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Philco 97 - RF problem... HELP! - Printable Version

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Philco 97 - RF problem... HELP! - kiwi_steve - 05-01-2016

Well I figured I could just pop a couple of caps in this and get it going again - then listen to it for a while before restoring it... the best-laid plans of mice and Philco owners...

Still, I got it going - but it took the better part of a day on and off... bakelite block caps, some rewiring and some interesting wiring took a little figuring out...

Overall its in pretty good condition though.  

Heres the dial, a very cool red one.  Its a little faded - especially in two spots - and unfortunately gouged along the back and there is a tiny break where its been pushed against the shadow meter bracketry I think.
[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/20160430_224118_zpsmfnql4c6.jpg]

[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/20160430_224146_zpstpmvsxtd.jpg]

The actual bracket for the dial lights and shadow meter are (I think) bent, which has caused this.  Can anyone confirm these bits should be straight and not bent?   The top section of the front plate of the tuning cap is bent over, and the bracket also looks bent although straightening that will probably break it given the cast crap-metal its made from... so hopefully its supposed to have this jaunty angle Icon_smile 

[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/bent_bracket_zpsqq8vvy5p.jpg]

And heres how the dial got its gouge...
[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/gouged_dial_zpsbhm2fi8k.jpg]

More to follow... work time...

RE: Philco 97 - KCMike - 05-01-2016

I think it is supposed to be angled as you describe. Just guessing but the dial scale might have been pushed in too far by someone before you got it causing it to rub.

RE: Philco 97 - kiwi_steve - 05-01-2016

(05-01-2016, 09:53 PM)Mike Wrote:  I think it is supposed to be angled as you describe. Just guessing but the dial scale might have been pushed in too far by someone before you got it causing it to rub.

Ok, I'll play with clearances etc once I get the chassis finished and can try to line everything up again properly then.   Thanks for the info

The chassis has had a few capacitors replaced over time but all the bakelite blocks are there by the looks of things, so I spent a day just replacing smoothing caps and rewiring things back (mostly) where they belong.  I decided to not restuff the main caps because only one was there, and because I don't want to fully restore this (not yet anyway).  I mounted two caps on some tagstrip and bolted that to the side of the chassis through an existing hole.  Fully reversible but also fully functional.  When I get around to a full restore I'll restuff probably... maybe.

I did restuff the little can which has one 1uF and two 2uF caps in it with a 1 and two 2.2's simply for space reasons - and it gives a nice tie point for them.  The finish isn't perfect but I didn't want to cut the can under the clamp in case it slipped out of the clamp at some point in the future.  I could probably have just done away with it entirely...
[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/20160501_154654_zpschkt3wq8.jpg]

[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/small_cap_can_zpsjm7woi8m.jpg]
Most of the resistors were well over spec as well, so I replaced them (is it just me or are the Philco style resistors with the pointy ends almost always still bang on value? The 89B I did had a few and they were all perfect too). 

I used poly caps because thats what I have - seems to work well (any thoughts on poly over electro in this particular application?  The relevant part of the schematic is here:
[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/small_caps.jpg_zpseh3gywud.png]

RE: Philco 97 - kiwi_steve - 05-02-2016

Quick question... I have some low level 100Hz (NZ mains is 50Hz) hum going on... not voume affected... Could using poly caps instead of electro's be responsible?  I tried paralleling a 10uF cap over each of the three in turn - no appreciable difference.  I also tried putting the 10uF cap across the second filter cap - again not much difference.  When I put it over the reservior (first filter) cap it halved the hum.  If I put a 22uF over it the hum almost disappeared although I can still hear it without straining to do so. This radio draws 90W so there's a reasonable load on the power supply.

The filter caps in the schematic call for a 12uF reservoir and an 8uF second filter... I used a 10uF reservoir and a 22uF second filter because thats what I had to hand... would this choice be partly responsible?  I've never struck this before and have always found that more uF's = less hum although I am aware that the combination of the 2 smoothing caps with the field coil forms a pi-filter of sorts - my knowledge of the theory on this is limited to sweet little or nothing though.

Other than that it is playing well.  All the IF's were off, but all in the same direction by approximately the same amount... maybe the previous tech working on this had a sig gen with a slightly out of whack dial... but its singing nicely.

