Help with Part Numbers for Siemens U273 and W293 components

[teyeteye]

Hello to all,

This is my first post here, though I've been a casual reader of the forum for some years.

I'm working with a tech who's repairing a couple of Siemens U273 and W293 units for me.

In order for him to proceed with his work, he needs to find equivalent modern part numbers for the original components he has identified as faulty. The tech believes that the Siemens components are numbered uniquely, as his usually reliable avenues of research have failed to turn up equivalents.

I'm wondering if anyone in this forum can help us. Here's an excerpt from an email I received, explaining John's problem in detail:

"...As I mentioned I think that a number of the semiconductor devices in these Siemens products are custom order and hence have unique part numbers.

In the compressor I have managed to find an equivalent for only one transistor: Ts 1 and Ts 2 are quoted as a BCY 66 which has an equivalent part number BC 184.

A number of other devices are Texas Instrument NPN with part numbers SST 116, SST 117, SST 116M and SST 117M, for which I can't find equivalents.

The high pass filters have a pair of 10 pin op amps with part numbers such as MC 1461R, MC 1554G, SC 5141G which also appear to be unique orders."

We'd be very grateful for any advice and information,

Thanks,

 

[moamps]

http://groupdiy.com/index.php?topic=55826.0

http://www.electronicpool.de/list/index_S_S_SST116-1_SST.html

http://www.ebay.de/itm/MC1554G-Integrated-Circuit-/161683376489?hash=item25a5148969:g:d~gAAOSwstxVOjmf

http://www.ebay.de/itm/MC1461R-INTEGRATED-CIRCUIT-/172088512367?hash=item2811464f6f:g:QuwAAOSw6aVUqnLW

http://www.ebay.de/itm/5-Stuck-Transistoren-SST117-1-/321993229317?hash=item4af84ac405:g:0zgAAOSwT6pVq02k

 

[teyeteye]

Thanks moamps, that's a great help.

 

[opacheco]

Hello to all,

This is my first post here, though I've been a casual reader of the forum for some years.

I'm working with a tech who's repairing a couple of Siemens U273 and W293 units for me.

In order for him to proceed with his work, he needs to find equivalent modern part numbers for the original components he has identified as faulty. The tech believes that the Siemens components are numbered uniquely, as his usually reliable avenues of research have failed to turn up equivalents.

I'm wondering if anyone in this forum can help us. Here's an excerpt from an email I received, explaining John's problem in detail:

"...As I mentioned I think that a number of the semiconductor devices in these Siemens products are custom order and hence have unique part numbers.

In the compressor I have managed to find an equivalent for only one transistor: Ts 1 and Ts 2 are quoted as a BCY 66 which has an equivalent part number BC 184.

A number of other devices are Texas Instrument NPN with part numbers SST 116, SST 117, SST 116M and SST 117M, for which I can't find equivalents.

The high pass filters have a pair of 10 pin op amps with part numbers such as MC 1461R, MC 1554G, SC 5141G which also appear to be unique orders."

We'd be very grateful for any advice and information,

Thanks,

Hi,

Did you find something about the SST transsitors ??.....I have some in bad condition in my U273 units and I found nothing about them and substitution either!!...The same history for the OA 154Q and SSD 55 Diodes!!

Any info will be great!

Opacheco

 

[Michael Tibes]

If necessary you might have to carefully match the output transistors, the stability of the output stage might depend on it very much. I would not swap transistors for new ones if they are not really broken. This is a very old design and tolerances between transistors were huge compared to modern parts. I don't know how, if and which transistors had been selected for special parameters, but I once had to fix a V276 which had been 'improved' by someone who had replaced working transistors with NOS ones without selecting them and it was impossible to get the unit into a stable working condition. After I made the owner chase after the original parts (which luckily hadn't been thrown away) and reinstalling them the amp worked perfectly. If the output stage really was broken then you might need to buy quite a few transistors to find a matching pair because parameters can be quite spread.

Michael

 

[etheory]

you might have to carefully match the output transistors, the stability of the output stage might depend on it very much

That's not been my experience at all.
For the class-A output stages of most of the old Siemens stuff, you just need to set the bias control correctly to bias the output stage and the imbalances then generally don't pose any issue.

In all the circuits from Siemens I've worked on thus far with this output arrangement, you adjust the bias control to obtain half the supply voltage at the output transistors when no signal is being passed, and then your bias should be good. If you don't adjust the bias to this point, things can go south quickly.

I've commented on suitable replacements that I've used successfully in these circuits here: http://groupdiy.com/index.php?topic=55826.msg712429#msg712429

my2c.