Picked up Philharmonic II, some questions, is it FM stereo?

[larryderouin]

Yes, the dash panel would have been the same for both models. The P-22 is identical to the P-25 chassis wise. Look at the schematic for the 1961 P22.

MPX was not approved by the .FCC until June of 61 which would have been 2/3 of the way thru a model year. But FISHER was putting MPX jacks in most chassis' all the way back to 1959 as they were gearing up for any eventuality. The TA-600 was the 1st "STEREO" receiver FISHER made in 1958-59. It had the FM-AM Simulcast, but had the MPX jack. As did the 500S in 1961, and the TA-800. If you look at the tuners from that era most of them have a MPX jack. My 101-R from 1959-60 has one also.

The problem was no one knew which of the two systems (Crosby or GE) was going to be picked by the FCC, hence the outboard jack and the two different designs for MPX units (mpx 20 was Crosby, all others GE mpx). I don't think Jack Kennedy had that much pull in the decision, as he had only been in office for less than 6 months when the FCC made their decision.

 

[gadget73]

Gadget; I've bought both trade in and straight from Gary and am pleased with both. Rubber was supple but firm and holds very well in the Garrards I've gotten them for.

Larry

Are the direct purchases NOS? I've always suspected they were rebuilds and the difference in price was the core charge but maybe thats not the case.

 

[little-al]

So, no RIAA eq in the P-22 chassis, what is performing the RIAA eq then?

It has been mentioned a few times in this thread that the P-22 preamp chassis doesn't have any RIAA eq built in, and in fact the phono inputs are just standard aux inputs.

So, do cartridges like the Sonotone 8T perform, or somehow not need, the RIAA equalization when they playback a record?

Very interesting...

Al

 

[little-al]

...oh and along with the other MPX info, my lowly FM-50 which I think is circa 1960 even has an MPX out jack.

 

[TheRed1]

As you can see in the lower, right hand corner above - Fisher's FM-80 from way back in 1956 had a multiplex out jack. I haven't done an exhaustive search to see if that was their absolute earliest inclusion of that feature but I don't believe it was ever claimed as a "Fisher First". Other brands had MPX jacks years before Fisher.

As Larry mentioned, Fisher initially bet on the wrong horse. He anticipated the FCC would choose the multiplex system which had the highest fidelity - the Crosby system. They did not. Obviously there were other factors besides fidelity in the FCC's decision. Perhaps Fisher was being a little naive thinking the best design would win.

 

[larryderouin]

Are the direct purchases NOS? I've always suspected they were rebuilds and the difference in price was the core charge but maybe thats not the case.

Yep. All rebuilds. So you are paying what amounts to a core charge.

 

[gadget73]

ok, thought so. I've never bought one outright. I have no reason to keep the petrified idlers around here, so I send them in and save a couple bucks.

 

[dcgillespie]

MPX jacks were in fact present on some FM tuners in the mid 50s -- this to allow connection of SCA (Storecast Allocation) adapters to receive the special music only transmissions that were offered by some commercial stations, for department stores and the like that needed such services. Later, it became the same jack for connection of FM stereo adapters.

The Crosby stereo broadcasting system was in fact superior to the GE/Zenith version, because the Crosby system utilized an FM sub-carrier, where as the GE/Zenith version uses AM for this carrier. As a result, to this day, FM stereo signals get rather noisy with anything less than excellent signal reception, due to the use of the AM sub-carrier.

The primary reason that the GE/Zenith system was chosen is because it was compatible with the already in place SCA transmissions, whereas the Crosby system was not. These transmissions were extremely important to the very few FM stations that existed at the time, as advertising revenues were almost nonexistent on that format.

Dave

 

[little-al]

It has been mentioned a few times in this thread that the P-22 preamp chassis doesn't have any RIAA eq built in, and in fact the phono inputs are just standard aux inputs.

So, do cartridges like the Sonotone 8T perform, or somehow not need, the RIAA equalization when they playback a record?

Very interesting...

Al

Looks like I've found the answer to my question about ceramic carts and not needing RIAA eq, etc. Very informative!

http://www.roger-russell.com/sonopg/sonopc.htm

 

[KentTeffeteller]

SCA= Subsidiary Communications Authorization. To be correct about semantics. Storecasting was for many years one of it's most common uses. Background Music services were one of the main profitable uses for FM until FM began getting commercially viable in the early 1970's. SCA was also used for remote control of stations, paging services, and other uses too. One of the biggest reasons why the GE/Zenith FM multiplex stereo system was legalized was the fact that it would work with SCA services. FM in many areas was operated often at break even or mild profits at best. The SCA services kept many early FM stations afloat and on the air until FM stations could make enough money to be profitable commercially. So, consider the times. AM/FM combo stations usually had the AM then to keep the business profitable. FM station owners needed the extra revenue to stay in business.

 

[little-al]

Where is rectifier in the P-22 chassis?

Looking at the schematic for the Philharmonic II P-22 chassis, I don't see a rectifier tube nor a single selenium or silicon rectifier.

I have attached the Fisher P-22 service manual for reference.

I do see four silicon diodes in four different locations (CR 1 through 4) which I assume are performing this function? Can anyone confirm, and perhaps even explain?

If this were a single rectifier tube, or block rectifier, as part of this refresh I could have just changed them out along with the old caps, etc. But not being a single rectifier unit, that isn't as simple an option perhaps.

