Wanted - HAFLER DH-500 RELAY

[john65b]

Hello all, looking for a Hafler DH-500 relay - looks to be a 48V,12A with rail voltage operating the coil?

Anyway, having a bear of a time finding a replacement.

Thanks

[jean-paul]

http://www.hafler.com/techsupport/pd...00_amp_man.pdf

Hi, what is written on the relay ? It seems an unusual (right current rating,chassis mount, large) one for this purpose. Good ! You can use another 48 V relay with contacts for 12 A or better 16 A. Other relays can be used if you add a small transformer with the right voltage. Use relays with "hard silver" contacts.

Being used to replacing 2 A rated relays in japanese power amps I replace those with Schrack/TE RT2 type relays. They have 8 A contacts and never failed on me till now. I wish they made 16 A double pole relays but they don't in this format. You can use the single pole RT1 version which is rated 16 A but you will need 2 of those. I have a hunch that you can use the coils of 2 x RT1 48 V rated relays in series if you change R120 to 0 Ohm but please measure power supply voltage that is over the coil of the old relay first....and check again if you choose this way after you added 2 relays and measure per coil.

Of course you will need to put a diode in reverse parallel of the coils (one diode per relay coil) to avoid reverse high voltage.

[john65b]

The existing relay Coil is open - and the amp never gets out of standby - I temporarily removed the relay and jumpered the speaker outs - works perfect with no relay, with a little turn on thump. No issues with DC Offset (within 15mv)

Kinda tempted to leave out the relay - as I said, works perfect, with a small turn on thump (I have heard much worse).

Here is what relay says (may not be original)

Magnecraft
388CQX-14
48VDC

12A @ 120VAC/28VDC
12A @240VAC UL
10A @240VAC CSA
1/3HP @ 120VAC
1/2HP @ 240VAC

[jean-paul]

Hi I left relays out in some cases many years ago but equipment does fail sometimes and then it will be your speakers that will hate this decision....they will forgive you for the few hundred power on thumps.

There is hope:

http://www.weisd.com/test/GenericPar...itid1=388CQX-3

http://www.weisd.com/store2/NTER10-5D10-24F.pdf

[john65b]

Its only 24V, not 48V??

[jean-paul]

Just saw it when you replied. Then the Schrack relays are an option. I possibly have some in stock but I doubt shipping costs will make it a good deal for you. Better find panel/chassis mount 48 V relays in the US. Like this one:

http://download.siliconexpert.com/pd...sheet_0910.pdf

http://www.arrow.com/item/detail/te-...ty/8-1393113-8

[bear]

It's a control voltage, change the circuit so that it does the required voltage - and actually relays don't care much about voltage, as long as you don't overdo it by a lot. I seem to recall altering the circuit so that I could use a 24vdc or 12vdc, don't remember which to power the relay. An LM317 might do the trick too, haven't looked at the schematic... I suggest a 4PDT relay, use paralleled contacts. I think that they sound better.

_-_-bear

[jean-paul]

Simplest would be to choose the right voltage straight away especially when they are available and one needs to order one anyway.

Using a relay rated for lower coil voltages will result in the need for a power dissipating circuit which won't be as reliable as a simple relay coil. Loss of power, conversion to useless heat, more parts. Something of the past.

Paralleling the contacts is OK but one of them will be slightly faster than the other which is why it is not done often in power circuits. There are special relays out there that have different contact materials for this purpose. The contacts that close first are purely for current switching and the second contacts are better conducting materials that do not like high current switching.

http://www.europe-audio.com/Product.asp?Product_ID=4469

[john65b]

Thanks guys - I found a perfect replacement, with all correct specs...

[compressit]

Mind sharing the info on this?