ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I am into a BM 1900, connected it showed standby light, selecting any source the relay clicked and it went back to standby, found 1 TIP141 gone bad, and a 0.47 resistor also bad.
changed all the electrolytic caps and lamps.
Are now changing all the small transistors in the end amps, came to the MPSH54, I dont find that one anywhere, but found a MPSA56, will that be OK ??
For the TIP141/146 I will use TIP142/147, will that change anything sound vise ??
Forum is working good now, except for the search function only a few hits coming up, and in archived forums nothing
Collecting Vintage B&O is not a hobby, its a lifestyle.
MPS H54 - There's really nothing like the real thing. Other types will typically show instability.They rarely come up for sale, be quick! - I even like to keep good used ones, their gold plated pins don't oxidize.
TIP141/146 or TIP142/147 - no problem at all.
Replace the idle current trimmers too if you didn't already.
Martin
http://www.ebay.co.uk/itm/MPSH54-Transistor-Silicon-PNP-CASE-TO92-MAKE-Motorola-/162605810059?epid=1948064576&hash=item25dc0fc18b:g:cysAAOSwqeFZeI7~
Dillen: MPS H54 - There's really nothing like the real thing. Other types will typically show instability.They rarely come up for sale, be quick! - I even like to keep good used ones, their gold plated pins don't oxidize. TIP141/146 or TIP142/147 - no problem at all. Replace the idle current trimmers too if you didn't already. Martin
Thanks Martin will try to get the MPS H54, but it will take time before they get here, the old ones shows good measuring off board, but I would like to change them, I sold this one, a BG 4002 and P45s to a good danish friend over here, I tried to sell him my good working pizza stack, but no such luck,
Jacques
chartz: Hi Søren, Do be weary of static measurements with these MPSH 54. I've been there.
Hi Søren,
Do be weary of static measurements with these MPSH 54. I've been there.
Found NOS in the US, but will have to wait for shipping they send with the postal service, and it will take at least 4 weeks, if they ever arrive.All the small TRs I changed until now tested good off board, but who knows when they get power, I am going through every component in the end amps, changing all diodes and resistors where they are way off limits. There is a small chance of me going to DK end of this month or beginning of Oct. so maybe Martin can provide something, will continue checking this weekend
Good to see you again here, there are few of us left
Hi Sorens,
Do yourself a favour and measure the HFE. I often find that NOS barely meet the min spec. I believe all the good ones are all gone and only the left overs are still available...
Soren, I have NOS of these if you are still interested.