Questions tagged [vintage]

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1answer
110 views

What is this symbol on a schematic for an old milling machine?

On the schematic below, I'm having trouble identifying what the symbol drawn on top of motors 2 and 3 means. I've never seen anything like it. They're only present on the high-power spindle and feed ...
0
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0answers
48 views

Intercepting signals from vintage computer (common ground)

I am trying to reverse engineer the signalling for a peripheral to an old 4-bit computer and eventually I want to emulate the peripheral and send the appropriate signals back to the computer. I know ...
0
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1answer
61 views

Identify components in an audio circuit schematic

In the attached image you can see a circuit part of a commercial audio amplifier. I'm trying to determine what kind of component is R-CH and what role it plays in ...
0
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2answers
61 views

Transistor substitution guidelines? (and the BC147A)

I'm in the US and fixing a vintage German integrated amp which has a crackle static issue I've isolated to a transistor in the preamp section. The transistor is specified in the schematic (below) as a ...
2
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2answers
97 views

Difference between junction points in old schematic

What's the difference between the black circle and the white one in this old schematic? Of course the black ones are junctions, but are the white circles a pin, or an input of some kind? I'm trying to ...
0
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1answer
41 views

Replace amplifier IC with a class D amplifier (AN7133N with TPA3116 board)

Today I received this nice 90's Panasonic RX-CT900 boombox in the mail. The specs claims it is 2x60W PMPO (PMPO b**llsh*t throw-of- a-cliff specification) but in fact it is just 2x5.5W RMS (...
1
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1answer
85 views

IPA becoming unobtainium, can I use denatured alcohol to clean vintage computers?

Due to COVID-19 and peoples' practice of hoarding, IPA is becoming incredibly difficult to find where I live (and online). Since we are all home so much these days, I like spending some of that time ...
1
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3answers
150 views

Can you identify this diode? (vintage audio amplifier)

I am restoring a Japanese Teisco mixing amplifier from the 1970s. It's a solid state 5-channel mixer with 16ohm speaker outs and a line out. Amongst other problems, I have discovered a couple of the ...
1
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2answers
72 views

ID a green ceramic component from a tachometer?

This component is from a 1960-70 vintage boat tachometer. It's about 1.25" long. It generates not a single reading on my 11-function multimeter (including capacitance). I may have fried it ...
0
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1answer
105 views

Performance changes to metal can transistors installed 40 years ago

What problems, if any, are to be expected when using 2N4037 metal can PNP transistors that were installed 40 years ago? I can't divulge much about the design, but transistors are in a voltage ...
0
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1answer
159 views

Repairing power circuit with reverse polarity damage

Recently I bought an old musical keyboard (a Casio HT-3000). It came with a PSU, and when it arrived I plugged it in without paying too much attention, and... nothing but a burning smell. I quickly ...
9
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3answers
2k views

Are screened transistors an endangered species?

In the germanium transistor era, the RF transistors were PNP small signal devices. Some of these small metal cased BJTs had 4 leads instead of the usual 3. The metal can was isolated and the 4th ...
0
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1answer
34 views

Capacitor ID? Polar or Nonpolar?

I have been trying to repair an old 14 transistor radio from the mid-60's and have no sign of any image of the radio or schematics for it online. One step I'm taking is to replace old caps (mostly ...
7
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2answers
982 views

Fixing old CRT oscilloscopes… what to look for first?

I've been amassing a pretty large collection of these old scopes, and it's about time I got to trying to fix them. About half of the ones I run across and buy don't have traces. I don't need to get ...
0
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0answers
145 views

Russian germanium transistors

The germanium transistor era was long over in the west when the Berlin wall came down. Nowadays, new old stock Russian germanium transistors are appearing on world markets. Some musicians prefer ...
3
votes
1answer
79 views

Why do they not make center tapped loadspeakers?

An early Australian solid state portable receiver manufactured by AWA used a 30 ohm centre tapper speaker that was directly driven by a push pull PNP germanium output stage. The orthodox arrangement ...
2
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3answers
108 views

Can I replace a dual section capacitor in a tube amplifier design with two single capacitors?

