1970s Diode identification help!

[Ixlreight]

Hi folks,

I am trying to identify this diode, please see images. It appears to have two green colour bands at one of the diode. It is in amplifier board bias/idle current circuit in a 1971 Hitachi SR700, schematic section included.

The receiver parts list, describes the diode as a HV-26G, same as on the schematic. Can't find any information about this online.

Other issue, idle/bias voltage on one side of amp is nearly impossible to adjust to other channel which Hitachi lists at 20mV plus/minus 2.5mV. The side in question can't go past 11mV. Swaped out differential transistors with no effect, caps were replaced. I suspect one of these old diodes are the issue.

If anyone has insights into these diodes, please share on the thread. I need specs on original to find a suitable match to replace. I could swap out but given their age and frailty, I don't want to chance desolder since the receiver does work.

Thanks,

JD

 

[DesertRatt]

I think they are "signal diodes" - such as 1N4148, 1N914, etc. Very common and sort of generic. I don't want to SWEAR TO IT (LOL), but I think you can trey a generic signal diode without risk of anything bad happening.

 

[MWH901]

I can't swear by the NTE cross-reference search, but the HV-26G crosses to an NTE116, which is basically a 1N4005 general-purpose rectifier.

 

[Brian1970]

Check the forward voltage. If it's germanium it should be around 0.3V instead of 0.6V for a Si diode. I only say that because it kinda looks like a germanium diode but not exactly like the common 1N34 or 1N60.

 

[Ixlreight]

A couple of them in circuit are measurable at 0.652.

 

[Ixlreight]

I can't swear by the NTE cross-reference search, but the HV-26G crosses to an NTE116, which is basically a 1N4005 general-purpose rectifier.

Thank you very much.

 

[Brian1970]

My understanding is for bias compensation diodes, you probably want something faster than a 1N400X. I used 1N4148's for that in the past and they worked. I've never used purpose made stabistors but I'm guessing they'd be a good choice too.

https://digitroncorp.com/getmedia/824DFFAE-F11A-451C-A8DF-65A92EFB02A5/1N4156-2c-1N4157-2c-1N4453-2c-1N4829-2c-1N4830-2c-1N5179-2c-MPD100-MPD400A.aspx?ext=.pdf

 

[JoseHH]

HV-26 are single junction stabistor diodes made by Hitachi (forward voltage reference at 0.68V-0.75V at 30mA). Replacement could be 1N4148 according to the data I found. (see attached).
Some stil available on the auction site. No affiliation whatsoever with that.

 

[Semanon]

Dang! You guys are good. I love this place, and this is one of the reasons.

 

[Ixlreight]

Excellent! Thank you very much!