UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Success Stories

Notices

Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

Reply
 
Thread Tools
Old 13th Apr 2018, 12:45 pm   #1
vinrads
Octode
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 1,677
Default Hacker Hunter RP38A

This radio was a repair I took on from a forum member. As I suspected both the output transistors and let's call it the driver were s/c, the insulation had melted on the outputs, which suggested to me that it had been run on an external power supply.
Having read up on this module I checked all the resistors, most were found to be way out of spec, so I replaced them all including the two pre sets. Also all the transistors were replaced.

With a 0 to 10ma meter in circuit, there is a convenient link for this purpose, a tweak on the pre set gave the 3 m/a quoted in the circuit then set the mid point. This has a direct effect on the idle current, but a bit of re tweaking got it spot on.

When connecting the amp to the radio I was greeted with a howling noise, not motor boating but a constant tone. I tried all the usual suspects like the five pin plug/socket, re soldered all the earth connections, on off switch high resistance, still the same. I found by reducing the 0.1uf capacitor on the input by half the set worked fine. But I needed to find the cause of the problem, tried linking parts of the print on the audio board, no the fault still persisted. Then I linked the earth on the amp board directly to the chassis of the radio, fault cured. In effect bridging the screen on the screened lead, which of course I had checked for continuity before, so I had spent too long on this at that stage. I soldered the link on the five pin plug, and to the radio chassis.

Then I noticed that the slightly noisy amp had gone very quiet. Did the link cure it, don't know, maybe someone who has the same radio would like to try it. Mick.
vinrads is offline   Reply With Quote
Old 26th Apr 2018, 10:09 am   #2
Hybrid tellies
Nonode
 
Hybrid tellies's Avatar
 
Join Date: Jan 2004
Location: Bristol, UK
Posts: 2,227
Default Re: Hacker Hunter RP38A

This is a common fault on many Hacker radios.
Below is the link to the write up of my Hacker Hunter TP38A repair which has been working perfectly ever since. I hope you find it helpful.

https://www.vintage-radio.net/forum/...d.php?t=111589
__________________
Simon
BVWS member
Hybrid tellies is offline   Reply With Quote
Old 26th Apr 2018, 10:30 am   #3
vinrads
Octode
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 1,677
Default Re: Hacker Hunter RP38A

Thank's for that Simon ,on my set I tried bridging all the earth paths on the audio board no cracks apparent , the fault persisted ,cleaned the plug /socket and re tension , the fault persisted , the cure was to add a separate earth wire soldered in the plug and onto the chassis of the radio section .
This also seemed to cure the slight rustling noise that was there even at min volume . I left well alone at that stage . Mick.
vinrads is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 5:19 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Copyright ©2002 - 2018, Paul Stenning.