sb 200 power transformer

[KB0KYT]

 Help my sb 200 transformer died i dont have the money to buy the harbach replacement i rebuilt the amp  from the bottom up . And the transformer worked when i took it out  but now nothing. if you have one please let me know thank you very much

[KA5N]

the transformer worked when i took it out  but now nothing. if you have one please let me know thank you very much

Are you sure the transformer is bad?  Unless you have checked it with an OHmeter
and found open windings? I would bet you a dollar to a hole in a donut that you have
made a wiring error or have bad circuit breakers or some other such problem.
I don't know why you felt that you needed to remove the transformer anyway.
You may have pulled a lead loose from the windings.  This could be "cured" by
resoldering.  I don't understand this current trend of "rebuilding from the bottom up"
of mature gear.  Chances are you remake errors that initial builders made.
Good Luck
Allen

[W1QJ]

Allen, when you're right, you're right!  I don't understand either, why would someone need to remove the transformer?  Unless one wants to buff up the chassis to a high gloss like I have seen a few times.  Unfortunately it looks pretty but does nothing for the operation of the amp.  That aside, I'll bet there is nothing wrong with the transformer either unless like you say, the transformer was damaged in handleing.  He needs to do a major ohm check and perhaps even a voltage check. (out of circuit)  Maybe however, he bought this amp and went right into the total rebuild without knowing the original state of affairs?  I just sold the one SB-200 transformer I had a couple weeks ago.  Last I looked N6CW had one for sale on QTH.COM.  Maybe he still has it?  Lou

[W1QJ]

OK, here it is:

AMPHF - FOR SALE: SB-200 POWER TRANSFORMER
SB200/SB-200/201 POWER TRANSFORMER
A good, stock, High Voltage/Filament/Bias transformer for the Heath SB-200/SB-201 amplifier. All voltages test good. $109.00 shipped Priority mail to USA. Foreign shipment for appropriate postage. Paypal, check or PMO.

Listing #936374 - Submitted on 09/08/11 by Callsign N6CW, Modified on 09/17/11
Click Here to Email -- Send this Ad to a Friend

[W8JI]

Help my sb 200 transformer died i dont have the money to buy the harbach replacement i rebuilt the amp  from the bottom up . And the transformer worked when i took it out  but now nothing. if you have one please let me know thank you very much

Rebuilding anything from the bottom up, unless you are restoring something  for a concourse show,
is silly.

I rebuilt my wife from bottom up, and she ran off with another man.

[5B4AET]

When I got my SB-200 few days ago, I was considering the idea of making a full rebuilt.
After making some reading and thinking and since this is my first HF amp project, decided to replace ONLY whats need. This helps alot in learning !! 

Follow KA5N advise check the transformer before you go for a new one.

Good luck

[KB0KYT]

i rebuilt it cause when i bought it it was in bad shape it had been abused and was used by a cb op who didnt have a clue it was pretty much a mess the tubes where flat the relay was toast and the hv board was cracked and the 2 caps that help with negative bias and the keying curcuit where dried out i have a cap tester and the transformer worked then but not now  i had a friend who is a repair tech  look it over and i have everything together like it should be but the high voltage winding  has no out put no ohm read nothing and i pulled the covers off and the wires are solder where they should be  but the amp was a mess when i got it so was best to start fresh instead of trying to figure out a mess of stuff over 40 years of use and abuse

[KA5N]

Well Gary even unlikely things happen, so if the winding is open then it's open.
There could be an intermitten deep inside the windings (wire burnt open but touching
from time to time).  If a CB'er was playing with it there is no telling what might have
occurred.  So I suppose it is time to get another transformer or junk the project.
Good Luck and 73
Allen

[W1QJ]

I suppose 5B4 does not have a basket full of SB-200's to pick from so he has an excuse to work with a poor example if a good one is not available. However, stateside, these amps a dime a dozen as far as availability is concerned.  I suggest anyone not 100% qualified to restore a unit that is a basket case without being spoon fed possible causes of each and every problem a "basket case" can present to buy a unit that is working 100% and spend an extra $50.00 up front for a better unit!  Your $ will be quickly eaten up with replacement parts top bring things up to par from a basket case.  Not to mention the aggravation if you don't know what you are doing.  There is just too many of these amps available and the range of price from poor to excellent units is only the difference of a few replacement parts that might not be needed anyway.

[K2DC]

The other option is to part it out and start over.  SB-200's (even basket cases) are typically worth more in parts than they are as a complete and working unit.  I've seen ads for pieces of parted-out amps whose asking prices add up to 2-3 times the cost of a used working unit.  Then you'd have a chance to find a decent one.

73,

Don, K2DC

 

[K8AXW]

Playing the devil's advocate here... I can perhaps understand KYT's position.  If he's anything like me, he might have picked up an SB-200 for a song or even free.  He's also in a situation where he can't afford a buncha bucks to buy another amplifier "for $50.00 more."  Depending on his original investment, $50 might not buy anything.

In the meantime, as with all Heathkits and the assembly manual, it's tempting to "tear it down and rebuild it."  Unfortunately, bad things happen and as with the last electronic project that I attempted to build. It was supposted to cost $50.00 has so far cost me approximately $300.00 and it still doesn't work properly.

Things like this is synonymous with drinking out of a spittoon.  Once you start your can't stop because it's all one long string!

Then there is one other consideration in KYT's case.  Perhaps he's also like me, he just can't throw something nice away.... because of the ingrained feeling, "I can fix this!"


BTW, I also rescued an SB-200 from a CB'r and had to invest some money in it because it was abused.

[N2EY]

i have everything together like it should be but the high voltage winding  has no out put no ohm read nothing

Do the other windings work?

73 de Jim, N2EY

[5B4AET]

Absolutely right W1QJ !!
Here in Cyprus there is hardly any market for second hand equipment. And even no source of such specialised parts. Everything has to be ordered and brought from abroad (shipping is expensive)!!
Starting a project where one of the most expensive parts needs to be replaced is not such a great idea. At the end it could cost more fixing it than just finding a another better from the "basket"!! If there is a "basket" around good enough - if not  (in my case) will have to stick and fix the one in hand !!
I wish there was a "basket" around too.....

Panicos

[N2EY]

Rebuilding anything from the bottom up, unless you are restoring something  for a concourse show,
is silly.

I disagree in the case of kits. Particularly ones that are relatively simple, like the SB-200.

Often it *does* make sense to tear down and rebuild them, particularly if they weren't built well the first time and/or if lots of parts need replacing/upgrading (electrolytics, carbon comps, hardware, etc.) The amp in question sounds like it was a real basket case.

However I find it extremely odd that the transformer failed when it did. I suspect there's an open in the circuit feeding the primary someplace.

I rebuilt my wife from bottom up, and she ran off with another man.

Did you do the Harbach mods as part of the rebuild?

73 de Jim, N2EY

[KB0KYT]

Yes i did the harbach mods new power supply board new soft start and soft key and relay and new fan and a friend gave me 2 new 572b all the other windings work it keys and everything just no hv  i even borrow a fluke meter and hv probe i thought it might be the meter or something but it wasnt the transformer has no 800 volts out . And i bought the amp for next to nothing i traded the guy some cb stuff i hadnt used in a longtime