What type of diode........

[Nails]

Quick one guys........what is the correct name for these type of diodes....
got to replace both on the side of caution as one had a dry joint and a broken leg .....the have two sets of numbers on them one side has 481 and the other 32...am I right in assuming 48132 is the correct diode number.???

[BobEllis]

Looks like a photocoupler like George uses in his LightSpeed attenuator. Look for a photresistor on the schematic it ought to tell you what the part number is. George uses a NSL32 series, but the Silonex data sheet doesn't say how the parts are marked.

[Nails]

Originally Posted by BobEllis

Looks like a photocoupler like George uses in his LightSpeed attenuator. Look for a photresistor on the schematic it ought to tell you what the part number is. George uses a NSL32 series, but the Silonex data sheet doesn't say how the parts are marked.

Thanks for the reply Bob.....not to sure on that one.
They are part of the power supply side of an input board on a Crown power amp...they seem to be fed by 2x 5k6 5 watt resistors green blue red from the main board..being part of the power supply would I be right in saying that they are some type of diode..Mmmm..not to sure on this one..

[BobEllis]

The input board says LDR1A and LDR1B where they connect. Sounds like Light Dependent Resistor to me. I think I would have mounted the photoresistor end on its board and used long leads on the power end.

Do you have a schematic? Perhaps as part of a mute or gain control circuit that you can do without.

[Enzo]

They look like LDRs, and if the board calls them LDRs then I'd guess they are LDRs. That is some sort of light, like an LED, and some sort of photocell, all in one part.

And LDR allows two separate circuits to be connected without any direct DC connection. For example when current exceeds some amount the LED lights and drives the photocell resistance down, attenuating the circuit drive. That is a pretty common application.

COntact Crown and ask for the service materials for this amp. Crown tends to be helpful. The parts list should ident the parts. And the circuit should show how they are used.

[Nails]

Originally Posted by Enzo

They look like LDRs, and if the board calls them LDRs then I'd guess they are LDRs. That is some sort of light, like an LED, and some sort of photocell, all in one part.

And LDR allows two separate circuits to be connected without any direct DC connection. For example when current exceeds some amount the LED lights and drives the photocell resistance down, attenuating the circuit drive. That is a pretty common application.

COntact Crown and ask for the service materials for this amp. Crown tends to be helpful. The parts list should ident the parts. And the circuit should show how they are used.

Originally Posted by Nails

Power from the main board is fed through the 2x 5w 5k6 ohm resistors..green blue red.. which can be seen on both sides of the power supply..



18v from HDR2/1 and HDR3/6 are the DC feed on both sides...

The two diodes ZD3 and ZD4 18v feed through to pins 4 and 8 on the op amp.....if that makes sense guys...there are some type of diode but I,am really unsure at the moment...may have to take them down to the components store and see what they can make of it all..Mmmmm

[BobEllis]

HDR means header - you have identified some of the power connections. You are partially correct, the device has an LED to illuminate the LDR.

See LDR1A just below SW2 on the schematic with the XLR connectors. With SW2 in the position opposite that shown, you have an attenuator with the 20K resistor. This is the same setup GeorgeHIFI used in his first version of the LightSpeed. Somewhere else is the gain control that powers and controls the brightness of the LED half of the device.

You can just remove the devices as long as you leave the switch in the position shown (measure across R2A and you should see 0R). You'll have to do any level matching required elsewhere. If you want to replace them, I suspect the ones used in the LightSpeed and Clones will be fine - anything that has a high dark resistance.

The LDR may also be part of a crossover - hard to tell without the full schematic. If so you'll want to replace it.

[Nails]

Originally Posted by BobEllis

HDR means header - you have identified some of the power connections. You are partially correct, the device has an LED to illuminate the LDR.

See LDR1A just below SW2 on the schematic with the XLR connectors. With SW2 in the position opposite that shown, you have an attenuator with the 20K resistor. This is the same setup GeorgeHIFI used in his first version of the LightSpeed. Somewhere else is the gain control that powers and controls the brightness of the LED half of the device.

You can just remove the devices as long as you leave the switch in the position shown (measure across R2A and you should see 0R). You'll have to do any level matching required elsewhere. If you want to replace them, I suspect the ones used in the LightSpeed and Clones will be fine - anything that has a high dark resistance.
The LDR may also be part of a crossover - hard to tell without the full schematic. If so you'll want to replace it.

Try this one Bob it may help...Thank you..

http://www.crownaudio.com/pdf/legacy/c1071-6.pdf

[AndrewT]

one PCB is printed LED, the other PCB is printed LDR.

It is an LED controlled LDR.

[zeonrider]

LDR 100% in Limiter circuit!

Regards zeoN_Rider