Unfortunately it had all Philco valves in it... unfortunately because most of them were shot.  I'm surprised it had any output at all... they both barely registered on my tester... so now there's a Ken-Rad and something else in there... but they work.  The diodes on the 85 1st audio tube are also quite low, with the triode being borderline... The 6A7 is ok but thats the only non-Philco valve in the lineup.

I also can't get the bulb behind the shadow meter to do anything at all... but I have a service note on that somewhere so I'll play with that later...

Happy though, it goes Icon_smile

RE: Philco 97 - kiwi_steve - 05-02-2016

Oh, and I can just hear the service tech's conversation with the production manager... "Hey, we're part way through this run of 97's and they've just told me we don't have any blocks left to make up the 3615-DG's we need."  "Ok, so see that pile of 7653-G's we've got left over from the last run?".  "Yep?!".  "We don't need those in this radio do we?".  "Nope...". "Go grab the Dremel!"  

Waste not want not Icon_lol

One side has this:
[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/20160502_171312_zps83ehi18u.jpg]

And the other side has this:
[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/20160502_171321_zpsogzvfskj.jpg]


And because it would be rude not to - a paper cap to go back into the radio... just for old times sake Icon_smile
[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/20160502_174721_zpsppvwhgyi.jpg]

Thats a PZB300MC13R30, from Kemet. Fits pretty well, although 2 of the legs needs to be bent past each other to fit in the block...

RE: Philco 97 - kiwi_steve - 05-02-2016

Anyone have any thoughts on the hum problem?

RE: Philco 97 - kiwi_steve - 05-03-2016

(05-02-2016, 11:50 PM)kiwi_steve Wrote:  Anyone have any thoughts on the hum problem?

Actually, never mind  Icon_redface slight miswire on my part... if you look at the photo of the completed small cap can above I've used 2 resistors in series to get the 2.9k shunt for the shadow meter... and wired it into the wrong place  Icon_eek.

Fixed, and now the hum is gone... but the meter isn't reading properly... but the vane was jammed up with wax - I suspect its been hot and some wax from the coil has seeped down into the vane assembly... weird... but I've cleaned it up as well as I can and it works sort of... but it slams to one side (only one side) when there is no signal and it jams there and won't come back - its also very sluggish when I manually move it to the right spot and move on and off frequency... and I don't know if thats residual wax I can't get to or if its lost magnetism... I'll pull it apart and clean it up properly and remagnetise it as a matter of course...

RE: Philco 97 - kiwi_steve - 05-07-2016

Ok, so I have 2 remaining problems

I can't peak the RF section.  I've checked:
- The wiring, and my repairs - nothing obvious there
- The mica caps in and around that area - all within co-ee of their expected values
- The tuning cap - no shorts in the RF (or other) plates
- The RF primary and secondary windings - no opens and the resistances are near enough to the circuit diagram

I have what seems common when the RF section won't peak - screwing the trimmer down tight causes the rf to roll off, but unscrewing it about 3/4 of a turn causes it to rise to a high point where it stays right until the screw is fully off.  Schematic is below, middle section is the RF.  Nostalgia air version here: http://www.nostalgiaair.org/Resources/download.asp?FN=\M0013903.pdf

[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/Philco%2097%20Schematic_zpsf7y5xels.png]

And just  the front end to try and make it a little clearer to read


[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/Philco%2097%20Schematic%20-%20rf_zpsseahxhrc.png]

I'd really appreciate any ideas or comments on the problem because I think I've been staring at it too long, and I can no longer see any wood in the trees at all.

The second problem I can probably fix with a little perseverance.  The vane assy in the shadow meter flicks around to one of the stops when the signal is not present, which completely blanks the display.  I believe because its had wax in it, no matter how much I clean it there seems to be enough residual wax to 'stick' it to the stop, and not enough magnetism to pull it off again.  So short of giving it a belt ever time I want to use it it's totally useless as-is.  I've given it a fairly thorough cleaning with cotton buds and my fingernail to scrape it - anyone have any chemical or other ideas for removing the wax permanently and completely?  Here is the wax problem after a bit of cleaning... I've had it completely apart and thought I'd got it all... but no.

   

RE: Philco 97 - Mondial - 05-08-2016

You can try flushing the movement with a petroleum solvent like paint thinner or cigarette lighter fluid to remove the wax. The solvent should dissolve the wax without leaving any residue. WD40 will also work, but may leave an oily coating.

