grundig: 5088 USA componant and alignment questions. |
Paul E. Pinyot † 2013
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Gentlemen, I am restoring a Grundig 5088 USA model and need some help with my first non-US radio restoration. I am using a schematic found at www.rad-io.de I have found it to be mostly accurate except for some of the audio frequency circuit architecture. There are differences. A friend of the family has translated most of the words. So my questions are with the missing information below: The resistors have the resitance printed on the body and a single color band on one end. What does this band represent and what are the values of the colors? I have identified three types of fixed capacitors; Paper (Papier), Syrofome (Styrofier?) and Ceramic/mica (Keromic?). However, there are some paper capacitors that have a plastic like blue coating. The schematic clearly identifies these as paper. Is there more to these capacitors? Are they special (i.e., inverse temperature, resonant) capacitors? Once I have replaced all of the paper and electrolytic capacitors (and the occational off tolerance resistor) RF alignment is next. The IF frequencies (10.7/460) and the transformers are identified. However, there are plenty of other adjustments with no explanation. Where might I find the alignment procedures? Please forgive me if this information is readily available on the internet. If so, then please recomend an appropriate web site. Thank you in advance for your time, Paul. Este artículo fue corregido 25.Jan.05 06:15 por Paul E. Pinyot † 2013 . |
Hans M. Knoll
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Hello Paul, i come back next time here with informations for You. First here Aligment. This the Export Version (not US) of the 5088. Maybe Waveranges are different. I mean, thats is not a great problem. AM/FM If are allways the same! Text for Components. Mr. ERB would have that these informations shall for general purposes. This is more to do for me, and finish next days. Now finish Look here: http://www.radiomuseum.org/dsp_forum_post.cfm?thread_id=42358 Short info for you: blue Condensers are Papertype , color on Resistors : minor matter. Greadings Hans Anexos:
Este artículo fue corregido 29.Jan.05 13:51 por Hans M. Knoll . |
Paul E. Pinyot † 2013
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Hans, Thank you so much for the alignment information. I have played the radio since replacing the paper capacitors, electrolytic and the single "out of 20% tolerance" resistor with a new 5%. The radio plays very well on FM. Clear and clean sound. The AM bands receive stations. Even the short wave bands receive with a three foot piece of wire. I discovered if my hand comes with in close proximity to the tone switch assembly a hum will be produced. I therefore deduce that is why there is a ground wire going to the missing screen that should be stapled on the cabinet bottom. Please comment. I am a bit curious about the low B+ voltage right after the bridge rectifier. I read 261v dc and 255v dc (MW/UKW) at 119vac line (mains) and the voltage selector is on 110volts. (There are two selections 220 and 110). The schematic notes 275 and 270. Is this B+ too low? (DVM input impedance 7 Meg ohms). Hopefully with additional trouble shooting and an alignment I can discover the problem of the low B+. Thanks again for the alignment information, Paul. Este artículo fue corregido 27.Jan.05 03:58 por Paul E. Pinyot † 2013 . |
Hans M. Knoll
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Hello Paul, its fine, that I can help you with GRUNDIG Service Paper. To your next question about B+ The only way is, replace this selenium with four-silicon diodes 1N4007 .in bridge configuration. Additional, must each diode are shunted with a high voltage condenser approx. 4,7 nF, 400V AC! Your question about hum. Sometime maybe 1957 the connection is made by a cooper plate and a wire to chassis. Later, under one of the circular gum and a copper foil on the right point inside of cabinet. Best regards Hans
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Paul E. Pinyot † 2013
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Hans, Este artículo fue corregido 02.Feb.05 05:29 por Paul E. Pinyot † 2013 . |
Hans M. Knoll
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Hello Paul, EM34 / 35 are in europa also rare and expensiv. both from nederland In Germany, collectors use the US Type 6E5 , from russia. I can give you information abaut that. Regards, Hans Este artículo fue corregido 05.Feb.05 17:50 por Hans M. Knoll . |
Paul E. Pinyot † 2013
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Hans, In the alignment procedure
The AM-IF Alignment 460kc "Remarks" call to dampen the opposite coil with a series resistor/capacitor string. To where should this string be connected? From the coil signal side to ground or across the coil winding? |
Hans M. Knoll
