• Please note that Audiokarma will be offline briefly for updates early on Monday morning, September 28th.

Strobe Replacement Thorens TD125 Mrk II?

W

wizard3571

New Member
Has anyone found a replacement for the strobe?
Thinking of trying two LED's in series with a resistor. The two LEDS will catch each half of the AC voltage - I figure this as the strobe was a neon. The circuit calls for a 6 volt 20 mlliamp lamp

What is the likely voltage being presented at the strobe contacts from the op amp?

Regards
Bill:yes:
 
Register to hide this ad
I think the strobe lamp is 120 v neon. If not, then the circuit has to be driven by an oscillator in the Thorens. A 6 volt incandescent won't flash enough to be easily readable. Double check your info.
 
Hi Nakdoc,

Placed a meter across the contacts and got 2.23Volts AC.
The LED on its own didn't light.
A circuit diagram for servicing the TD 125 II has a bulb shown at 6Volt and 20 mA.

So either the op amp is shot - or some other components have gone west.
The op amp spes give a 28 volt max swing output for 15 volt supply.
Other than that I'm lost at the moment - and unfortunately the old strobe is in pieces.
Best Regards
Bill
 
Keep in mind that most AC meters do not read (Vpk / sqrt(2)), they "assume" a 60 Hz sine wave signal. The peak voltage is probably much higher than what you are reading, since you have a strobe function, and the duty cycle is not going to be anywhere near 100%. You have pulses along a 0V signal. So, you'd really need a scope to see at what amplitude the pulses are.

Does that make sense? Hard for me to verbalize without drawing a picture.

rooster.
 
wizard3571 said:
Has anyone found a replacement for the strobe?
Thinking of trying two LED's in series with a resistor. The two LEDS will catch each half of the AC voltage - I figure this as the strobe was a neon. The circuit calls for a 6 volt 20 mlliamp lamp

What is the likely voltage being presented at the strobe contacts from the op amp?

Regards
Bill:yes:
Click to expand...

Do you know about the analogdept.com? It's a site with tons of info and Help on Thorens tables.

http://www.theanalogdept.com/
 
I thought about this for a bit. Depending on the circuit, you could put an electrolytic cap across the leads for the bulb, and let the cap charge to the max voltage of the pulses. That would give you some idea of the peak voltage the driver was putting out. However, I don't know what the bulb driver circuit looks like, so I'd want to make sure that the first few pulses didn't blow the driver, as the cap would look like a very low resistance load until it starts "filling up."

Does this make sense?

rooster.
 
You must log in or register to reply here.
Back
Top Bottom