Fisher transistor replacement LONGSHOT??

[larryderouin]

Unit: 1969 FISHER 500TX.
SERVICE MANUAL: Sitting in my Lap.
PROBLEM: NONE with Unit. Making up a parts list and xref old #'s to new #'s. Having problem locating Main power amp transistors.
Schematic of AMP shows TR1038-5 and TR1039-5
Actual Transistors MOTOROLA 01059-7 and 02059-7. All cases are domed, and all match physically. Lettering is good (authentic) as far as I can tell. The Motorola M then the 01059-7# and 139 under that on all 4. Mounting is intact, screw heads unmolested, showing as original. They are Silicon, TO-3cased. I will be renewing the Mica insulators and grease.

I run this unit 18-20 hours a day and it never gets warm. I did idle adjustment and it's @ 15mv per spec. I checked all voltage readings on all boards per schematic and values gotten are all within +1v to -1/2v. Line voltage is 120-122 depending on time of day. Schematic readings based on line voltage of 120.

I ran all 4 numbers thru Onsemi, Fairchild Rohm.........NADA!!!

SK shows sk9136 and 9134 for 1038 and 1039 respectively.
nte shows 180 and 181 respectively.

NTE is LAST RESORT. Destroying unit to save it humiliation of having had NTE parts in it is choice before NTE parts.

I don't know how to xref using what ever the mumbo jumbo is that MTF, Echowars, Avionic and others use to come up with other #'s.
Can someone please help with some numbers I can use @ Mouser or Digikey if I need these in the forseeable future.

Thanks in Advance

Larry

 

[larryderouin]

Thanks PC. All I need is he #'s right now.

Larry

 

[avionic]

OK .Looking through and old ECG X-ref manual..print date Jan 1989
the TR1038-5 crosses to a ECG/NTE 280
the TR1039-5 crosses to a ECG/NTE 281

Specs for the ECG/NTE's are met and exceeded by
Onsemi's MJ21193G-----NTE281
Onsemi's MJ21194G-----NTE280

 

[larryderouin]

Many thanks guys. #'s are written down in SM and on parts list equiv.

Larry

 

[PacificStereo]

Well... this is difficult. For sure the TR-xxx P/N is a Fisher designation. It appears that the later P/N is ALSO a Fisher part number, though I can't confirm this 100%. I don't have info on any of these parts directly in any of my references or cross-lists.

That being said, ECG does cross the first ones to the 180/181 p/n. My SK book (which is old) crosses those parts to the SK3188A and 3189A. What's odd is that my SK book does list 9136/9134 parts, but it doesn't cross the Fisher part over to those. The 3188 part is a smaller part in both current and voltage, but looks to have an Ft of 5 MHz. The ECG180/181 parts look to be about 2 MHz.

I haven't looked at the OnSemi parts, but I'm sure they're comparable.

In the meantime, while looking, I did run across THIS:

You may wish to see if your unit has this done.

Wish I could help better with the parts, but that's all I gots...!

 

[Detailman]

Thanks for posting that service bulletin. I've got one of those and will check to see if it's been done.

For the Op, I seem to remember doing some research on those funny looking transistors on the driver board when I first got mine. It's been a couple years so I don't recall details of what I did but I know that I didn't have any success finding up to date replacements for those.
Maybe there are some but I couldn't find them.

 

[avionic]

NTE shows 180 and 181 respectively.

Thats strange..My ECG paper manual crosses to 280 & 281
NTE online x-ref. 180 &181
NTE and ECG are one in the same.
If they are indeed 180 and 181

 

[larryderouin]

I got the Bulletin with the S.M. from Rick Stout. 1st thing I re-checked. It looks like it was done at the factory. Pretty sure no work done on this unit, no marks on the screws, and no funny looking replacement parts. If worse come to worse I'll get the SK's over the NTE's if they are available in the future.

I've got it 60% re-capped now. It has some distortion if the bass is cranked up all the way and the loudness control is ON. Volume has to be louder than 9 oclock. It diminished with the re-capping of the Power supply and the AMP. Haven't finished the pre-amp yet. I disconnected the "REVERB" and hooked up a tape deck to the monitor and ran it that way just thru the tone control, filter, and amp boards. The distoration is less but still there. Hooked up the preamp and the distortion came back. So I need to at least finish the re-cap and then see what's what.

It plays great. It's the bedroom unit and doesn't get turned up much past 8 o'clock. Mainly classical station and background volume levels at that . So it's not really critical but it is annoying that it's there. Wife doesn't notice it, but I do more so in that I know it does it. So guess I'll finish the re-cap after I get my 400 and see what happens.

Thanks for all the help guys.

Larry

 

[larryderouin]

Avionic: How about an mj802G for the 181 and mj4502 (ONSEMI) for the 180. I ran ONSEMI xref for ecg180 and 181.

MJ802G is in stock @ Mouser.

MJ4502 is on order @ Mouser and delivery due on 3-31.

Larry

 

[EchoWars]

What is this 30A thing? This is a 65WPC receiver...

The On-Semi MJ15003 an MJ15004 would be very tough transistors for that receiver.

 

[larryderouin]

EW:

Tough as in barely able to keep up, or Tough as in Overkill??? I'd like to be able to replace with known good replacements when/if I need to that won't be at their limits when running normally. Is there data on how FISHER ran the OPT's on their 1st generation SS units? At the ragged edge, in the middle of the operating range, or barely loafing? As apparently the only direct cross connect to the FISHER #'s is TWO DIFFERENT NTE #'s, and the others are crossed off them, I'm kind of concerned with operational longevity based on load capability vs. unit load limits. Not trying to be a pain, but I really don't understand all the different values and interactions. So getting the best match, is really asking a bunch of questions.

