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72LB Lowboy Ch= 7H3

72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 1114897) Radio
 
72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 142451) Radio
 
72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 142453) Radio
 
72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 142454) Radio
 
72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 142452) Radio
 
72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 1114898) Radio
72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 1271959) Radio 72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 1267899) Radio
72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 1267423) Radio
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72LB Lowboy Ch= 7H3; Crosley Radio Corp.; (ID = 1271959) Radio
Crosley Radio Corp.;: 72LB Lowboy Ch= 7H3 [Radio] ID = 1271959 544x933
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Pour le modèle 72LB Lowboy Ch= 7H3, Crosley Radio Corp.; Cincinnati (OH):
photo processed
 
Pays:  Etats-Unis
Fabricant / Marque:  Crosley Radio Corp.; Cincinnati (OH)
Année: 1934 Catégorie: Radio - ou tuner d'après la guerre 1939-45
Lampes / Tubes 7: 6D6 6A7 6B7 6D6 6F7 42 80
Principe général Super hétérodyne avec étage HF; FI/IF 456 kHz
Gammes d'ondes OM (PO) et OC.
Particularités
Tension / type courant Alimentation Courant Alternatif (CA). / 110 Volt
Haut-parleur HP dynamique à aimant électrodynamique (avec bobine)
Puissance de sortie
De Radiomuseum.org Modèle: 72LB Lowboy Ch= 7H3 - Crosley Radio Corp.;
Matière Boitier en bois
Forme Console basse. Pieds < 50% de la hauteur.
Remarques A.V.C. controlled 1. AF-amplifier - see schematics
Source extérieure Ernst Erb
Source du schéma Rider's Perpetual, Volume 5 = ca. 1934 and before
Littérature Pre-War Consoles


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Contributions du forum pour ce modèle
Crosley Radio Corp.;: 72LB Lowboy Ch= 7H3
Discussions: 2 | Publications: 8
Vus: 1357     Répondre: 1
crosley: Ch= 7H3; 72LB Lowboy
Dave Turner
05.Jul.12
  1

After collecting dust for three years I sent this chassis off for repair to find out that the transformer was shorted out, the speaker was shorted out and other major problems.  Turns out the repairman had another 7H3 chassis in a bad tombstone cabinet.  We worked a deal and he repaired that chassis for my loboy cabinet.  She's up and running now!

A big thank you to Mario and all the rest of you who helped me.  I've uploaded some pictures of the finished project.  It plays beautifully with excellent reception on the broadcast band, but few stations in my area for good a.m. selection.

Dave

Mario Bermejo
10.Jul.12
  2

Great to hear that you finally have it working Dave, congratulations!
Mario
 

 
Vus: 1387     Répondre: 5
crosley: Ch= 7H3 (7 H 3); 72LB Lowboy
Dave Turner
02.Apr.09
  1
I've been "studying" this old chassis for a while.
I put it on my dim bulb tester with a 60w bulb and the bulb does not dim, and none of the tubes light up.  However, two tubes, (69 and 70 on the schematic) a 6D6 and a 6B7, have broken cap connections.  I've ordered two new tubes to replace but don't have them yet.
Meanwhile, since this is a 75W or 100W power requirement, I exchanged the bulb for a 250W, (didn't have a 75 or 100), turned it on and the 250 bulb is very dim and the chassis started to smell and I could hear it "cooking". Transformer was getting warm.
 
Did I burn it up?
 
I'd really like to get this old radio running, but fear a new transformer will be pretty costly, and have no idea where to search for one.  The whole radio is probably worth a hundred bucks.
 
Hope you can give me some ideas.
Dave
Mario Bermejo
02.Apr.09
  2

Hi Dave, if you use a series light bulb the voltage applied to the transformer will be substantially lower and therefore you cannot expect the tubes to light up. If the transformer is bad, it probably was that way before you started your tests. You need to make sure there are no shorts on the transformer secondary (80 tube, electrolitics, etc) before applying any power. The smell can come from a number of different parts, did you visually inspect the chassis?

Since you did not get full bright in your dimm bulb we can safely assume the transformer's primary is not shorted. The very dimm glow on the 250W bulb, on the other hand, indicates the primary winding is not open.

To properly finish testing the transformer, remove the 80 tube and connect to the mains. If you want to be 100% sure then disconnect all secondary windings as well. You should measure high tension, 5V for the 80's filament and 6,3v at the other filament winding.

Good luck.

Dave Turner
02.Apr.09
  3

Thanks Mario,   If you bear with me, I'll ask some more questions. You stated:

>> did you visually inspect the chassis? 

Yes, I looked it over carefully, and I did find one wire leading to tube 80 that looked as if the insulation was burned off, but not burned through, in a section about 1/2" long or less.

>>Since you did not get full bright in your dimm bulb we can safely assume the transformer's primary is not shorted. The very dimm glow on the 250W bulb, on the other hand, indicates the primary winding is not open. 

ie: shorted out?

 >>To properly finish testing the transformer, remove the 80 tube and connect to the mains.  

Not sure what "connect to the mains" means

Sorry for my ignorance, but I'm trying.

Thanks, Dave

 
 

Mario Bermejo
02.Apr.09
  4

No problem at all Dave, can you post a picture of the underside of the chassis showing the transformer connections? This way we can figure it out together.

Mario

 

Dave Turner
18.Apr.09
  5

Getting back to this old 7H3, I did confirm that the transformer is 'gone'!  Also, the speaker coil has mega resistance.  I understand this is a vital part of the circuitry on this chassis.  sounds like I have major problems.  I'm about ready to put this one on the shelf or pass it one to someone who is capable of repairing it.  I really hate to do that, it's a nice looking dial with the 82:1 ratio 'fishing rod' tuning dial.

Anyway, I'm going to try to post the requested pictures here, in hopes that the generous wisdom of this list has some beneficial guidance for me.

 

 

Pièces jointes

Dave Turner
18.Apr.09
  6

Will attempt to load some better pictures regarding my last message, on The poor old Crosley.

Dave

Pièces jointes

 
Crosley Radio Corp.;: 72LB Lowboy Ch= 7H3
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