Questions tagged [vintage]

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2answers
85 views

Identifying missing component from vintage synthesizer [closed]

I acquired a Hillwood C-1A synthesizer with a burnt circuit board with 3 empty holes where a part needs to go. I'd like to repair the board but I don't know what component to look for... Help? The ...
10
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3answers
2k views

What is this component? 1970s electronics

I broke it while trying to repair a nearby component on a 1970s board. It has two wires at one end that look like they are going to a coil and two axial wires. One of the axial wires came out with ...
0
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0answers
47 views

Need help identifying antique porcelain fuse block

This is an antique 30 amp porcelain fuse block from a house, built before electricity, that was first wired around 1900. I would like to identify the manufacturer and the year of manufacture of this ...
0
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2answers
30 views

Positive Grid current in valves

Vacuum tubes are much more idiotproof than transistors. Grid current does flow during a significant part of the drive cycle in some classes of amplifier operation. Many high power tubes have really ...
0
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1answer
80 views

I need help identifying a vintage battery

I found what looks like an old battery in the middle of nowhere. The plates are thick and soldered by hand. There is a matting between the plates like an AGM or maybe nickel iron battery. It's housed ...
0
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1answer
63 views

Powering an old TI Silent 707 with a missing external AC/AC adapter

I just got my hands on a TI Silent 700 model 707, but it's missing the external power transformer. Unlike similar Silent 700 models, this features an optional battery pack which complicates things ...
2
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2answers
125 views

What is a modern 2sd669 transistor replacement

I have an old Nad 302 integrated amp where one of the 2sd669 transistors is blown. I Cannot find any suggestion on modern replacements. To be honest I am a software engineer and analogue circuits is a ...
-1
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4answers
169 views

Snap in capacitor in place of through hole

I have an old Technics SU-V5 amplifier from 1980. It has through hole capacitors with very thin legs. All new capacitors are snap in and their legs are very thick. They won't fit in the PCB. How ...
7
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3answers
1k views

Can anyone help identify this mystery integrated circuit?

These were in a box belonging to my grandfather. I don't know if it's relevant, but he worked at a navy yard. I'm guessing they're around 50 years old. Nothing comes up on google search. I don't know ...
2
votes
2answers
147 views

Soft errors from SEUs/SETs in early 8-bit microprocessors?

Why is it that soft errors due to single-event upsets/transients never seemed to be a problem in early 8-bit microprocessors, like the MOS 6502 or the Zilog Z80? The microprocessors themselves were ...
2
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0answers
81 views

'P.V.' marking on 1940's electrolytic capacitors

I am replacing the paper and wax capacitors in a tube radio of 1949 vintage. Puzzled by the initials P.V. where I'd expect to read VAC or VDC. Can anyone explain this puzzling jargon? For some reason ...
4
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2answers
356 views

Can this WWII era rheostat be modified to dim an LED bulb?

I have a WWII era RAF chart-board lamp in perfect unused condition. I want to use an LED bulb with the original dimmer as tungsten runs so hot. I want to avoid rewiring or bypassing the dimmer as the ...
0
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2answers
89 views

MRC Variac+ — NEED HELP identifying this antique electronic

I gather, so far, that there is a variac component to this equipment. And that it was manufactured by the MRC Manufacturing Corporation (a Subsidiary of Materials Research Corporation), which once ...
1
vote
1answer
62 views

Need Clarification on Choke Placement (Vintage PS)

I came into possession of an old Electro D-612T variable DC power supply. Based on what I've read here and other places it was manufactured in the 1950s, and sold for a whopping $39.95 US at Radio ...
1
vote
1answer
103 views

How to create an ATX -5 volt rail for vintage Macintosh

I am trying to build a simple adapter for a mini ATX power supply for a vintage mac, I need a 5 volt rail that has it’s own separate ground (+5 volts to -5 volts) how would I go about doing this?
0
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2answers
76 views

Trimming a power supply to 0 V output in current limit

Here is another question on the originally Czech bench power supply that I recently built, but in the version¹ of it sold by various places (e.g. eBay) very cheaply. The circuit has two potentiometers ...
2
votes
0answers
52 views

Appreciate help in identifying this vintage IC - Fairchild HL41109 QB

Trying to find out what this one is has been a real head-scratcher. Google leads me down numerous rabbit-holes to dead ends. And I see 1 or 2 for sale on eBay, but apparently they have no idea what it ...
2
votes
2answers
118 views

How to find a Pin-to-Pin Replacement for TL-081, but with higher VCC? [closed]

After ordering and assembling one of those¹ "red" 0-30V/0-3A power supplies from eBay/AliExpress and taking a bit of a closer look at it, I'd like to replace the TL-081 op-amps. It's working ...
2
votes
2answers
135 views

Converting old relaxation oscillator vacuum tube circuit to a more modern circuit?

I am trying to figure out how to convert an old relaxation oscillator circuit from the late 30's. The history of this circuit, is this is the buzz generator for the Bell Labs Voder, which is a speech ...
2
votes
2answers
107 views

Finding replacement PNP transistors

Hello and I apologise if my first question is rather basic as I am new to electronics. I have started to repair vintage amplifiers and have found transistors that I need to replace are no longer ...
1
vote
1answer
240 views

Can I replace a 101 ceramic capacitor with a close value one?

I'm kind of new to electronics and sorry if this is a bad question. I am trying to repair my father's old radio transmitter and I noticed that the PTT won't pick up your voice. I opened it up and ...
1
vote
1answer
135 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
52 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
votes
1answer
76 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
162 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
votes
2answers
154 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 ...
1
vote
1answer
231 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 (Panasonic ...
1
vote
1answer
339 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
vote
3answers
309 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
vote
2answers
79 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
votes
1answer
116 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
votes
2answers
755 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
votes
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
votes
1answer
56 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
votes
2answers
1k 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
232 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
114 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
votes
3answers
224 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
votes
2answers
251 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
vote
1answer
77 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
votes
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
votes
1answer
145 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
3answers
250 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
vote
1answer
107 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
votes
1answer
207 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
35 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
2k 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
vote
2answers
427 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
votes
1answer
113 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
807 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 ...