In any case, using any of the above should make an improvement in freeing up the motion of the vane.

RE: Philco 97 - HOTWIRE - 05-08-2016

Hi Steve.

Any chance of some more images.  Say a full one of under the hood.     I got me one of these which is outside the US. but designated a model 98 series.1.   I believe my chassis to be a model 97E. but no marking plate on it. Different cabinet to yours though.

Do you know the history of Philco there in NZ. eg.  Did they have a production plant or just import to NZ from the US or via AUS.

Regards.

Will.

RE: Philco 97 - kiwi_steve - 05-08-2016

(05-08-2016, 10:25 AM)Mondial Wrote:  You can try flushing the movement with a petroleum solvent like paint thinner or cigarette lighter fluid to remove the wax. The solvent should dissolve the wax without leaving any residue. WD40 will also work, but may leave an oily coating.

In any case, using any of the above should make an improvement in freeing up the motion of the vane.
Thanks for the tips - I have used some solvent, and I thought the problem was still wax... but I pulled it all down again and checked - it seems to be a combination of a couple of things... I can only get the AVC voltage down to about 4.5V on a strong station now (I was able to get it close to 2V when I started)... so there is too much voltage on the coil to keep the vane straight.  And, I've also just noticed its sticking magnetically, not with wax.  I remagnetised the bar magnet because it was barely able to lightly hold the tip of a jewelers screwdriver... its now a lot stronger at the tips but weak in the middle... I may have overcooked the magnetising process?


(05-08-2016, 11:44 AM)HOTWIRE Wrote:  Hi Steve.

Any chance of some more images.  Say a full one of under the hood.     I got me one of these which is outside the US. but designated a model 98 series.1.   I believe my chassis to be a model 97E. but no marking plate on it. Different cabinet to yours though.

Do you know the history of Philco there in NZ. eg.  Did they have a production plant or just import to NZ from the US or via AUS.

Regards.

Will.
Hi Will, I read somewhere that the 98 was a UK model?  Here in NZ, Philco was imported lock-stock-n-barrel until around 1936 I believe... after that (taxes?) they were just imported as Chassis' and locally made cabinets were used - in a similar style to the US cabinets.  At some point after that Dominion Radio and Electrical Co. (DRECO) was started here to design and build Philco sets in New Zealand... So yes, we had Philco manufacturing here but the brand died off (was killed off?) in the 50's some time when DRECO started pushing names like La Gloria and Majestic (often on very similar sets).  Thats my understanding of the history of it here... its probably not quite right, but it should be close...

Photo under the hood (post-repair so you'll have to imagine it with more dogbones and waxies in there):
[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/20160505_222217_zpsfjjyvzr9.jpg]

RE: Philco 97 - HOTWIRE - 05-09-2016

Thanks Steve. Icon_thumbup

Yep same as mine from what I can see.  I see you have no wave trap or A.E. connector.  Did it come to you without them.?

Nice and clean underneath, Mine is a rusty rats nest mess.  Have a look at what I have woken up to for the past year. Its going to be a total strip down and restoration for mine. Still I am going to really enjoy doing it.  Don't ye just  Heart these things.

When I restored the 98 series 2 which had a 640B chassis (Thanks again Ron) I re- stuffed those Cap blocks but this time I think I will leave the old caps inside and top mount the new ones.  Who knows but maybe someone in another 70 years might be interested in the looking at the originals eh. 

Steve. Where did ye get those corner rubbers mine are perished to bits same as yours were and can I ask you where did you get the schematics mine are the ould John Riders bless him but they are quite smudgy.

The dial on mine is in super condition. one little nick on the rim. The part number is 27-9054.  Am I correct in reading yours as 27-5083 Mine also has "Synthane Corp" stamped on it as the manufacturer.

Regards.  Will.

RE: Philco 97 - HOTWIRE - 05-09-2016

Under Chassis View.

   

RE: Philco 97 - kiwi_steve - 05-09-2016

(05-09-2016, 09:55 AM)HOTWIRE Wrote:  Thanks Steve. Icon_thumbup

Yep same as mine from what I can see.  I see you have no wave trap or A.E. connector.  Did it come to you without them.?

From what I can tell mine never had the wavetrap - there isn't even scratching on the chassis from a bolt head where it would have been... and the plate over the AE connector looks factory - it does have the Fahnestock clips topside though.

