Archive for the ‘Repair, alignment’ Category:

2020-07-11 Lawn Sprinkler System Losing Pressure?

I’ve been seeing the sprinklers reaching a smaller radius after several years, and brown spots between. I was thinking that it was caused by a clogged pipe. I also had some constantly leaky sprinklers that were causing the grass to become soggy and mushrooms were growing. Then I noticed my water bill was several tens

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2020-06-13 MLCC Replacements For Electrolytic Capacitors

Reply from FB comment Mark French I got a roll (on tape) of 22 uF, 10V and 47 uF, 10V tiny surface mount MLCCs. They’re not polarized, but I’ve heard they tend to be microphonic. I’m going to try leaving the old caps in and bridge a MLCC across them. They’re small enough to to

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2020-02-19 Nobility 15 transistor Radio Repair

2020 Feb 18 – Nobility 15 transistors OTL S/N (?J)29549 I replaced the electrolytic capacitors. The spkr buzzed when I touched the volume control. Nothing from the detector (transistor). It’s unusual. I pulled and tested some IF parts including one of the transistors, no problems found – transistor tested good. I called it a night.

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2020-02-14 Zenith Royal 400 S/N Z551549 Replaced Capacitors, Driver Transformer

Zenith Royal 400 s/n Z551549 I soldered broken orange wire to battery holder. Replaced all four electrolytic capacitors. Silent speaker and nothing from earphone jack. I checked the voltage at the collector of the driver transistor, it was zero. One pin of the driver transformer primary measures 5.8 V, the other pin measured 0. Checked,

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2020-02-06 Royal 500H Alignment

From FB group This Zenith Royal 500H radio has the extra 8th transistor for the RF amplifier, so it should have excellent sensitivity and be able to pick up those weak stations. Most of the problems with old radios are with the electrolytic capacitors, but the Zeniths all use the carbon composition resistors and they

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2020-01-30 Royal 200 Silicon Conversion, Part 3

Also to FB group Vintage Transistor Radios I finally drew the line and said I’m finished fiddling with this Zenith Royal 200 and put it back together. I got it without knobs or handle, and with all the transistors missing. It’s not pretty, and the speaker cone is warped and sounds bad. This is the

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2020-01-18 More Zenith Royal 200 Conversion to Silicon

Continued from post 2020-01-15 I dug through my drawers and boxes of transistors and found a bunch of MPSA56 PNP general purpose on tape, and put them into the LO and mixer. I think they helped slightly – they are lower minimum fT than the 2N3906s. I adjusted – optimized – the trimpots I had

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2019-01-15 Zenith Royal 200 Conversion to Silicon

I’m thinking of pulling up the end of the 100 ohm and looping the lead a few times through the ferrite bead. If that still doesn’t stop the ringing, I’m thinking about replacing the bead with an RF choke. Every time the ringing is reduced the reception gets better.  I checked to see if I

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2020-01-10 Corrosion and Damage On Diode Leads

This photo is a detector diode that was broken during replacing the electrolytic capacitors.  The lead on the top was twisted, apparently putting stress on the glass package.  I replaced it with a 1N270 germanium diode. comment from fb group Vintage Transistor Radios Did you notice that the leads are magnetic? They stick to the

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2020-01-06 Two Similar Transistor Radios

I posted this a few days ago.https://m.facebook.com/groups/606087512820068?view=permalink&id=2638214152940717 Now I’ve replaced the capacitors in another one very similar, a DE LUXE. It’s not quite as complete and in as good a shape as the Encore. What surprised me was that some of the electrolytic capacitors were bad (measured open) and the symptom was no sound whatsoever

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