I was planning on building this schematic, but found it hard to source their 20/20 dual section cap (C3/C4). Could I replace this with two single 20uF caps, or is it a dual-section for a reason?
2
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2answers
90 views

Ferrite rod antenna improvements

Most early solid state portable MW AM radios used a ferrite rod antenna. Some valve receivers like Phillips in the late 1950s used ferrite rods also. The early Germanium RF transistors were not too ...
1
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1answer
62 views

Envelope Detector Improvements?

The classic Envelope Detector is very old and very cheap and very simple .Sure there are now better schemes like synchronous detection ,PLL etc.The circuit is responding to the peak of the Amplitude ...
34
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1answer
5k views

Why were germanium diodes so fast and germanium transistors so slow?

Germanium diodes were used for Radar during WW2. Germanium transistors appeared about a decade later. Most early transistors were only specified for audio use, like the OC71. The specified RF types ...
0
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1answer
116 views

Identify component in 1970s vintage video game from photo

Can anyone identify these two components, marked "SKY 4433" and "2.000000 K.D.S", respecitvely? Are they capacitors, crystals, or something else? They are from a vintage 1970s ball-and-paddle-style ...
1
vote
2answers
128 views

Why do older (green) PCBs have primarily a darker color, whereas new ones are lighter

Note the difference in color between this old commodore board and this newer board. It might seem like lighting, but after looking at my own collection of scrap boards, the older ones tend to have a ...
1
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1answer
75 views

What is an impedance bridge?

Today, I saw a very old historical piece of lab equipment at the university. It had a large number of dials, although not as large as you would see in an oscilloscope. The size was similar to an ...
3
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1answer
197 views

What are these hybrids from National Semiconductor?

I found some parts in my junk drawer that I can't identify. I'm pretty sure they're National Semiconductor hybrid circuits from 1969-1970, but I have no access to a National Hybrid Products databook. ...
0
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0answers
34 views

Volume control reliability

Log potentiometers were the mainstay for volume controls in radios .I have seen values of 5 to 10K in early solid state radios .Valve radios would use 250K to 1 meg .Crystal cartridge record players ...
2
votes
2answers
754 views

RIFA PME271M547 replacement

I just broke my sewing machine (it's an old Viktoria machine about 30-40 years old) and now I am looking for a replacement safety capacitor. The one installed is a RIFA PME 271 M 547 paper capacitor. ...
1
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2answers
226 views

EM Vs PM Speaker

Modern Speakers have permanent magnets and are called PM speakers.Permanent magnet materials technology has improved a lot over the last 80 years .Around WW2 EM speakers were common because permanent ...
0
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1answer
100 views

Design questions regarding LM2735 (boost-converter) for DC-DC

I'm doodling with a future circuit. The application (Commodore 64) expects 5VDC (which I will provide with a pass-through) and 9VAC 50Hz. I do not have any working circuit or a schematic, because the ...
1
vote
2answers
295 views

What connector did this IBM Model M keyboard have?

I got got hold of an old IBM Model M (Model 1391403, to be precise). Unfortunately, the fixed cable was cut off by an unknown idiot. Does anyone know what kind of connector (I assume PS/2?) was ...
2
votes
1answer
118 views

old 80C31 circuit not working. EPROM data retention issue?

I have an old piece of pro-audio gear in for repair. It dates from 1990. It was a fairly high-end piece of gear at the time and still has some value so it is worth repairing. But the symptoms I see ...
2
votes
1answer
174 views

Can old vintage quartz crystals handle more power?

Old crystals are very large compared to present day devices. Vintage transmitter circuits did not have many valves in their line up. I have seen a 2 valve 50 watt CW transmitter for 80 meters in a ...
7
votes
1answer
530 views

Identify Vintage Power Cord for 1980s Organ [closed]

I Recently acquired a Technics SX-C600 organ but it needs a power cord. Does anyone know what type of power cord I should get for this? My understanding is that this is a rare organ.
0
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1answer
110 views

How does a rocking arm voltage regulator work?