HOTWIRE Wrote:Nice and clean underneath, Mine is a rusty rats nest mess.  Have a look at what I have woken up to for the past year. Its going to be a total strip down and restoration for mine. Still I am going to really enjoy doing it.  Don't ye just  Heart these things.

Actually I do - looks like a couple of the radios I've done in the last couple of years including the 89B which was about my first ever post on here - although that was not quite as rusty as your one.  Joys of living and collecting near the coast Icon_smile

HOTWIRE Wrote:When I restored the 98 series 2 which had a 640B chassis (Thanks again Ron) I re- stuffed those Cap blocks but this time I think I will leave the old caps inside and top mount the new ones.  Who knows but maybe someone in another 70 years might be interested in the looking at the originals eh.

Interesting theory... I just don't like the look of caps mounted on the blocks - and it makes it confusing.  I still remember the utter mind-bending confusion I went through with the 89B (my first Philco and the oldest radio I'd ever done at the time).  I'd like to see a T-Rex - but not up close... I'm ok with a photo in a book  Icon_lol

HOTWIRE Wrote:Steve. Where did ye get those corner rubbers mine are perished to bits same as yours were and can I ask you where did you get the schematics mine are the ould John Riders bless him but they are quite smudgy.

The rubber parts came from Renovated Radios - I see he now has the correct(?) spider-style tuning knobs for this models too.  There is a rubber bumper on the front of the chassis which looks like it could be part# GPH-18 on his list, and the corners are part# PHS-COR.  I had a problem with my second (first was for the 89B - all went well there) order - I don't know if this is common but I paid then heard nothing and had to jump through a few hoops including opening a dispute with PayPal to get it sorted.  I don't know what the actual problem was aside from being told PayPal never released my payment although they took it from me - but the parts did eventually get here... and they seem pretty good.  His communication was pretty good too.

The schematic and all other service info for this came from Chuck Schwark (Philco Repair Bench).  Legendary service, a great guy... I'd have been lost on this radio without what he supplied.  Actually I'm still a little lost in the RF section, but I'd have been a lot more lost  Icon_lol

HOTWIRE Wrote:The dial on mine is in super condition. one little nick on the rim. The part number is 27-9054.  Am I correct in reading yours as 27-5083 Mine also has "Synthane Corp" stamped on it as the manufacturer.

It looks like an 8 in the photo but its a 9... 27-5093.  This is the same part number as Radio Daze has on their repro dial, but theirs is yellow and has slightly different graphics around the hub.  Ron mentioned that the red dials appeared (only?) in 1935, randomly, on some models... there is no documented reason for it apparently - possibly due to yellow phenolic shortages?  If only there Philco employees from 1935 still alive... why did nobody think to ask them in the 60's and 70's when there probably were still a few of them about the place?  Makes me wonder who we should be interviewing now, and about what?

Cheers

Steve

PS:  I still have this RF problem... posted over at the other forum as well and was given some hints but I just can't find anything wrong with it... it just won't peak on Police or BC - but I can peak the SW band.  Interestingly the BC and Police trimmers are on the same assembly.  The wire running around the central column ties both trimmer assemblies together, and this is well soldered and not broken.

[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/RF%20trimmers%201_zpsnwxsgmer.jpg]

[Image: http://i241.photobucket.com/albums/ff222/4wdstuff/Philco%2097/RF%20trimmers%202_zpssaubimxk.jpg]

Any thoughts on this would be much appreciated

RE: Philco 97 - HOTWIRE - 05-09-2016

Hi Steve. Typo on my post. The dial number should be 27-5094.

If you can engage the other members to work with you on the rf problem they are top end when it comes to these philcos. I have only done one of em before but I would say this.

I think you really should be fitting Electrolitics where it says Electrolitics and stay with the Cap values as stated on the service sheets. The philco engineers determined these values for a reason. I would also check the routing of the wiring.

It is important to keep the original routing intact. A simple thing like moving a wire away from the chassis can cause problems. Check all the voltages you have on the service sheets and check that 78 RF tube.

I think you should complete the resistor and cap replacement including the mica. I dont buy in to the notion that mica seldom goes gaga. Any radio I have ever fiddled with has had dodgy mica's.

Finally, I have a spare wave trap (again thanks Ron) Maybe I can email it to you or drop it into your local pub.

Kind Regards Steve.

Will.




I have a spare wave trap