Transformer Identification

Afternoon,

Anyone help in identifying this PCB transformer make /spec? Other than it has a 220VAC primary originally. It's a bit cooked.

There's a label says 010921 420461.



Then one side is screen printed:

DT-4362-1

3323012

18/04/01





Cheers

Can't make anything of the markings, but  can you work out what it does from the pcb?   

eg is it connected to a bridge or bi-phase rectifier?  What DC voltage is required? 

Are the two terminals on same side the mains input?  Do the three terminals connect when resistance measured? Is there any connection to the one terminal on its own?

Geoff1946 said:

Can't make anything of the markings, but  can you work out what it does from the pcb?   

eg is it connected to a bridge or bi-phase rectifier?  What DC voltage is required? 

Are the two terminals on same side the mains input?  Do the three terminals connect when resistance measured? Is there any connection to the one terminal on its own?

Click to expand...

Crispy is the word I'd use! Meters I have here measure up to 200MOhm. Open circuit on primary. 

This is all I get on the secondary:

Doesn't leave you much wiser!  Is the bit to the right the pcb track?   If it is then it's just a simple single secondary,   Can you deduce anything more from the circuit board, voltage, etc ?

Geoff1946 said:

Doesn't leave you much wiser!  Is the bit to the right the pcb track?   If it is then it's just a simple single secondary,   Can you deduce anything more from the circuit board, voltage, etc ?

Click to expand...

Yes, scribble to the right it the PCB track. Odd that the secondary isn't taken from the two outside pins...

The 4 diodes of the rectifier circuit check out OK. This then from the regulator datasheet:



R1 in this case is 270R, R2 is 2400R. Not sure about IAdj so I just plumbed in 100uA as a figure. Vout then calcs as 12.6V.....I think?

I've ordered a 2KVA, 0-15V transformer from RS that should fit the pcb. I'll need to break one track and bridge a couple of others as the secondary pin out is different. Fingers crossed.

2KVA   ?   I assume the 2400 ohms is the "as set" value of the potentiometer, as opposed to the total track.  In that case, looks a good shot to me. 

If the regulator runs hot I suspect a 12 volt transformer may suffice.

I bought a 120VAC unit cheap, s/hand from the States. Thinking to desolder the 120VAC/?AC transformer from the board and stick a 110VAC transformer on the primary. Then measure the secondary and figure a new 230VAC PCB transformer from that. The original was an FPD1901 220. The US one is an FPD1900 120. The tech guy at the maker confirms the "code" module should work in both. 

Rather than butcher it, just buy a small autotransformer so you can feed it with 110V?

ProDave said:

Rather than butcher it, just buy a small autotransformer so you can feed it with 110V?

Click to expand...

I did think of that. Space in the panel, on the DIN rail, is ridiculously tight  but I haven't ruled it out. A one module wide 230/115 DIN rail mounting trannie is a maybe!

Interesting, the inside of the earlier version of the unit, on the left, compared to the later design on the right (they do the self same thing). I remember now damp used to affect the open frame pots:



No luck on finding info on the 120VAC primary pcb transformer (on the left) either. Part numbers stamped on the laminations ""16874...". There was a label pasted over that with "168801400" on.

I removed the PCB transformer from the unit I bought from America which is designed for 120VAC supply. The one that burnt out was for 220VAC. A 110VAC transformer I have here puts out 117V...near enough I figure.



Measuring the secondary of the trannie with my meter and it's saying 17.6VAC. But that's the "open circuit" voltage coming off the secondary. When I measured the 230/15V trannie I was seeing 22VAC on the open circuit secondary.

Aiming to fit a 230VAC trannie in place of the 120VAC one. Not sure whether to go with the 230/15 I have or grab a 230/12? Thinking with the 12V one the open circuit voltage might be closer to 17.6 rather than 22.  Wondering tbh if the LM317T will in fact be that fussy.

Onoff said:

Wondering tbh if the LM317T will in fact be that fussy.

Click to expand...

It will depend on the current being drawn and the amount of power it has to dissipate as heat, - and of course the heat sinking arrangement.  If the input voltage is too high it will get hot and bothered. If the input is too low it won't be able to maintain the set output voltage on load.

Geoff1946 said:

It will depend on the current being drawn and the amount of power it has to dissipate as heat, - and of course the heat sinking arrangement.  If the input voltage is too high it will get hot and bothered. If the input is too low it won't be able to maintain the set output voltage on load.

Click to expand...

There is no heatsink on the voltage regulator. See the left hand unit, on the left of the big capacitor:

View attachment 11168

The tab of the device IS the heat sink when so used. That indicates that the designer isn't expecting much power dissipation. 

Geoff1946 said:

The tab of the device IS the heat sink when so used. That indicates that the designer isn't expecting much power dissipation. 

Click to expand...

It's also a bolt hole to go on a bigger heatsink with heat transfer compound...

Geoff1946 said:

It will depend on the current being drawn and the amount of power it has to dissipate as heat, - and of course the heat sinking arrangement.  If the input voltage is too high it will get hot and bothered. If the input is too low it won't be able to maintain the set output voltage on load.

Click to expand...

This on the case of the 120VAC unit

Update: I got the 120V generator bought from the States, working on 230V after changing the PCB transformer. Worked a treat on the system.

I didn't leave it in there though. Fitted instead a modern equivalent from the same maker some 4 or 5 generations newer. That one needed programming via a laptop to knock the number of scanned channels down from 128 as otherwise there was overrun on the functions. Also the new one is 24vdc rather that 230vac. 

The repaired one will do as a spare.