I am trying to determine the suitability of replacing a (ancient) rocking arm voltage regulator with a modern digital device. I assume a rocking arm regulator has an electromechanical or magnetic ...
0
votes
1answer
48 views

Increase rotational velocity of synchronous motor

I recently got my hands on a Philips PM8110 (a single pen recorder which is basically an analog printer for voltages) which sadly provides paper with a velocity of 8 cm/hour. Although this would ...
14
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1answer
632 views

Old equipment to identify

I volunteer at the Dauphin Railway Museum in Manitoba, where we recently received a donation of equipment collected by CNCP Telecommunications in the 1970s and earlier. Most has been identified, ...
2
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0answers
122 views

Please help identify this vintage component [closed]

I got this item in a bidding lot and have been trying to figure out what it is ever since. The nearest I can tell it is either an electro shock therapy device or perhaps a remote detonator. It has ...
14
votes
1answer
1k views

What is a “universal bridge”?

I recently came across this intriguing instrument from the 1970s(?): It's a "Universal Bridge" made by Wayne Kerr. It's not a type of device I've come across before and I'm curious what these are (...
2
votes
2answers
238 views

Old-school pseudorandom pulse generator (requesting assistance with hardware design)

I would like to design an old-school pseudorandom pulse generator to trigger various types of events (hardware suggestions only please - no programmable ICs). The events that I want to control need to ...
9
votes
2answers
635 views

Identifying an old RF circuit

I got an old RF circuit (I guess), probably used for pedagogical purposes. Here's the schematic: I chose the positive and ground rails as it seems right to me, looking at transistors and resistor ...
12
votes
7answers
1k views

What kind of capacitor blew up in my old IBM monitor?

I pulled this out of an old IBM 5154 EGA monitor from the 80's. Clearly both are bad (though the monitor itself works anyway...). I know they're capacitors, but what kind? What would a replacement for ...
1
vote
1answer
86 views

Stereo Enhanced Mono

Medium Wave AM in most countries is monophonic. AM stereo was never universally adopted. Given a monophonic signal, how can one create a stereo output? I know there are some 'tricks' you can play on ...
7
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2answers
259 views

1977 GE 6RS20SP9B9 - what the heck is this component?

Ok so, ordinarily I'd not ask a "what is this" question, but this component really has me scratching my head - both at its function in the circuit and how it is constructed. Anyone know what a GE ...
0
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0answers
26 views

Restore or replace an old NiCad battery

I was finally able to buy a used Toshiba T4700CT to play my DOS games. I cleaned it, disassembled it and replaced both the backup battery and CMOS battery, but I have a question regarding the main ...
0
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1answer
34 views

Pearmability Tuning Vs Cap tuning for MW AM

I constructed a wide band Hi Fi TRF tuner for MW AM that sounds great. It used an old 365 pF air spaced 3 gang variable capacitor that had equal sections. Selectivity was marginal at the top of the ...
3
votes
1answer
265 views

Amplify Raspberry Pi Zero W Audio with 60s Tube amplifier circuit

First of all, thank you for taking a look at my question. Electronics is not my field of expertise, and I have found myself a bit stuck. I have been restoring some old 50s and 60s tube amplified ...
0
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1answer
234 views

Tape Deck solenoids

I found an old Tape Deck recorder that I tore apart to scavenge for interesting parts. Two different kinds of solenoids left me wondering: From an old service manual (not related to the tape deck ...
0
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1answer
165 views

Help looking for an 220V AC transformer replacement [closed]

My old Philips MC-M250 stereo transformer has died after a power surge. I can't find spares so I'm looking for some compatible replacement. I found a power board circuit in the service manual. AC is ...
0
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1answer
377 views

Germanium Diode 455KHz AM Detector

Ge Diodes have been used for AM detection many decades before Si Diodes became cheap.They were attractive when compared to the large power hungry valve .Nowdays Si diodes are much cheaper and easier ...
5
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2answers
1k views

What do “cycles” in a capacitor mean?

I'm trying to replace some old leaky capacitors for this radio I'm working on and in the data sheet they have this rating of cycles for the large capacitors near the bottom of the sheet here: What ...
1
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1answer
192 views

how to drive 1930s bakelite headphones

I’ve received a very old pair of mono bakelite headphones that I would like to re-use for demonstration purposes. Just for voice audio and morse code tones. The writings on the side of each headphone:...