TEKtronix 465/475 scope: How to easily replace bulbs. - UK Vintage Radio Repair and Restoration Discussion Forum

REDGUUZ · 20th Dec 2017, 5:48 pm

Hi,

I have a TEK 475 scope in which one of the indicator bulbs ("READY") DS610, has burned out.

Is there an easy way to replace this bulb (e.g. from the front, by using pliers) or do I have to dismantle half of the scope to get at the trigger board?

TEK part no 150-0130-00 hints at a wire micro lamp (5V 60mA identical to 7153AS15 of Farnell, which is a wire lamp.

However looking at a photo in the TEK 475 service manual, I see a sort of white plastic socket for this lamp (DS610) and its neighbour (DS608), "TRG'D".

I could hardly believe that TEK came up with a design where one has to dismantle half the scope to replace a little lamp!
I suspect that maybe after all they used lamps with Pins, which could be removed from the front (using small pliers).

Could somebody please confirm what the correct procedure is to remove these lamps?
If indeed lamps with Pins are used, could you please give a reference to a substitute (maybe even a Led lamp?

Thanks in advance!!

Regards, Martin

evingar · 20th Dec 2017, 6:31 pm

I can't answer that categorically becuase I've never attempted that particular task on the instruments of this type I've owned in the past. However, nothing would surprise me with these 'scopes. The design appears to have zero thought towards servicing and repair.

I would strongly recommend engineering in a LED replacement solution.

MrBungle · 20th Dec 2017, 6:43 pm

There is no easy way. It requires disassembly. I have done it

Got to be honest I don’t like these scopes. Some of the least reliable bits are the hardest to get to (multiplier, power supply caps, vertical amp, bulbs, attenuator contacts).

I would agree with putting LEDs in there although the last 475 I had all the bulbs were original and worked.

ColinTheAmpMan1 · 20th Dec 2017, 8:41 pm

I agree totally with Mr Bungle - there is no other way than disassembly. These lamps are wire-ended and sit in small plastic "pods", for one description. You can get some idea of the appearance by checking out TekWiki. The job isn't that difficult or time-consuming, so long as you have the manual and follow the procedure. You could take photos as you go, but following the manual is straightforward.
Do you have the correct lamps? If they are the same as the 475A (which I have replaced), they are Tek 150-0130-00 and are T-1¾ size, 5V, 60mA. I got mine from Mouser (P/N 560-2200). I think I recall that the ones Tek used were also pre-aged, but I don't see that as being essential.
Good Luck, Colin.

MrBungle · 20th Dec 2017, 10:51 pm

I couldn’t find 5v bulbs when I did my last one so it got 3v bulb with series resistor. I did consider LED installation but I’d have had to do all of them or it would grate on me and I didn’t fancy that after getting to the first one.

REDGUUZ · 20th Dec 2017, 11:53 pm

Hi,

Thanks for all the advice. I did expect this answer, although I had hoped for an easier solution.

I guess I leave it as it is, for the time being. The repair is quite complex (with quite some risk of damaging something), compared to the nuissance of not having a B "READY" Trigger lamp.
I have a X-mas decoration which has reale cute small leds with the same color as the filament bulbs, and which would easily fit and work with a series resistor.
I guess I will install those if one or more bulbs would fail.

Thanks and Cheers! Martin

20th Dec 2017, 5:48 pm	#1
REDGUUZ Triode Join Date: May 2017 Location: Assen, Netherlands. Posts: 13	TEKtronix 465/475 scope: How to easily replace bulbs. Hi, I have a TEK 475 scope in which one of the indicator bulbs ("READY") DS610, has burned out. Is there an easy way to replace this bulb (e.g. from the front, by using pliers) or do I have to dismantle half of the scope to get at the trigger board? TEK part no 150-0130-00 hints at a wire micro lamp (5V 60mA identical to 7153AS15 of Farnell, which is a wire lamp. However looking at a photo in the TEK 475 service manual, I see a sort of white plastic socket for this lamp (DS610) and its neighbour (DS608), "TRG'D". I could hardly believe that TEK came up with a design where one has to dismantle half the scope to replace a little lamp! I suspect that maybe after all they used lamps with Pins, which could be removed from the front (using small pliers). *Could somebody please confirm what the correct procedure is to remove these lamps?* If indeed lamps with Pins are used, could you please give a reference to a substitute (maybe even a Led lamp? Thanks in advance!! Regards, *Martin* Attached Thumbnails

20th Dec 2017, 6:31 pm	#2
evingar Octode Join Date: Oct 2003 Location: Newbury, Berkshire, UK. Posts: 1,770	Re: TEKtronix 465/475 scope: How to easily replace bulbs. I can't answer that categorically becuase I've never attempted that particular task on the instruments of this type I've owned in the past. However, nothing would surprise me with these 'scopes. The design appears to have zero thought towards servicing and repair. I would strongly recommend engineering in a LED replacement solution. __________________ Chris

20th Dec 2017, 6:43 pm	#3
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: TEKtronix 465/475 scope: How to easily replace bulbs. There is no easy way. It requires disassembly. I have done it Got to be honest I don’t like these scopes. Some of the least reliable bits are the hardest to get to (multiplier, power supply caps, vertical amp, bulbs, attenuator contacts). I would agree with putting LEDs in there although the last 475 I had all the bulbs were original and worked.

20th Dec 2017, 8:41 pm	#4
ColinTheAmpMan1 Octode Join Date: Jan 2012 Location: Wimbledon, London, UK. Posts: 1,465	Re: TEKtronix 465/475 scope: How to easily replace bulbs. I agree totally with Mr Bungle - there is no other way than disassembly. These lamps are wire-ended and sit in small plastic "pods", for one description. You can get some idea of the appearance by checking out TekWiki. The job isn't that difficult or time-consuming, so long as you have the manual and follow the procedure. You could take photos as you go, but following the manual is straightforward. Do you have the correct lamps? If they are the same as the 475A (which I have replaced), they are Tek 150-0130-00 and are T-1¾ size, 5V, 60mA. I got mine from Mouser (P/N 560-2200). I think I recall that the ones Tek used were also pre-aged, but I don't see that as being essential. Good Luck, Colin.

20th Dec 2017, 10:51 pm	#5
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: TEKtronix 465/475 scope: How to easily replace bulbs. I couldn’t find 5v bulbs when I did my last one so it got 3v bulb with series resistor. I did consider LED installation but I’d have had to do all of them or it would grate on me and I didn’t fancy that after getting to the first one.

20th Dec 2017, 11:53 pm	#6
REDGUUZ Triode Join Date: May 2017 Location: Assen, Netherlands. Posts: 13	Re: TEKtronix 465/475 scope: How to easily replace bulbs. Hi, Thanks for all the advice. I did expect this answer, although I had hoped for an easier solution. I guess I leave it as it is, for the time being. The repair is quite complex (with quite some risk of damaging something), compared to the nuissance of not having a B "READY" Trigger lamp. I have a X-mas decoration which has reale cute small leds with the same color as the filament bulbs, and which would easily fit and work with a series resistor. I guess I will install those if one or more bulbs would fail. Thanks and Cheers! Martin