I can certainly replace these individual silicon diodes if necessary due to age, but do they really go bad?

If so, the two types listed are:

CR1 SD94
CR2 SD94
CR3 & CR4 matched pair 1N542

Assuming they are the rectifiers, and need replacing after about 50 years, are there recommended modern replacements?

....or are they OK to leave in place as is?


I should add that the unit powered up and operated just fine prior to my beginning its refresh. So I don't have any current suspicion that there are any power issues with the unit.



Thanks
Al

 

[dcgillespie]

Is it me, my computer, or I just don't see the P-22 attachment?

Dave

 

[little-al]

Nope, not you Dave

I tried to attach it and didn't notice that it failed (too big).

Here is a link to the schematic:

http://www.fisherconsoles.com/service manuals/philharmonic p22 sm.pdf

 

[larryderouin]

CR1 and CR2 are your rectifier. It's what's called a Voltage doubler. C53 and C54 are the Voltage Doubler Caps. Voltage Doublers were fairly popular in the mid 60's. All the tube heaters on the philharmonic are AC powered. The Voltage Doubler was also used in the 400/500/800B&C's for B+.

CR1 and CR2 would be replaced by today's 1n5404. 400V 3A. Personally with 300V on the high side, I'd like to see a bit more headroom on the diodes, so a 1n5406 (600V 3A) would work fine here.

As for CR3 and CR4. Leave them alone. They are in the tuner. Dave can explain what they are for and why not to touch if working fine. I don't know, but being in the tuner, unless they are broke, I leave them alone.

Larry

 

[little-al]

Thanks, perfect!

 

[dcgillespie]

CR3&4 are the detector diodes in the Ratio Detector portion of the FM tuner. There would be no reason to routinely replace them unless malfunction was indicated. There is no particular reason for them to ever go out.

Each diode in the V-doubler circuit "see" 300 volts of Peak Inverse Voltage (PIV) across it when operating at rated AC line voltage. To account for line surges and transients, I would suggest using diodes with a 600 volt PIV rating, and never worry about them again.

Good luck with the Philharmonic II!

Dave

 

[larryderouin]

Each diode in the V-doubler circuit "see" 300 volts of Peak Inverse Voltage (PIV) across it when operating at rated AC line voltage. To account for line surges and transients, I would suggest using diodes with a 600 volt PIV rating, and never worry about them again.

Good luck with the Philharmonic II!

Dave

Those are the 1n5406. Get a QUALITY part. Fairchild, OnSemi, Vishay. I'm partial to Fairchilds and these part numbers from Mouser are for Fairchild parts.

512-1N5406 Prices 1-9 $0.48ea 10-99 $0.279ea 100-~ $0.132ea

512-1N5408 Prices Same as 1N5406. These are 1000V PIV 3A

Get 10 or more and hold on to the rest for other projects.

 

[biscuithead]

Yes, the dash panel would have been the same for both models. The P-22 is identical to the P-25 chassis wise. Look at the schematic for the 1961 P22.

MPX was not approved by the .FCC until June of 61 which would have been 2/3 of the way thru a model year. But FISHER was putting MPX jacks in most chassis' all the way back to 1959 as they were gearing up for any eventuality. The TA-600 was the 1st "STEREO" receiver FISHER made in 1958-59. It had the FM-AM Simulcast, but had the MPX jack. As did the 500S in 1961, and the TA-800. If you look at the tuners from that era most of them have a MPX jack. My 101-R from 1959-60 has one also.

The problem was no one knew which of the two systems (Crosley or GE) was going to be picked by the FCC, hence the outboard jack and the two different designs for MPX units (mpx 20 was Crosley, all others GE mpx). I don't think Jack Kennedy had that much pull in the decision, as he had only been in office for less than 6 months when the FCC made their decision.

Mr. Larry, Forgive the ancient thread resurrection... I have a chance to scoop up a P-22 pull for half the going price of a 400. Probably not a great price, but I don't mind paying a premium for Fisher. I've seen the schematic, and it seems respectable for a budget Fishy, but I was wondering if you had any experience with one of these? Would you warn me away for any reason? The one I am looking at has a beautiful wood face-plate, and I will try to build a matching cabinet. Thanks! It is great to have you here as a resource! -BH

 

[larryderouin]

Gadget 73 is the one you should be talking to about the philharmonic. He's familiar with the chassis, I'm not, other than what I've seen on the 'net.

 

[gadget73]

I have one, its not bad sounding but its not exactly of the quality of their better gear. The tuner is pretty good and the FM stereo is top notch though, probably a few steps up from most other makers. Its the same FM stereo circuits as Fisher used in most of their other gear, and they really knew how to make a good MPX decoder.

The power amp section is comparable to one of the better consoles from RCA or Magnavox, etc. Its about 10 watts per channel, but it uses a pair of relatively expensive and hard to find ELL80 output tubes. Those are basically 2 tubes in one bottle. These do not have a magnetic phono stage, so if you want to run a better turntable setup than it came with, you'll have to add that.

Not sure exactly what the going price of a Fisher 400 is, but I don't think the Philly is half a 400. I got mine with a Garrard Type A and a pair of 12" University drivers together, and I'm pretty sure I paid less than a Grant for all of it. It was missing the 12AX7's but that wasn't the end of the world. If you lived closer I'd be happy to loan you mine for a test run to see if you truly want to own one. Rebuilding one isn't too hard, there is a fair bit of room under the chassis to work in.