Carver PM1.5 120 to 240V question

[Silver Stealth]

Hi everyone

I've a Carver amp I've been using for a few years in Australia (PM1.5) with a step down transformer.

Still works fine, just would like to get rid of the step down transformer...

I've opened up the amp and seen the diac/triac board which has a section indicating some jumpers possibly to change when using 240V (J3-J5). However J2 is supposed to be connected for 120V operation and currently it isn't! (and is working fine !!! )

I also noticed R9, C6 and C7 are not fitted on the board, and was curious if they needed to be for 240V operation. See pic attached.

Would appreciate any knowledgable opinions on what is the likely best course of action without blowing it up!

Cheers, Kendrick

[anatech]

Hi Kendrick,
Just a quick from the hip remark for you. I am positive the triac would need to be changed out. I recall there was a different part number for it. That and the Mag coil windings need to be put in series.

There are other things to do. I would highly recommend this be done at an ex-Carver warranty shop. Make sure it's a tech that actually used to work on these. The circuit you are changing is fundamental to the way this amp operates.

Due to the nature of the way this amplifier draws power from the AC supply, use a step down transformer sized much larger than you would normally think it requires. At least you are step down, rather than up!

-Chris

[Silver Stealth]

Hi Anatech

Thanks for the post - I also sent an enquiry through Phoenix Gold (Carver Pro) and they've sent me the pdf which describes MANY things required to change. Many thanks Phoenix, great customer support.

You are right the Triac needs to be changed also...why they have misleading information under the lid is beyond me...

If anyone needs a copy just send me a PM.

[anatech]

Hi Kendrick,
The guys in Carver engineering were a great bunch. I wonder if Phoenix got any. It's good to hear these fellas are concerned about customer service.

-Chris

[Silver Stealth]

I agree Anatech.

Now I need to find a Q6035 (600V, 35A) Triac to fit (most of the other parts required I should have if I scrounge around here). Mouser lists some by Littlefuse, will these suffice if the above V and I specs are met?

Digikey have Q6035P5 in stock which is an Alternistor made by Teccor - similarly, would this do the job? (T03 Fastpack P package - different to the current package but shouldn't be a major issue to fit)

http://rocky.digikey.com/WebLib/Tecc...pak%20Triac%20(25%20and%2035%20Amp).pdf

Any help appreciated.

[anatech]

Hi Kendrick,
That's exactly the one I was thinking of. Got a 404 message by clicking on the link.

Teccor is the manufacturer that the newer triacs were sourced from, so you are using exactly the same part that Carver warranty was using.

I'll try the link here: http://rocky.digikey.com/WebLib/Tecc...035%20Amp).pdf

-Chris

[Silver Stealth]

Thanks Chris, that's very reassuring to know. I'll get me some.

I have the 120V version spares if anyone needs them (Q2035 I think).

[Silver Stealth]

I now have a full workshop manual which is most helpful (thanks again to Phoenix Gold). Some useful owners manuals also at http://www.carverpro.com/download.html . Managed to set the main HT DC voltage and biases within spec - dropped the HT down to more like 119V vs 125V (hate running caps close to their upper rating of 130V- 80% is more sensible!) Horrible hard to adjust pots....arrrgh!

EVA, if you're listening in, would you care to comment on the most suitable caps to suit this amp (2200uf/50V and 2200uf/80V in the lower supplies)? I presume high ripple current is important - most I've seen are around 3.1-3.2A and impedance 23-61mohms. Packaging replacing the dual voltage caps is a constraint though. Anatech suggested SMPS types would be useful but having no experience with SMPS I thought I'd ask someone more knowledgable.