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Hello Paul, damping the Circuits means, each from the hot point ( anode or grid) to ground. The opposite side from the circuit, is alllways groundet with an condenser. The reason of damping, ist not to become a lower signal, but to make a decoupling from the fast coupled ( more then critical) circuits. If jou not like to make that, you must repeat the procedure 3 to 4 times, for each filter, exactly. In production, for an exact alignments of a 3 circuit filter, or moving bandwide 2 circuit filter, it is necessarry to use an Sweeper and screen. This procure is much more komplicated and expensive. I think, all is clear now. Best regards, Hans Este artículo fue corregido 15.Feb.05 22:40 por Hans M. Knoll . |
Paul E. Pinyot † 2013
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Thanks to everyone (and a special thanks to Hans) who contributed and answered my questions regarding the Grundig 5088 USA. I posted some pictures on Este artículo fue corregido 27.May.09 15:14 por Paul E. Pinyot † 2013 . |
Hans M. Knoll
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Hello Paul, I say: verry good. Thanks for the report, good luck. Hans On what positions you can or must, post all this,
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Paul E. Pinyot † 2013
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There is an adjustment R32 rheostat (a two wire variable resistor in a network with R30, C62 and C63) on one of the plates of the EAA91 tube. With an oscilloscope on the plate the voltage responds to the signal strength as the tuner passes transmissions. Este artículo fue corregido 02.Mar.05 05:04 por Paul E. Pinyot † 2013 . |
Hans M. Knoll
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Hello Paul, The questions: There is an adjustment R32 rheostat (a two wire variable resistor in a network with R30, C62 and C63) on one of the plates of the EAA91 tube. With an oscilloscope on the plate the voltage responds to the signal strength as the tuner passes transmissions. What is the function of this adjustment and how should it be adjusted properly? my answer: this trimmer R32, adjust and brings, the AM-Rejection to an maximum. AM- Rejection makes a supression of amplidute modulated (unwanted) signals. This function is the primary performance of the Ratio -Detector invented from Stuart Wm. Seely and Jack Avins from RCA Labs. To adjust this function the equipment must have an high standard. In 1958 GRUNDIG brings this simple message: " Alignment can be done with Scope only" Thats a little bit naivety i think. Two yeahrs later, " Allign control R... until a max. AM supression is obtained ( with Sweep Frequency Generator_ oscilloscope possible only)
Now my advice to you: For your better understanding, i spend an original picture with text, from an RCA Print ( Seely, Avins) There you can see, what is shows on an Sweeper_Scope Equipment. Only as PDF ( to much bits) So Paul, i hoppe is all clear?
Anexos:
Este artículo fue corregido 02.Mar.05 11:40 por Hans M. Knoll . |
Paul E. Pinyot † 2013
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Hans, I used both of your methods for adjusting R32 below: Now my advice to you: Now my advice to you: Now that the radio is getting regular exercise a new problem has cropped up. When it is tuned on the SWII band (8.3 - 18.5 Mhz) at about 17Mhz it begins to change tone. More treble with a phasing sound and the reception gets louder (along with the static). Then a little higher it begins to quietly oscilate. At about 17.5 - 18 Mhz it thumps and goes silent. Further up twards 18.5 Mhz it starts to "motor-boat" or thump (no reception here). I re-alingned the IF and the two SW and the BC bands. It seems to be a little bit more stable. If I tune through this zone slowly it will not thump and motor-boat. But it sounds as though there is an increase in sensitivity. I will be trouble shooting this tomorrow. The first thing I will do is inspect the Variable Air capacitor. I hope to make progress and report back. Thanks again for all your help, Paul Pinyot. |
Hans M. Knoll
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Hello Paul, In case 2: align with Antenna -signal, must additional to the wanted FM Signal an AM - modulated are present. More infos then when i have an new scanner. Greadings, Hans
Este artículo fue corregido 16.Mar.05 21:36 por Hans M. Knoll . |
Paul E. Pinyot † 2013
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Hans,
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Hans M. Knoll
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Hello Paul, Additional to the cause off close wiring of RF and Osc. If you repeat once more, the distance beetwen OSC and RF is to low and you can observe the Problems you hat describe. Hum screening. That's good what you have done! EM34 O.K. Paul, I wish you all the best with your hobby, good luck. Hans from Franconia near Nuremberg, Este artículo fue corregido 06.Apr.05 00:06 por Hans M. Knoll . |