B500B Transformer

[rnolan]

We have the B500B transformer specs etc, the company that looked at it recons ADA got it wrong IIRC  . It's not that you can't get a transformer to do the job, it's just fitting it in the case  .  So if I go with an external transformer, it will work.

[Ravendk]

I'm thinking....has the B500B been notorious history of frying the tranny....if not, then ADA got it right, and the company that you approached got it wrong.....
To my knowledge the B500B and the G500S are nearly identical, except that the G500s has two identical amp boards delivering 2 x385w in 4ohm, whereas the B500B delivers 1 x 385w/4ohm for the low end and 1 x 275w/4ohm for the high end...bi-amp...I haven't seen the schematic of the B500B, but I would guess that the two amp boards in the B500B are identical and that there is some kind of damping circuit in front of the board that is used for the high end....my best guess would also been that the trannies in the two amps are identical....it would make sense production wise to use parts that are that would work in both amps....
Could I ask you to email me with the specs for the tranny, and I'll do some research and ask around some of the companies here in DK if they are up for the job...making a tranny that will fit size requirements and the electrical specs needed....

Production wise it would have made sense for ADA to put in a tranny that could be wired for different main voltages, so that they didn't have to make four different trannies for four different main voltages...

[Ravendk]

Was there a specific company that made the trannies for ADA or did they make them "in the the house"....
There should be some numbers on the side of the tranny...stamped straight on to the iron...these numbers reflects the company that made the tranny and the parts/model...from what I know there is a transformer database where one could search and maybe get some more info...

[rnolan]

Hey Ravendk, I'll split this off to the amp section (before Kim does LoL). And appreciate the offer of help  .

[rnolan]

Ok so many good questions, and this is a topic close to my heart LoL.  As far as I know (others know the history better than me) ADA got the transformers made, by who  .  They had different transformers for all their gear, typically a US (117v), Japanese (110v) and the rest of us (240v). I agree, why didn't they use a single transformer for all that could change input voltage ?

So there are 240v B500B transformers (that fit in the case) maybe MJMP has one we could get reverse engineered ?  MJMP recons there is NO difference between the B500B and G500S (I've asked him this question a few times as the amp specs are slightly different in the B500B ie one channel less output than the other).  MJMP said there's no difference and it's just marketing ....

[rnolan]

So have attached what MJMP sent me re the transformer and amp specs and schematics.

[Ravendk]

Hi Again....
I have been looking over the specs for the tranny and did some calculations in order to figure out what kind of AC voltage we´re looking for on the secondary side of the tranny before the rectifier.....
We have 79vdc unloaded and rectified, so it will be 79Vdc divided by 1,4142 (Square root of 2) = 55,86vac (lets just say 55vac). This we have x 2 .....the outtake(s) on the tranny should then provide us with 55Vac - 0v (CT) - 55vac.
The schematic for the 220/240v tranny and the 110/117v tranny both say that if we have a current draw of 5Adc the dc voltage will be 64v. This provide us with some values for calculating the power consumption in VA (watt). This will then be 64v x 5A = 320VA, and we have 2 outtakes, so the total will then be 64V x 5A x 2 = 640VA, or in plain English 640 Watts.
This goes well with the 675 Watts that is printed on the back of the amp close to the AC cord. My guess is that the fan uses about 15-30 watts, so this is within the limit of the 675 Watts total at normal use....and it goes well with the main fuses of 7A for 117V use and 4A for 240V use
On the schematic for both trannies there are some numbers that reflect the the size of the bobbing (the plastic thing were the coils are wound around. they used a standard EI-125 bobbing, but there is a slight differens between the 117v tranny and the 240v tranny. In the 117V tranny the size (I guess lenght or Width) is 2 7/16 inches and in the 240V tranny it´s 3 inches (more wire on the 240V tranny on the primary Windings...this is also why the 240V tranny is slightly bigger in pfysical size.
So all in all we´re looking at a tranny with the following specs: 240V pri and 55V-0-55V sec. and a capacity of delievering around 640-650 VA or Watts.
Then there is the pfysical size of the tranny that the producer has to stay within (3.125in x 3.75in x 4.50in)(240V tranny). In cm this is roughly 8cm x 9,5cm x 11,5 cm calculated with the international standard that 1 inch equals 2,54cm....
Ok...now we have something to go with on the search for a tranny Company that will make the damn thing :whoohoo!: :banana-jazz-smiley-emoticon: :headbanger:

[rnolan]

Cool, thanks Ravendk, hopefully someone can make one.

[MarshallJMP]

I'll takes some pics this evening Raven

[MarshallJMP]

Here you go

[Ravendk]

Hi MJMP....
Thanks for the pics ....Is the tranny in the pics the one for 117V mains.....it looks like it....
Is it possible for you to measure the secondary AC voltages and the DC voltages after the rectifier..
Ravendk

[Ravendk]

Hey guys...

I'm still researching regarding the power tranny for the B500B, and I'm in need of knowing the actual AC voltage that is available on the secondary side of the transformer. I suspect that the secondary DC voltages are lower than what is written in the schematic for the 220v/240v and 100v/117v trannies.....
I also took a closer look at the amp circuit.....according to the specs for the amp it is supposed to deliver around 2 x 385W in 4ohms, but it is actually a 2 x 250w power amp circuit if it is run in 8 ohms.....I did some searching on the net for other/equivalent amp circuits in order to find out the necessary power (voltages and amperes) to drive these circuits with a goog result.....during the search I came across this...

http://www.elcircuit.com/2016/09/2-x-250-watt-power-amplifier-blazer-st.html

It has a very familiar look and could work as a replacement amp board for the B500B if needed....and since it also contains the bridge rectifier and smoothening caps, you can bypass the original in the amp....

Another interesting question is who produced the original trannies for ADA....does anybody have any knowledge or hints about this....if we could track down the original company, they might have stuff in their archives that could be useful.....

[rnolan]

Hey Ravendk, thanks for looking into this  .  The link to the other amp circuit comes up server not found  , I also tried it as https just in case but same result.

[Ravendk]

That is a little strange...try this...

www.elcircuit.com/2016/09/2-x-250-watt-power-amplifier-blazer-st.html

Or this

http://audiorakitan.com/shopping-cart/power-amplifier-blazer-st-plus-2-x-250-watt-ct-42v-ac

[rnolan]

Cool, they both work  . Neat looking unit.