1.) what are the values of the ORIGINAL Motorola transistors? I haven't been able to find anything. Either using the FISHER # or the Motorola #.

2.) NTE. Being notoriously vilified by the board as a general rule....even by me, has on occasion to prove the only source for near obsolete or obsolete semi's. But when it comes to transistors, I'm leery of using them in this case even as a last resort, due to the above discrepancies (180-181 vs. 280/281). How are we to know which part is the correct one. There was another case of this on I believe a PIONEER unit about a year back where the online catalog didn't jive with the downloadable or paper catalog. In this case which is correct.

3.) Is there a Non destructable way to test the original transistors to get the values needed to corrolate a reliable working xref?

4.) The SK #'s are based off NTE/ECG #'s, so they aren't a direct xref.

Like I said in the First Post this IS a Working receiver. It has been about 60-70% recapped, and is working with a slight distortion when the bass is maxxed out, and the volume is turned up to approx 10:00. When the Bass is turned down the distortion goes away. The distortion is generally less when the pre/amp jumpers are pulled. When the jumpers are put back in the distortion returns to original levels. Other than that it works perfectly.

As long as the spec meet or exceed what the original is/was I'm not really that picky except for NTE. Again that would be last choice. I just want to be able to get one set that will run reliably, and cool when I finally need to get one. I ran it today at about 1030 on volume for 3 hours today with tone controls centered, loudness on. Source was R2R. Tested temp from heatsink every 1/2 hour. Temps NEVER Exceeded 105*F (4 samples above each transistor on the heatsink) and averaged 102*.
Coolest running receiver I've ever seen. Maybe that's a good sign.

Again guys thanks for all the help. Even if I don't understand all of it. (time to ask Dad more questions I guess. It's his turn!).

Larry

 

[EchoWars]

1. No, unless you have the old data sheets.
2. NTE blows. And your choice of output transistors is nowhere near as important as you seem to believe.
3. In essence, no.
4. Hah!

Whatever trouble you're having is unlikely to be related to your output transistors. The unit needs to be benched and scoped with a sine wave, and tested for any freq. response problems and to see that it is making its rated power on both channels. If so, chances are good that you're simply pushing the amp too hard.

 

[PacificStereo]

Uh, the SK numbers aren't based on the NTE numbers, they're based on the parts the SK book suggests for your original part numbers.

And, what Echo said. Are your output devices actually bad, or is this a mouse-on-a-wheel exercise?

 

[Nakdoc]

One trick when subbing OEM part numbered transistors is to use the manufacturer's replacement guide. In the case of Motorola, it would be a HEP Transistor replacement guide. Does anyone have one? Motorola would spec the exact transistorin their book.

 

[larryderouin]

The Unit runs fine except for the slight to moderate distortion when you turn up the bass and the volume is above 3 on the face plate (or 10:00). I'm trying to find xref numbers for my service manual IF/WHEN I need to replace them, and the OPT's are the sticking point, that's all. If you think it's a Mouse on a wheel exercise, I apologize.

As for the SK #'s. When I ran the FISHER AND/OR Motorola #'s thru the SK XREF it came up No such xref. But when I ran the ECG or NTE #'s I got the above SK #'s. That's why i said the SK's were based on the NTE's.

Larry

 

[tarior]

IMO, you are way overthinking a problem that doesn't even exist. Dog-slow TO-3 cased outputs with high current carrying capability will likely be around for a very long time. Don't sweat it, just finish the re-cap and enjoy the music.
The bass distortion you hear when you turn the bass all the way up while the loudness is engaged is either from overdriving the amp or overdriving the preamp.

If you're dead set on having spare set of OTs, I would second EchoWars' suggestion of MJ15003/4 or if for some reason the originals spec a higher Vbeo, I'd go with MJ15015/16. Compare for yourself.
http://www.onsemi.com/pub_link/Collateral/2N3055A-D.PDF
http://www.onsemi.com/pub_link/Collateral/MJ15003-D.PDF

 

[PacificStereo]

I just ran across one of these that it looks like I will be restoring in the near future. Aside from the fact that some nitwit subbed two uncomplimentary output devices (one wonders how these people get soldering licenses!), it looks remarkably original.

It's missing the serial number sticker, but it looks like the early production. One thing is trouble, though, and that's the aluminum bracket that holds the AM antenna. It looks like someone did not heed the instructions about "not bending it beyond this point..."

I'm going to need to fabricate a new bracket. Larry, can you take some photos of yours and how it mounts to the chassis so I can reproduce it?

Thanks!

 

[larryderouin]

Good Score. I think you'll like the Auto Scan and the presets. One of mine is really touchy (pops back out), but I think I can fix it by re-aligning the physical unit against the faceplate holes.

NO PROBLEM on the PICTURES for the ANTENNA.

You need a copy of the O.M. and S.M. ? Send me a pm with your e-mail address and I'll shoot you a scanned copy of mine.

Larry

 

[larryderouin]

PacificStereo; The Serial # on mine, 59833 is stamped on the chassis above the LEFT REAR Speaker Terminals. I fixed the distortion, Leaky cap on the chassis just to the right of the AMP. 1000uf/50V with 1500uf/75v(C-15). After testing replaced the 2-2000uf/55V with 3000uf/75V Nichicons (c975/976) and the 4 Diodes on the boardCR-971,72,73.74 with in4007's. Distortion GONE! Plus I re-capped the rest of the signal boards, and the Autoscan board. Works fine. No scope yet, but b-day is coming up in APRIL. Just Maybe.

This one was way easier to work on than the 175-T. Lots more Room.

Larry

 

[PacificStereo]

Thanks. I'll definitely be changing all caps on this puppy. Looks like FM alignment will be fun!

Yeah, you definitely need a scope- handy little things!