3 replies to this topic

[Prana69]

Hey all

I recently acquired an Akai AT-550 tuner, circa 1973. All four dial lamps are blown. They are 6v 150ma fuse lamps, but I cannot find these anywhere. The closest matches I can find are 6.3v 250ma and 6v 250ma lamps.

What would be the impact of using the wrong amperage lamps? I’m thinking in terms of:

• Danger in that it might cause an electrical failure or fire through excess heat.
  
• Danger in jeopardising the life of the tuner and components.
  
• Will it simply reduce the life of the fuse lamps themselves so that they will need more frequent replacement?

Bear in mind that I will probably only use the tuner once a month for a period of maybe 1-2 hours max. Is it safe to use those 250ma rated lamps?

There is a 12v 150ma version I have found also. But that might be too much of a jump?

I also have some 8v 250ma lamps from a Marantz receiver. Would they be safe?

Advice appreciated.
Thanks
Dave

[Zaphod Beeblebrox]

It is not advisable to use different lamps in such devices. Sometimes the power supply may be overloaded. Worse, plastic components can be damaged by the extra heat. WES Components stock exactly the lamps you require. Part # 754-6. Use them. If you want to really do a number on your tuner, use LEDs. That will require some considerable engineering however.

[Prana69]

Thanks Zaph! I actually did go to WES yesterday but that site is so hard to navigate for the "occasional" buyer. I didn't really know where to look. But I eventually found the catalog and found the lamps, and have made an enquiry.

The fuse lamps are fully encased in an aluminium housing, and are at least 1 inch away from the plastic dial window - so I think it would have been safe from that perspective. But yes, far better to use the original spec if I can find them.

The tuner also has a blown meter lamp. It is one of the small axial lamps. However, I can't find any specs or ratings on it. I am pretty sure it is 3mm diam, but WES lists 6V, 9V and 12V versions. Is it safe to assume that because the dial lamps are 6V versions, the axials would be 6 volts too?

Oh yeah, I'm not going to be doing the LED thing. Not in my skill-set. That would probably end up being terminal for me, the tuner or both.

Thanks
Dave

Edited by Prana69, 28 March 2012 - 11:45 AM.

[Zaphod Beeblebrox]

Thanks Zaph! I actually did go to WES yesterday but that site is so hard to navigate for the "occasional" buyer. I didn't really know where to look. But I eventually found the catalog and found the lamps, and have made an enquiry.

The fuse lamps are fully encased in an aluminium housing, and are at least 1 inch away from the plastic dial window - so I think it would have been safe from that perspective. But yes, far better to use the original spec if I can find them.

The tuner also has a blown meter lamp. It is one of the small axial lamps. However, I can't find any specs or ratings on it. I am pretty sure it is 3mm diam, but WES lists 6V, 9V and 12V versions. Is it safe to assume that because the dial lamps are 6V versions, the axials would be 6 volts too?

Oh yeah, I'm not going to be doing the LED thing. Not in my skill-set. That would probably end up being terminal for me, the tuner or both.

Thanks
Dave

Probably more likely to be 12 Volts, but I don't know for certain. I'll try to locate some service data and let you know.

Oops. More likely you are correct. Probably is 6 Volts. I'll get back to you.

Edited by Zaphod Beeblebrox, 28 March 2012 - 11:54 AM.