

That right there is ~$80 to budget, for a W60P. You'll also need a bigger tip than what comes with it. Something like a 700 degree, 3/32 "screwdriver" tip. Or closer to ~$180-200 for a "station."

Don't drop a dollar to pick up a dime- meaning, don't go cheep on soldering equipment. And, for your sanity, do NOT get a cheep aoyoue thing- if they were a power supply, they'd make Deers look like NASA-spec stuff.

AVOID AOYOUE like the plague.

[dmill89]

Re: Should I power this thing up?(I HAVE NO VARIAC)

That right there is ~$80 to budget, for a W60P. You'll also need a bigger tip than what comes with it. Something like a 700 degree, 3/32 "screwdriver" tip. Or closer to ~$180-200 for a "station."

If your going to spend $80 on a Weller W60P, you might as well spend the extra $15 for a Hakko FX-888:
https://www.amazon.com/Hakko-FX888D-...s=hakko+fx-888

or Pick up a used Hakko 936 on eBay for around $50-$75.

[kaboom]

Re: Should I power this thing up?(I HAVE NO VARIAC)

If your going to spend $80 on a Weller W60P, you might as well spend the extra $15 for a Hakko FX-888:
https://www.amazon.com/Hakko-FX888D-...s=hakko+fx-888

or Pick up a used Hakko 936 on eBay for around $50-$75.

Also good.


TG, do not attempt to use those cheep irons with only a setscrew holding the tip. Those awful 40W things with poor tip thermal coupling. They hit 1000+ degrees, but the tip cools off the moment you try to "solder." Nothing better for ripping off traces...

A 25W Weller "Marksman" (the orange ones) from Home Depot is a dream by comparison.

[momaka]

Re: Should I power this thing up?(I HAVE NO VARIAC)

AVOID AOYOUE like the plague.

It's not just AOYUE. Every cheap China-made station has poor built quality. That said, some of them do perform quite well. This is one of them, IMO:
https://www.circuitspecialists.com/l...l-display.html
I've had mine (the CSI 2900) for close to 5 years now.
It's based on the Aoyue 2900 and uses the T12 / T15 style tips that have a heating element inside each tip. Thus, you get excellent thermal response from the tips. Nothing at all like the super-cheap stations that use crappy 900M clone tips that can't even melt leaded solder properly. Heck, even the Weller Magnastat tips don't come close to the performance of the T12 / T15 tips. I have used mine to remove an entire thru-hole VGA connector from a motherboard simply by flooding all of its pins with solder. No wick or desolder pump nonsense for that part. Got the connector out in under 30 seconds. All with lead-free solder too.

Now, I am not going to claim that this station is built well (it isn't). But it works, it's not a fire hazard as far as I've checked it, and is very well priced for what it does.

As for the amplifier in this topic...
I say first learn to solder well. Perhaps on some less important stuff. Maybe even grab a few cheap blank PCBs and try building some easy projects first. Then move to the amp. Also, if you mess up the amp, it's NOT the end of the world. Don't get frustrated and smash it or throw it away. Simply just stash it away and come back to it another time (even if that is a few years from now). I've done that with many projects back in the day, and I am glad I did that.

TG, do not attempt to use those cheep irons with only a setscrew holding the tip. Those awful 40W things with poor tip thermal coupling. They hit 1000+ degrees, but the tip cools off the moment you try to "solder." Nothing better for ripping off traces...

Actually, even those are better than the cheap "stations" that use cheap 900M series tips.

A 25W Weller "Marksman" (the orange ones) from Home Depot is a dream by comparison.

They also have these two, which are quite respectable IMO:
http://www.homedepot.com/p/Hakko-40-...-1-P/204215977
http://www.homedepot.com/p/Weller-40...NKUS/204195330
Back in high school some many years ago, I think we had an older version of those 40-Watt Weller irons. They worked great.

[TechGeek]

Re: Should I power this thing up?(I HAVE NO VARIAC)

conflicting information all over the place... help?

[diif]

Re: Should I power this thing up?(I HAVE NO VARIAC)

conflicting information all over the place... help?

Help us to help you by providing some detail on the what you're finding conflicting.

Have you got the stripped screw out yet ?

[stj]

Re: Should I power this thing up?(I HAVE NO VARIAC)

get an iron with T2 tips.
blackjack solderwerkz, circuit specialists (CSI), chinese - it's not important as long as it's got T12 tips.

[TechGeek]

Re: Should I power this thing up?(I HAVE NO VARIAC)

SNIP
The other ones are STV-3s. Just use 3 1N4004s in series, but be careful mounting them! Shorts to the heatsink are bad. As in "blow the amp up" bad. SNIP

Couldn't I put some electrical insulation material below the transistor/rectifier to avoid electrical shorts against the heatsink?

Also, got the screw out.

[ReeceyBurger123]

Re: Should I power this thing up?(I HAVE NO VARIAC)

Couldn't I put some electrical insulation material below the transistor/rectifier to avoid electrical shorts against the heatsink?

Also, got the screw out.

Use thermal insulation pads for that size transistor and screws with nylon washers on to help stop it shorting to the heatsink.

[rhomanski]

Re: Should I power this thing up?(I HAVE NO VARIAC)

Those are thermistors, not varistors.

Too little sleep. I've always used 1n4148 diodes because a guy in Kansas city tested several kinds and found they have the closest thermal reaction to the original STV-3's and 4's. Some Sansui's use a dual diode that I replace with two 1n4148's solder them together side by side and heat shrink over them. They work just fine that way.